JP6566313B2 - Display device and light emitting device - Google Patents

Description

  The present disclosure relates to a display device and a light-emitting device, and particularly relates to a display device and a light-emitting device including a light-emitting element having a photoluminescence layer.

  Optical devices such as lighting fixtures, displays, and projectors are required to emit light in a necessary direction in many applications. Photoluminescent materials used in fluorescent lamps, white LEDs and the like emit isotropically. Therefore, such a material is used together with optical components such as a reflector and a lens in order to emit light only in a specific direction. For example, Patent Document 1 discloses an illumination system that secures directivity using a light distribution plate and an auxiliary reflector.

JP 2010-231941 A

  In an optical device, when optical components such as a reflector and a lens are arranged to emit light in a specific direction, it is necessary to increase the size of the optical device itself in order to secure the space. It is desirable to eliminate these optical components or to reduce the size as much as possible.

  The present disclosure provides a light emitting device having a novel structure that utilizes a photoluminescent material.

The display device according to one embodiment of the present disclosure, an excitation light source, a light emitting element, comprising an optical shutter or light guide plate, wherein the light-emitting element includes the first wavelength in the air by receiving excitation Okoshiko is lambda _a And a surface structure formed on at least one surface of the photoluminescence layer and the light-transmitting layer, and the surface structure includes a plurality of convex portions and a plurality of concave portions. And restricts the directivity angle of the first light having _a wavelength in air of λa.

  The generic or specific aspects described above may be implemented by elements, devices, systems, methods, or any combination thereof.

  According to an embodiment of the present disclosure, it is possible to provide a light emitting device having a novel structure using a photoluminescent material.

It is a perspective view which shows the structure of the light emitting element by a certain embodiment. It is a fragmentary sectional view of the light emitting element shown to FIG. 1A. It is a perspective view which shows the structure of the light emitting element by other embodiment. It is a fragmentary sectional view of the light emitting element shown to FIG. 1C. It is a figure which shows the result of having calculated the increase | augmentation intensity | strength of the light radiate | emitted in a front direction, changing the light emission wavelength and the height of a periodic structure, respectively. It is the graph which illustrated the conditions of m = 1 and m = 3 in Formula (10). It is a figure which shows the result of having calculated the increase | augmentation intensity | strength of the light output to a front direction by changing the light emission wavelength and the thickness t of a photo-luminescence layer. It is a figure which shows the result of having calculated the electric field distribution of the mode guided to x direction when thickness t = 238 nm. It is a figure which shows the result of having calculated the electric field distribution of the mode guided to x direction when thickness t = 539 nm. It is a figure which shows the result of having calculated the electric field distribution of the mode guided to x direction when thickness t = 300nm. It is a figure which shows the result of having calculated the light increase intensity | strength about the case where the polarization of light is a TE mode which has an electric field component perpendicular | vertical to ay direction on the same conditions as the calculation of FIG. It is a top view which shows the example of a two-dimensional periodic structure. It is a figure which shows the result of having performed the calculation similar to FIG. 2 regarding the two-dimensional periodic structure. It is a figure which shows the result of having calculated the intensification of the light which changes the light emission wavelength and the refractive index of a periodic structure, and outputs it to a front direction. It is a figure which shows the result at the time of setting the film thickness of a photo-luminescence layer to 1000 nm on the conditions similar to FIG. It is a figure which shows the result of having calculated the increase | augmentation intensity | strength of the light which changes the light emission wavelength and the height of a periodic structure, and outputs it to a front direction. It is a figure which shows the calculation result when the refractive index of a periodic structure is set to _np = 2.0 on the conditions similar to FIG. It is a figure which shows the result of having performed the calculation similar to the calculation shown in FIG. 9, assuming that the polarization of light is a TE mode having an electric field component perpendicular to the y direction. It is a figure which shows the result at the time of changing the refractive index _nwav of a photo-luminescence layer to 1.5 on the conditions similar to the calculation shown in FIG. It is a figure which shows the calculation result at the time of providing the photo-luminescence layer and periodic structure of the same conditions as the calculation shown in FIG. 2 on the transparent substrate whose refractive index is 1.5. It is a graph which illustrated the conditions of Formula (15). It is a figure which shows the structural example of the light-emitting device 200 provided with the light emitting element 100 shown to FIG. 1A and 1B and the light source 180 which makes excitation light inject into the photo-luminescence layer 110. FIG. It is a diagram showing a one-dimensional periodic structure having the x direction of the period p _x. x-direction period p _x, illustrates a two-dimensional periodic structure having a period p _y in the y direction. It is a figure which shows the wavelength dependence of the light absorption factor in the structure of FIG. 17A. It is a figure which shows the wavelength dependence of the light absorption factor in the structure of FIG. 17B. It is a figure which shows an example of a two-dimensional periodic structure. It is a figure which shows the other example of a two-dimensional periodic structure. It is a figure which shows the modification which formed the periodic structure on the transparent substrate. It is a figure which shows the other modification which formed the periodic structure on the transparent substrate. FIG. 19B is a diagram illustrating a result of calculating the enhancement of light output in the front direction by changing the emission wavelength and the period of the periodic structure in the configuration of FIG. 19A. It is a figure which shows the structure which mixed several powdery light emitting element. It is a top view which shows the example which arranged the several periodic structure from which a period differs on the photo-luminescence layer in two dimensions. It is a figure which shows an example of the light emitting element which has the structure where the several photo-luminescence layer 110 in which the uneven structure was formed on the surface was laminated | stacked. FIG. 6 is a cross-sectional view illustrating a configuration example in which a protective layer 150 is provided between a photoluminescence layer 110 and a periodic structure 120. It is a figure which shows the example which formed the periodic structure 120 by processing only a part of photo-luminescence layer 110. FIG. It is a figure which shows the cross-sectional TEM image of the photo-luminescence layer formed on the glass substrate which has a periodic structure. It is a graph which shows the result of having measured the spectrum of the front direction of the emitted light of the light emitting element made as an experiment. FIG. 4 is a diagram showing a situation where a light emitting element that emits TM mode linearly polarized light is rotated about an axis parallel to the line direction of the one-dimensional periodic structure 120 as a rotation axis. It is a graph which shows the result of having measured the angle dependence of the emitted light when rotating the prototype light emitting element as shown to FIG. 27A. It is a graph which shows the result of having calculated the angle dependence of the emitted light when rotating the prototype light emitting element as shown to FIG. 27A. FIG. 4 is a diagram showing a situation where a light emitting element that emits TE mode linearly polarized light is rotated about an axis parallel to the line direction of the one-dimensional periodic structure 120 as a rotation axis. It is a graph which shows the result of having measured the angle dependence of the emitted light when rotating the prototype light emitting element as shown to FIG. 27D. It is a graph which shows the result of having calculated the angle dependence of the emitted light when rotating the prototype light emitting element as shown to FIG. 27D. FIG. 4 is a diagram showing a situation where a light emitting element that emits TE mode linearly polarized light is rotated about an axis perpendicular to the line direction of the one-dimensional periodic structure 120 as a rotation axis. It is a graph which shows the result of having measured the angle dependence of the emitted light when rotating the prototype light emitting element as shown to FIG. 28A. It is a graph which shows the result of having calculated the angle dependence of the emitted light when rotating the prototype light emitting element as shown to FIG. 28A. FIG. 5 is a diagram showing a situation where a light emitting element that emits TM mode linearly polarized light is rotated about an axis perpendicular to the line direction of the one-dimensional periodic structure 120 as a rotation axis. It is a graph which shows the result of having measured the angle dependence of the emitted light when rotating the prototype light emitting element as shown to FIG. 28D. It is a graph which shows the result of having calculated the angle dependence of the emitted light when rotating the prototype light emitting element as shown to FIG. 28D. It is a graph which shows the result of having measured the angle dependence of the emitted light (wavelength 610nm) of the light emitting element made as an experiment. It is a perspective view which shows typically an example of a slab type | mold waveguide. It is a schematic diagram for explaining the relationship between the wavelength of light that receives the light emission enhancement effect and the emission direction in a light emitting device having a periodic structure 120 on the photoluminescence layer. It is a typical top view which shows the example of the structure which arranged the several periodic structure from which the wavelength which shows the light emission enhancing effect differs. It is a typical top view which shows the example of the structure which arranged the some periodic structure from which the direction where the convex part of a one-dimensional periodic structure extends differs. It is a typical top view showing an example of composition which arranged a plurality of two-dimensional periodic structures. It is typical sectional drawing of a light emitting element provided with a micro lens. It is typical sectional drawing of the light emitting element which has several photo-luminescence layer from which light emission wavelengths differ. It is typical sectional drawing of the other light emitting element which has several photo-luminescence layer from which light emission wavelength differs. It is typical sectional drawing which shows an example of the light emitting element which has a diffusion prevention layer (barrier layer) under a photo-luminescence layer. It is typical sectional drawing which shows the other example of the light emitting element which has a diffusion prevention layer (barrier layer) under a photo-luminescence layer. It is typical sectional drawing which shows the other example of the light emitting element which has a diffusion prevention layer (barrier layer) under a photo-luminescence layer. It is typical sectional drawing which shows the other example of the light emitting element which has a diffusion prevention layer (barrier layer) under a photo-luminescence layer. It is typical sectional drawing which shows an example of the light emitting element which has a crystal growth layer (seed layer) under a photo-luminescence layer. It is typical sectional drawing which shows the other example of the light emitting element which has a crystal growth layer (seed layer) under a photo-luminescence layer. It is typical sectional drawing which shows the other example of the light emitting element which has a crystal growth layer (seed layer) under a photo-luminescence layer. It is typical sectional drawing which shows an example of the light emitting element which has a surface protective layer for protecting a periodic structure. It is typical sectional drawing which shows the other example of the light emitting element which has a surface protective layer for protecting a periodic structure. It is typical sectional drawing which shows an example of the light emitting element which has a transparent high heat conductive layer. It is typical sectional drawing which shows the other example of the light emitting element which has a transparent high heat conductive layer. It is typical sectional drawing which shows the other example of the light emitting element which has a transparent high heat conductive layer. It is typical sectional drawing which shows the other example of the light emitting element which has a transparent high heat conductive layer. It is typical sectional drawing which shows an example of the light-emitting device with which the thermal radiation characteristic was improved. It is typical sectional drawing which shows the other example of the light-emitting device by which the thermal radiation characteristic was improved. It is typical sectional drawing which shows the other example of the light-emitting device by which the thermal radiation characteristic was improved. It is typical sectional drawing which shows the other example of the light-emitting device by which the thermal radiation characteristic was improved. It is a schematic cross section which shows an example of the light emitting element which has a high heat conductive member. It is a top view of the light emitting element shown to FIG. 40A. It is a schematic cross section which shows the other example of the light emitting element which has a high heat conductive member. It is a top view of the light emitting element shown to FIG. 40C. It is a schematic diagram which shows the example of arrangement | positioning of the high heat conductive member in the several light emitting element by which it was tiled. FIG. 41B is a plan view of the light emitting element shown in FIG. 41A. It is a schematic diagram which shows the example of a light-emitting device provided with an interlock circuit. It is a schematic diagram which shows the structure of a light-emitting device provided with an interlock circuit. It is a 1st figure for demonstrating the formation method of the submicron structure using a bead. It is the 2nd figure for demonstrating the formation method of the submicron structure using bead. It is a figure which shows typically an example of the filling state of a bead, and the figure which shows the pattern of the light scattering obtained from the bead of this filling state. It is a figure which shows typically the other example of the filling state of a bead, and the figure which shows the pattern of the light scattering obtained from the bead of this filling state. It is a figure which shows typically the other example of the filling state of a bead, and the figure which shows the pattern of the light scattering obtained from the bead of this filling state. It is a figure which shows typically the other example of the filling state of a bead, and the figure which shows the pattern of the light scattering obtained from the bead of this filling state. It is a perspective view which shows typically the display apparatus in a certain embodiment. It is sectional drawing which shows typically the structure of the display apparatus 300a which has the optical shutter 350 implement | achieved by the liquid crystal module. It is a model perspective view which shows an example of the display apparatus 300b further provided with the touch screen 370. FIG. FIG. 6 is a schematic cross-sectional view showing a part of the configuration of a display device 300c in which a light guide plate 330 is arranged to propagate excitation light from an excitation light source 310 to a photoluminescence layer 321. It is a model perspective view which shows other embodiment of a display apparatus. It is a schematic cross section which shows a part of other embodiment of a display apparatus. It is a perspective view which shows typically the illuminating device in a certain embodiment. It is a fragmentary sectional view which shows typically the illuminating device in other embodiment. It is sectional drawing which shows typically the illuminating device in other embodiment. It is sectional drawing which shows the structural example of the illuminating device which has a some light emitting element. It is a figure which shows schematic structure of the illuminating device (headlight) in which light distribution control by a micromirror is possible. It is a figure which simplifies and shows an example of the light-emitting device which has a rotation mechanism and a wheel-shaped light emitting element. It is a figure which shows the structure at the time of seeing the light emitting element 320 from an axial direction. It is a figure which shows an example of the visible light communication system of this indication. It is a schematic diagram which shows the structure of a transparent display provided with the light emitting element of this indication as a screen. It is a figure which shows the example of application to a traffic signal. It is a figure which shows the more detailed structure of a traffic light. It is a figure which shows the example of application to the light source device for plants. It is a figure which shows the example of application to a distance sensor. It is a figure which shows schematic structure of the light-emitting device in a distance sensor. 6 is a diagram for explaining generation of pulsed light by a control circuit 820. FIG. It is a figure which shows an example of the time change of a drive signal and a light reception signal. FIG. 10 is a view showing a modification in which an optical shutter 850 is disposed on the light emitting side of the light emitting element 840. It is a figure for demonstrating generation | occurrence | production of the pulsed light in the structure shown to FIG. 64A. 6 is a diagram illustrating an example in which lenses 860a and 860b are provided between the light emitting element 840 and the optical shutter 850 and on the light emission side of the optical shutter 850. It is typical sectional drawing which shows an example of the surface structure which has at least one of a some convex part and a some recessed part.

[1. Outline of Embodiment of Present Disclosure]
The present disclosure includes a light-emitting element, a light-emitting device, a display device, a traffic light, a plant light-emitting device, and a distance sensor described in the following items.

[Item 1]
A photoluminescence layer;
A translucent layer disposed proximate to the photoluminescence layer;
A submicron structure formed on at least one of the photoluminescence layer and the light transmissive layer and extending in the plane of the photoluminescence layer or the light transmissive layer,
The submicron structure includes a plurality of convex portions or a plurality of concave portions,
The light emitted by the photoluminescence layer includes first light having _a wavelength λ _a in the air,
When the distance between adjacent convex portions or concave portions is D _int and the refractive index of the photoluminescence layer with respect to the first light is n _wav-a , λ _a / n _wav-a <D _int <λ _a A light-emitting element in which the relationship is established.

[Item 2]
The submicron structures, the comprising a plurality of at least one periodic structure formed by the projections or the plurality of recesses, said at least one periodic structure, when the period as _{p a, λ a / n wav} -a <p _a <lambda relationship _a comprises a first periodic structure holds the light-emitting device according to claim 1.

[Item 3]
Item 3. The light-emitting element according to Item 1 or 2, wherein a refractive index n _ta of the light transmitting layer with respect to the first light is smaller than _a refractive index n _{wav-a of the} photoluminescence layer with respect to the first light.

[Item 4]
The light emitting device according to any one of items 1 to 3, wherein the first light has a maximum intensity in a first direction predetermined by the submicron structure.

[Item 5]
Item 5. The light-emitting element according to Item 4, wherein the first direction is a normal direction of the photoluminescence layer.

[Item 6]
Item 6. The light-emitting element according to Item 4 or 5, wherein the first light emitted in the first direction is linearly polarized light.

[Item 7]
7. The light emitting element according to any one of items 4 to 6, wherein a directivity angle when the first light is based on the first direction is less than 15 °.

[Item 8]
The second light having a wavelength λ _b different from the wavelength λ _{a of} the first light has a maximum intensity in a second direction different from the first direction, according to any one of items 4 to 7 Light emitting element.

[Item 9]
Item 9. The light emitting device according to any one of items 1 to 8, wherein the light transmitting layer has the submicron structure.

[Item 10]
10. The light emitting device according to any one of items 1 to 9, wherein the photoluminescence layer has the submicron structure.

[Item 11]
The photoluminescence layer has a flat main surface,
9. The light emitting device according to any one of items 1 to 8, wherein the light transmitting layer is formed on the flat main surface of the photoluminescence layer and has the submicron structure.

[Item 12]
Item 12. The light emitting device according to Item 11, wherein the photoluminescence layer is supported on a transparent substrate.

[Item 13]
The translucent layer is a transparent substrate having the submicron structure on one main surface,
9. The light emitting device according to any one of items 1 to 8, wherein the photoluminescence layer is formed on the submicron structure.

[Item 14]
The refractive index n _ta of the translucent layer with respect to the first light is equal to or higher than the refractive index n _{wav-a of the} photoluminescence layer with respect to the first light, and the plurality of convex portions of the submicron structure Item 3. The light emitting device according to Item 1 or 2, wherein the height of each of the plurality of recesses is 150 nm or less.

[Item 15]
The submicron structures, the comprising a plurality of at least one periodic structure formed by the projections or the plurality of recesses, said at least one periodic structure, when the period as _{p a, λ a / n wav} -a <include p _a <lambda first periodic structure relationship holds for _a,
Item 15. The light-emitting element according to any one of Items 1 and 3 to 14, wherein the first periodic structure is a one-dimensional periodic structure.

[Item 16]
The light emitted from the photoluminescence layer includes second light having _a wavelength λ _b different from λ _a in the air, and the refractive index of the photoluminescence layer with respect to the second light is n _wav-b .
Wherein at least one of the periodic structure, when the period as p _b, further comprising a _{λ b / n wav-b <} p b <λ b second periodic structure relationship holds for,
Item 16. The light-emitting element according to Item 15, wherein the second periodic structure is a one-dimensional periodic structure.

[Item 17]
The submicron structure includes at least two periodic structures formed by the plurality of convex portions or the plurality of concave portions, and the at least two periodic structures include a two-dimensional periodic structure having periodicity in different directions. The light emitting device according to any one of items 1 and 3 to 14.

[Item 18]
The submicron structure includes a plurality of periodic structures formed by the plurality of convex portions or the plurality of concave portions,
Item 15. The light-emitting element according to any one of Items 1 and 3 to 14, wherein the plurality of periodic structures include a plurality of periodic structures arranged in a matrix.

[Item 19]
The submicron structure includes a plurality of periodic structures formed by the plurality of convex portions or the plurality of concave portions,
When the wavelength of the excitation light of the photoluminescence material of the photoluminescence layer in air is λ _ex and the refractive index of the photoluminescence layer with respect to the excitation light is n _wav-ex ,
Item 15. The light-emitting element according to any one of Items 1 and 3 to 14, wherein the plurality of periodic structures include a periodic structure in which a period p _ex satisfies a relationship of λ _ex / n _wav-ex <p _ex <λ _ex .

[Item 20]
Having a plurality of photoluminescence layers and a plurality of light-transmitting layers;
20. At least two of the plurality of photoluminescence layers and at least two of the plurality of light transmission layers respectively independently correspond to the photoluminescence layer and the light transmission layer according to any one of items 1 to 19, respectively. , Light emitting element.

[Item 21]
Item 21. The light-emitting element according to Item 20, wherein the plurality of photoluminescence layers and the plurality of light-transmitting layers are laminated.

[Item 22]
A photoluminescence layer;
A translucent layer disposed proximate to the photoluminescence layer;
A submicron structure formed on at least one of the photoluminescence layer and the light transmissive layer and extending in the plane of the photoluminescence layer or the light transmissive layer,
The light emitting element which radiate | emits the light which forms a pseudo waveguide mode inside the said photo-luminescence layer and the said translucent layer.

[Item 23]
A waveguiding layer through which light can be guided;
A periodic structure disposed in proximity to the waveguide layer;
The waveguiding layer comprises a photoluminescent material;
The light emitting device, wherein the waveguide layer has a pseudo waveguide mode in which light emitted from the photoluminescent material is guided while acting on the periodic structure.

[Item 24]
A photoluminescence layer;
A translucent layer disposed proximate to the photoluminescence layer;
A submicron structure formed on at least one of the photoluminescence layer and the light transmissive layer and extending in the plane of the photoluminescence layer or the light transmissive layer,
The submicron structure includes a plurality of convex portions or a plurality of concave portions,
The distance between adjacent convex portions or concave portions is D _int , the wavelength of the excitation light of the photoluminescence material of the photoluminescence layer in air is λ _ex, and the photoluminescence layer or the translucent layer for the excitation light A light _- emitting element in which the relationship of λ _ex / n _wav-ex <D _int <λ _ex is established, where n _wav-ex is the refractive index of the medium having the largest refractive index among the media existing in the optical path leading to.

[Item 25]
The submicron structures, the comprising a plurality of at least one periodic structure formed by the projections or the plurality of recesses, said at least one periodic structure, when the period as _{p ex, λ ex / n wav} -ex Item 25. The light-emitting element according to Item 24, including a first periodic structure in which a relationship of < _pex < _λex is satisfied.

[Item 26]
A translucent layer;
A submicron structure formed in the light transmissive layer and extending in a plane of the light transmissive layer;
A photoluminescence layer disposed proximate to the submicron structure;
The submicron structure includes a plurality of convex portions or a plurality of concave portions,
The light emitted by the photoluminescence layer includes first light having _a wavelength λ _a in the air,
The submicron structure includes at least one periodic structure formed by the plurality of convex portions or the plurality of concave portions,
The refractive index of the photoluminescence layer for said first light and n _wav-a, wherein when the period of at least one periodic structure and p _a, the relationship _{λ a / n wav-a <} p a <λ a A light-emitting element that holds.

[Item 27]
A photoluminescence layer;
A translucent layer having a higher refractive index than the photoluminescent layer;
A submicron structure formed in the light-transmitting layer and extending in the plane of the light-transmitting layer;
The submicron structure includes a plurality of convex portions or a plurality of concave portions,
The light emitted by the photoluminescence layer includes first light having _a wavelength λ _a in the air,
The submicron structure includes at least one periodic structure formed by the plurality of convex portions or the plurality of concave portions,
The refractive index of the photoluminescence layer for said first light and n _wav-a, wherein when the period of at least one periodic structure and p _a, the relationship _{λ a / n wav-a <} p a <λ a A light-emitting element that holds.

[Item 28]
A photoluminescence layer;
A submicron structure formed in the photoluminescence layer and extending in the plane of the photoluminescence layer,
The submicron structure includes a plurality of convex portions or a plurality of concave portions,
The light emitted by the photoluminescence layer includes first light having _a wavelength λ _a in the air,
The submicron structure includes at least one periodic structure formed by the plurality of convex portions or the plurality of concave portions,
The refractive index of the photoluminescence layer for said first light and n _wav-a, wherein when the period of at least one periodic structure and p _a, the relationship _{λ a / n wav-a <} p a <λ a A light-emitting element that holds.

[Item 29]
29. The light emitting device according to any one of items 1 to 21, and 24 to 28, wherein the submicron structure includes both the plurality of convex portions and the plurality of concave portions.

[Item 30]
28. The light emitting device according to any one of items 1 to 22, and 24 to 27, wherein the photoluminescence layer and the light transmitting layer are in contact with each other.

[Item 31]
Item 24. The light emitting device according to Item 23, wherein the waveguide layer and the periodic structure are in contact with each other.

[Item 32]
The light emitting device according to any one of items 1 to 31,
An excitation light source that irradiates the photoluminescence layer with excitation light;
A light emitting device comprising:

[Item 33]
An excitation light source;
A light emitting element located on an optical path of excitation light from the excitation light source;
An optical shutter positioned on an optical path of light from the light emitting element,
The light emitting element is
A photoluminescence layer that receives the excitation light and emits light including first light having _a wavelength of λ _{a in} air;
A translucent layer disposed proximate to the photoluminescence layer;
A surface structure formed on at least one surface of the photoluminescence layer and the translucent layer, and
The surface structure includes at least one of a plurality of convex portions and a plurality of concave portions, and restricts a directivity angle of the first light having _a wavelength in air of λa.
Display device.

[Item 34]
Item 34. The display device according to Item 33, wherein the photoluminescence layer and the light transmitting layer are in contact with each other.

[Item 35]
An excitation light source;
A light emitting element located on an optical path of excitation light from the excitation light source;
An optical shutter positioned on an optical path of light from the light emitting element,
The light emitting element is
A photoluminescence layer that receives the excitation light and emits light including first light having _a wavelength of λ _{a in} air;
A surface structure provided on the surface of the photoluminescence layer,
The surface structure includes at least one of a plurality of convex portions and a plurality of concave portions, and restricts a directivity angle of the first light having _a wavelength in air of λa.
Display device.

[Item 36]
If the distance between the centers of two adjacent convex portions or two adjacent concave portions in the surface structure is D _int and the refractive index of the photoluminescence layer with respect to the first light is n _wav-a , λ _a / n The display device according to any one of items 33 to 35, wherein _a relationship of _wav-a < _Dint <λa is established.

[Item 37]
The item according to any one of items 33 to 36, further comprising a color filter array including a plurality of color filters having different transmission wavelength bands on a side where light from the light emitting element is incident or a side where the light is emitted in the optical shutter. Display device.

[Item 38]
38. The display device according to any of items 33 to 37, further comprising a light guide plate that propagates light from the light emitting element to the optical shutter.

[Item 39]
The display device according to any one of items 33 to 37, further comprising a light guide plate for propagating the excitation light from the excitation light source to the photoluminescence layer.

[Item 40]
40. The display device according to any one of items 33 to 39, further comprising a drive circuit that drives the optical shutter according to an image signal.

[Item 41]
Item 41. The display device according to Item 40, further comprising a touch screen on a side where light from the light emitting element is emitted in the optical shutter.

[Item 42]
The surface structure comprises at least one periodic structure, wherein the at least one periodic structure, when the period as p _a, a _{λ a / n wav-a <} p a <λ first periodic structure relationship holds for _a Including,
Item 42. The display device according to any one of items 33 to 41.

[Item 43]
The light emitted from the photoluminescence layer includes second light having _a wavelength λ _b different from λ _a in the air, and the refractive index of the photoluminescence layer with respect to the second light is n _wav-b ,
Wherein at least one of the periodic structure, when the period as p _b, further comprising a _{λ b / n wav-b <} p b <λ b second periodic structure relationship holds for,
The wavelength λ _a belongs to the red wavelength band,
The wavelength λ _b belongs to the green wavelength band,
Item 43. The display device according to Item 42.

[Item 44]
When the refractive index of the photoluminescence layer for the third light having a wavelength λ _c different from λ _a and λ _b in the air is n _wav-c ,
Wherein at least one of the periodic structure, when the period as p _c, further comprises a third periodic structure relationship holds for _{λ c / n wav-c <} p c <λ c,
The wavelength λ _c belongs to the blue wavelength band,
Item 44. The display device according to Item 43.

[Item 45]
Item 45. The display device according to Item 43 or 44, wherein the excitation light source emits light in a blue wavelength band.

[Item 46]
An excitation light source;
A light emitting element located on an optical path of excitation light from the excitation light source;
A light guide plate arranged to take in light from the light emitting element and emit it to the outside,
The light emitting element is
A photoluminescence layer that receives the excitation light and emits light including first light having _a wavelength of λ _{a in} air;
A translucent layer disposed proximate to the photoluminescence layer;
A surface structure formed on at least one surface of the photoluminescence layer and the translucent layer, and
The surface structure includes at least one of a plurality of convex portions and a plurality of concave portions, and restricts a directivity angle of the first light having _a wavelength in air of λa.
Light emitting device.

[Item 47]
An excitation light source;
A light guide plate arranged to take in the excitation light from the excitation light source and emit it to the outside;
A light emitting element located on the optical path of the excitation light emitted from the light guide plate,
The light emitting element is
A photoluminescence layer that receives the excitation light and emits light including first light having _a wavelength of λ _{a in} air;
A translucent layer disposed proximate to the photoluminescence layer;
A surface structure formed on at least one surface of the photoluminescence layer and the translucent layer, and
The surface structure includes at least one of a plurality of convex portions and a plurality of concave portions, and restricts a directivity angle of the first light having _a wavelength in air of λa.
Light emitting device.

[Item 48]
48. The light-emitting device according to item 46 or 47, wherein the photoluminescence layer and the translucent layer are in contact with each other.

[Item 49]
An excitation light source;
A light emitting element located on an optical path of excitation light from the excitation light source;
A light guide plate arranged to take in light from the light emitting element and emit it to the outside,
The light emitting element is
A photoluminescence layer that receives the excitation light and emits light including first light having _a wavelength of λ _{a in} air;
A surface structure formed on the surface of the photoluminescence layer,
The surface structure includes at least one of a plurality of convex portions and a plurality of concave portions, and restricts a directivity angle of the first light having _a wavelength in air of λa.
Light emitting device.

[Item 50]
An excitation light source;
A light guide plate arranged to take in the excitation light from the excitation light source and emit it to the outside;
A light emitting element located on the optical path of the excitation light emitted from the light guide plate,
The light emitting element is
A photoluminescence layer that receives the excitation light and emits light including first light having _a wavelength of λ _{a in} air;
A surface structure formed on the surface of the photoluminescence layer,
The surface structure includes at least one of a plurality of convex portions and a plurality of concave portions, and restricts a directivity angle of the first light having _a wavelength in air of λa.
Light emitting device.

[Item 51]
If the distance between the centers of two adjacent convex portions or two adjacent concave portions in the surface structure is D _int and the refractive index of the photoluminescence layer with respect to the first light is n _wav-a , λ _a / n _51. The light emitting device according to any one of items 46 to 50, wherein _a relationship of _wav-a <D _int <λa is established.

[Item 52]
The surface structure comprises at least one periodic structure, wherein the at least one periodic structure, when the period as p _a, a _{λ a / n wav-a <} p a <λ first periodic structure relationship holds for _a Including,
Item 52. The light emitting device according to any one of Items 46 to 51.

[Item 53]
The light emitted from the photoluminescence layer includes second light having _a wavelength λ _b different from λ _a in the air, and the refractive index of the photoluminescence layer with respect to the second light is n _wav-b ,
Wherein at least one of the periodic structure, when the period as p _b, further comprising a _{λ b / n wav-b <} p b <λ b second periodic structure relationship holds for,
The wavelength λ _a belongs to the red wavelength band,
The wavelength λ _b belongs to the green wavelength band,
Item 53. The light emitting device according to Item 52.

[Item 54]
When the refractive index of the photoluminescence layer for the third light having a wavelength λ _c different from λ _a and λ _b in the air is n _wav-c ,
Wherein at least one of the periodic structure, when the period as p _c, further comprises a third periodic structure relationship holds for _{λ c / n wav-c <} p c <λ c,
The wavelength λ _c belongs to a blue or yellow wavelength band,
Item 54. The light emitting device according to Item 53.

[Item 55]
Item 55. The light emitting device according to Item 53 or 54, wherein the excitation light source emits light in a blue wavelength band.

[Item 56]
Item 54, a light-emitting device according to item 4 , and
A housing for housing the light emitting device;
With
The wavelength λ _c belongs to a yellow wavelength band,
traffic lights.

[Item 57]
An excitation light source;
A light emitting element located on an optical path of excitation light from the excitation light source;
An optical shutter positioned on an optical path of light from the light emitting element,
The light emitting element is
A translucent layer;
A surface structure formed on the surface of the light-transmitting layer and including at least one of a plurality of convex portions and a plurality of concave portions;
A photoluminescence layer that is disposed in proximity to the surface structure and emits light including first light having _a wavelength of λ _a in the air upon receiving the excitation light;
The surface structure limits a directivity angle of the first light having _a wavelength λ _{a in} the air;
Display device.

[Item 58]
An excitation light source;
A light emitting element located on an optical path of excitation light from the excitation light source;
An optical shutter positioned on an optical path of light from the light emitting element,
The light emitting element is
A photoluminescence layer that receives the excitation light and emits light including first light having _a wavelength of λ _{a in} air;
A translucent layer having a higher refractive index than the photoluminescent layer;
A surface structure formed on the surface of the translucent layer and including at least one of a plurality of convex portions and a plurality of concave portions, and
The surface structure limits a directivity angle of the first light having _a wavelength λ _{a in} the air;
Display device.

[Item 59]
59. A display device according to item 57 or 58, wherein the photoluminescence layer and the translucent layer are in contact with each other.

[Item 60]
If the distance between the centers of two adjacent convex portions or two adjacent concave portions in the surface structure is D _int and the refractive index of the photoluminescence layer with respect to the first light is n _wav-a , λ _a / n The display device according to any one of items 57 to 59, wherein _a relationship of _wav-a < _Dint <λa is established.

[Item 61]
The surface structure comprises at least one periodic structure, wherein the at least one periodic structure, when the period as p _a, a _{λ a / n wav-a <} p a <λ first periodic structure relationship holds for _a Including,
Item 60. The display device according to any one of Items 57 to 59.

[Item 62]
An excitation light source;
A light emitting element located on an optical path of excitation light from the excitation light source;
A light guide plate arranged to take in light from the light emitting element and emit it to the outside,
The light emitting element is
A translucent layer;
A surface structure formed on the surface of the light-transmitting layer and including at least one of a plurality of convex portions and a plurality of concave portions;
A photoluminescence layer that is disposed in proximity to the surface structure and emits light including first light having _a wavelength of λ _a in the air upon receiving the excitation light;
The surface structure limits a directivity angle of the first light having _a wavelength λ _{a in} the air;
Light emitting device.

[Item 63]
An excitation light source;
A light emitting element located on an optical path of excitation light from the excitation light source;
A light guide plate arranged to take in light from the light emitting element and emit it to the outside,
The light emitting element is
A photoluminescence layer that receives the excitation light and emits light including first light having _a wavelength of λ _{a in} air;
A translucent layer having a higher refractive index than the photoluminescent layer;
A surface structure formed on the surface of the translucent layer and including at least one of a plurality of convex portions and a plurality of concave portions, and
The surface structure limits a directivity angle of the first light having _a wavelength λ _{a in} the air;
Light emitting device.

[Item 64]
An excitation light source;
A light guide plate arranged to take in the excitation light from the excitation light source and emit it to the outside;
A light emitting element located on the optical path of the excitation light emitted from the light guide plate,
The light emitting element is
A translucent layer;
A surface structure formed on the surface of the light-transmitting layer and including at least one of a plurality of convex portions and a plurality of concave portions;
A photoluminescence layer that is disposed in proximity to the surface structure and emits light including first light having _a wavelength of λ _a in the air upon receiving the excitation light;
The surface structure limits a directivity angle of the first light having _a wavelength λ _{a in} the air;
Light emitting device.

[Item 65]
An excitation light source;
A light guide plate arranged to take in the excitation light from the excitation light source and emit it to the outside;
A light emitting element located on the optical path of the excitation light emitted from the light guide plate,
The light emitting element is
A photoluminescence layer that receives the excitation light and emits light including first light having _a wavelength of λ _{a in} air;
A translucent layer having a higher refractive index than the photoluminescent layer;
A surface structure formed on the surface of the translucent layer and including at least one of a plurality of convex portions and a plurality of concave portions, and
The surface structure limits a directivity angle of the first light having _a wavelength λ _{a in} the air;
Light emitting device.

[Item 66]
66. The light emitting device according to any one of items 62 to 65, wherein the photoluminescence layer and the translucent layer are in contact with each other.

[Item 67]
An excitation light source;
A light emitting element located on an optical path of excitation light from the excitation light source;
A reflection mirror located on the optical path of the light from the light emitting element,
The light emitting element is
A photoluminescence layer that receives the excitation light and emits light including first light having _a wavelength of λ _{a in} air;
A translucent layer disposed proximate to the photoluminescence layer;
A surface structure formed on at least one surface of the photoluminescence layer and the translucent layer, and
The surface structure includes at least one of a plurality of convex portions and a plurality of concave portions, and restricts a directivity angle of the first light having _a wavelength in air of λa.
Light emitting device.

[Item 68]
An excitation light source;
A micromirror located on the optical path of the excitation light from the excitation light source;
A light emitting element positioned on the optical path of the excitation light reflected by the micromirror,
The light emitting element is
A photoluminescence layer that receives the excitation light and emits light including first light having _a wavelength of λ _{a in} air;
A translucent layer disposed proximate to the photoluminescence layer;
A surface structure formed on at least one surface of the photoluminescence layer and the translucent layer, and
The surface structure includes at least one of a plurality of convex portions and a plurality of concave portions, and restricts a directivity angle of the first light having _a wavelength in air of λa.
Light emitting device.

[Item 69]
If the distance between the centers of two adjacent convex portions or two adjacent concave portions in the surface structure is D _int and the refractive index of the photoluminescence layer with respect to the first light is n _wav-a , λ _a / n _69. The light emitting device according to any one of items 62 to 68, wherein _a relationship of _wav-a < _Dint <λa is established.

[Item 70]
The surface structure comprises at least one periodic structure, wherein the at least one periodic structure, when the period as p _a, a _{λ a / n wav-a <} p a <λ first periodic structure relationship holds for _a Including,
Item 69. The light emitting device according to any one of Items 62 to 68.

[Item 71]
An excitation light source;
A light emitting element located on an optical path of excitation light from the excitation light source;
A mechanism for rotating the light emitting element,
The light emitting element is
A central portion coupled to the mechanism;
First to third regions located around the central portion,
Each of the first and second regions is
A photoluminescence layer that emits light by the excitation light;
A translucent layer disposed proximate to the photoluminescence layer;
And at least one periodic structure formed on at least one of the photoluminescence layer and the translucent layer,
The periodic structure includes at least one of a plurality of convex portions and a plurality of concave portions,
The light emitted from the photoluminescence layer in the first region includes first light having _a wavelength λ _a in the air, and the distance between adjacent convex portions or concave portions in the first region is _expressed as D _{int− a} and the refractive index of the photoluminescence layer with respect to the first light is n _wav-a , the relationship of λ _a / n _wav-a <D _int-a <λ _a holds.
The light emitted from the photoluminescence layer in the second region includes second light having a wavelength λ _b in the air, and the distance between adjacent convex portions or concave portions in the second region is _expressed as D _{int−. b} and the refractive index of the photoluminescence layer with respect to the second light is n _wav-b , the relationship of λ _b / n _wav-b <D _int-b <λ _b holds,
The third region is a transparent region;
The excitation light source sequentially enters the excitation light into the first to third regions when the mechanism rotates the light emitting element.
Lighting device.

[Item 72]
The wavelength λ _a is included in the red wavelength band,
The wavelength λ _b is included in the green wavelength band,
The excitation light emits light in a blue wavelength band.
72. The lighting device according to item 71.

[Item 73]
A photoluminescent layer having first to third light emitting regions arranged in a row;
A translucent layer disposed proximate to the photoluminescence layer;
A surface structure formed on at least one surface of the photoluminescence layer and the translucent layer and including at least one of a plurality of convex portions and a plurality of concave portions;
Have
The first light emitting region receives excitation light and generates first light having _a wavelength λ _a in the air,
The second light emitting region receives excitation light and generates second light having a wavelength λ _b in the air,
The third light emitting region receives excitation light and generates third light having a wavelength λ _c in the air,
The surface structure limits a directivity angle of the first light generated from the first light emission region and a directivity angle of the second light generated from the second light emission region. And a third part for limiting a directivity angle of the third light generated from the third light emitting region, and
The wavelength λ _a is included in the red wavelength band,
The wavelength λ _b is included in the green wavelength band,
The wavelength λ _c is included in the yellow wavelength band,
traffic lights.

[Item 74]
A photoluminescent layer having first and second light emitting regions arranged in a row;
A translucent layer disposed proximate to the photoluminescence layer;
A surface structure formed on at least one surface of the photoluminescence layer and the translucent layer and including at least one of a plurality of convex portions and a plurality of concave portions;
Have
The first light emitting region receives excitation light and generates first light having _a wavelength λ _a in the air,
The second light emitting region receives excitation light and generates second light having a wavelength λ _b in the air,
The surface structure limits a directivity angle of the first light generated from the first light emission region and a directivity angle of the second light generated from the second light emission region. A second part to be
The wavelength λ _a is included in the red wavelength band,
The wavelength λ _b is included in the green wavelength band.
traffic lights.

[Item 75]
A mounting table for mounting plants;
A light emitting element that emits light toward the plant;
With
The light emitting element is
A photoluminescence layer that emits light having _a wavelength λ _{a in} air;
A translucent layer disposed proximate to the photoluminescence layer;
A surface structure formed on at least one surface of the photoluminescence layer and the light-transmitting layer, including at least one of a plurality of convex portions and a plurality of concave portions, and directing the light having _a wavelength of λ _{a in} the air A surface structure that limits the corners;
Having
Light emitting device for plants.

[Item 76]
A mounting table for mounting plants;
A first light emitting element that emits a first light toward the plant;
A second light emitting element that emits second light toward the plant;
With
The first light emitting element includes:
A first photoluminescence layer emitting light having _a wavelength λ _{a in} air;
A first light transmissive layer disposed proximate to the first photoluminescence layer;
A first surface structure formed on at least one surface of the first photoluminescence layer and the first light-transmitting layer, including at least one of a plurality of first protrusions and a plurality of first recesses. A first surface structure that limits a directivity angle of the light having _a wavelength λ _a in the air;
Have
The second light emitting element is:
A second photoluminescence layer that emits light having _a wavelength λ _b different from λ _{a in} air;
A second light transmissive layer disposed proximate to the second photoluminescence layer;
A second surface structure formed on at least one surface of the second photoluminescence layer and the second light-transmitting layer, including at least one of a plurality of second convex portions and a plurality of second concave portions. A second surface structure that limits a directivity angle of the light having a wavelength of λ _b in the air;
Having
Light emitting device for plants.

[Item 77]
A light emitting device;
An image sensor,
A control circuit for controlling the light emitting device and the image sensor;
With
The light emitting device
A photoluminescence layer that emits light having _a wavelength λ _{a in} air;
A translucent layer disposed proximate to the photoluminescence layer;
A surface structure formed on at least one surface of the photoluminescence layer and the light-transmitting layer, including at least one of a plurality of convex portions and a plurality of concave portions, and directing the light having _a wavelength of λ _{a in} the air A surface structure that limits the corners;
Have
Wherein the control circuit, while emitting pulse light in the wavelength band including the wavelength lambda _a to the light emitting device, the image sensor is captured, and the pulsed light emitted from the light emitting device, the pulsed light object Detecting a distance to the object based on a phase difference between the light reflected by the image sensor and detected by the image sensor;
Distance sensor.

[Item 78]
The distance sensor according to Item 77, wherein the wavelength λ _a belongs to a wavelength band of near infrared rays.

A light emitting device according to an embodiment of the present disclosure includes a photoluminescence layer that receives the excitation light and emits light having _a wavelength of λa in the air, a translucent layer disposed in proximity to the photoluminescence layer, and the photoluminescence layer. A surface structure including at least one of a plurality of protrusions and a plurality of recesses formed on at least one surface of the luminescence layer and the light-transmitting layer, and the surface structure is in the air emitted by the photoluminescence layer Restricts the directivity angle of the light whose wavelength is λ _a . The wavelength λ _a is, for example, in the wavelength range of visible light (for example, 380 nm to 780 nm). In applications that use infrared, the wavelength λ _a may exceed 780 nm. On the other hand, in applications using ultraviolet light, the wavelength λ _a may be less than 380 nm.
In this disclosure, electromagnetic waves in general including infrared rays and ultraviolet rays are expressed as “light” for convenience.

  The photoluminescent layer includes a photoluminescent material. The photoluminescent material means a material that emits light upon receiving excitation light. The photoluminescent material includes a fluorescent material and a phosphorescent material in a narrow sense, includes not only an inorganic material but also an organic material (for example, a dye), and further includes a quantum dot (that is, a semiconductor fine particle). The photoluminescent layer may include a matrix material (ie, host material) in addition to the photoluminescent material. The matrix material is, for example, an inorganic material such as glass or oxide, or a resin.

  The light-transmitting layer disposed in the vicinity of the photoluminescence layer is formed of a material having a high transmittance with respect to light emitted from the photoluminescence layer, for example, an inorganic material or a resin. The light transmitting layer can be formed of, for example, a dielectric (particularly, an insulator that absorbs little light). The light transmissive layer may be, for example, a substrate that supports the photoluminescence layer. When the air-side surface of the photoluminescence layer has a submicron structure, the air layer can be a light-transmitting layer.

  A surface structure including at least one of a plurality of convex portions and a plurality of concave portions is formed on at least one surface of the photoluminescence layer and the light transmitting layer. Here, the “surface” means a portion in contact with another substance (that is, an interface). When the light-transmitting layer is a gas layer such as air, the interface between the gas layer and another substance (for example, a photoluminescence layer) is the surface of the light-transmitting layer. This surface structure can also be referred to as an “uneven structure”. The surface structure typically includes a portion in which a plurality of convex portions or a plurality of concave portions are periodically arranged in one or two dimensions. Such a surface structure can be referred to as a “periodic structure”. The plurality of convex portions and the plurality of concave portions are formed at the boundary between two members (or media) having different refractive indexes that are in contact with each other. Therefore, it can be said that the “periodic structure” includes a portion in which the refractive index periodically varies in a certain direction. Here, the term “periodic” is not limited to an aspect that is strictly periodic, but includes an aspect that can be said to be approximately periodic. In this specification, among a plurality of continuous convex portions or concave portions, a distance between two adjacent centers (hereinafter sometimes referred to as “center interval”) is any two adjacent convex portions or concave portions. Is also considered to be a periodic structure having a period p when it falls within a range of ± 15% of a certain value p.

  In the present specification, the “convex portion” means a raised portion with respect to a reference height portion. The “recessed portion” means a recessed portion with respect to a reference height portion. Depending on the shape, size, and distribution of the convex and concave portions, it may not be easy to determine which is the convex portion and which is the concave portion. For example, in the cross-sectional view shown in FIG. 65, it can be interpreted that the member 610 has a concave portion and the member 620 has a convex portion, or vice versa. Whatever the interpretation, it can be said that each of the member 610 and the member 620 has at least one of a plurality of convex portions and concave portions.

The distance between the centers of two adjacent convex portions or two adjacent concave portions in the surface structure (period p in the periodic structure) is typically shorter than the wavelength λ _a of the light emitted from the photoluminescence layer in the air. . When the light emitted from the photoluminescence layer is visible light, short-wavelength near infrared light, or ultraviolet light, the distance is shorter than the order of micrometers (that is, the order of microns). Therefore, such a surface structure may be referred to as a “submicron structure”. A “submicron structure” may include a portion having a central interval or period exceeding 1 micrometer (μm) in part. In the following description, a photoluminescence layer that emits visible light is mainly assumed, and the term “submicron structure” is mainly used as a term meaning a surface structure. However, the following discussion holds true for the surface structure having a fine structure exceeding the sub-micron order (for example, a fine structure of the micron order used in applications using infrared rays).

  In the light emitting device according to the embodiment of the present disclosure, a unique electric field distribution is formed inside the photoluminescence layer and the light transmitting layer, as will be described in detail later with reference to calculation results and experimental results. This is formed by the guided light interacting with the submicron structure (ie, the surface structure). The mode of light forming such an electric field distribution can be expressed as a “pseudo-waveguide mode”. By utilizing this pseudo waveguide mode, as described below, it is possible to obtain the effects of increased photoluminescence emission efficiency, improved directivity, and polarization selectivity. In the following description, the term pseudo-waveguide mode may be used to describe a new configuration and / or a new mechanism found by the present inventors. The description is merely one illustrative description and should not limit the present disclosure in any way.

The submicron structure includes, for example, a plurality of convex portions, and can satisfy the relationship of λ _a / n _wav−a <D _int <λ _a where D _int is the distance between the centers of adjacent convex portions. The submicron structure may include a plurality of concave portions instead of the plurality of convex portions. Hereinafter, for the sake of simplicity, the submicron structure will be described as having a plurality of convex portions. λ represents the wavelength of light, and λ _a represents the wavelength of light in the air. n _wav is the refractive index of the photoluminescence layer. When the photoluminescence layer is a medium in which a plurality of materials are mixed, the average refractive index obtained by weighting the refractive index of each material by the respective volume ratio is _defined as n _wav . Since generally the refractive index n depends on the wavelength, that is a refractive index to light of lambda _a it is desirable to express the n _wav-a, may be omitted for simplicity. n _wav is basically the refractive index of the photoluminescence layer. When the refractive index of the layer adjacent to the photoluminescence layer is larger than the refractive index of the photoluminescence layer, the refractive index and the photoluminescence of the layer having the larger refractive index are used. Let n _{wav be the} average refractive index obtained by weighting the refractive indices of the layers by their respective volume ratios. This is because this is optically equivalent to the case where the photoluminescence layer is composed of a plurality of layers of different materials.

When the effective refractive index of the medium with respect to the light in the pseudo waveguide mode is n _eff , n _a <n _eff <n _wav is satisfied. Here, n _a is the refractive index of air. Considering that the light in the quasi-waveguide mode propagates while totally reflecting inside the photoluminescence layer at the incident angle θ, the effective refractive index n _eff can be written as n _eff = n _wav sin θ. Further, since the effective refractive index n _eff is determined by the refractive index of the medium existing in the region where the electric field of the pseudo waveguide mode is distributed, for example, when the submicron structure is formed in the light transmitting layer, the photoluminescence layer It depends not only on the refractive index but also on the refractive index of the translucent layer. In addition, since the electric field distribution varies depending on the polarization direction of the pseudo waveguide mode (TE mode and TM mode), the effective refractive index n _eff may be different between the TE mode and the TM mode.

The submicron structure is formed in at least one of the photoluminescence layer and the light transmission layer. When the photoluminescence layer and the light transmission layer are in contact with each other, a submicron structure may be formed at the interface between the photoluminescence layer and the light transmission layer. At this time, the photoluminescence layer and the translucent layer have a submicron structure. The photoluminescent layer may not have a submicron structure. At this time, the light-transmitting layer having a submicron structure is disposed in the vicinity of the photoluminescence layer. Here, the phrase “the light-transmitting layer (or its submicron structure) is close to the photoluminescence layer” typically means that the distance between them is not more than half the wavelength λ _a . As a result, the electric field of the waveguide mode reaches the submicron structure, and the pseudo waveguide mode is formed. However, when the refractive index of the light-transmitting layer is larger than the refractive index of the photoluminescent layer, the light reaches the light-transmitting layer even if the above relationship is not satisfied. Therefore, the submicron structure of the light-transmitting layer and the photoluminescent layer the distance between the may be more than half of the wavelength lambda _a. In this specification, when the photoluminescence layer and the light-transmitting layer are in a positional relationship such that the electric field of the guided mode reaches a submicron structure and a pseudo-guided mode is formed, the two are associated with each other. Sometimes expressed.

As described above, when the submicron structure satisfies the relationship of λ _a / n _wav-a <D _int <λ _a , the submicron structure is characterized by a size on the order of submicron in applications using visible light. The submicron structure may include at least one periodic structure, for example, in the light emitting device of the embodiment described in detail below. At least one of the periodic structure, when the period as _{p a, λ a / n wav} -a <p a <λ relationship _a holds. That is, the sub-micron structures, the distance D _int between adjacent convex portions may comprise constant of the periodic structure in the p _a. When the submicron structure includes such a periodic structure, the light in the pseudo waveguide mode is diffracted by the submicron structure by repeating the interaction with the periodic structure while propagating. This is different from the phenomenon in which light propagating in free space is diffracted by the periodic structure, and is a phenomenon in which light acts on the periodic structure while being guided (that is, repeating total reflection). Therefore, even if the phase shift due to the periodic structure is small (that is, the height of the periodic structure is small), light can be efficiently diffracted.

If the mechanism as described above is used, the luminous efficiency of photoluminescence increases due to the effect of the electric field being enhanced by the pseudo waveguide mode, and the generated light is coupled to the pseudo waveguide mode. The light of the quasi-waveguide mode is bent at a traveling angle by a diffraction angle defined by the periodic structure. By utilizing this, light of a specific wavelength can be emitted in a specific direction. That is, the directivity is remarkably improved as compared with the case where no periodic structure is present. Further, since the effective refractive index n _eff (= n _wav sin θ) is different between the TE mode and the TM mode, high polarization selectivity can be obtained at the same time. For example, as shown in an experimental example later, it is possible to obtain a light emitting element that emits linearly polarized light (for example, TM mode) having a specific wavelength (for example, 610 nm) strongly in the front direction. At this time, the directivity angle of the light emitted in the front direction is, for example, less than 15 °. Here, “directivity angle” is defined as an angle between the direction in which the intensity is maximum and the direction in which the intensity is 50% of the maximum intensity with respect to the linearly polarized light having a specific wavelength to be emitted. That is, the directivity angle is an angle on one side when the direction in which the intensity is maximum is 0 °. Thus, the periodic structure (that is, the surface structure) in the embodiment of the present disclosure limits the directivity angle of light having _a specific wavelength λa. In other words, the distribution of light of the wavelength lambda _a, to narrow angle as compared to when there is no periodic structure. Such a light distribution in which the directivity angle is reduced as compared with the case where there is no periodic structure may be referred to as “narrow angle light distribution”. The periodic structure of the embodiment of the present disclosure, limits the directivity angle of light of wavelength lambda _a, but the embodiment is not emit any light of the wavelength lambda _a narrow angle. For example, in the example shown in FIG. 29 described later, light having _a wavelength λa is slightly emitted also in a direction away from the direction in which the intensity is maximum (for example, 20 ° to 70 °). Overall, however, the emitted light having a wavelength lambda _a is concentrated in the range of 0 ° to 20 °, the orientation angle is limited.

Note that the periodic structure in the exemplary embodiment of the present disclosure has a period shorter than the wavelength λ _{a of} light, unlike a general diffraction grating. A general diffraction grating has a period sufficiently longer than the wavelength λ _{a of} light, and as a result, a specific wavelength of light is a plurality of diffracted lights such as 0th order light (ie, transmitted light), ± 1st order diffracted light, and the like The light is emitted separately. In such a diffraction grating, high-order diffracted light is generated on both sides of zero-order light. High-order diffracted light generated on both sides of zero-order light in the diffraction grating makes it difficult to realize narrow-angle light distribution. In other words, the conventional diffraction grating does not have an effect peculiar to the embodiment of the present disclosure in which the directivity angle of light is limited to a predetermined angle (for example, about 15 °). In this regard, the periodic structure according to the embodiment of the present disclosure has properties that are significantly different from those of conventional diffraction gratings.

  When the periodicity of the submicron structure is lowered, the directivity, light emission efficiency, polarization degree, and wavelength selectivity are weakened. What is necessary is just to adjust the periodicity of a submicron structure as needed. The periodic structure may be a one-dimensional periodic structure with high polarization selectivity or a two-dimensional periodic structure capable of reducing the degree of polarization.

  The submicron structure can include a plurality of periodic structures. The plurality of periodic structures have different periods (pitch), for example. Alternatively, the plurality of periodic structures are different from each other in the direction (axis) having periodicity, for example. The plurality of periodic structures may be formed in the same plane or may be stacked. Of course, the light-emitting element has a plurality of photoluminescence layers and a plurality of light-transmitting layers, and these may have a plurality of submicron structures.

The submicron structure can be used not only to control the light emitted from the photoluminescence layer, but also to efficiently guide the excitation light to the photoluminescence layer. That is, the excitation light is diffracted by the submicron structure and coupled to the pseudo-waveguide mode in which the excitation light is guided through the photoluminescence layer and the light transmission layer, so that the photoluminescence layer can be efficiently excited. Λ _ex / n _wav-ex <D _int <λ _ex , where λ _ex is the wavelength of light in the air that excites the photoluminescent material, and n _wav-ex is the refractive index of the photoluminescence layer for this excitation light. A sub-micron structure in which is satisfied may be used. n _wav-ex is the refractive index at the excitation wavelength of the photoluminescent material. If the period is p _ex , a submicron structure having a periodic structure in which the relationship of λ _ex / n _wav-ex <p _ex <λ _ex may be used. The wavelength λ _{ex of the} excitation light is, for example, 450 nm, but may be shorter than visible light. When the wavelength of the excitation light is within the range of visible light, the excitation light may be emitted together with the light emitted from the photoluminescence layer.

[2. Knowledge underlying this disclosure]
Before describing specific embodiments of the present disclosure, first, knowledge that is the basis of the present disclosure will be described. As described above, photoluminescent materials used in fluorescent lamps, white LEDs, and the like emit light isotropically. In order to illuminate a specific direction with light, optical components such as a reflector and a lens are required. However, if the photoluminescence layer itself emits light with directivity, the optical component as described above becomes unnecessary (or can be reduced). Thereby, the magnitude | size of an optical device or an instrument can be reduced significantly. Based on such an idea, the present inventors have studied in detail the configuration of the photoluminescence layer in order to obtain directional light emission.

The inventors of the present invention first considered that the light emission itself has a specific directionality so that light from the photoluminescence layer is biased in a specific direction. The light emission rate Γ, which is an index characterizing light emission, is expressed by the following formula (1) according to Fermi's golden rule.

In equation (1), r is a position vector, λ is the wavelength of light, d is a dipole vector, E is an electric field vector, and ρ is a density of states. In many materials except some crystalline materials, the dipole vector d has a random orientation. Further, when the size and thickness of the photoluminescence layer are sufficiently larger than the wavelength of light, the magnitude of the electric field E is almost constant regardless of the direction. Therefore, in most cases, the value of <(d · E (r))> ² does not depend on the direction. That is, the light emission rate Γ is constant regardless of the direction. For this reason, in most cases, the photoluminescence layer emits isotropically.

  On the other hand, in order to obtain anisotropic light emission from the formula (1), it is necessary to devise either a dipole vector d aligned in a specific direction or a component in a specific direction of the electric field vector to be enhanced. is there. Directional emission can be realized by any one of these devices. In an embodiment of the present disclosure, a pseudo waveguide mode in which an electric field component in a specific direction is enhanced due to the effect of confining light in the photoluminescence layer is used. The structure for that purpose is examined and the result analyzed in detail is demonstrated below.

[3. Configuration to strengthen only the electric field in a specific direction]
The inventors of the present application considered controlling light emission by using a waveguide mode with a strong electric field. When the waveguide structure itself includes a photoluminescence material, the generated light can be coupled to the waveguide mode. However, if the waveguide structure is simply formed using a photoluminescence material, the emitted light becomes a waveguide mode, so that almost no light is emitted in the front direction. Therefore, the inventors of the present application considered combining a waveguide including a photoluminescent material with a periodic structure. When the periodic structure is close to the waveguide and the light is guided while overlapping the periodic structure, a pseudo waveguide mode exists due to the action of the periodic structure. That is, this pseudo waveguide mode is a waveguide mode limited by the periodic structure, and is characterized in that the antinodes of the electric field amplitude are generated in the same period as the period of the periodic structure. This mode is a mode in which the electric field in a specific direction is strengthened by confining light in the waveguide structure. Furthermore, since this mode interacts with the periodic structure and is converted into propagating light in a specific direction by the diffraction effect, light can be emitted to the outside of the waveguide. Furthermore, since the light other than the pseudo waveguide mode has a small effect of being confined in the waveguide, the electric field is not enhanced. Therefore, most of the light emission is coupled to the pseudo waveguide mode having a large electric field component.

  In other words, the inventors of the present application configure a waveguide having a periodic structure close thereto by a photoluminescence layer containing a photoluminescence material (or a waveguide layer having a photoluminescence layer), thereby generating generated light. We considered to realize a directional light source by coupling to a quasi-guided mode that is converted into propagating light in a specific direction.

  As a simple structure of the waveguide structure, attention was paid to a slab type waveguide. The slab type waveguide is a waveguide in which a light guiding portion has a flat plate structure. FIG. 30 is a perspective view schematically showing an example of the slab waveguide 110S. When the refractive index of the waveguide 110S is higher than the refractive index of the transparent substrate 140 that supports the waveguide 110S, there is a mode of light propagating in the waveguide 110S. By constructing such a slab-type waveguide including a photoluminescence layer, the electric field of light generated from the light emitting point greatly overlaps the electric field of the waveguide mode, so that most of the light generated in the photoluminescence layer is guided. Can be coupled to wave mode. Furthermore, by setting the thickness of the photoluminescence layer to be approximately the wavelength of light, it is possible to create a situation in which only a waveguide mode having a large electric field amplitude exists.

  Further, when the periodic structure is close to the photoluminescence layer, the pseudo-waveguide mode is formed by the electric field of the waveguide mode interacting with the periodic structure. Even when the photoluminescence layer is composed of a plurality of layers, if the electric field of the waveguide mode reaches the periodic structure, a pseudo waveguide mode is formed. It is not necessary for all of the photoluminescence layer to be a photoluminescence material, and it is sufficient that at least a part of the photoluminescence layer has a function of emitting light.

  When the periodic structure is formed of a metal, a mode based on the waveguide mode and the effect of plasmon resonance is formed. This mode has different properties from the quasi-guided mode described above. In addition, in this mode, since the absorption by the metal is large, the loss becomes large and the effect of enhancing the light emission becomes small. Therefore, it is desirable to use a dielectric material with low absorption as the periodic structure.

First, the present inventors form a periodic structure on the surface of such a waveguide to couple the generated light to a pseudo-waveguide mode that can be emitted as propagating light in a specific angular direction. It was investigated. FIG. 1A is a perspective view schematically showing an example of a light emitting device 100 having such a waveguide (for example, a photoluminescence layer) 110 and a periodic structure (for example, a part of a light transmitting layer) 120. Hereinafter, when the light transmitting layer has a periodic structure (that is, when a periodic submicron structure is formed in the light transmitting layer), the periodic structure 120 may be referred to as the light transmitting layer 120. In this example, the periodic structure 120 is a one-dimensional periodic structure in which a plurality of stripe-shaped convex portions each extending in the y direction are arranged at equal intervals in the x direction. FIG. 1B is a cross-sectional view of the light emitting device 100 taken along a plane parallel to the xz plane. When the periodic structure 120 having a period p is provided so as to be in contact with the waveguide 110, the pseudo-waveguide mode having the wave number k _wav in the in-plane direction is converted into propagating light outside the waveguide, and the wave number k _out is It can be represented by Formula (2).

  M in Formula (2) is an integer and represents the order of diffraction.

Here, for the sake of simplicity, it is assumed that the light guided in the waveguide approximately is a light beam propagating at an angle θ _wav , and the following equations (3) and (4) hold.

In these equations, λ ₀ is the wavelength of light in the air, n _wav is the refractive index of the waveguide, n _out is the refractive index of the medium on the exit side, and θ _out is the light emitted to the substrate or air outside the waveguide. Is the exit angle. From the equations (2) to (4), the emission angle θ _out can be expressed by the following equation (5).

From equation (5), it can be seen that when n _wav sin θ _wav = mλ ₀ / p holds, θ _out = 0, and light can be emitted in a direction perpendicular to the plane of the waveguide (ie, the front).

  Based on the above principle, the generated light is coupled to a specific quasi-waveguide mode, and further converted into light having a specific emission angle using a periodic structure, thereby emitting strong light in that direction. It is considered possible.

In order to realize the above situation, there are some constraints. First, in order for the pseudo waveguide mode to exist, it is necessary that the light propagating in the waveguide is totally reflected. The condition for this is expressed by the following formula (6).

In order to diffract this pseudo waveguide mode by the periodic structure and to emit light outside the waveguide, it is necessary to satisfy −1 <sin θ _out <1 in the equation (5). Therefore, it is necessary to satisfy the following formula (7).

On the other hand, considering the equation (6), it can be seen that the following equation (8) should be satisfied.

Further, in order to make the direction of the light emitted from the waveguide 110 the front direction (θ _out = 0), it can be seen from the equation (5) that the following equation (9) is necessary.

From formula (9) and formula (6), it can be seen that the necessary condition is the following formula (10).

When the periodic structure as shown in FIGS. 1A and 1B is provided, the first-order diffracted light with m = 1 should be designed mainly because the high-order diffraction efficiency with m = 2 or higher is low. . For this reason, in the periodic structure in the present embodiment, m = 1 and the period p is determined so as to satisfy the following expression (11) obtained by modifying expression (10).

As shown in FIG. 1A and FIG. 1B, when the waveguide (photoluminescence layer) 110 is not in contact with the transparent substrate, n _out becomes the refractive index of air (about 1.0). The period p may be determined so as to satisfy 12).

On the other hand, a structure in which the photoluminescence layer 110 and the periodic structure 120 are formed on the transparent substrate 140 as illustrated in FIGS. 1C and 1D may be employed. In this case, determined from the refractive index n _s of the transparent substrate 140 is larger than the refractive index of air, the following equation was n _out = n _s in equation (11) the period p to satisfy (13) do it.

In equations (12) and (13), it is assumed that m = 1 in equation (10), but m ≧ 2 may be satisfied. That is, when both surfaces of the light emitting element 100 are in contact with the air layer as shown in FIGS. 1A and 1B, the period p is set so that m is an integer of 1 or more and the following expression (14) is satisfied. It only has to be done.

Similarly, when the photoluminescence layer 110 is formed on the transparent substrate 140 as in the light emitting element 100a shown in FIGS. 1C and 1D, the period p is set so as to satisfy the following formula (15). It only has to be.

  By determining the period p of the periodic structure so as to satisfy the above inequality, light generated from the photoluminescence layer 110 can be emitted in the front direction, so that a light emitting device having directivity can be realized.

[4. Verification by calculation]
[4-1. Period, wavelength dependence]
The present inventors have verified by optical analysis whether light can be emitted in a specific direction as described above. The optical analysis was carried out by calculation using the Cybernet DiffractMOD. In these calculations, when light is vertically incident on the light emitting element from the outside, the increase or decrease in light absorption in the photoluminescence layer is calculated, thereby obtaining the enhancement of the light emitted vertically to the outside. The process in which light incident from the outside is coupled to the quasi-waveguide mode and absorbed by the photoluminescence layer is converted into propagating light that is emitted from the photoluminescence layer to the quasi-waveguide mode and exits perpendicularly to the outside. This corresponds to the calculation of the opposite process. Further, in the calculation of the electric field distribution in the pseudo waveguide mode, the electric field when light is incident from the outside was calculated in the same manner.

The film thickness of the photoluminescence layer is 1 μm, the refractive index of the photoluminescence layer is n _wav = 1.8, the height of the periodic structure is 50 nm, the refractive index of the periodic structure is 1.5, the emission wavelength and the period of the periodic structure are FIG. 2 shows the result of calculating the intensities of the light emitted in the front direction while changing each. As shown in FIG. 1A, the calculation model was calculated with a uniform one-dimensional periodic structure in the y direction, and the polarization of light was a TM mode having an electric field component parallel to the y direction. From the result of FIG. 2, it can be seen that a peak of enhancement exists at a certain combination of wavelength and period. In FIG. 2, the magnitude of the enhancement is represented by the shade of the color, and the darker (that is, black) has a larger enhancement and the lighter (that is, white) has a smaller enhancement.

  In the above calculation, the cross section of the periodic structure is assumed to be rectangular as shown in FIG. 1B. A graph illustrating the conditions of m = 1 and m = 3 in equation (10) is shown in FIG. Comparing FIG. 2 and FIG. 3, it can be seen that the peak positions in FIG. 2 exist at locations corresponding to m = 1 and m = 3. The reason why m = 1 is stronger is that the diffraction efficiency of the first-order diffracted light is higher than that of the third-order or higher-order diffracted light. The reason why the peak of m = 2 does not exist is that the diffraction efficiency in the periodic structure is low.

  In the region corresponding to each of m = 1 and m = 3 shown in FIG. 3, it can be confirmed that there are a plurality of lines in FIG. This is considered to be because there are a plurality of pseudo waveguide modes.

[4-2. Thickness dependence]
In FIG. 4, the refractive index of the photoluminescence layer is n _wav = 1.8, the period of the periodic structure is 400 nm, the height is 50 nm, the refractive index is 1.5, and the emission wavelength and the thickness t of the photoluminescence layer are changed. It is a figure which shows the result of having calculated the intensification of the light output in a front direction. It can be seen that the light intensity reaches a peak when the thickness t of the photoluminescence layer is a specific value.

  FIG. 5A and FIG. 5B show the results of calculating the electric field distribution of the mode guided in the x direction when the wavelength where the peak exists in FIG. 4 is 600 nm and the thickness is t = 238 nm and 539 nm. For comparison, FIG. 5C shows the result of the same calculation performed when t = 300 nm where no peak exists. The calculation model was assumed to be a one-dimensional periodic structure uniform in the y direction, as described above. In each figure, the black region indicates that the electric field strength is high, and the white region indicates that the electric field strength is low. In the case of t = 238 nm and 539 nm, there is a high electric field intensity distribution, whereas in the case of t = 300 nm, the electric field intensity is low overall. This is because when t = 238 nm and 539 nm, a waveguide mode exists and light is strongly confined. Furthermore, there is always a convex portion or a portion (antinode) where the electric field is strongest immediately below the convex portion, and it can be seen that the electric field correlated with the periodic structure 120 is generated. That is, it can be seen that a guided mode is obtained according to the arrangement of the periodic structure 120. Further, comparing the case of t = 238 nm with the case of t = 539 nm, it can be seen that the mode is different in the number of nodes (white portions) in the z direction by one.

[4-3. Polarization dependence]
Next, in order to confirm the polarization dependence, the light enhancement was calculated for the case where the polarization of the light is a TE mode having an electric field component perpendicular to the y direction under the same conditions as those in FIG. The result of this calculation is shown in FIG. Compared to the TM mode (FIG. 2), the peak position is slightly changed, but the peak position is within the region shown in FIG. Therefore, it was confirmed that the configuration of this embodiment is effective for both TM mode and TE mode polarization.

[4-4.2 Two-dimensional periodic structure]
Furthermore, the effect by a two-dimensional periodic structure was examined. FIG. 7A is a plan view showing a part of a two-dimensional periodic structure 120 ′ in which concave and convex portions are arranged in both the x and y directions. The black area in the figure indicates a convex portion, and the white area indicates a concave portion. In such a two-dimensional periodic structure, it is necessary to consider diffraction in both the x and y directions. Diffraction only in the x direction or only in the y direction is the same as in the one-dimensional case, but there is also diffraction in a direction having both x and y components (for example, an oblique 45 ° direction). It can be expected that different results will be obtained. FIG. 7B shows the result of calculating the light enhancement for such a two-dimensional periodic structure. The calculation conditions other than the periodic structure are the same as the conditions in FIG. As shown in FIG. 7B, in addition to the peak position in the TM mode shown in FIG. 2, a peak position that coincides with the peak position in the TE mode shown in FIG. 6 was also observed. This result shows that the TE mode is also converted and output by diffraction due to the two-dimensional periodic structure. In addition, regarding the two-dimensional periodic structure, it is necessary to consider diffraction that satisfies the first-order diffraction conditions simultaneously in both the x direction and the y direction. Such diffracted light is emitted in the direction of an angle corresponding to a period √2 times (that is, 2 ^1/2 times) the period p. Therefore, in addition to the peak in the case of the one-dimensional periodic structure, it is considered that a peak is generated for a period that is √2 times the period p. In FIG. 7B, such a peak can also be confirmed.

  The two-dimensional periodic structure is not limited to a square lattice structure having the same period in the x direction and the y direction as shown in FIG. 7A, but is a lattice structure in which hexagons and triangles are arranged as shown in FIGS. 18A and 18B. Also good. Moreover, the structure where the period of a direction differs (for example, x direction and y direction in the case of a square lattice) may be sufficient.

  As described above, in this embodiment, the characteristic pseudo-waveguide mode light formed by the periodic structure and the photoluminescence layer is selectively emitted only in the front direction using the diffraction phenomenon due to the periodic structure. I was able to confirm that it was possible. With such a configuration, light emission having directivity can be obtained by exciting the photoluminescence layer with excitation light such as ultraviolet rays or blue light.

[5. Study of periodic structure and photoluminescence layer configuration]
Next, the effect when various conditions such as the structure of the periodic structure and the photoluminescence layer and the refractive index are changed will be described.

[5-1. Refractive index of periodic structure]
First, the refractive index of the periodic structure was examined. The film thickness of the photoluminescence layer is 200 nm, the refractive index of the photoluminescence layer is n _wav = 1.8, the periodic structure is a uniform one-dimensional periodic structure in the y direction as shown in FIG. 1A, the height is 50 nm, and the period is The calculation was performed on the assumption that the light polarization was TM mode having an electric field component parallel to the y direction. FIG. 8 shows the result of calculating the enhancement of the light output in the front direction by changing the emission wavelength and the refractive index of the periodic structure. Further, FIG. 9 shows the results when the film thickness of the photoluminescence layer is 1000 nm under the same conditions.

  First, focusing on the thickness of the photoluminescence layer, the light intensity with respect to the change in the refractive index of the periodic structure is more peak when the thickness is 1000 nm (FIG. 9) than when the thickness is 200 nm (FIG. 8). It can be seen that the shift of the wavelength (referred to as the peak wavelength) becomes small. This is because the pseudo-waveguide mode is more susceptible to the refractive index of the periodic structure as the film thickness of the photoluminescence layer is smaller. That is, the higher the refractive index of the periodic structure, the higher the effective refractive index, and the corresponding peak wavelength shifts to the longer wavelength side. This effect becomes more pronounced as the film thickness decreases. The effective refractive index is determined by the refractive index of the medium existing in the region where the electric field of the pseudo waveguide mode is distributed.

  Next, paying attention to the change in the peak with respect to the change in the refractive index of the periodic structure, it can be seen that the higher the refractive index, the wider the peak and the lower the intensity. This is because the higher the refractive index of the periodic structure, the higher the rate at which the light in the pseudo waveguide mode is emitted to the outside, so that the effect of confining the light decreases, that is, the Q value decreases. In order to keep the peak intensity high, a configuration in which light is appropriately emitted to the outside by using a pseudo-waveguide mode having a high light confinement effect (that is, a high Q value) may be used. In order to realize this, it is understood that it is not desirable to use a material having a refractive index that is too large compared to the refractive index of the photoluminescence layer for the periodic structure. Therefore, in order to increase the peak intensity and the Q value to some extent, the refractive index of the dielectric (that is, the translucent layer) constituting the periodic structure may be made equal to or less than the refractive index of the photoluminescence layer. The same applies when the photoluminescence layer contains a material other than the photoluminescence material.

[5-2. Periodic structure height]
Next, the height of the periodic structure was examined. The film thickness of the photoluminescence layer is 1000 nm, the refractive index of the photoluminescence layer is n _wav = 1.8, the periodic structure is a uniform one-dimensional periodic structure in the y direction as shown in FIG. 1A, and the refractive index is n _p = 1. 5. Calculation was performed assuming that the period was 400 nm and the polarization of light was TM mode having an electric field component parallel to the y direction. FIG. 10 shows the result of calculating the enhancement of the light output in the front direction by changing the emission wavelength and the height of the periodic structure. FIG. 11 shows the calculation result when the refractive index of the periodic structure is n _p = 2.0 under the same conditions. In the result shown in FIG. 10, the peak intensity and the Q value (that is, the line width of the peak) do not change at a height above a certain level, whereas in the result shown in FIG. 11, the height of the periodic structure is large. It can be seen that the peak intensity and the Q value are lowered. This is because, when the refractive index n _{wav of the} photoluminescence layer is higher than the refractive index n _{p of the} periodic structure (FIG. 10), the light is totally reflected, so that the electric field bleeds out (evanescent) in the pseudo waveguide mode. Only due to the interaction with the periodic structure. When the height of the periodic structure is sufficiently large, the influence of the interaction between the evanescent part of the electric field and the periodic structure is constant even if the height changes further. On the other hand, when the refractive index n _{wav of the} photoluminescence layer is lower than the refractive index n _{p of the} periodic structure (FIG. 11), the light reaches the surface of the periodic structure without being totally reflected, so the height of the periodic structure The larger the is, the more affected. As can be seen from FIG. 11, it is sufficient that the height is about 100 nm, and the peak intensity and the Q value are lowered in the region exceeding 150 nm. Therefore, when the refractive index n _{wav of the} photoluminescence layer is lower than the refractive index n _p of the periodic structure, the height of the periodic structure may be set to 150 nm or less in order to increase the peak intensity and the Q value to some extent. .

[5-3. Polarization direction]
Next, the polarization direction was examined. FIG. 12 shows the result of calculation assuming that the polarization of light is a TE mode having an electric field component perpendicular to the y direction under the same conditions as those shown in FIG. In the TE mode, the electric field of the quasi-guided mode is larger than that in the TM mode, so that it is easily affected by the periodic structure. Therefore, in the region where the refractive index n _p of the periodic structure is larger than the refractive index n _{wav of the} photoluminescence layer, the peak intensity and the Q value are significantly decreased as compared with the TM mode.

[5-4. Refractive index of photoluminescence layer]
Next, the refractive index of the photoluminescence layer was examined. FIG. 13 shows the result when the refractive index n _wav of the photoluminescence layer is changed to 1.5 under the same conditions as the calculation shown in FIG. It can be seen that the same effect as in FIG. 9 is obtained even when the refractive index n _{wav of the} photoluminescence layer is 1.5. However, it can be seen that light having a wavelength of 600 nm or more is not emitted in the front direction. This is because λ ₀ <n _wav × p / m = 1.5 × 400 nm / 1 = 600 nm from Equation (10).

  From the above analysis, if the refractive index of the periodic structure is less than or equal to the refractive index of the photoluminescence layer, or if the refractive index of the periodic structure is greater than or equal to the refractive index of the photoluminescence layer, the height should be 150 nm or less. It can be seen that the peak intensity and the Q value can be increased.

[6. Modified example]
Hereinafter, modifications of the present embodiment will be described.

[6-1. Configuration with substrate]
As described above, the light-emitting element may have a structure in which the photoluminescence layer 110 and the periodic structure 120 are formed on the transparent substrate 140 as illustrated in FIGS. 1C and 1D. In order to manufacture such a light-emitting element 100a, first, a thin film is formed on a transparent substrate 140 with a photoluminescent material (including a matrix material, if necessary, the same applies below) constituting the photoluminescent layer 110, A method of forming the periodic structure 120 thereon can be considered. In such a configuration, in order for the photoluminescence layer 110 and the periodic structure 120 to have a function of emitting light in a specific direction, the refractive index n _s of the transparent substrate 140 is less than the refractive index n _{wav of the} photoluminescence layer. It is necessary to. When the transparent substrate 140 is provided so as to be in contact with the photoluminescence layer 110, it is necessary to set the period p so as to satisfy the equation (15) where the refractive index n _out of the emission medium in the equation (10) is n _s. .

In order to confirm this, a calculation was performed when the photoluminescence layer 110 and the periodic structure 120 having the same conditions as the calculation shown in FIG. 2 were provided on the transparent substrate 140 having a refractive index of 1.5. The result of this calculation is shown in FIG. As in the result of FIG. 2, it can be confirmed that a peak of light intensity appears in a specific period for each wavelength, but it can be seen that the range of the period in which the peak appears is different from the result of FIG. In contrast, shows the condition of the expression condition of (10) was n _out = n _s equation (15) in FIG. 15. In FIG. 14, it can be seen that the peak of the light intensity appears in the region corresponding to the range shown in FIG.

  Therefore, in the light emitting element 100a in which the photoluminescence layer 110 and the periodic structure 120 are provided on the transparent substrate 140, an effect is obtained in the range of the period p that satisfies the expression (15), and the period p that satisfies the expression (13). In particular, a remarkable effect can be obtained in this range.

[6-2. Light emitting device having excitation light source]
FIG. 16 is a diagram illustrating a configuration example of a light-emitting device 200 including the light-emitting element 100 illustrated in FIGS. 1A and 1B and a light source 180 that causes excitation light to enter the photoluminescence layer 110. As described above, in the configuration of the present disclosure, light emission having directivity can be obtained by exciting the photoluminescence layer with excitation light such as ultraviolet light or blue light. By providing the light source 180 configured to emit such excitation light, the light emitting device 200 having directivity can be realized. The wavelength of the excitation light emitted from the light source 180 is typically a wavelength in the ultraviolet or blue region, but is not limited thereto, and is appropriately determined according to the photoluminescent material constituting the photoluminescent layer 110. In FIG. 16, the light source 180 is arranged so that the excitation light is incident from the lower surface of the photoluminescence layer 110. However, the present invention is not limited to such an example. For example, the excitation light is emitted from the upper surface of the photoluminescence layer 110. It may be incident. The excitation light may be incident from a direction inclined (ie, obliquely) with respect to a direction perpendicular to the main surface (ie, upper surface or lower surface) of the photoluminescence layer 110. By making the excitation light incident obliquely at an angle at which total reflection occurs in the photoluminescence layer 110, light can be emitted more efficiently.

There is also a method for efficiently emitting light by coupling excitation light into a pseudo-guide mode. 17A to 17D are diagrams for explaining such a method. In this example, the photoluminescence layer 110 and the periodic structure 120 are formed on the transparent substrate 140 as in the configuration shown in FIGS. 1C and 1D. First, as shown in FIG. 17A, the period p _x in the x direction is determined for light emission enhancement, and then, the period in the y direction is used to couple the excitation light to the pseudo waveguide mode as shown in FIG. 17B. to determine the p _y. The period p _x is determined so as to satisfy the condition in which p is replaced with p _x in Equation (10). On the other hand, in the period _py , m is an integer equal to or larger than 1, the wavelength of the excitation light is λ _ex , and the medium having the highest refractive index excluding the periodic structure 120 out of the medium in contact with the photoluminescence layer 110 is n _out. The following equation (16) is satisfied.

Here, n _out is n _s of the transparent substrate 140 in the example of FIG. 17B, but in the configuration in which the transparent substrate 140 is not provided as in FIG. 16, it is the refractive index of air (about 1.0).

In particular, if m = 1 and the period _py is determined so as to satisfy the following expression (17), the effect of converting the excitation light into the pseudo-waveguide mode can be further enhanced.

In this way, by setting the period p _y so as to satisfy the condition (in particular the condition of equation (17)) of formula (16) can be converted excitation light to the pseudo guided mode. As a result, the photoluminescence layer 110 can efficiently absorb the excitation light having the wavelength λ _ex .

FIG. 17C and FIG. 17D are diagrams showing the results of calculating the ratio of light absorption for each wavelength when light is incident on the structure shown in FIG. 17A and FIG. 17B, respectively. In this calculation, p _x = 365 nm and p _y = 265 nm, the emission wavelength λ from the photoluminescence layer 110 is about 600 nm, the wavelength λ _{ex of the} excitation light is about 450 nm, and the extinction coefficient of the photoluminescence layer 110 is 0.003. It is said. As shown in FIG. 17D, not only the light generated from the photoluminescence layer 110 but also light having a wavelength of about 450 nm that is excitation light is shown. This is because the incident light is effectively converted into the pseudo-waveguide mode, so that the proportion absorbed by the photoluminescence layer can be increased. In addition, the absorptance is increased with respect to the emission wavelength of about 600 nm. This is because if the light having a wavelength of about 600 nm is incident on this structure, the pseudo-waveguide mode can be effectively effectively applied. Is converted to. As described above, the periodic structure 120 illustrated in FIG. 17B is a two-dimensional periodic structure having structures with different periods (referred to as periodic components) in each of the x direction and the y direction. Thus, by using a two-dimensional periodic structure having a plurality of periodic components, it is possible to increase the emission intensity while increasing the excitation efficiency. In FIGS. 17A and 17B, the excitation light is incident from the substrate 140 side, but the same effect can be obtained even if it is incident from the periodic structure 120 side.

  Furthermore, as a two-dimensional periodic structure having a plurality of periodic components, a configuration as shown in FIG. 18A or 18B may be adopted. A configuration in which a plurality of convex portions or concave portions having a hexagonal planar shape are periodically arranged as shown in FIG. 18A, or a plurality of convex portions or concave portions having a triangular planar shape as shown in FIG. 18B are periodically arranged. By arranging them in a line, a plurality of main axes (in the example of the figure, axes 1 to 3) that can be regarded as periods can be determined. For this reason, a different period can be assigned to each axial direction. Each of these periods may be set to increase the directivity of light having a plurality of wavelengths, or may be set to efficiently absorb the excitation light. In any case, each cycle is set so as to satisfy the condition corresponding to the equation (10).

[6-3. Periodic structure on transparent substrate]
As shown in FIGS. 19A and 19B, the periodic structure 120a may be formed on the transparent substrate 140, and the photoluminescence layer 110 may be provided thereon. In the configuration example of FIG. 19A, the photoluminescence layer 110 is formed so as to follow the periodic structure 120 a made of unevenness on the substrate 140. As a result, a periodic structure 120b having the same period is also formed on the surface of the photoluminescence layer 110. On the other hand, in the configuration example of FIG. 19B, the surface of the photoluminescence layer 110 is processed to be flat. Also in these configuration examples, directional light emission can be realized by setting the period p of the periodic structure 120a so as to satisfy Expression (15).

In order to verify this effect, in the configuration of FIG. 19A, the intensity of light output in the front direction was calculated by changing the emission wavelength and the period of the periodic structure. Here, the film thickness of the photoluminescence layer 110 is 1000 nm, the refractive index of the photoluminescence layer 110 is n _wav = 1.8, the periodic structure 120a is a uniform one-dimensional periodic structure in the y direction, the height is 50 nm, and the refractive index is It was assumed that n _p = 1.5, the period was 400 nm, and the polarization of light was a TM mode having an electric field component parallel to the y direction. The result of this calculation is shown in FIG. 19C. Also in this calculation, a peak of light intensity was observed at a period satisfying the condition of Expression (15).

[6-4. powder]
According to the above embodiment, light emission of an arbitrary wavelength can be emphasized by adjusting the period of the periodic structure and the film thickness of the photoluminescence layer. For example, if a photoluminescent material that emits light in a wide band is used as shown in FIGS. 1A and 1B, only light of a certain wavelength can be emphasized. Therefore, the structure of the light emitting element 100 as shown in FIGS. 1A and 1B may be powdered and used as a fluorescent material. 1A and 1B may be used by being embedded in a resin or glass.

  1A and 1B, since only a specific wavelength can be emitted in a specific direction, it is difficult to realize light emission such as white having a spectrum in a wide wavelength range. Therefore, as shown in FIG. 20, by using a mixture of a plurality of powdered light emitting elements 100 having different conditions such as the period of the periodic structure and the film thickness of the photoluminescence layer, a light emitting device having a spectrum in a wide wavelength range Can be realized. In this case, the size of each light emitting element 100 in one direction is, for example, about several μm to several mm, and may include, for example, a one-dimensional or two-dimensional periodic structure of several cycles to several hundred cycles.

[6-5. Arrange structures with different periods]
FIG. 21 is a plan view showing an example in which a plurality of periodic structures having different periods are two-dimensionally arranged on the photoluminescence layer. In this example, three types of periodic structures 120a, 120b, and 120c are arranged without a gap. For example, the periodic structures 120a, 120b, and 120c have a period set so as to emit light in the red, green, and blue wavelength ranges to the front. Thus, directivity can be exhibited with respect to a spectrum in a wide wavelength region by arranging a plurality of structures with different periods on the photoluminescence layer. The configuration of the plurality of periodic structures is not limited to the above, and may be set arbitrarily.

[6-6. Laminated structure]
FIG. 22 illustrates an example of a light-emitting element having a structure in which a plurality of photoluminescence layers 110 having an uneven structure formed on the surface are stacked. A transparent substrate 140 is provided between the plurality of photoluminescence layers 110, and the concavo-convex structure formed on the surface of the photoluminescence layer 110 of each layer corresponds to the periodic structure or the submicron structure. In the example shown in FIG. 22, the three-layer periodic structures having different periods are formed, and the periods are set so as to emit light in the red, blue, and green wavelength ranges to the front. Further, the material of the photoluminescence layer 110 of each layer is selected so as to emit light of a color corresponding to the period of each periodic structure. In this way, directivity can be exhibited with respect to a spectrum in a wide wavelength range by laminating a plurality of periodic structures having different periods.

  Note that the number of layers, the structure of the photoluminescence layer 110 of each layer, and the periodic structure are not limited to those described above, and may be arbitrarily set. For example, in the structure of two layers, the first photoluminescence layer and the second photoluminescence layer are formed so as to face each other through the light-transmitting substrate, and the surface of the first and second photoluminescence layers is formed on the surface. The first and second periodic structures will be formed respectively. In this case, for each of the first photoluminescence layer and the first periodic structure pair and the second photoluminescence layer and the second periodic structure pair, the condition corresponding to the equation (15) may be satisfied. That's fine. Similarly, in the configuration of three or more layers, the condition corresponding to the formula (15) may be satisfied for the photoluminescence layer and the periodic structure in each layer. The positional relationship between the photoluminescence layer and the periodic structure may be reversed from that shown in FIG. In the example shown in FIG. 22, the period of each layer is different, but they may all be the same period. In that case, the spectrum cannot be widened, but the emission intensity can be increased.

[6-7. Configuration with protective layer]
FIG. 23 is a cross-sectional view illustrating a configuration example in which a protective layer 150 is provided between the photoluminescence layer 110 and the periodic structure 120. As described above, the protective layer 150 for protecting the photoluminescence layer 110 may be provided. However, when the refractive index of the protective layer 150 is lower than the refractive index of the photoluminescence layer 110, an electric field of light oozes out only about half the wavelength inside the protective layer 150. Therefore, when the protective layer 150 is thicker than the wavelength, light does not reach the periodic structure 120. For this reason, there is no pseudo waveguide mode, and a function of emitting light in a specific direction cannot be obtained. When the refractive index of the protective layer 150 is about the same as or higher than the refractive index of the photoluminescence layer 110, the light reaches the inside of the protective layer 150. Therefore, there is no restriction on the thickness of the protective layer 150. However, even in that case, a larger light output can be obtained by forming most of a portion where light is guided (hereinafter, this portion is referred to as a “waveguide layer”) from a photoluminescent material. Therefore, it is desirable that the protective layer 150 is thin even in this case. Note that the protective layer 150 may be formed using the same material as the periodic structure (translucent layer) 120. At this time, the light-transmitting layer having a periodic structure also serves as a protective layer. The refractive index of the light transmitting layer 120 is preferably smaller than that of the photoluminescent layer 110.

[7. material]
If the photoluminescence layer (or waveguide layer) and the periodic structure are made of a material that satisfies the above conditions, directional light emission can be realized. Any material can be used for the periodic structure. However, if the light absorptivity of the medium forming the photoluminescence layer (or waveguide layer) or the periodic structure is high, the effect of confining light is reduced, and the peak intensity and the Q value are reduced. Therefore, a medium having a relatively low light absorption can be used as a medium for forming the photoluminescence layer (or waveguide layer) and the periodic structure.

As the material of the periodic structure, for example, a dielectric having low light absorption can be used. Examples of the material of the periodic structure include, for example, MgF ₂ (magnesium fluoride), LiF (lithium fluoride), CaF ₂ (calcium fluoride), SiO ₂ (quartz), glass, resin, MgO (magnesium oxide), ITO (indium tin oxide), TiO ₂ (titanium oxide), SiN (silicon nitride), Ta ₂ O ₅ (tantalum pentoxide), ZrO ₂ (zirconia), ZnSe (zinc selenide), ZnS (zinc sulfide), etc. Can be mentioned. However, as described above, when the refractive index of the periodic structure is made lower than the refractive index of the photoluminescence layer, MgF ₂ , LiF, CaF ₂ , SiO ₂ , glass, resin having a refractive index of about 1.3 to 1.5. Can be used.

The photoluminescent material includes a fluorescent material and a phosphorescent material in a narrow sense, includes not only an inorganic material but also an organic material (for example, a dye), and further includes a quantum dot (that is, a semiconductor fine particle). In general, a fluorescent material having an inorganic material as a host tends to have a high refractive index. Examples of fluorescent materials that emit blue light include M ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ (M = at least one selected from Ba, Sr and Ca), BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , M ₃ MgSi ₂ O ₈ : Eu ²⁺ (at least one selected from M = Ba, Sr and Ca), M ₅ SiO ₄ Cl ₆ : Eu ²⁺ (at least one selected from M = Ba, Sr and Ca) Can be used. Examples of fluorescent materials that emit green light include M ₂ MgSi ₂ O ₇ : Eu ²⁺ (M = at least one selected from Ba, Sr and Ca), SrSi ₅ AlO ₂ N ₇ : Eu ²⁺ , SrSi _2. O ₂ N ₂ : Eu ²⁺ , BaAl ₂ O ₄ : Eu ²⁺ , BaZrSi ₃ O ₉ : Eu ²⁺ , M ₂ SiO ₄ : Eu ²⁺ (at least one selected from M = Ba, Sr and Ca) BaSi ₃ O ₄ N ₂ : Eu ²⁺ , Ca ₈ Mg (SiO ₄ ) ₄ Cl ₂ : Eu ²⁺ , Ca ₃ SiO ₄ Cl ₂ : Eu ²⁺ , CaSi _{12-(m + n)} Al _{(m + n)} O _n N _16-n : Ce ³⁺ , β-SiAlON: Eu ²⁺ can be used. Examples of the fluorescent material emitting red light include CaAlSiN ₃ : Eu ²⁺ , SrAlSi ₄ O ₇ : Eu ²⁺ , M ₂ Si ₅ N ₈ : Eu ²⁺ (at least one selected from M = Ba, Sr and Ca). Species), MSiN ₂ : Eu ²⁺ (at least one selected from M = Ba, Sr and Ca), MSi ₂ O ₂ N ₂ : Yb ²⁺ (at least one selected from M = Sr and Ca), Y ₂ O ₂ S: Eu ³⁺ , Sm ³⁺ , La ₂ O ₂ S: Eu ³⁺ , Sm ³⁺ , CaWO ₄ : Li ¹⁺ , Eu ³⁺ , Sm ³⁺ , M ₂ SiS ₄ : Eu ²⁺ (M = SiO, at least one selected from Ba, Sr and Ca), M ₃ SiO ₅ : Eu ²⁺ (M = at least one selected from Ba, Sr and Ca) can be used. Examples of fluorescent materials that emit yellow light include Y ₃ Al ₅ O ₁₂ : Ce ³⁺ , CaSi ₂ O ₂ N ₂ : Eu ²⁺ , Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce ³⁺ , and CaSc ₂ O _4. : Ce ³⁺ , α-SiAlON: Eu ²⁺ , MSi ₂ O ₂ N ₂ : Eu ²⁺ (at least one selected from M = Ba, Sr and Ca), M ₇ (SiO ₃ ) ₆ Cl ₂ : Eu ²⁺ (M = at least one selected from Ba, Sr and Ca) can be used.

  For the quantum dots, for example, materials such as CdS, CdSe, core / shell CdSe / ZnS, and alloy type CdSSe / ZnS can be used, and various emission wavelengths can be obtained depending on the material. As the matrix of quantum dots, for example, glass or resin can be used.

The transparent substrate 140 shown in FIGS. 1C, 1D, and the like is made of a light-transmitting material having a refractive index lower than that of the photoluminescence layer 110. Examples of such a material include MgF ₂ (magnesium fluoride), LiF (lithium fluoride), CaF ₂ (calcium fluoride), SiO ₂ (quartz), glass, and resin. Note that it is not essential for the substrate 140 to be transparent in a configuration in which excitation light is incident on the photoluminescence layer 110 without passing through the substrate 140. The substrate 140 may be, for example, BaF ₂ , SrF ₂ , MgO, MgAl ₂ O ₄ , sapphire (Al ₂ O ₃ ), SrTiO ₃ , LaAlO ₃ , TiO ₂ , Gd ₃ Ga ₅ O ₁₂ , LaSrAlO ₄ , LaSrGaO ₄ , LaTaO. ₃ , SrO, YSZ (ZrO ₂ .Y ₂ O ₃ ), YAG, or Tb ₃ Ga ₅ O ₁₂ may be used.

[8. Production method]
Then, an example of a manufacturing method is demonstrated.

  As a method of realizing the configuration shown in FIGS. 1C and 1D, for example, a thin film of the photoluminescence layer 110 is formed on the transparent substrate 140 by a process such as vapor deposition, sputtering, and coating, and then a dielectric is formed. There is a method of forming the periodic structure 120 by patterning by a method such as photolithography. Instead of the above method, the periodic structure 120 may be formed by nanoimprinting. Further, as shown in FIG. 24, the periodic structure 120 may be formed by processing only a part of the photoluminescence layer 110. In that case, the periodic structure 120 is formed of the same material as the photoluminescence layer 110.

  The light-emitting element 100 illustrated in FIGS. 1A and 1B can be realized by, for example, manufacturing the light-emitting element 100a illustrated in FIGS. 1C and 1D and then performing a process of removing the portions of the photoluminescence layer 110 and the periodic structure 120 from the substrate 140. is there.

  In the configuration shown in FIG. 19A, for example, after the periodic structure 120a is formed on the transparent substrate 140 by a method such as a semiconductor process or nanoimprint, the material constituting the photoluminescence layer 110 is formed thereon by a method such as vapor deposition or sputtering. This is possible by doing. Alternatively, the structure shown in FIG. 19B can be realized by embedding the concave portion of the periodic structure 120a with the photoluminescence layer 110 using a method such as coating.

  In addition, said manufacturing method is an example and the light emitting element of this indication is not limited to said manufacturing method.

[9. Experimental example]
Hereinafter, an example in which a light emitting device according to an embodiment of the present disclosure is manufactured will be described.

  A sample of a light-emitting element having the same structure as that in FIG. 19A was prototyped, and the characteristics were evaluated. The light emitting element was manufactured as follows.

  A glass substrate was provided with a one-dimensional periodic structure (stripe-shaped convex portion) having a period of 400 nm and a height of 40 nm, and YAG: Ce, which is a photoluminescence material, was formed to a thickness of 210 nm thereon. FIG. 25 shows a TEM image of this cross-sectional view, and FIG. 26 shows the result of measuring the spectrum in the front direction when YAG: Ce is emitted by exciting it with a 450 nm LED. FIG. 26 shows measurement results (ref) in the absence of a periodic structure, results of measuring a TM mode having a polarization component parallel to the one-dimensional periodic structure, and a TE mode having a perpendicular polarization component. . In the case where there is a periodic structure, it can be seen that the light of a specific wavelength is remarkably increased compared to the case where there is no periodic structure. It can also be seen that the TM mode having a polarization component parallel to the one-dimensional periodic structure has a larger light enhancement effect.

  Furthermore, in the same sample, the results of measuring the angle dependency of the emitted light intensity and the calculation results are shown in FIGS. 27A to 27F and FIGS. 28A to 28F. FIG. 27A shows a state in which a light emitting element that emits TM mode linearly polarized light is rotated about an axis parallel to the line direction of the one-dimensional periodic structure 120 as a rotation axis. FIG. 27B and FIG. 27C respectively show the measurement results and calculation results for the case of rotating in this way. On the other hand, FIG. 27D shows a situation in which the light emitting element that emits TE mode linearly polarized light is rotated about an axis parallel to the line direction of the one-dimensional periodic structure 120 as a rotation axis. FIG. 27E and FIG. 27F show the measurement result and the calculation result in this case, respectively. FIG. 28A shows a state in which a light emitting element that emits TE mode linearly polarized light is rotated about an axis perpendicular to the line direction of the one-dimensional periodic structure 120 as a rotation axis. FIG. 28B and FIG. 28C show measurement results and calculation results in this case, respectively. On the other hand, FIG. 28D shows a situation where the light emitting element that emits TM mode linearly polarized light is rotated about the axis perpendicular to the line direction of the one-dimensional periodic structure 120 as the rotation axis. FIG. 28E and FIG. 28F show the measurement result and the calculation result in this case, respectively. As is clear from FIGS. 27A to 27F and FIGS. 28A to 28F, the TM mode has a higher effect of enhancement. It can also be seen that the wavelength of the enhanced light shifts with angle. For example, it can be seen that light having a wavelength of 610 nm has a high directivity and emits polarized light because the light exists only in the TM mode and in the front direction. 27B and 27C, FIG. 27E and FIG. 27F, FIG. 28B and FIG. 28C, and FIG. 28E and FIG. Supported by.

  FIG. 29 shows the angle dependence of the intensity when light having a wavelength of 610 nm is rotated about a direction perpendicular to the line direction as the rotation axis, as shown in FIG. 28D. There is a strong light emission enhancement in the front direction, and it can be seen that the light is hardly enhanced at other angles. It can be seen that the directivity angle of the light emitted in the front direction is less than 15 °. As described above, the directivity angle is an angle at which the intensity is 50% of the maximum intensity, and is represented by an angle on one side with respect to the direction of the maximum intensity. From the results shown in FIG. 29, it can be seen that directional light emission is realized. Furthermore, since all the emitted light is a TM mode component, it can be seen that polarized light emission is realized at the same time.

  The verification experiment described above was performed using YAG: Ce that emits light in a wide wavelength band. Even if an experiment is performed with a similar configuration using a photoluminescent material that emits light in a narrow band, high directivity and polarized light emission can be realized for light of that wavelength. Further, when such a photoluminescent material is used, a light source that does not generate light in other directions and in other polarization states can be realized because light of other wavelengths is not generated.

[10. Other variations]
Next, another modified example of the light emitting element and the light emitting device of the present disclosure will be described.

As described above, the wavelength and emission direction of light subjected to the light emission enhancement effect by the submicron structure of the light emitting element of the present disclosure depend on the configuration of the submicron structure. Consider a light-emitting element having a periodic structure 120 on a photoluminescence layer 110 shown in FIG. Here, the periodic structure 120 is formed of the same material as that of the photoluminescence layer 110, and the case where the periodic structure 120 includes the one-dimensional periodic structure 120 illustrated in FIG. 1A is illustrated. The light receiving the emission enhancement by the one-dimensional periodic structure 120 is defined as a period p (nm) of the one-dimensional periodic structure 120, a refractive index n _wav of the photoluminescence layer 110, and a refractive index n _out of an external medium from which the light is emitted, When the incident angle to the one-dimensional periodic structure 120 is θ _wav and the exit angle from the one-dimensional periodic structure 120 to the external medium is θ _out , p × n _wav × sin θ _wav −p × n _out × sin θ _out = mλ The relationship is satisfied (see the above formula (5)). Here, λ is the wavelength of light in the air, and m is an integer.

From the above equation, θ _out = arcsin [(n _wav × sin θ _wav −mλ / p) / n _out ] is obtained. Therefore, in general, when the wavelength λ is different, the emission angle θ _{out of the} light subjected to the emission enhancement is different. As a result, as schematically shown in FIG. 31, the color of the visible light differs depending on the direction of observation.

In order to reduce the viewing angle dependency, n _wav and n _out may be selected so that (n _wav × sin θ _wav −mλ / p) / n _out is constant regardless of the wavelength λ. Since the refractive index of the material has wavelength dispersion (wavelength dependence), the wavelength of n _wav and n _out such that (n _wav × sin θ _wav −mλ / p) / n _out does not depend on the wavelength λ. A material having dispersibility may be selected. For example, when the external medium is air, n _out is approximately 1.0 regardless of the wavelength. Therefore, as a material for forming the photoluminescence layer 110 and the one-dimensional periodic structure 120, a material having a small wavelength dispersion of the refractive index n _wav. It is desirable to select. Furthermore, a reverse dispersion material is preferable in which the refractive index is low for light having a shorter refractive index n _wav .

  Also, as shown in FIG. 32A, white light can be emitted by arranging a plurality of periodic structures having different wavelengths that exhibit a light emission enhancement effect. In the example shown in FIG. 32A, a periodic structure 120r that can enhance red light (R), a periodic structure 120g that can enhance green light (G), and a periodic structure 120b that can enhance blue light (B) are arranged in a matrix. Has been. The periodic structures 120r, 120g, and 120b are, for example, one-dimensional periodic structures, and the convex portions are arranged in parallel to each other. Therefore, the polarization characteristics are the same for all colors of red, green, and blue. By the periodic structures 120r, 120g, and 120b, the light of the three primary colors that has received light emission enhancement is emitted and mixed, resulting in white light and linearly polarized light.

  When the periodic structures 120r, 120g, and 120b arranged in a matrix are called unit periodic structures (or pixels), the size of the unit periodic structure (that is, the length of one side) is, for example, three times or more of the period. is there. In order to obtain a mixed color effect, it is desirable that the unit periodic structure is not recognized by the human eye. For example, the length of one side is preferably smaller than 1 mm. Here, although each unit periodic structure is drawn in the square, it is not restricted to this, For example, the periodic structures 120r, 120g, and 120b which adjoin each other may be shapes other than squares, such as a rectangle, a triangle, and a hexagon.

  In addition, the photoluminescence layer provided under the periodic structures 120r, 120g, and 120b may be common to the periodic structures 120r, 120g, and 120b, or different photoluminescence materials corresponding to light of the respective colors. A photoluminescence layer may be provided.

  As shown in FIG. 32B, a plurality of periodic structures (including periodic structures 120h, 120i, and 120j) having different orientations in which the convex portions of the one-dimensional periodic structure extend may be arranged. The wavelengths of light with which a plurality of periodic structures enhance light emission may be the same or different. For example, when the same periodic structure is arranged as shown in FIG. 32B, unpolarized light can be obtained. Further, when the arrangement of FIG. 32B is applied to each of the periodic structures 120r, 120g, and 120b in FIG. 32A, unpolarized white light can be obtained as a whole.

  Of course, the periodic structure is not limited to a one-dimensional periodic structure, and a plurality of two-dimensional periodic structures (including periodic structures 120k, 120m, and 120n) may be arranged as shown in FIG. 32C. At this time, as described above, the periods and orientations of the periodic structures 120k, 120m, and 120n may be the same as or different from each other, and may be set as necessary.

  As shown in FIG. 33, for example, an array of microlenses 130 may be arranged on the light emission side of the light emitting element. By using the array of microlenses 130 to bend light emitted in an oblique direction in the normal direction, a color mixing effect can be obtained.

  The light-emitting element shown in FIG. 33 has regions R1, R2, and R3 having the periodic structures 120r, 120g, and 120b in FIG. 32A, respectively. In the region R1, the red light R is emitted in the normal direction by the periodic structure 120r, for example, the green light G is emitted in an oblique direction. The green light G emitted in the oblique direction is bent in the normal direction by the refraction action of the microlens 130. As a result, in the normal direction, the red light R and the green light G are mixed and observed. Thus, by providing the microlens 130, the phenomenon that the wavelength of the emitted light differs depending on the angle is suppressed. Here, a microlens array in which a plurality of microlenses corresponding to a plurality of periodic structures are integrated is illustrated, but the present invention is not limited to this. Of course, the periodic structure to be tiled is not limited to the above example, and can be applied to the case where the same periodic structure is tiled, and can also be applied to the configuration shown in FIG. 32B or 32C.

  The optical element having an action of bending light emitted in an oblique direction may be a lenticular lens instead of the microlens array. In addition to a lens, a prism can also be used. An array of prisms may be used. You may arrange | position a prism separately corresponding to a periodic structure. The shape of the prism is not particularly limited. For example, a triangular prism or a pyramid prism can be used.

  A method for obtaining white light (or light having a wide spectral width) is not only based on the above-described periodic structure but also based on a photoluminescence layer as shown in FIGS. 34A and 34B, for example. As shown in FIG. 34A, white light can be obtained by stacking a plurality of photoluminescence layers 110b, 110g, and 110r having different emission wavelengths. The stacking order is not limited to the illustrated example. As shown in FIG. 34B, a photoluminescence layer 110y that emits yellow light may be stacked on the photoluminescence layer 110b that emits blue light. The photoluminescence layer 110y can be formed using, for example, YAG.

  In addition, when using a photoluminescent material that is mixed with a matrix (host) material such as a fluorescent dye, a plurality of photoluminescent materials having different emission wavelengths are mixed with the matrix material, and a single photoluminescent layer is used. White light can be emitted. Such a photoluminescence layer capable of emitting white light can be used in the configuration in which the unit periodic structure is tiled as described with reference to FIGS. 32A to 32C.

  When an inorganic material (for example, YAG) is used as a material for forming the photoluminescence layer 110, heat treatment exceeding 1000 ° C. may be performed in the manufacturing process. At that time, impurities may diffuse from the base (typically the substrate), and the light emission characteristics of the photoluminescence layer 110 may be deteriorated. In order to prevent impurities from diffusing into the photoluminescence layer, for example, as shown in FIGS. 35A to 35D, a diffusion prevention layer (barrier layer) 108 may be provided under the photoluminescence layer. As shown in FIGS. 35A to 35D, the diffusion prevention layer 108 is formed under the photoluminescence layer 110 in various configurations exemplified so far.

For example, as illustrated in FIG. 35A, the diffusion prevention layer 108 is formed between the substrate 140 and the photoluminescence layer 110. In addition, as shown in FIG. 35B, in the case of having a plurality of photoluminescence layers 110a and 110b , diffusion preventing layers 108a or 108b are formed in the lower layers of the photoluminescence layers 110a and 110b, respectively.

  When the refractive index of the substrate 140 is larger than the refractive index of the photoluminescence layer 110, the low refractive index layer 107 may be formed on the substrate 140 as shown in FIGS. 35C and 35D. As shown in FIG. 35C, when the low refractive index layer 107 is provided on the substrate 140, the diffusion preventing layer 108 between the low refractive index layer 107 and the photoluminescence layer 110 is formed. Furthermore, as shown in FIG. 35D, in the case of having a plurality of photoluminescence layers 110a and 100b, diffusion preventing layers 108a and 108b are formed under the photoluminescence layers 110a and 110b, respectively.

The low refractive index layer 107 is formed when the refractive index of the substrate 140 is equal to or larger than the refractive index of the photoluminescence layer 110. The refractive index of the low refractive index layer 107 is lower than the refractive index of the photoluminescence layer 110. The low refractive index layer 107 is, for example, MgF ₂ ,
LiF, CaF ₂ , BaF ₂ , SrF ₂ , quartz, resin, and room temperature curable glass such as HSQ · SOG are used. The thickness of the low refractive index layer 107 is desirably larger than the wavelength of light. The substrate 140 is, for example, MgF ₂ , LiF, CaF ₂ , BaF ₂ , SrF ₂ , glass, resin, MgO, MgAl ₂ O ₄ , sapphire (Al ₂ O ₃ ), SrTiO ₃ , LaAlO ₃ , TiO ₂ , Gd _3. Ga ₅ O ₁₂ , LaSrAlO ₄ , LaSrGaO ₄ , LaTaO ₃ , SrO, YSZ (ZrO ₂ .Y ₂ O ₃ ), YAG, Tb ₃ Ga ₅ O ₁₂ are used.

  The diffusion prevention layers 108, 108a, and 108b may be suitably selected depending on the element to be prevented from diffusion, and can be formed using, for example, an oxide crystal or nitride crystal having strong covalent bond. The thickness of the diffusion preventing layers 108, 108a, 108b is, for example, 50 nm or less.

In a structure having a layer adjacent to the photoluminescence layer 110 such as the diffusion prevention layer 108 or the crystal growth layer 106 described later, when the refractive index of the adjacent layer is larger than the refractive index of the photoluminescence layer, Let n _{wav be the} average refractive index obtained by weighting the refractive index of the layer having a large refractive index and the refractive index of the photoluminescence layer by the respective volume ratios. This is because this is optically equivalent to the case where the photoluminescence layer is composed of a plurality of layers of different materials.

  In addition, in the photoluminescence layer 110 formed using an inorganic material, the light emission characteristics of the photoluminescence layer 110 may be low because the crystallinity of the inorganic material is low. In order to enhance the crystallinity of the inorganic material constituting the photoluminescence layer 110, a crystal growth layer (also referred to as “seed layer”) 106 is formed on the base of the photoluminescence layer 110 as shown in FIG. 36A. May be. The crystal growth layer 106 is formed using a material that lattice-matches with the crystal of the photoluminescence layer 110 formed thereon. The lattice matching is desirably within ± 5%, for example. When the refractive index of the substrate 140 is larger than the refractive index of the photoluminescence layer 110, it is desirable that the refractive index of the crystal growth layer 106 or 106 a is smaller than the refractive index of the photoluminescence layer 110.

  When the refractive index of the substrate 140 is larger than the refractive index of the photoluminescence layer 110, a low refractive index layer 107 may be formed on the substrate 140 as shown in FIG. 36B. Since the crystal growth layer 106 is in contact with the photoluminescence layer 110, when the low refractive index layer 107 is formed on the substrate 140, the crystal growth layer 106 is formed on the low refractive index layer 107. As shown in FIG. 36C, in the configuration having a plurality of photoluminescence layers 110a and 110b, it is desirable to form crystal growth layers 106a or 106b corresponding to the plurality of photoluminescence layers 110a and 110b, respectively. The thickness of the crystal growth layers 106, 106a and 106b is, for example, 50 nm or less.

  As shown in FIGS. 37A and 37B, a surface protective layer 132 may be provided to protect the periodic structure 120.

  As shown in FIG. 37A, the surface protective layer 132 is also provided for a type having no substrate, as shown in FIG. 37B. In the light-emitting element that does not include the substrate illustrated in FIG. 37A, a surface protective layer may be provided below the photoluminescence layer 110. Thus, the surface protective layer 132 may be provided on the surface of any of the light-emitting elements described above. The periodic structure 120 is not limited to those illustrated in FIGS. 37A and 37B, and may be any type described above.

The surface protective layer 132 can be formed using, for example, a resin, a hard coat material, SiO ₂ , Al ₂ O ₃ (alumina), SiOC, or DLC. The thickness of the surface protective layer 132 is, for example, 100 nm to 10 μm.

  By providing the surface protective layer 132, the light-emitting element can be protected from the external environment and deterioration of the light-emitting element can be suppressed. The surface protective layer 132 protects the surface of the light emitting element from scratches, moisture, oxygen, acid, alkali, or heat. The material and thickness of the surface protective layer 132 can be appropriately set according to the application.

  In addition, the photoluminescent material may be deteriorated by heat. Heat is generated mainly by non-radiation loss or Stokes loss of the photoluminescence layer 110. For example, the thermal conductivity of quartz (1.6 W / m · K) is about an order of magnitude smaller than that of YAG (11.4 W / m · K). Therefore, heat generated in the photoluminescence layer (for example, YAG layer) 110 is not easily dissipated through heat conduction to the outside through the substrate (for example, quartz substrate) 140, and the temperature of the photoluminescence layer 110 is increased, which may cause thermal degradation. is there.

  Therefore, as shown in FIG. 38A, by forming the transparent high thermal conductive layer 105 between the photoluminescent layer 110 and the substrate 140, the heat of the photoluminescent layer 110 is efficiently conducted to the outside and the temperature rise is prevented. be able to. At this time, the refractive index of the transparent high thermal conductive layer 105 is desirably lower than the refractive index of the photoluminescence layer 110. When the refractive index of the substrate 140 is lower than the refractive index of the photoluminescence layer 110, the refractive index of the transparent high thermal conductive layer 105 may be higher than the refractive index of the photoluminescence layer 110. However, in this case, since the transparent high thermal conductive layer 105 forms a waveguide layer together with the photoluminescence layer 110, it is desirable that the thickness be 50 nm or less. As shown in FIG. 38B, if the low refractive index layer 107 is formed between the photoluminescence layer 110 and the transparent high thermal conductive layer 105, the thick transparent high thermal conductive layer 105 can be used.

  Further, as shown in FIG. 38C, the periodic structure 120 may be covered with a low refractive index layer 107 having high thermal conductivity. Furthermore, as shown in FIG. 38D, the transparent high thermal conductive layer 105 may be formed after the periodic structure 120 is covered with the low refractive index layer 107. In this configuration, the low refractive index layer 107 does not need to have a high thermal conductivity.

Examples of the material for the transparent high thermal conductive layer 105 include Al ₂ O ₃ , MgO, Si ₃ N ₄ , ZnO, AlN, Y ₂ O ₃ , diamond, graphene, CaF ₂ , and BaF ₂ . Of these, CaF ₂ and BaF ₂ have a low refractive index and can be used as the low refractive index layer 107.

  Next, with reference to FIGS. 39A to 39D, a structure with improved heat dissipation characteristics of a light emitting device including the light emitting element 100 and the light source 180 will be described.

  The light emitting device illustrated in FIG. 39A includes an LED chip 180 as the light source 180 and the light emitting element 100. The light emitting element 100 may be any type described above. The LED chip 180 is mounted on the support substrate 190, and the light emitting element 100 is disposed at a predetermined interval from the LED chip. The light emitting element 100 receives the excitation light emitted from the LED chip and emits light. On the support substrate 190, the LED chip 180 and the light emitting element 100 are covered with a sealing portion 142.

The sealing portion 142 has high thermal conductivity and translucency. The material for forming the sealing portion 142 (sometimes referred to as “sealing material”) is, for example, a composite material including a highly thermally conductive filler and a resin material. Examples of the high thermal conductive filler include Al ₂ O ₃ , ZnO, Y ₂ O ₃ , graphene, and AlN. Moreover, as a resin material, an epoxy resin and a silicone resin can be illustrated. In particular, as the sealing material, a nanocomposite material using a nanometer size (that is, a submicron size) of the high thermal conductive filler can be used. When a nanocomposite material is used, diffuse reflection (or scattering) of light can be suppressed. Examples of the nanocomposite material include those using ZnO or Al ₂ O ₃ as a filler and an epoxy resin or a silicone resin as a resin.

  When the light emitting element 100 is of a type in which the periodic structure is exposed on the surface as illustrated in FIG. 39A, the refractive index of the medium around the periodic structure is lower than the refractive index of the periodic structure. Is desirable. That is, the refractive index of the sealing portion 142 is lower than the refractive index of the light-transmitting layer when the periodic structure is formed of the light-transmitting layer, and the periodic structure is formed of the same material as the photoluminescence layer. Is preferably lower than the refractive index of the photoluminescence layer.

  As illustrated in FIG. 39B, the sealing portion 142 may be provided so as to expose the vicinity of the surface of the light-emitting element 100 (for example, a light-transmitting layer or a photoluminescence layer having a periodic structure). At this time, the refractive index of the sealing portion 142 is not particularly limited.

  As shown in FIG. 39C, when the light emitting element 100 is of a type in which the periodic structure is covered with the low refractive index layer 107 (see FIG. 38C), the refractive index of the sealing portion 142 is It may be higher than the refractive index of the periodic structure. By adopting such a configuration, the material selection range of the sealing portion 142 is expanded.

Further, as shown in FIG. 39D, the periphery of the light emitting element 100 may be fixed to a holder 152 having high thermal conductivity. The holder 152 can be made of metal, for example. For example, when the sealing material cannot be filled between the light emitting element 100 and the light source as in the case where the laser diode 182 is used as the light source, the above structure can be suitably used. For example, since the light emitting device 100 having the configuration illustrated in FIGS. 38A to 38D includes the transparent high thermal conductive layer 105 or the low refractive index layer 107 having high thermal conductivity, the thermal conductivity in the plane of the device is high. Heat can be radiated through the holder 152 effectively.

As illustrated in FIGS. 40A to 40D, a high thermal conductive member 144 or 146 may be disposed on the surface of the light emitting element 100. The high heat conductive member 144 or 146 is made of metal, for example.

  For example, as shown in a cross-sectional view in FIG. 40A and a plan view in FIG. 40B, the high thermal conductive member 144 may be disposed so as to cover a part of the periodic structure 120 of the light emitting element 100. Although FIG. 40A and 40B show the linear high heat conductive member 144 that covers only one of the plurality of convex portions forming the one-dimensional periodic structure, the present invention is not limited to this.

  Further, as shown in a sectional view in FIG. 40C and a plan view in FIG. 40D, a high thermal conductive member 146 is formed so as to cover the convex portions at both ends of the periodic structure 120 of the light emitting element 100 and the end face of the photoluminescence layer 110 May be. In any case, if the area of the portion covered with the high thermal conductive member 146 in the periodic structure and the photoluminescence layer is increased, the characteristics of the light emitting element 100 may be affected. The area of the member 146 should be small.

  In addition, as shown in a cross-sectional view in FIG. 41A and a plan view in FIG. 41B, when a plurality of light-emitting elements 100r, 100g, and 100b having different structures are tiled, light emission between adjacent light-emitting elements is performed. The high heat conductive member 148 may be disposed so as to cover the end portion of the element. For example, as illustrated here, when arranging a light emitting element 100r that enhances red light, 100g that enhances green light, and 100b that enhances blue light, for example, a high heat conductive member 148 made of metal is adjacent. When arranged between the light emitting elements, the high thermal conductive member 148 has a light shielding property, so that color mixing can be suppressed. As described above, the high thermal conductivity member 148 can be used like a black matrix in a display panel.

  42A and 42B show an example of a light emitting device including an interlock circuit 185. FIG. 42A is a schematic diagram illustrating the back surface of the light emitting element 100, and FIG. 42B is a schematic diagram of the light emitting device including a cross-sectional view of the light emitting element 100. FIG. As shown in FIGS. 42A and 42B, an annular wiring 172 is formed on the back surface of the substrate 140 included in the light emitting element 100. The annular wiring 172 is formed in the vicinity of the outer periphery of the back surface of the light emitting element 100, and is formed so as to be disconnected when the substrate 140 is damaged. The annular wiring 172 is made of, for example, a metal material. Two ends of the annular wiring 172 are electrically connected to the relay circuit of the interlock circuit 185. When the disconnection occurs in the annular wiring 172, the relay circuit cuts off the power supply to the light source 182. In particular, when the light source 182 emits strong light such as a laser diode, it is desirable to provide an interlock circuit 185 from the viewpoint of safety and the like.

  The submicron structure included in the light emitting element of the above-described embodiment is, for example, a periodic structure, and can be formed using a photolithography technique or a nanoprint technique. With reference to FIGS. 43A to 43F, another method of forming a submicron structure will be described.

  As shown in FIG. 43A, beads 122 are arranged on the surface of the photoluminescence layer 110 supported by the substrate 140. The beads 122 can be fixed to the photoluminescence layer 110 by evenly embedding a part of the beads 122 in the photoluminescence layer 110. In this way, when a part of each of the large number of beads 122 is evenly embedded in the photoluminescence layer 110 and the remaining part protrudes from the photoluminescence layer 110, the refractive index of the beads 122 has the photoluminescence layer 110. The refractive index may be equal to or smaller. For example, when the refractive index of the beads 122 is smaller than the refractive index of the photoluminescence layer 110, a layer formed by a large number of beads 122 (both a portion protruding from the photoluminescence layer 110 and an embedded portion) is submicron. It functions as the light-transmitting layer 120 having a structure. When the refractive index of the bead 122 is equal to the refractive index of the photoluminescence layer 110, the bead 122 and the photoluminescence layer 110 are substantially integrated, and a portion protruding from the photoluminescence layer 110 has a submicron structure. It functions as the optical layer 120.

  Alternatively, as shown in FIG. 43B, the photoluminescence layer 110 may be formed on a substrate 140 after arranging a large number of beads 122. At this time, the refractive index of the beads 122 is preferably lower than the refractive index of the photoluminescence layer 110.

Here, the diameter of the bead 122 is, for example, equal to or smaller than the above-mentioned D _int . When the beads 122 are densely packed, the diameter of the beads 122 substantially coincides with _Dint . When a gap is formed between adjacent beads 122, the length obtained by adding the gap to the diameter of the bead 122 corresponds to _Dint .

  Further, the beads 122 may be hollow beads or solid beads.

  FIGS. 43C to 43F are diagrams schematically showing the filled state of various beads and light scattering patterns obtained from the filled beads. 43C to 43F, black portions indicate solid portions in solid beads or hollow beads, and white portions indicate void portions in hollow beads or hollow beads.

  FIG. 43C shows a state in which hollow beads having an oval outer shape are densely packed and a light scattering pattern thereof. The hollow portion of the hollow bead is substantially spherical and is formed at the bottom of the egg. FIG. 43D shows a state in which hollow beads having a substantially spherical outer shape are closely packed and a light scattering pattern thereof. The hollow portion of the hollow bead is substantially spherical and is formed so as to be in contact with the outer sphere. FIG. 43E shows a state in which hollow beads having a substantially spherical outer shape are closely packed and a light scattering pattern thereof. The void portion of the hollow bead includes two substantially spherical voids, and the two spherical voids are arranged along the diameter of the outer sphere. FIG. 43F shows a state in which hollow beads having a substantially spherical outer shape and solid beads having a substantially spherical outer shape are closely packed, and the light scattering pattern. Hollow beads and solid beads have approximately the same diameter and are mixed in approximately the same volume ratio. Further, the arrangement of the hollow beads and the solid beads is not regular and is almost random.

  As hollow beads and solid beads, those made of various kinds of glass or resin are commercially available. The beads exemplified here are, for example, alumina powder that is widely marketed as an abrasive material, hollow silica manufactured by Nittetsu Mining Co., Ltd., etc., a dispersant is added to the obtained beads, and a solvent (for example, water or In this case, a layer in which a large number of beads are densely packed can be formed by applying the dispersion liquid onto the substrate 140 or the photoluminescence layer 110 and drying the dispersion liquid.

[ 11 . Application example]
As described above, the light-emitting element of the present disclosure and the light-emitting device including the light-emitting element have various advantages. Therefore, when applied to various optical devices, advantageous effects can be obtained. Examples of applications are given below.

[11 -1. Display device]
The light-emitting element of the present disclosure can emit light having high directivity in a specific direction. This high directivity is suitably used, for example, as an edge light type backlight using a light guide plate of a liquid crystal display device. In a conventional display device using a light source with low directivity, it is necessary to introduce light emitted from the light source into the light guide plate using a reflector and / or a diffusing material. On the other hand, in the display device using the light source in the embodiment of the present disclosure having high directivity in a specific direction, light can be efficiently introduced into the light guide plate even if these optical components are omitted or simplified.

FIG. 44 is a perspective view schematically showing an example of such a display device. The display device 300 includes an excitation light source 310, a light emitting element 320 positioned on the optical path of the excitation light from the excitation light source 310, and an optical shutter 350 positioned on the optical path of the light from the light emitting element 320. In this embodiment, the display device 300 further includes a light guide plate 330 that propagates light from the light emitting element 320 to the optical shutter 350, and a color filter that is disposed on the side of the optical shutter 350 on which light from the light emitting element 320 is incident. And an array 340.

  The light emitting element 320 has a plurality of regions (R, G, B) that receive excitation light and emit light in the red, green, and blue wavelength bands in the normal direction of the photoluminescence layer. Although only six regions are depicted in FIG. 44, there may actually be more regions.

  Here, the wavelength bands of red, green, and blue are red: 600 to 750 nm, green: 490 to 570 nm, and blue: 430 nm to 470 nm, respectively.

  The light-emitting element 320 is formed on at least one of the photoluminescence layer that emits light by excitation light, the light-transmitting layer disposed in the vicinity of the photoluminescence layer, and the photoluminescence layer and the light-transmitting layer, as in the above-described embodiments. And a submicron structure extending in the plane of the photoluminescence layer or the light transmission layer. Here, “proximity” includes direct contact. A periodic structure of each region of R, G, and B is formed by at least one of the plurality of convex portions and the plurality of concave portions in the submicron structure.

The light emitted from the photoluminescence layer includes a first light having _a wavelength λ _a in the air, a second light having a wavelength λ _b in the air, and a third light having a wavelength λ _c in the air. Including. λ _a , λ _b , and λ _c belong to the red, green, and blue wavelength bands, respectively. In the region R, the refractive index of the photoluminescence layer to the first light and n _wav-a, when the period of the periodic structure and _{p a, λ a / n wav} -a <p a <λ relationship _a holds. In the region G, the relationship of λ _b / n _wav-b <p _b <λ _b is established, where n _wav-b is the refractive index of the photoluminescence layer for the second light and p _b is the period of the periodic structure. In the region B, when the refractive index of the photoluminescence layer with respect to the third light is n _wav-c and the period of the periodic structure is p _c , the relationship of λ _c / n _wav-c <p _c <λ _c is established.

  The light guide plate 330 is disposed so that light from the light emitting element 320 is incident on a side surface thereof. The light guide plate 330 has the same configuration as a general light guide plate used in an edge light type backlight. For example, the configuration of the light guide plate disclosed in JP-A-8-234200 can be employed. In such a configuration, a reflection plate is provided on one surface of the light guide plate 330 and a diffusion plate is provided on the other surface. While light propagates through the light guide plate 330, the light is emitted almost uniformly from the surface on the diffusion plate side.

  The color filter array 340 has a plurality of color filters arranged two-dimensionally. The plurality of color filters include three types of color filters that selectively transmit red, green, and blue light, respectively. A set of three color filters of red, green, and blue arranged close to each other is arranged in a lattice pattern. These sets correspond to one pixel, and one color filter corresponds to a sub-pixel. Note that the color filter array 340 is not limited to the light incident side of the optical shutter 350, and may be provided on the emission side. As in the example described later, the color filter array 340 may be provided inside the optical shutter 350.

  The optical shutter 350 is divided into a plurality of unit areas each corresponding to a sub-pixel. The light transmittance can be changed for each unit region. The optical shutter 350 can be realized by a liquid crystal module, for example.

  Hereinafter, an example of the optical shutter 350 using liquid crystal will be described. In the following example, the color filter array 340 is provided inside the optical shutter 350 (that is, the liquid crystal module).

FIG. 45 is a cross-sectional view schematically showing a configuration of a display device 300a having an optical shutter 350 realized by a liquid crystal module. The thickness and the mutual distance of each layer in FIG. 4. 5, it does not reflect the thickness and spacing of the reality. The same applies to other figures. The display device 300a further includes a drive circuit 360 that drives the optical shutter 350 according to an image signal. The optical shutter 350 in this example has a structure in which a polarizing filter 351, a transparent substrate 352, a transparent electrode 353, a liquid crystal layer 355, a transparent electrode 356, a color filter array 340, a transparent substrate 357, and a polarizing filter 358 are formed in this order. Have. The polarization transmission axis direction of the polarizing filter 351 close to the light guide plate 330 and the polarizing filter 358 far from the light guide plate 330 are shifted by 90 degrees. The two transparent electrodes 353 and 356 are electrically connected to the drive circuit 360. The voltage applied to the two transparent electrodes 353 and 356 by the drive circuit 360 is changed for each subpixel, thereby changing the orientation of the liquid crystal molecules in the liquid crystal layer 355. Thereby, the light transmittance is changed for each sub-pixel.

  If the light emitted from the light guide plate 330 is linearly polarized light, the polarizing filter 351 can be omitted. An alignment layer may be provided on both sides of the liquid crystal layer 355. The alignment layer aligns liquid crystal molecules in a specific direction when no voltage is applied to the liquid crystal layer 355.

  Next, the operation in this embodiment will be described.

  Excitation light emitted from the excitation light source 310 enters the photoluminescence layer in the light emitting element 320. The photoluminescence layer receives excitation light and generates light in the wavelength bands of red, green, and blue. The red, green, and blue lights are emitted from the periodic structures in the regions R, G, and B substantially perpendicularly and introduced into the light guide plate 330. The light introduced into the light guide plate 330 is mixed while being guided while being repeatedly reflected inside the light guide plate 330, and is emitted from one surface of the light guide plate 330 as substantially uniform white light. The light emitted from the light guide plate 330 is modulated in intensity for each sub-pixel by the optical shutter 350 and is emitted to the outside. As a result, an image corresponding to the image signal input to the drive circuit 360 is displayed.

  The display device in the present embodiment can be used for devices such as a television, a PC monitor, a smartphone, and a tablet terminal. When used for a device capable of touch input operation, such as a smartphone or a tablet terminal, the display device further includes a touch screen (or touch panel).

  FIG. 46 is a schematic perspective view showing an example of a display device 300b further provided with a touch screen 370. FIG. The touch screen 370 is provided on the light exit surface side of the optical shutter 350. The touch screen 370 detects contact of a finger or the like by a known method such as a capacitance method.

  Next, another embodiment of the display device will be described.

  FIG. 47 is a schematic cross-sectional view showing a part of the configuration of the display device 300 c in which the light guide plate 330 is arranged to propagate the excitation light from the excitation light source 310 to the photoluminescence layer 321. In the display device 300 c, the excitation light emitted from the excitation light source 310 is incident on the photoluminescence layer 321 substantially uniformly while propagating through the light guide plate 330. The photoluminescence layer 321 and the submicron structure 322 formed on the surface thereof are designed to emit white light substantially perpendicular to the photoluminescence layer 321. For this reason, the submicron structure 322 has one of the structures described with reference to FIGS. For example, it has a structure in which a plurality of unit periodic structures are tiling, or a structure in which three photoluminescence layers respectively corresponding to three colors of R, G, and B are stacked. In a structure in which a plurality of unit periodic structures are tiled, the size of each unit periodic structure is smaller than the size of the sub-pixel.

  In the present embodiment, a color filter array 340 is provided between the optical shutter 350 and the polarizing filter 358. As described above, the color filter array 340 may be provided on the light incident side of the optical shutter 350 or inside the optical shutter 350.

  The submicron structure 322 in the present embodiment is a one-dimensional periodic structure. Therefore, the light emitted from each unit periodic structure is linearly polarized light. For this reason, a polarizing filter is not provided between the light emitting element 320 and the optical shutter 350. When the submicron structure 322 is a two-dimensional periodic structure, a polarizing filter is necessary.

  White light emitted from the light emitting element 320 passes through the optical shutter 350, the color filter array 340, and the polarization filter 358. As in the previous embodiment, the optical shutter 350 changes the light transmittance for each sub-pixel according to the image signal. Thereby, an image is displayed.

  FIG. 48 is a schematic perspective view showing still another embodiment of the display device. The display device 300d has a structure in which the color filter array 340 is removed from the embodiment shown in FIG. In this embodiment, light of each color emitted from the light emitting element 320 propagates through the light guide plate 330 so as not to be mixed with light of other colors, and enters the optical shutter 350 almost uniformly regardless of the position in the propagation direction. To do. Although simplified in FIG. 48, each region of R, G, and B (that is, a unit periodic structure) is fine, and the number of each region is the number of pixels in one direction of the displayed image (for example, Tens to tens of thousands). When the size of one unit periodic structure is, for example, 100 μm and the number of pixels in one direction of the image is, for example, 1000, the length of the arrangement of all unit periodic structures is about 0.3 m (= 100 μm × 3 × 1000). It can be. The size and number of the R, G, and B regions in the light-emitting element 320 are not limited to this example, and are appropriately determined according to the definition of the displayed image and the difficulty level of manufacturing. The optical shutter 350 changes the light transmittance for each sub-pixel according to the image signal, as in the embodiment described above. Thereby, a color image can be displayed without using the color filter array 340.

  FIG. 49 is a schematic cross-sectional view showing a part of still another embodiment of the display device. The display device 300e in this embodiment has a structure in which the color filter array 340 is removed from the display device 300c shown in FIG. Further, the submicron structure 322 includes a periodic structure 322R that emits light in the red wavelength band in a substantially vertical direction, a periodic structure 322G that emits light in the green wavelength band in a substantially vertical direction, and light in the blue wavelength band. And a periodic structure 322B that emits substantially vertically. The three types of periodic structures 322R, 322G, and 322B are repeatedly arranged in order in one direction. The adjacent regions of the three periodic structures 322R, 322G, and 322B correspond to one pixel, and the region of each periodic structure corresponds to one subpixel.

  The optical shutter 350 changes the intensity of light emitted from each sub-pixel by changing the light transmittance for each sub-pixel. With such a structure, the same color display as that of the display device 300c shown in FIG. 47 can be performed without providing the color filter array 340.

In this embodiment, the photoluminescence layer 321 emits red light in the region corresponding to the periodic structure 322R, emits green light in the region corresponding to the periodic structure 322G, and blue in the region corresponding to the periodic structure 322B. The light may be emitted. That is, the light emitting material may be changed for each of these regions. In the case where the excitation light source 310 emits excitation light in the blue wavelength band, the photoluminescence layer 321 may be made of a light emitting material that emits light in the red and green (that is, yellow) wavelength bands. Examples of such a light emitting material include YAG such as Y ₃ Al ₅ O ₁₂ : Ce ³⁺ .

  According to the display device as described above, it is possible to omit or simplify an optical component such as a reflector or a diffusing material required when a conventional light source with low directivity is used. In addition, the conventional color filter absorbs unnecessary light from white light, thereby transmitting desired blue, green, and red light, resulting in loss. On the other hand, since this method generates only the light of the necessary color, the loss can be reduced. As a result, it is possible to reduce the size and power consumption of the display device.

[11 -2. Lighting (light emission) device]
The light-emitting element of the present disclosure can also be used for an illumination (or light-emitting) device. Conventional lighting fixtures use optical components including lenses and / or reflectors to guide isotropically emitted light in a desired direction. On the other hand, these can be omitted by using the light emitting element of the present disclosure. Alternatively, a complicated design for isotropic light can be replaced with a simple design for light with high directivity. As a result, the luminaire can be downsized or the design process can be simplified. Hereinafter, an example of such an illumination device will be described.

  FIG. 50 is a perspective view schematically showing an example of a lighting device. The illumination device 400 includes an excitation light source 310, a light emitting element 320 positioned on the optical path of excitation light from the excitation light source 310, and a light guide plate 330 that takes in the light from the light emitting element 320 and radiates it to the outside. The light guide plate 330 is arranged so that the light emitted from the light emitting element 320 is incident on the side surface thereof.

  As already described, the light emitting element 320 has a plurality of regions that emit light of each wavelength band of red, green, and blue. Although simplified in FIG. 50, each region is actually fine and can be designed to emit almost white light macroscopically. As the configuration for emitting white light, the above-described other configuration such as a laminated structure may be adopted. Or you may make it radiate | emit the light of colors other than white (for example, red, green, or blue) by changing the structure of a photo-luminescence layer or a submicron structure. In an application in which only narrow-band monochromatic light is emitted in a direction perpendicular to the photoluminescence layer, the submicron structure may have only one periodic structure. The structure of the light guide plate 330 is the same as that already described.

  Light emitted from the light emitting element 320 is emitted from one surface while propagating through the light guide plate 330. This emitted light can be used as illumination.

  FIG. 51 is a partial cross-sectional view schematically showing another example of the illumination device. The illuminating device 400a is positioned on the optical path of the excitation light source 310, the light guide plate 330 that is arranged to take in the excitation light from the excitation light source 310 and emit it to the outside, and the excitation light emitted from the light guide plate 330. A light emitting element 320.

  The excitation light emitted from the excitation light source 310 is emitted almost uniformly from one surface of the light guide plate 330 while propagating through the light guide plate 330. The emitted excitation light is incident on the photoluminescence layer 321. The photoluminescence layer 321 in the light emitting element 320 emits light by excitation light. The photoluminescence layer 321 and the submicron structure 322 emit white light with any of the above-described configurations. This emitted light can be used as illumination. Also in this embodiment, light of a color other than white (for example, red, green, or blue) may be emitted by changing the configuration of the photoluminescence layer or the submicron structure.

  FIG. 52 is a cross-sectional view illustrating another example of the lighting device according to the present disclosure. The illumination device 400b includes a heat dissipation substrate 420, two light emitting elements 320 fixed to the heat dissipation substrate 420, and a reflection mirror 410 surrounding the light emitting element 320. Each of the two light emitting elements 320 has the same configuration as the light emitting element in any of the embodiments described above. The heat dissipation substrate 420 supports the light emitting element 320 and the reflection mirror 410 and releases heat generated from the light emitting element 320 to the outside.

  The light generated from the two light emitting elements 320 is reflected by the reflecting mirror 410 having a concave surface and emitted to the outside. As described above, the light emitting element 320 and the reflection mirror 410 may be combined.

  The configuration of the light-emitting device using the reflection mirror is not limited to the above. Since the light emitted from the light emitting element has directivity, the area of the reflecting mirror can be reduced. For example, you may employ | adopt the structure of the other reflective mirror disclosed by the special table 2013-533583 gazette, the special table 2009-535775 gazette, or the special table 2005-537665 gazette.

  The heat dissipation mechanism that releases heat generated from the light emitting element 320 to the outside can have various configurations other than the above configuration. For example, as disclosed in JP 2014-146509 A, a heat dissipating member provided so as to cover a part of a reflecting mirror provided around the light emitting element may be used.

  The light source of the illumination device according to the present disclosure may be mounted on a printed board. For example, the light emitting element of the present disclosure may be used instead of the LED chip in the LED casing disclosed in JP 2010-537437 A. Or you may use the light emitting element of this indication instead of the LED element in the polarized LED module currently disclosed by Unexamined-Japanese-Patent No. 2014-183192.

  A plurality of light emitting elements can be arranged to realize high-luminance illumination. For example, as described in Japanese Patent Application Laid-Open No. 2011-181429, an illumination device provided with 10 or more LEDs may be used to realize illumination with high luminance by arranging 10 or more light emitting elements.

  FIG. 53 is a cross-sectional view showing a configuration example of such an illumination device 400c. The illumination device 400 c includes a circuit board 430, a plurality of light emitting elements 320 formed thereon, a concave reflecting mirror 410, a diffusion plate 440 formed inside the reflecting mirror 410, and the reflecting mirror 410. And a lens 450 provided at the outer edge. Each of the plurality of light emitting elements 320 has the same configuration as any of the light emitting elements described above. In general, the light incident on the lens near the central axis has a small incident angle and is easy to design. Since the emitted light can be made near the central axis by the directional light emission, the optical design can be facilitated.

  Light emitted from the plurality of light emitting elements 320 is diffused by the diffusion plate 440 and reaches the lens 450. The lens 450 refracts the light reaching the lens and emits the light over a wide range.

  In addition to the above, the configuration using the lens may employ, for example, the configuration disclosed in Japanese Patent No. 4632899. A plurality of lenses may be combined as disclosed in JP 2012-059575 A. As disclosed in Japanese Patent No. 4523100, another configuration in which a reflector and a lens are combined may be employed.

  The light emitting element of this indication is applicable also to a headlight for vehicles. For example, the present invention can be applied to a headlight capable of light distribution control by a micromirror as disclosed in JP 2013-526759 A.

  FIG. 54 is a diagram showing a schematic configuration of such an illumination device (headlight) 400d. The illumination device 400d includes an excitation light source 310, a light emitting element 320, a lens 450, and a micromirror 460. A driving circuit (not shown) is connected to the micromirror 460.

  Excitation light emitted from the excitation light source 310 is reflected by the micromirror 460 and enters a specific position of the light emitting element 320. At that position of the light emitting element 320, light emission occurs, and light of a specific color is emitted in a direction perpendicular to the photoluminescence layer. This light is focused by the lens 450 and illuminates the outside.

  The micromirror 460 can be rotated around a specific axis (for example, a horizontal axis) by a drive circuit. By this rotation, the position of the light emitting element 320 to which the excitation light reaches can be changed.

  The configuration of this embodiment can be used for switching between a high beam and a low beam, for example. When combined with a sensor (not shown), for example, it is possible to automatically perform control such as switching to a high beam when no person or vehicle is present ahead, and switching to a low beam when a person or vehicle is present ahead. Alternatively, when there is a person in front, it is possible to control the excitation light source 310 to automatically stop and turn off the illumination.

  As described above, according to the illumination device of the present disclosure, it is possible to omit or simplify an optical component for guiding isotropically emitted light in a desired direction. For this reason, it is possible to reduce the size of the lighting fixture or simplify the design process.

  In the field of lighting, techniques of chromatic color illumination and beautiful color illumination have been developed. These make the color of the object to be illuminated beautifully. The chromatic color illumination has an effect of making food such as vegetables look more delicious, and the beautiful color illumination has an effect of making the skin look more beautiful. These are all performed by controlling the spectrum of the light source (that is, the intensity distribution of the wavelength of the emitted light) according to the object. Conventionally, the spectrum of light used for illumination has been controlled by selectively transmitting light emitted from a light source using an optical filter. That is, unnecessary light is absorbed by the optical filter, which reduces the light use efficiency. On the other hand, since the light emitting element of this indication can reinforce the light of a specific wavelength, an optical filter is not required, As a result, the utilization efficiency of light can be improved.

  The light-emitting element of the present disclosure can emit polarized light (linearly polarized light). Conventionally, linearly polarized light has been produced by absorbing one of two orthogonal linearly polarized light components constituting non-polarized light emitted from a light source using a polarizing filter (also referred to as “polarizing plate”). Therefore, the utilization efficiency of light was 50% or less. If the light-emitting element of the present disclosure is used as a polarized light source, it is not necessary to use a polarizing filter, so that the light use efficiency can be improved. Polarized illumination is used, for example, when it is desired to reduce reflected light, such as a show window or a window glass of an observation restaurant. Further, it is used for facilitating observation of a lesioned part with an endoscope, and also for illumination for washing and makeup utilizing the fact that the reflection characteristic of the skin surface depends on polarization.

[11 -3. Projector light source]
In various optical devices, it is necessary to efficiently guide light from a light source in a predetermined direction. Therefore, as described above, for example, a lens, a prism, or a reflector is often used. For example, in a projector, a configuration in which a light guide is used to guide light from a light source to a display panel is known (for example, JP 2010-156929 A). By using the light emitting element of the present disclosure as a light source, the light guide can be omitted.

  The polarized light source can also be used as a light source for a liquid crystal projector. When used as a light source of a liquid crystal projector, a light source capable of emitting polarized light of three primary colors can be configured in combination with the above-described wavelength selectivity. For example, a light emitting element that emits red linearly polarized light, a light emitting element that emits green linearly polarized light, and a light emitting element that emits blue linearly polarized light are connected to form a disk, and this disk is irradiated with excitation light. However, a light source that emits polarized light of the three primary colors of red, green, and blue in time series can be realized by rotating the disk. Such a disk is called a phosphor wheel.

  Thus, the light emitting element of this indication can be used also for the phosphor wheel used for a projector. For example, the light-emitting element of the present disclosure can be used in place of the phosphor in the phosphor wheel disclosed in JP2012-8177A or JP2014-191003A. As an example, instead of the red phosphor layer and the green phosphor layer in the configuration disclosed in Japanese Patent Application Laid-Open No. 2014-191003, a light emitting element that emits red light substantially perpendicularly to the photoluminescence layer, and green light A light emitting element that emits light almost perpendicularly to the photoluminescence layer may be used.

  FIG. 55 is a diagram schematically illustrating an example of such a light-emitting device. The light emitting device 500 includes an excitation light source 310, a wheel-shaped light emitting element 320, and a rotation mechanism 510. The light emitting device 500 may include other components such as a diffusion plate, a lens, a mirror, and a control circuit, but description of these components is omitted.

  The light emitting element 320 has a disk shape (or donut shape), and a central portion is connected to the rotation mechanism 510. It arrange | positions so that the excitation light from the excitation light source 310 may inject into the peripheral part of the light emitting element 320. FIG. The rotation mechanism 510 includes a motor for rotating the light emitting element 320 in one direction or both directions around the center thereof. For example, the rotation mechanism 510 rotates the light emitting element 320 at an angular velocity of one rotation per 1/60 seconds.

  FIG. 56 is a diagram showing a configuration when the light emitting element 320 is viewed from the axial direction. The light emitting element 320 includes a region 320R for emitting light in the red wavelength band in a direction substantially perpendicular to the photoluminescence layer, a region 320G for emitting light in the green wavelength band in a direction substantially perpendicular to the photoluminescence layer, and a transparent And a region 320T. For example, when the excitation light is light in a blue wavelength band, blue light is emitted from the transparent region 320T.

  The excitation light source 310 emits excitation light while the rotation mechanism 510 rotates the light emitting element 320, so that light of three primary colors of red, green, and blue can be emitted in time series. With such a configuration, for example, the control circuit connected to the rotation mechanism 510 and the excitation light source 310 adjusts the output of the excitation light source 310 while rotating the motor of the rotation mechanism 510, thereby changing the color of light emitted from the projector. Can be changed.

[11 -4. Narrowband imaging]
The light emitting device of the present disclosure can enhance only light of a specific wavelength. Therefore, a light source that emits only the required wavelength can be easily realized. Moreover, the wavelength of the emitted light can be changed only by changing the periodic structure without changing the material of the photoluminescence layer. Furthermore, it is possible to emit light having different wavelengths depending on the angle with respect to the periodic structure. Such wavelength selectivity can be used, for example, for a technique called narrow band imaging (NBI). Narrow band imaging is a technique for observing capillaries and fine patterns on the mucosal surface layer by irradiating the mucous membrane with light of two narrow band wavelengths, blue and green. Narrow-band imaging can facilitate observation of a lesion with an endoscope.

[11 -5. Visible light communication]
The light-emitting element of the present disclosure can also be used for visible light communication. Visible light communication is a technique for transmitting a signal by modulating the intensity of illumination light. The signal from such a lighting device is received by a receiver with a photodiode or a general purpose image sensor. Accordingly, information can be transmitted from the lighting device to the receiving device. Visible light communication is disclosed in, for example, Japanese Patent No. 5179260 or Japanese Patent Application Laid-Open No. 2014-135716. In a visible light communication system, a light emitting diode (LED) is usually used as a light source. Instead of the LED, the light emitting device in the present disclosure can be used.

  FIG. 57 is a diagram showing an example of such a visible light communication system. The visible light communication system 600 includes a lighting device 610 and a receiving device 620. The illumination device 610 includes a modulation circuit 612, an excitation light source 310, and a light emitting element 320. The modulation circuit 612 modulates the intensity of the excitation light emitted from the excitation light source 310 at a high frequency in accordance with the signal transmitted to the receiving device 620. Thereby, the intensity of the light emitted from the light emitting element 320 is also modulated according to the signal. A signal can be received by detecting this change in light intensity with an image sensor or the like included in the receiving device 620.

  In such a system, by providing directivity to the light emitting element, light can be efficiently delivered to the light receiving element.

[11 -6. Transparent display device]
The light emitting element of this indication can also be used as the screen 100S of a transparent display apparatus, as typically shown in FIG.

  The screen 100S has, for example, pixels formed of a light emitting element that enhances red light (R), a light emitting element that enhances green light (G), and a light emitting element that enhances blue light (B) in a matrix. It is arranged. These light emitting elements can emit predetermined color light and display an image only when the corresponding excitation light (for example, ultraviolet rays) is irradiated from the excitation light source 180S1. Since each light emitting element transmits visible light, the observer can observe the background through the screen 100S. When the screen 100S is not irradiated with excitation light, it looks like a transparent window. By using a laser diode as the excitation light source 180S1 and scanning while changing the output according to the image data, high-resolution display is possible. Further, since the laser light is coherent light, the excitation efficiency can be increased by causing interference with the periodic structure. When light having an unfavorable wavelength such as ultraviolet rays is used as excitation light, an excitation light source is installed on the side opposite to the viewer of the screen 100S, and a filter for cutting the excitation light is provided on the viewer side of the screen 100S. Therefore, unnecessary light leakage can be prevented.

  Since the screen 100S can have high directivity, for example, only the person who observes from a predetermined direction can observe the image.

Instead of the excitation light source 180S1, an excitation light source 180S2 can be used. At this time, the light guide sheet S is arranged on the back surface of the screen 100S (that is, the side opposite to the observer side), and the light guide sheet S is irradiated with excitation light from the excitation light source 180S2. The excitation light incident on the light guide sheet S irradiates the screen 100S from the back surface while propagating through the light guide sheet S. In this case, disposing the light emission element in accordance with the portion of the image to be displayed, can not be displayed in the active any image, when the excitation light is not irradiated is transparent as a window, the excitation A display device in which an image, a graphic, a character, or the like is displayed only when light is irradiated can be configured.

[11 -7. sensor]
In the light emitting device of the present disclosure, for example, as described above with reference to FIGS. 8 and 9, when the refractive index of the periodic structure changes, the wavelength of the enhanced light changes, and the emission direction of the enhanced light also changes. To do. Also depending on the refractive index of the photoluminescence layer, the wavelength of the enhanced light and the emission direction change. Therefore, it is possible to easily detect the change in the refractive index of the medium in the vicinity of the light emitting element with high sensitivity based on at least one of the wavelength and the emission direction of the light emitted from the light emitting element.

  For example, a sensor that detects various substances can be configured using the light-emitting element of the present disclosure as follows.

  In the vicinity of the periodic structure of the light emitting element of the present disclosure, a substance (such as an enzyme) that selectively binds to a substance to be measured (such as a protein, odor molecule, or virus) is disposed. When the substance to be measured is bonded, the refractive index of the medium near the light emitting element changes. The presence of various substances can be detected by detecting the change in the refractive index based on the above-described change in the wavelength of the enhanced light or the emission direction.

[11 -8. traffic lights]
The light-emitting element of the present disclosure can emit light having high directivity in a specific direction. This high directivity is also preferably used for a display device that provides information only to a traffic vehicle or a person from a specific direction such as a traffic signal or a public display device. For example, when a conventional light source with low directivity is used, the light emitted from the light source is also emitted to the side, so that a traffic light or a display device can be visually recognized from the side, which may cause misidentification. . For this reason, a display device related to the safety of a traffic light or the like that has a problem especially when misidentification occurs, such as a shielding component that prevents lateral injection as disclosed in registered utility model publication No. 3014799, for example. (Louver) was used. When a light source having high directivity in a specific direction is used, such as the light emitting device in the present disclosure, information can be efficiently provided to a traffic vehicle or a person in a predetermined direction. it can. Furthermore, since the display device can be made smaller, the force received from wind and snow can be reduced. Therefore, a structure for supporting a display device such as a traffic light can be simplified.

FIG. 59 is a diagram schematically showing a traffic signal 700 that is an example of such a directional display device. The illustrated signal device 700 includes a light emitting device 710 including three display portions 710r, 710y, and 710g that respectively emit light in the red, yellow, and green (or blue) wavelength bands, and a housing 740 that houses the light emitting device 710. And have. The traffic light 700 is supported by two arms 750 and a pole 760. The traffic light 700 is connected to a control circuit 732 in the display control device 730 fixed to the pole 760 via a cable 720. The control circuit 732 controls light emission in the display portions 710r , 710y, and 710g.

FIG. 60 is a schematic diagram illustrating an example of a more detailed configuration of the traffic light 700. In this example, the traffic light 700 further includes three excitation light sources 180 and three light guide plates 330 that guide the excitation light from the excitation light source 180 to the display units 710r, 710y, and 710g, respectively. Excitation light is incident on the photoluminescence layers 110r, 110y, and 110g in the display portions 710r, 710y, and 710g through the transparent substrate 140. The photoluminescence layers 110r, 110y, and 110g receive excitation light and emit light belonging to the red (R), yellow (Y), and green (G) wavelength bands, respectively. The surface structures 120r, 120y, and 120g formed on the surfaces of the photoluminescence layers 110r, 110y, and 110g respectively emit light belonging to the red, yellow, and green wavelength bands at a narrow angle in a predetermined direction. The control circuit 732 is connected to the three excitation light sources 180 and supplies a control signal for controlling these on and off. Thereby, the display units 710r, 710y, and 710g can be sequentially turned on, and the yellow display unit 710y can be blinked.

  As described above, in this specification, the wavelength bands of red, green, and blue are red: 600 to 750 nm, green: 490 to 570 nm, and blue: 430 nm to 470 nm, respectively. The yellow wavelength band is 570 nm to 600 nm, which is the wavelength band between red and green. The display unit 710r can be designed to emit light having a center wavelength of 642 nm in a predetermined direction, for example. The display unit 710y can be designed to emit light having a central wavelength of 595 nm, for example, in a predetermined direction. The display unit 710g may be designed to emit light having a center wavelength of 500 nm in a predetermined direction, for example.

  In this way, the display units 710r, 710y, and 710g are designed to emit red, yellow, and green light required as a traffic display device with high directivity. The display control device 730 can emit specific one of the photoluminescence layers 110r, 110y, and 110g with directivity. Thereby, the signal apparatus which can be visually recognized only from a specific direction is realizable. By being visible only from a specific direction, it is possible to reduce the possibility of signal misrecognition by the driver.

  The configurations shown in FIGS. 59 and 60 are examples, and various modifications are possible. For example, the display units 710r, 710y, and 710g are not limited to the structure illustrated in FIG. 60, and may have the structure of another light-emitting element already described. Further, the excitation light source 180 may be disposed in the vicinity of the control circuit 732, and excitation light may be supplied from the excitation light source 180 to each display unit via a light guide such as an optical fiber. Further, the light guide plate 330 may be omitted if unnecessary.

  In the above example, the traffic light 700 that emits light of three colors of red, yellow, and green has been described. For example, a traffic light for pedestrians that emit light of two colors of red and green (or blue) has the same configuration. Applicable.

  Such a traffic display device can also be applied to, for example, a driving support system that indicates whether or not an intersection can be entered by an image. Such a system is disclosed in, for example, JP2013-114557A. By applying the traffic display device to such a system, the driver's recognition accuracy can be increased, so that safety is improved.

[11 -9. Light source for plant factories]
The light emitting device in the present disclosure can also be used as a light source in a plant factory. In plant factories, plants are irradiated with light of various wavelength bands for the healthy growth of plants. For example, light of 640 nm to 690 nm is mainly used for growth by photosynthesis. For normal leaf morphogenesis (plant germination, flower bud differentiation, flowering, cotyledon development, chlorophyll synthesis, internode elongation, and other plant qualitative changes), light of 420 nm to 470 nm is mainly used. A light source in a plant factory is required to emit light having a relatively narrow band.

  In conventional plant factories, light sources such as fluorescent lamps, high-pressure sodium lamps, and LEDs have been used. Since these light sources have a wide line width (that is, a wavelength range), there is a problem that the light use efficiency is low. The use efficiency of light can be improved by using the highly directional light emitting element in the present disclosure instead of these light sources.

  An example of a light source used in a plant factory is disclosed in, for example, Japanese Patent Application Laid-Open No. 2011-97900. Instead of the light source disclosed in this document, the light emitting element in the present disclosure can be used.

  FIG. 61 is a diagram showing a light source device for a plant factory having the same configuration as FIG. 12 of the above document. The light source device includes a mounting table 30 on which a plant is mounted, a main light source unit 10 installed above the plant, and a plurality of auxiliary light source units 20. The main light source unit 10 may be configured to emit light in red and blue wavelength bands, for example. The auxiliary light source unit 20 may be configured to emit light in the near-infrared, near-ultraviolet, green, or yellow wavelength band, for example. Here, the near-infrared wavelength band is approximately 700 nm to 2500 nm, and the near-ultraviolet wavelength band is approximately 200 nm to 380 nm. By configuring the main light source unit 10 and the auxiliary light source unit 20 using any one of the light emitting elements in the present disclosure, light can be efficiently irradiated onto a plant. In addition, the light emitting element in this indication is not restricted to the example shown in FIG. 61, It can utilize for arbitrary light sources for plant factories. The number, arrangement, and emission wavelength of the light emitting elements used may be arbitrarily determined.

[11 -10. Photodynamic therapy]
The high directivity of the light-emitting element of the present disclosure is also useful for photodynamic therapy in which light is used to treat skin diseases (for example, cancer lesions). For example, light near 400 nm is used for the treatment of skin diseases near the surface. Further, light of around 600 nm is used for the treatment of deep skin diseases. In performing such photodynamic therapy, conventionally, a specific light from a lamp light source is extracted by a filter and used, which causes a loss of light. On the other hand, if the light emitting element with high directivity according to the present disclosure is used as a light source, the light use efficiency can be improved. In addition to photodynamic treatment, the light-emitting element of the present disclosure can also be used for uses such as light to improve acne, improve skin redness, and promote hair growth.

[11 -11. Distance sensor]
The light emitting element in the present disclosure can also be applied to a distance sensor. The distance sensor is a sensor that emits pulsed light from a light source, detects pulsed light reflected from an object, and detects a distance to the object based on a phase difference of the pulsed light. The distance sensor can be used as, for example, a distance image sensor that generates a distance image of the entire shooting range or a motion sensor that detects the movement of a main subject within the shooting range. Conventionally, LED light sources have been mainly used in such distance sensors. Instead of the LED light source, the highly directional light-emitting element in the present disclosure can be used.

  FIG. 62 is a schematic diagram illustrating a configuration example of a distance sensor using the light emitting element according to the present disclosure. This distance sensor includes a light emitting device 800, an image sensor 810, and a control circuit 820 for controlling them.

FIG. 63A is a diagram showing a schematic configuration of the light emitting device 800. The light-emitting device 800 includes a light-emitting element 840 having any of the structures described above and an excitation light source 830. The light-emitting element 840 has a surface structure that emits near-infrared light or visible light at a narrow angle. The light emitting device 800 drives the excitation light source 830 in accordance with a control signal from the control circuit 820, and emits near-infrared or visible pulsed light. The image sensor 810 includes a plurality of light detection cells, and detects pulsed light emitted from the light emitting device 800 and reflected from the object. The control circuit 820 may be an integrated circuit such as a microcontroller (microcomputer). The control circuit 820 may be a combination of a processor such as a CPU and an image processing circuit such as a digital signal processor (DSP). The control circuit 820 controls light emission timing of the light emitting device 800 and signal charge accumulation and readout timing of the image sensor 810. The control circuit 820 further measures the distance to the object based on the difference between the phase of the pulsed light emitted from the light emitting device 800 and the phase of the pulsed light detected by the image sensor 810.

  FIG. 63B is a diagram for explaining generation of pulsed light by the control circuit 820. The control circuit 820 inputs a drive signal that is a pulse signal to the excitation light source 830. The excitation light source 830 makes the excitation light whose intensity changes in a pulse manner incident on the light emitting element 840 in response to the drive signal. In response to this, light (referred to as pulsed light) whose intensity changes with the same period as the excitation light is emitted from the light emitting element 840. The emitted pulsed light is reflected by the object and enters the image sensor 810. The image sensor 810 detects reflected light using a plurality of light detection cells, and outputs an electrical signal corresponding to the intensity of received light (also referred to as a received light amount) for each light detection cell (also referred to as a pixel). This electric signal is called a light reception signal.

FIG. 63C is a diagram illustrating an example of temporal changes in the drive signal and the light reception signal. The control circuit 820 measures the distance L to the object based on the delay time Δt between the drive signal and the light reception signal for each pixel. The distance L is calculated based on the following formula.
L = light speed c × delay time Δt / 2

  The control circuit 820 can obtain the distance L for each pixel, and can generate an image having different luminance as the distance image according to the value. The distance sensor in this example can be used as a motion sensor by using an image sensor 810 capable of high-speed shooting and sufficiently increasing the frequency of pulsed light.

  In the above example, the control circuit 820 generates the pulsed light by driving the excitation light source 830, but other methods may be used. For example, as shown in FIG. 64A, an optical shutter 850 may be disposed on the light emitting side of the light emitting element 840, and the control circuit 820 may control the light transmittance of the optical shutter 850 to generate pulsed light. The optical shutter 850 includes, for example, a liquid crystal layer and electrode layers on both sides thereof. The optical shutter 850 has a state where light is transmitted by application of a drive signal (referred to as a light-transmitting state) and a state where light is blocked (referred to as a light-blocking state). Can be switched. As shown in FIG. 64B, the control circuit 820 inputs a pulsed drive signal to the optical shutter 850, and the light transmitting state and the light shielding state are switched accordingly. As a result, pulsed light is emitted from the optical shutter 850.

As shown in FIG. 64C, lenses 860a and 860b may be provided between the light emitting element 840 and the optical shutter 850 and on the light emission side of the optical shutter 850. By disposing the optical shutter 850 at a position where the light from the light emitting element 840 is imaged by the lens 860a, the optical shutter 850 can be reduced in size and can be switched between the light transmitting state and the light shielding state at a higher speed. Such a small shutter can be realized by, for example, MEMS (Micro Electro Mechanical Systems). By using the light emitting element according to the present disclosure, it is possible to emit near-infrared light or visible light having a specific wavelength in the front direction and emit near-infrared light having a wavelength around it in the peripheral direction. When the image sensor 810 receives light in these wavelength bands, the distance to the object can be measured.

  Application examples of the light-emitting element of the present disclosure are not limited to the above, and can be applied to various optical devices.

  The entire disclosure of all patent documents cited in the above description is incorporated herein by reference.

  The light-emitting element and the light-emitting device of the present disclosure can be applied to various optical devices such as a lighting fixture, a display, and a projector.

DESCRIPTION OF SYMBOLS 10 Main light source unit 20 Auxiliary light source unit 30 Mounting stand 100, 100a Light emitting element 110 Photoluminescence layer (waveguide layer)
120, 120 ′, 120a, 120b, 120c Translucent layer (periodic structure, submicron structure)
140 Transparent substrate 150 Protective layer 180 Light source 200 Light emitting device 300, 300a, 300b, 300c, 300d, 300e Display device 310 Excitation light source 320 Light emitting element 321 Photoluminescence layer 322 Submicron structure (periodic structure)
330 Light Guide Plate 340 Color Filter Array 350 Optical Shutter 351 Polarization Filter 352 Transparent Substrate 353 Transparent Electrode 355 Liquid Crystal Layer 357 Transparent Substrate 358 Polarization Filter 360 Drive Circuit 370 Touch Screen 400 Illumination Device 410 Concave Reflector 420 Heat Dissipation Substrate 430 Circuit Substrate 440 Diffusion Plate 450 Lens 460 Micromirror 500 Light emitting device 510 Rotating mechanism 600 Visible light communication system 610 Illuminating device 612 Modulating circuit 620 Receiving device 700 Traffic light 710r, 710y, 710b Display unit 720 Cable 730 Display control device 732 Control circuit 740 Housing 750 Pole Arm 760 Pole 800 Light Emitting Device 810 Image Sensor 820 Control Circuit 830 Excitation Light Source 840 Light Emitting Element 850 Optical Shutter 860a, 860 b Lens

Claims (16)

An excitation light source;
A light emitting element located on an optical path of excitation light from the excitation light source;
An optical shutter positioned on an optical path of light from the light emitting element,
The light emitting element is
A photoluminescence layer that receives the excitation light and emits light including first light having _a wavelength of λ _{a in} air;
A translucent layer disposed proximate to the photoluminescence layer;
A surface structure formed on at least one surface of the photoluminescence layer and the translucent layer, and
The surface structure includes at least one of a plurality of convex portions and a plurality of concave portions,
If the distance between the centers of two adjacent convex portions or two adjacent concave portions in the surface structure is D _int and the refractive index of the photoluminescence layer with respect to the first light is n _wav-a , λ _a / n The relationship _wav-a <D _int <λ _a holds,
Display device.   The display device according to claim 1, wherein the photoluminescence layer and the translucent layer are in contact with each other. An excitation light source;
A light emitting element located on an optical path of excitation light from the excitation light source;
An optical shutter positioned on an optical path of light from the light emitting element,
The light emitting element is
A photoluminescence layer that receives the excitation light and emits light including first light having _a wavelength of λ _{a in} air;
A surface structure provided on the surface of the photoluminescence layer,
The surface structure includes at least one of a plurality of convex portions and a plurality of concave portions,
If the distance between the centers of two adjacent convex portions or two adjacent concave portions in the surface structure is D _int and the refractive index of the photoluminescence layer with respect to the first light is n _wav-a , λ _a / n The relationship _wav-a <D _int <λ _a holds,
Display device.   The display device according to claim 1, further comprising a color filter array including a plurality of color filters having different transmission wavelength bands on a side where light from the light emitting element is incident or a side where the light is emitted in the optical shutter.   The display device according to claim 1, further comprising a light guide plate for propagating light from the light emitting element to the optical shutter.   The display device according to claim 1, further comprising a light guide plate that propagates the excitation light from the excitation light source to the photoluminescence layer.   The display device according to claim 1, further comprising a drive circuit that drives the optical shutter according to an image signal.   The display device according to claim 7, further comprising a touch screen on a side of the optical shutter from which light from the light emitting element is emitted. The surface structure comprises at least one periodic structure, wherein the at least one periodic structure, the periodic and p _a, and the refractive index of the photoluminescence layer for said first light and n _wav-a, λ _a / including _{n wav-a <p a <} λ first periodic structure relationship holds for _a,
The display device according to claim 1. The light emitted from the photoluminescence layer includes second light having _a wavelength λ _b different from λ _a in the air, and the refractive index of the photoluminescence layer with respect to the second light is n _wav-b ,
Wherein at least one of the periodic structure, when the period as p _b, further comprising a _{λ b / n wav-b <} p b <λ b second periodic structure relationship holds for,
The wavelength λ _a belongs to the red wavelength band,
The wavelength λ _b belongs to the green wavelength band,
The display device according to claim 9. When the refractive index of the photoluminescence layer for the third light having a wavelength λ _c different from λ _a and λ _b in the air is n _wav-c ,
Wherein at least one of the periodic structure, when the period as p _c, further comprises a third periodic structure relationship holds for _{λ c / n wav-c <} p c <λ c,
The wavelength λ _c belongs to the blue wavelength band,
The display device according to claim 10.   The display device according to claim 10, wherein the excitation light source emits light in a blue wavelength band.   The display device according to claim 1, wherein the surface structure includes at least one periodic structure, and a period of the at least one periodic structure is the same as a period of a maximum value of an electric field amplitude inside the photoluminescence layer.   The display device according to claim 3, wherein the surface structure includes at least one periodic structure, and a period of the at least one periodic structure is the same as a period of a maximum value of an electric field amplitude inside the photoluminescence layer.   The display device according to claim 1, wherein the photoluminescence layer has a thickness that generates a pseudo waveguide mode in the photoluminescence layer.   The display device according to claim 3, wherein the photoluminescence layer has a thickness for generating a pseudo waveguide mode in the photoluminescence layer.

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