WO2013103038A1

WO2013103038A1 - Optical device and image display device

Info

Publication number: WO2013103038A1
Application number: PCT/JP2012/075696
Authority: WO
Inventors: 昌尚棗田; 雅雄今井; 慎冨永; 鈴木　尚文; 瑞穂冨山; 友嗣大野
Original assignee: 日本電気株式会社
Priority date: 2012-01-07
Filing date: 2012-10-03
Publication date: 2013-07-11
Also published as: JPWO2013103038A1

Abstract

Provided is an optical device and image display device capable of improving absorption efficiency of excited light. This optical device (1) is equipped with: light emitting elements (101a, 101b); a carrier generation layer (103) upon which light from the light emitting elements (101a, 101b) is incident and carriers are generated; a plasmon excitation layer (105) for exciting plasmons and having a plasma frequency higher than the frequency of light generated when the carrier generation layer (103) is excited by light from the light emitting elements (101a, 101b), the plasmon excitation layer being layered on top of the carrier generation layer (103); and a light emission layer (107) for emitting light by converting the surface plasmons or the light generated on the surface of the plasmon excitation layer (105) to light with a predetermined emission angle; the incident angle of light incident upon the carrier generation layer (103) being 40 degrees or greater.

Description

Optical device and image display device

The present invention relates to an optical device and an image display device.

In recent years, as a light source of an image display apparatus such as a projector, for example, a light emitting element, a light guide on which light (excitation light) from the light emitting element is incident, and the light guide Plasmons having a plasma frequency higher than the frequency of the light generated when the carrier generation layer is stacked on the carrier generation layer and the carrier generation layer is excited by the light of the light emitting element An optical device has been developed which includes a plasmon excitation layer to be excited, and an emission layer which is laminated on the plasmon excitation layer and converts light incident from the plasmon excitation layer into light of a predetermined emission angle and emits the light. (Patent Document 1).

Such an optical device emits light according to the following principle. That is, first, the excitation light emitted from the light emitting element is absorbed in the carrier generation layer, whereby carriers are generated in the carrier generation layer. This carrier combines with free electrons in the plasmon excitation layer to excite surface plasmons. Then, the excited surface plasmons are emitted as light.

International Publication No. 2011/040528

In the optical device described in Patent Document 1 or the like, improvement in light emission efficiency is desired, and improvement in absorption efficiency of excitation light emitted from a light emitting element is an important factor in improvement of light emission efficiency.

An object of the present invention is to provide an optical device and an image display device capable of improving the absorption efficiency of excitation light.

In order to achieve the above object, the optical device of the present invention is
A light emitting element,
A carrier generation layer in which light from the light emitting element is incident and carriers are generated;
A plasmon excitation layer for exciting plasmons, which is stacked on the carrier generation layer and has a plasma frequency higher than the frequency of light generated when the carrier generation layer is excited by the light of the light emitting element;
And an emission layer for converting light or surface plasmon generated on the surface of the plasmon excitation layer into light of a predetermined emission angle and emitting the light.
The incident angle of light incident on the carrier generation layer is 40 degrees or more.

The image display apparatus of the present invention is
The optical device of the present invention,
And an image display unit capable of displaying an image.

According to the present invention, it is possible to provide an optical device and an image display device capable of improving the absorption efficiency of excitation light.

FIG. 1 is a perspective view schematically showing the configuration of an example (first embodiment) of the optical device of the present invention. FIG. 2A is a view showing the incident angle and the polarization dependency of the absorptivity of excitation light in the carrier generation layer when the thickness of the carrier generation layer is 50 nm. FIG. 2B is a view showing the incident angle and the polarization dependency of the absorptivity of excitation light in the carrier generation layer when the thickness of the carrier generation layer is 100 nm. FIG. 3 is a view showing the thickness dependency of the carrier generation layer of the absorptivity of excitation light. FIG. 4 is a view showing the excitation light incident angle dependency of the emission spectrum from the optical device. FIG. 5 is a diagram showing an emission spectrum from the optical device when the thickness of the carrier generation layer is 50 nm. FIG. 6 is a diagram showing an emission spectrum from the optical device when the thickness of the carrier generation layer is 100 nm. FIG. 7 is a perspective view schematically showing the configuration of another example (Embodiment 2) of the optical device of the present invention. FIG. 8 is a perspective view schematically showing the configuration of still another example (third embodiment) of the optical device of the present invention. FIG. 9 is a schematic view showing a configuration of an example (Embodiment 5) of the image display device (LED projector) of the present invention. FIG. 10 is a view for explaining an emission wavelength of an optical device used for the LED projector of the fifth embodiment, and an excitation wavelength and an emission wavelength of a phosphor. FIG. 11 is a perspective view schematically showing the configuration of still another example (Embodiment 4) of the optical device of the present invention.

Hereinafter, the optical device and the image display device of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. In addition, in the following FIGS. 1-11, the same code | symbol may be attached | subjected to an identical part and the description may be abbreviate | omitted. Further, in the drawings, for convenience of explanation, the structure of each part may be appropriately simplified and shown, and the dimensional ratio of each part may be schematically shown differently from the actual one.

(Embodiment 1)
The optical device of the present embodiment is an example of an optical device having a dielectric layer. The configuration of the optical device of the present embodiment is shown in the perspective view of FIG.

As shown in FIG. 1, the optical device 1 of the present embodiment includes

light emitting elements

101a and 101b and a light control unit 3 as main components. The light control unit 3 is stacked on the carrier generation layer 103, the dielectric layer 104 stacked on the carrier generation layer 103, the plasmon excitation layer 105 stacked on the dielectric layer 104, and the plasmon excitation layer 105. And a wave number vector conversion layer 107 stacked on the dielectric layer 106. The wave vector conversion layer 107 has a function as the “emission layer” in the present invention. The

light emitting elements

101 a and 101 b are disposed around the side surface of the light control unit 3. The relationship between the arrangement position of the

light emitting elements

101a and 101b and the incident angle of light incident on the carrier generation layer 103 will be described later.

In the light control unit 3, the effective dielectric constant of the excitation light incident side portion (hereinafter, sometimes referred to as "incident side portion") is that of the light emission side portion (hereinafter, sometimes referred to as "output side portion"). It is configured to be lower than the effective dielectric constant. The incident side portion includes the entire structure stacked on the carrier generation layer 103 side of the plasmon excitation layer 105 and an ambient atmosphere medium (hereinafter, may be referred to as a “medium”) in contact with the carrier generation layer 103. The entire structure includes dielectric layer 104 and carrier generation layer 103. The emission side portion includes the entire structure stacked on the wave number vector conversion layer 107 side of the plasmon excitation layer 105 and a medium in contact with the wave number vector conversion layer 107. The entire structure includes a dielectric layer 106 and a wave vector conversion layer 107. For example, even if the dielectric layer 104 and the dielectric layer 106 are removed, if the effective dielectric constant of the incident side portion is lower than the effective dielectric constant of the emission side portion, the dielectric layer 104 and the dielectric Layer 106 is not necessarily an essential component.

Here, the effective dielectric constant (ε _eff ) is a direction parallel to the interface of the plasmon excitation layer 105 as x-axis and y-axis, a direction perpendicular to the interface of the plasmon excitation layer 105 (the surface of the plasmon excitation layer 105 has irregularities When the carrier generation layer 103 alone is excited with excitation light, the angular frequency of the light emitted from the carrier generation layer 103 is ω, and the plasmon excitation is ω when the carrier generation layer 103 alone is excited by excitation light. Ε (ω, x, y, z) of the dielectric constant distribution of the dielectric in the incident side portion or the emission side portion with respect to the layer 105, the z component of the wave number of surface plasmons k _{spp, z} , the imaginary unit j, Re If [] is a symbol indicating the real part of the numerical value in [], it is represented by the following formula (1).

The effective dielectric constant ε _eff may be calculated using a formula represented by the following formula (7). However, it is particularly desirable to use the formula (1).

In the formula (1) and the formula (7), the integration range D is a range of three-dimensional coordinates of the incident side portion or the emission side portion with respect to the plasmon excitation layer 105. In other words, the range in the x-axis and y-axis directions in the integration range D is a range not including the medium to the outer peripheral surface of the entire structure of the incident side portion or the outer peripheral surface of the entire structure of the output side portion; It is a range up to the outer edge in the plane parallel to the surface on the wave number vector conversion layer 107 side of the plasmon excitation layer 105. The range in the z-axis direction in the integration range D is the range of the incident side portion or the emission side portion. The range in the z-axis direction in the integration range D is the interface between the plasmon excitation layer 105 and the dielectric layer (dielectric layer 104 or dielectric layer 106) adjacent to the plasmon excitation layer 105, z = The position from 0 to this point is the range from these interfaces to infinity on the dielectric layer 104 or dielectric layer 106 side of the plasmon excitation layer 105, and the direction away from these interfaces is the above equation (1) and The (+) z direction in the equation (7) is used. For example, when unevenness is formed on the surface of the plasmon excitation layer 105, if the origin of the z coordinate is moved along the unevenness of the plasmon excitation layer 105, the effective dielectric can be obtained from the above equations (1) and (7). The rate is determined. For example, in the calculation range of the effective dielectric constant, when a material having optical anisotropy is included, ε (ω, x, y, z) becomes a vector, which is different for each radial direction perpendicular to the z axis It has a value. That is, for each radial direction perpendicular to the z-axis, there is an effective dielectric constant of the incident side portion and the outgoing side portion. In this case, the value of ε (ω, x, y, z) is a dielectric constant in a direction parallel to the radial direction perpendicular to the z axis. Therefore, all phenomena related to the effective dielectric constant, such as k _{spp, z} , k _spp and _deff described later, have different values in each radial direction perpendicular to the z axis.

The z component k _{spp, z} of the wave number of the surface plasmon and the x and y component k _spp of the wave number of the surface plasmon are ε _metal of the real part of the dielectric constant of the plasmon excitation layer 105, the wave number of light in vacuum Let k ₀ be the following equation (2) and (3).

Furthermore, in the optical device 1, the distance from the surface on the carrier generation layer 103 side of the plasmon excitation layer 105 to the surface on the plasmon excitation layer 105 side of the carrier generation layer 103 is set shorter than the effective interaction distance d _{eff of} surface plasmons. . _Assuming that d _eff is a symbol indicating the imaginary part of the numerical value in [] as Im [], and the effective interaction distance of the surface plasmon is the distance at which the intensity of the surface plasmon is e ^-2 , the following equation (4) Is represented by

Therefore, using the above equation (1) or the above equation (7), the above equation (2) and the above equation (3), ε (ω, x, y, z) Substituting the real part ε _in (ω, x, y, z) of the dielectric constant distribution and the real part ε _out (ω, x, y, z) of the dielectric constant distribution of the emission side of the plasmon excitation layer 105 Te, by calculating the effective permittivity epsilon _effin of the incident-side portion relative to plasmon excitation layer 105, and the effective permittivity epsilon _Effout of the exit-side portion, obtained respectively. For example, when there is anisotropy of the dielectric constant in a plane perpendicular to the z axis, the effective dielectric constants of the incident side portion and the emission side portion exist in each radial direction perpendicular to the z axis. Therefore, as described above, all phenomena related to the effective dielectric constant, such as k _{spp, z} , k _spp , and d _eff described later, have different values in the radial direction perpendicular to the z-axis. In practice, the effective permittivity is obtained by repeatedly calculating the equation (1) or the equation (7), the equation (2) and the equation (3) by giving an appropriate initial value as the effective permittivity ε _eff. ε _eff can be easily obtained. Note that, for example, when the real part of the dielectric constant of the layer in contact with the plasmon excitation layer 105 is very large, the z component k _{spp, z} of the wave number of the surface plasmon represented by the formula (2) becomes a real number. This corresponds to the absence of surface plasmons at the interface. Therefore, the dielectric constant of the layer in contact with the plasmon excitation layer 105 corresponds to the effective dielectric constant in this case. The effective dielectric constant in the embodiments described later is also defined in the same manner as the formula (1) or the formula (7).

In the optical device 1, the incident angle at which the light emitted from the

light emitting elements

101 a and 101 b (hereinafter sometimes referred to as “excitation light”) is incident on the carrier generation layer 103 is set to 40 degrees or more There is. With such a configuration, the optical device 1 has a function of absorbing excitation light in the carrier generation layer 103, that is, a waveguide including the carrier generation layer 103, the dielectric layer 104, and the plasmon excitation layer 105 (hereinafter referred to as “waveguide Coupling efficiency is improved. It will be described in detail that the optical device 1 exerts such an effect.

In order to improve the light emission efficiency of the optical device, it is important to improve the absorptivity of the excitation light from the light emitting element. As a result of intensive studies from the viewpoint of improving the absorption efficiency of excitation light, the present inventors show that the absorption efficiency of excitation light in the carrier generation layer significantly depends on the incident angle of the excitation light to the carrier generation layer. I found it. Furthermore, the present inventors have found that the absorption efficiency also depends on the polarization characteristics of the excitation light. These findings are found for the first time by the present inventors. The incident angle dependency and the polarization dependency of the absorption efficiency will be further described based on the optical device 1 of the present embodiment.

FIGS. 2A and 2B show the incident angle and the polarization dependency of the absorptivity of the excitation light in the carrier generation layer 103. FIG. In the example shown in FIG. 2A, the thickness of the carrier generation layer 103 is set to 50 nm, and in the example shown in FIG. 2B, the thickness of the carrier generation layer 103 is set to 100 nm. In the example shown in FIGS. 2A and 2B, the optical device 1 is set to the following conditions including the thickness condition of the carrier generation layer 103. In this example, the light reflected by the plasmon excitation layer 105 is not reused. In the present embodiment, the “incident angle” refers to the light beam and the carrier generation layer 103 when the light (light beam) emitted from the

light emitting elements

101 a and 101 b enters the carrier generation layer 103 (light control unit 3). Indicates the angle formed by the normal to the incident surface. Hereinafter, in the present invention, the “incident angle” is indicated by the same concept as described above.
Light emitting element 101: Laser diode (emission wavelength: 460 nm)
Carrier generation layer 103: Forming material: phosphor (refractive index: 1.7 + 0.03 j)
Thickness: 50 nm (FIG. 2A) or 100 nm (FIG. 2B)
Dielectric layer 104: Forming material: SiO ₂ , thickness: 10 nm
Plasmon excitation layer 105: Forming material: Ag, thickness: 50 nm
Dielectric layer 106: Forming material: TiO ₂ , thickness: 0.5 mm
Wave vector conversion layer 107: hemispherical lens (diameter: 10 mm)

As shown in FIG. 2A, when the thickness of the carrier generation layer 103 is 50 nm, as the incident angle of the excitation light to the carrier generation layer 103 is larger, the absorptivity is significantly increased when the polarization of the excitation light is s-polarization. When the polarization of the excitation light is p polarization, the absorptivity is significantly reduced. Here, when the polarization of the excitation light is s-polarization, the absorptivity of the excitation light is 31% or more at an incident angle of 40 degrees or more, 42% or more at an incident angle of 60 degrees or more, and an incident angle of 70 More than 53%. When the polarization of the excitation light was s-polarization, the maximum value of the absorptivity was 77% when the incident angle of the excitation light was 84 degrees. Thus, it can be seen that the absorption efficiency depends on the incident angle and polarization of the excitation light.

As shown in FIG. 2B, when the thickness of the carrier generation layer 103 is 100 nm, as the incident angle of the excitation light to the carrier generation layer 103 is larger, the absorptivity is significantly increased when the polarization of the excitation light is p polarization. When the polarization of the excitation light is s-polarization, the absorptivity is significantly reduced. Here, when the polarization of the excitation light is p polarization, the absorptivity of the excitation light is 19% or more at an incident angle of 40 degrees or more, 27% or more at an incident angle of 60 degrees or more, and an incident angle of 70 More than 33%. When the polarization of the excitation light was p polarization, the maximum value of the absorptivity was 37% when the incident angle of the excitation light was 78 degrees. Thus, it can be seen that the absorption efficiency depends on the incident angle and polarization of the excitation light.

The relationship between the absorptivity of excitation light and the thickness of the carrier generation layer 103 is shown in FIG. In the example shown in FIG. 3, conditions were the same as those in the example shown in FIG. 2 except that the incident angle of the excitation light was 70 degrees. In FIG. 3, the horizontal axis indicates the ratio of s-polarization component in the excitation light, 100% indicates that the excitation light is only s-polarization, and 0% indicates that the excitation light is only p-polarization. Show. As shown in FIG. 3, when the thickness of the carrier generation layer 103 is 50 nm, the absorptivity of the excitation light is improved as the s-polarization component increases in the excitation light. On the other hand, when the thickness of the carrier generation layer 103 is 100 nm, the absorptivity of the excitation light is improved as the s-polarization component decreases in the excitation light, that is, the p-polarization component increases. It can be said that under any conditions, the maximum value of the absorptivity is obtained in s-polarized light or p-polarized light. In addition, it can be said that the absorptivity does not reach the maximum value in the polarization between s-polarization and p-polarization, that is, in the middle polarization.

FIG. 4 shows the relationship between the emission spectrum from the optical device 1 and the incident angle of the excitation light when the thickness of the carrier generation layer 103 in the example shown in FIG. 2A and FIG. 3 is 50 nm. “0 °”, “10 °”, “20 °”, “30 °”, “40 °”, “50 °”, “60 °”, “70 °” and “80 °” in FIG. 4 indicate the incident angles of the excitation light. In FIG. 4, the vertical axis is normalized to 1 as the emission spectrum when the incident angle of the excitation light is 0 degree. As shown in FIG. 4, as the incident angle of the excitation light to the carrier generation layer 103 is larger, the light emission power is improved. From the comparison with FIG. 2A, it can be seen that there is a correlation (for example, a proportional relationship) between the excitation light amount absorbed by the carrier generation layer 103 and the light emission power.

FIG. 5 shows an emission spectrum from the optical device 1 when the thickness of the carrier generation layer 103 in the example shown in FIG. 2A and FIG. 3 is 50 nm. “0%”, “33%”, “66%” and “100%” in FIG. 5 indicate the ratio of the s-polarization component to the excitation light. In FIG. 5, the ordinate represents the emission spectrum when the excitation light is p-polarized light (“0%” in FIG. 5), and is normalized to 1. As shown in FIG. 5, the light emission power is maximum when the excitation light is s-polarized light (100%), and is eight times as large as that when the excitation light is p-polarized light (0%). From the comparison with FIG. 3, it can be seen that there is a correlation (for example, a proportional relationship) between the excitation light amount absorbed by the carrier generation layer 103 and the light emission power.

FIG. 6 shows an emission spectrum from the optical device 1 when the thickness of the carrier generation layer 103 in the example shown in FIG. 2B and FIG. 3 is 100 nm. “0%”, “33%”, “66%” and “100%” in FIG. 6 indicate the ratio of the s-polarization component to the excitation light. In FIG. 6, the ordinate represents the emission spectrum when the excitation light is s-polarized light (“100%” in FIG. 6). As shown in FIG. 6, the light emission power is maximum when the excitation light is p polarization (0%), and is four times as high as the case where the excitation light is s polarization (100%). From the comparison with FIG. 3, as in the case where the thickness of the carrier generation layer 103 is 50 nm, there is a correlation (for example, a proportional relationship) between the excitation light amount absorbed by the carrier generation layer 103 and the emission power. I understand.

As described above, the absorption efficiency of excitation light in the carrier generation layer depends on the incident angle of the excitation light. Based on this finding, the present inventors have found that the absorption efficiency of excitation light can be improved by setting the incident angle of the excitation light to the carrier generation layer to 40 degrees or more, and the present invention has been completed. According to the present invention, by improving the absorption efficiency of excitation light, it is possible to realize, for example, an optical device having high light emission efficiency and high light output rating. For example, since the maximum value of the absorptivity of excitation light is the case where the incident angle is 40 degrees or more, the incident angle is preferably 50 degrees or more, more preferably 60 degrees or more, still more preferably 70 to 88 degrees It is a range.

In addition, the absorption efficiency of excitation light is maximized in either s-polarization or p-polarization, depending on the thickness of the carrier generation layer. Therefore, if only s-polarized light or p-polarized light is incident on the carrier generation layer at the predetermined incident angle or more according to the thickness of the carrier generation layer, for example, the absorption efficiency of excitation light can be further improved.

Next, with regard to the optical device 1, an operation will be described in which excitation light emitted from the

light emitting elements

101a and 101b enters the light control unit 3 and light is emitted from the wave number vector conversion layer 107 of the light control unit 3.

The excitation light emitted from the

light emitting elements

101a and 101b enters the light control unit 3 at the predetermined incident angle (and polarization). The excitation light is then coupled to the waveguide and confined therein. The confined excitation light excites the carrier generation layer 103 to generate carriers in the carrier generation layer 103. The carrier combines with free electrons in the plasmon excitation layer 105 separated by the dielectric layer 104 to excite surface plasmons at the interface between the dielectric layer 104 and the plasmon excitation layer 105. The excited surface plasmons are emitted as light from the interface between the plasmon excitation layer 105 and the dielectric layer 106 (hereinafter sometimes referred to as “emission light”). The light emission occurs because the effective dielectric constant of the incident side portion is lower than the effective dielectric constant of the output side portion. The wavelength of the emitted light is equal to the wavelength of light generated when the carrier generation layer 103 is excited alone. Further, assuming that the refractive index of the dielectric layer 106 is n _out , the emission angle θ _out of the emitted light is expressed by the following formula (5).

The wave number of the excited surface plasmon is present only in the vicinity uniquely set in the equation (2). The emitted light is only a wave number vector of the surface plasmon converted. Therefore, the emission angle of the emitted light is uniquely determined, and its polarization state is always p-polarization. That is, the emitted light is p-polarized light having very high directivity. The emitted light enters the wave vector conversion layer 107, is diffracted or refracted by the wave vector conversion layer 107, and is extracted outside the optical device 1. Of the excitation light incident on the carrier generation layer 103, the one not coupled to the waveguide is reflected by the light control unit 3 (for example, the plasmon excitation layer 105). The reflected light is reflected by a reflector such as, for example, a metal mirror, a dielectric mirror, or a prism, and the light is incident on the light control unit 3 again to further improve the utilization efficiency of the excitation light.

The

light emitting elements

101 a and 101 b emit light (excitation light) of a wavelength that can be absorbed by the carrier generation layer 103. Specifically, for example, a light emitting diode (LED), a laser diode, a super luminescent diode and the like can be mentioned. In the case of the LED, it is preferable to devise a device that emits light having a uniform emission angle and polarization. In the case of the super luminescent diode, it is preferable that a device for emitting light with uniform polarization is provided. The incident angle of the excitation light to the carrier generation layer 103 is as described above. For example, the

light emitting elements

101a and 101b are arranged such that the incident angle falls within the predetermined range.

The carrier generation layer 103 is a layer that absorbs the excitation light to generate carriers. The carrier generation layer 103 includes, for example, a light emitter. The light emitter is, for example, a phosphor or a phosphor. Examples of the phosphor include organic phosphors, inorganic phosphors, quantum dot phosphors, and semiconductor phosphors. Examples of the organic fluorescent substance include rhodamine (Rhodamine 6G) and sulforhodamine (Sulforhodamine 101). Examples of the inorganic phosphor include Y ₂ O ₂ S: Eu, BaMgAl _x O _y : Eu, and BaMgAl _x O _y : Mn. Examples of the quantum dot phosphor include quantum dots such as CdSe and CdSe / ZnS. Examples of the semiconductor phosphor include phosphors of inorganic material semiconductors and organic material semiconductors. Examples of the inorganic material semiconductor include GaN and GaAs. Examples of the organic material semiconductor include (thiophene / phenylene) co-oligomer, Alq3 (tris (8-quinolinolato) aluminum), and the like. The carrier generation layer 103 may be made of, for example, a plurality of materials that generate light of a plurality of wavelengths having the same or different emission wavelengths. The thickness of the carrier generation layer 103 is not particularly limited, and is, for example, preferably 1 μm or less, and particularly preferably 100 nm or less.

The carrier generation layer 103 may include, for example, metal particles. The metal particle excites surface plasmons on the surface of the metal particle by interaction with the excitation light, and induces an enhanced electric field near 100 times the electric field strength of the excitation light in the vicinity of the surface. By this enhanced electric field, carriers generated in the carrier generation layer 103 can be increased, and, for example, the utilization efficiency of the excitation light in the light control unit 3 can be improved.

The metal constituting the metal particles is, for example, gold, silver, copper, platinum, palladium, rhodium, osmium, ruthenium, iridium, iron, tin, zinc, cobalt, nickel, chromium, titanium, tantalum, tungsten, indium, aluminum Or these alloys and the like. Among these, gold, silver, copper, platinum, aluminum, or an alloy containing any of these as a main component is preferable, and gold, silver, aluminum, or an alloy containing any of these as a main component is particularly preferable. The metal particle has, for example, a core-shell structure different in metal species in the periphery and in the center; a combined hemispherical combined structure of hemispheres of two metals; a cluster-in-cluster structure in which different clusters assemble to form particles And the like. By setting the metal particles to, for example, the alloy or the special structure described above, the resonance wavelength can be controlled without changing the size, shape, etc. of the metal particles.

The shape of the metal particle may be a shape having a closed surface, and examples thereof include a rectangular parallelepiped, a cube, an ellipsoid, a sphere, a triangular pyramid, a triangular prism and the like. The metal particles include, for example, those obtained by processing a metal thin film into a structure constituted by a closed surface having a side of less than 10 μm by fine processing represented by semiconductor lithography technology. The size of the metal particles is, for example, in the range of 1 to 100 nm, preferably in the range of 5 to 70 nm, and more preferably in the range of 10 to 50 nm.

The plasmon excitation layer 105 is formed to have a plasma frequency higher than the frequency of light generated in the carrier generation layer 103 (hereinafter sometimes referred to as “light emission frequency”) when the carrier generation layer 103 alone is excited with excitation light. It is a fine particle layer or a thin film layer formed of a material. That is, plasmon excitation layer 105 has a negative dielectric constant at the light emission frequency. For example, in the range from the interface of the plasmon excitation layer 105 on the carrier generation layer 103 side to the carrier generation layer 103 side of the plasmon excitation layer 105 to the effective interaction distance of the surface plasmon represented by the formula (4), for example A portion of the dielectric layer having anisotropy may be disposed. This dielectric layer has, for example, an optical anisotropy that differs in dielectric constant depending on the direction in the plane perpendicular to the stacking direction of the components of the light control unit 3, in other words, in the plane parallel to the interface of each layer . That is, in the dielectric layer, in a plane perpendicular to the stacking direction of the components of the light control unit 3, there is a magnitude relation between the dielectric constants in a certain direction and a direction perpendicular thereto. Due to this dielectric layer, in a plane perpendicular to the stacking direction of the components of the optical device 1, the effective dielectric constant of the incident side portion is different between a certain direction and a direction perpendicular thereto. Then, if the effective dielectric constant of the incident side portion is set high enough to cause no plasmon coupling in a certain direction and low enough to cause plasmon coupling in the direction orthogonal thereto, for example, light incident on the wave number vector conversion layer 107 The angle of incidence and polarization of Therefore, for example, the light extraction efficiency of the wave vector conversion layer 107 can be further improved.

Theoretically, when the sum of the effective permittivity of the incident side portion and the permittivity of the plasmon excitation layer 105 is negative or 0, the carriers generated in the carrier generation layer 103 are surface plasmons in the plasmon excitation layer 105. Excite. On the other hand, when the sum is positive, the carriers do not excite surface plasmons. That is, the above-mentioned effective dielectric constant high enough that the plasmon coupling does not occur is such a dielectric constant that the sum of the dielectric constant of the plasmon excitation layer 105 and the effective dielectric constant of the incident side becomes positive. The effective dielectric constant low enough to cause coupling is a dielectric constant such that the sum of the dielectric constant of the plasmon excitation layer 105 and the effective dielectric constant of the incident side portion becomes negative or zero. The efficiency with which the carriers generated in the carrier generation layer 103 couple to the surface plasmon is a condition under which the effective dielectric constant of the incident side portion and the sum of the dielectric constants of the plasmon excitation layer 105 become zero. Therefore, the condition that the sum of the dielectric constant of the plasmon excitation layer 105 and the lowest value of the effective dielectric constant of the incident side portion is 0 is the most preferable in that the directivity with respect to the azimuth angle is enhanced. However, under the above conditions, for example, there is a concern that the emission of light passing through the plasmon excitation layer 105 may be reduced due to excessive directivity with respect to the azimuth angle, and the heat generation in the plasmon excitation layer 105 may be caused. For this reason, it is preferable that the directivity of the azimuth angle is not excessively enhanced in practice. Specifically, under the condition that the sum of the dielectric constant of the plasmon excitation layer 105 and the intermediate value of the effective dielectric constant of the incident side becomes 0, for example, azimuth angles of 315 degrees to 45 degrees, 135 degrees to 225 degrees High directional radiation is obtained in the range. Therefore, for example, it is possible to simultaneously improve the directivity with respect to the azimuth angle and suppress the decrease in light emission. Examples of the constituent material of the dielectric layer having optical anisotropy include anisotropic crystals such as TiO ₂ , YVO ₄ , and Ta ₂ O ₅ . Examples of the structure of the dielectric layer include a diagonal vapor deposition film of a dielectric, a diagonal sputtering film, and the like.

The constituent material of the plasmon excitation layer 105 is, for example, gold, silver, copper, platinum, palladium, rhodium, osmium, ruthenium, iridium, iron, tin, zinc, cobalt, nickel, chromium, titanium, tantalum, tungsten, indium, aluminum Or these alloys and the like. Among these, gold, silver, copper, platinum, aluminum, and a mixture with a dielectric containing these as the main component is preferable, and gold, silver, aluminum, and a dielectric containing these as the main component are preferable. Mixtures with are particularly preferred. The thickness of the plasmon excitation layer 105 is not particularly limited, and is preferably 200 nm or less, and particularly preferably about 10 to 100 nm.

The surface on the carrier generation layer 103 side of the plasmon excitation layer 105 may be roughened, for example. The rough surface provides, for example, the scattering of the excitation light and the excitation of localized plasmons at the tip of the rough surface, thereby increasing the number of carriers excited in the carrier generation layer 103. As a result, for example, the utilization efficiency of the excitation light in the light control unit 3 can be improved.

The dielectric layer 104 is a layer containing a dielectric, and specifically, for example, SiO ₂ nanorod array film; SiO ₂ , AlF ₃ , MgF ₂ , Na ₃ AlF ₆ , NaF, LiF, CaF ₂ , BaF ₂ And thin films or porous films such as low dielectric constant plastics. The thickness of the dielectric layer 104 is not particularly limited, and is, for example, in the range of 1 to 100 nm, preferably in the range of 5 to 50 nm, and more preferably in the range of 5 to 20 nm.

The constituent material of the dielectric layer 106 is, for example, diamond, TiO ₂ , CeO ₂ , Ta ₂ O ₅ , ZrO ₂ , Sb ₂ O ₃ , HfO ₂ , La ₂ O ₃ , NdO ₃ , Y ₂ O ₃ , ZnO, A high dielectric constant material such as Nb ₂ O ₅ can be mentioned. The thickness of the dielectric layer 106 is not particularly limited.

The wave vector conversion layer 107 is an emission unit that emits light emitted from the interface between the plasmon excitation layer 105 and the dielectric layer 106 from the optical device 1 by converting the wave vector. The wave number vector conversion layer 107 has a function of causing the optical device 1 to emit the radiation in the direction substantially orthogonal to the interface between the plasmon excitation layer 105 and the dielectric layer 106.

The shape of the wave number vector conversion layer 107 is, for example, a surface relief grating; a periodic structure represented by a photonic crystal, or a quasi-periodic structure; a texture structure whose size is larger than the wavelength of light emitted from the optical device 1 Surface structure constituted by a surface); hologram; microlens array etc. The quasi-periodic structure indicates, for example, an incomplete periodic structure in which part of the periodic structure is missing. From the viewpoint of improvement of light extraction efficiency and directivity control, the shape is preferably a periodic structure represented by a photonic crystal, or a quasi-periodic structure; a microlens array or the like. The photonic crystal preferably has a triangular lattice structure. The wave number vector conversion layer 107 may have, for example, a structure in which a convex portion is provided on a flat base.

As described above, in the optical device 1, the distance from the surface on the carrier generation layer 103 side of the plasmon excitation layer 105 to the surface on the plasmon excitation layer 105 side of the carrier generation layer 103 is set shorter than the effective interaction distance d _{eff of} surface plasmons. It is done. By setting in this way, carriers generated in the carrier generation layer 103 and free electrons in the plasmon excitation layer 105 can be efficiently coupled, and as a result, for example, luminous efficiency can be improved. The region with high coupling efficiency is, for example, the carrier generation layer 103 side surface of the plasmon excitation layer 105 from the position in the carrier generation layer 103 where carriers are generated (for example, the position in the carrier generation layer 103 where the phosphor is present). Area until The region is, for example, as narrow as about 200 nm, for example, in the range of 1 to 200 nm or in the range of 10 to 100 nm. In the optical device 1, when the region is in the range of 1 to 200 nm, for example, the carrier generation layer 103 is preferably disposed in the range of 1 to 200 nm from the plasmon excitation layer 105. When the region is in the range of 10 to 100 nm, for example, the carrier generation layer 103 is preferably disposed in the range of 10 to 100 nm from the plasmon excitation layer 105, and specifically, for example, The thickness of the dielectric layer 104 is 10 nm, and the thickness of the carrier generation layer 103 is 90 nm. From the viewpoint of light extraction efficiency, it is preferable that the carrier generation layer 103 be thinner. On the other hand, from the viewpoint of light output rating, it is preferable that the carrier generation layer 103 be thicker. Therefore, the thickness of the carrier generation layer 103 is determined based on, for example, the required light extraction efficiency and the light output rating. The range of the region changes depending on the dielectric constant of the dielectric layer disposed between the carrier generation layer and the plasmon excitation layer, so that, for example, the dielectric may be selected according to the range of the region under predetermined conditions. The thickness of the layer, the thickness of the carrier generation layer, and the like may be set as appropriate.

In the optical device of the present embodiment shown in FIG. 1, two light emitting elements are arranged, but the present invention is not limited to this example. The number of light emitting elements is not particularly limited. The excitation light may be incident on the light control unit 3 through, for example, a light guide. The shape of the light guide may be, for example, a rectangular parallelepiped or a wedge shape, or a shape having a light emitting portion of the light guide or a light extraction structure inside the light guide. The structure for light extraction preferably has, for example, a function of converting the incident angle of the excitation light to the carrier generation layer to an angle equal to or more than the predetermined incident angle to improve the absorptivity. It is preferable that the surface of the light guide excluding the light emitting portion is subjected to a process for preventing the excitation light from being emitted from the surface, using, for example, a reflective material or a dielectric multilayer film. Also, for example, the optical device of the present invention may include an optical member (for example, a mirror or the like) capable of adjusting the incident angle of the excitation light to the carrier generation layer to be equal to or more than the predetermined incident angle.

Moreover, in the optical device of the present embodiment, the plasmon excitation layer is sandwiched between the two dielectric layers, but as described above, the dielectric layer is not essential in the present invention, and, for example, The plasmon excitation layer may be disposed on the carrier generation layer. The dielectric layer may be laminated only on one side of the plasmon excitation layer.

Second Embodiment
The configuration of the optical device of the present embodiment is shown in the perspective view of FIG. The optical device of the present embodiment has the same configuration as the optical device of the first embodiment except that the light control unit does not include a dielectric layer. As shown in FIG. 7, the optical device 11 of the present embodiment includes

light emitting elements

101 a and 101 b and a light control unit 13 as main components. The light control unit 13 includes a carrier generation layer 103, a plasmon excitation layer 105 stacked on the carrier generation layer 103, and a wave number vector conversion layer (emission layer) 207 stacked on the plasmon excitation layer 105. The

light emitting elements

101 a and 101 b are disposed around the side surface of the light control unit 13.

The optical device 11 is configured such that the effective dielectric constant of the incident side portion is higher than or equal to the effective dielectric constant of the emission side portion. The incident side portion includes the entire structure stacked on the carrier generation layer 103 side of the plasmon excitation layer 105 and a medium in contact with the carrier generation layer 103. The entire structure includes a carrier generation layer 103. The emission side portion includes the entire structure stacked on the wave number vector conversion layer 207 side of the plasmon excitation layer 105 and a medium in contact with the wave number vector conversion layer 207. The whole structure includes a wave vector conversion layer 207.

Next, an operation of the optical device 11 in which excitation light from the light emitting element 101 is incident on the light control unit 13 and light is emitted from the wave number vector conversion layer 207 of the light control unit 13 will be described.

The excitation light emitted from the

light emitting elements

101a and 101b enters the light control unit 13 at the predetermined incident angle (and polarization). The excitation light is then coupled to the waveguide and confined therein. The confined excitation light excites the carrier generation layer 103 to generate carriers in the carrier generation layer 103. The carriers couple with free electrons in the plasmon excitation layer 105 and excite surface plasmons at the interface between the carrier generation layer 103 and the plasmon excitation layer 105 and at the interface between the plasmon excitation layer 105 and the wave vector conversion layer 207. The surface plasmon excited at the interface between the carrier generation layer 103 and the plasmon excitation layer 105 passes through the plasmon excitation layer 105 and propagates to the interface between the plasmon excitation layer 105 and the wave vector conversion layer 207. As described above, the optical device 11 is configured such that the effective dielectric constant of the incident side portion is higher than or equal to the effective dielectric constant of the emission side portion, and the plasmon excitation layer of the wave number vector conversion layer 207 The distance from the surface of the wave number vector conversion layer 207 of the plasmon excitation layer 105 is arranged within the range of the effective interaction distance of surface plasmons at the end on the 105 side. Here, when the wave number vector conversion layer 207 is a flat dielectric layer, surface plasmons at the interface between the plasmon excitation layer 105 and the wave number vector conversion layer 207 are not converted to light at the interface. The surface plasmon at the interface is emitted (emitted) as light to the outside of the optical device 11 because the wave number vector conversion layer 207 has a function of extracting the surface plasmon as light, for example, a diffractive action. The wavelength of the emitted light is equal to the wavelength of light generated when the carrier generation layer 103 is excited alone. Further, the radiation angle θ _rad of the emitted light is the refractive index of the light extraction side of the wave vector conversion layer 207 (that is, the medium in contact with the wave vector conversion layer 207), where the pitch of the periodic structure of the wave vector conversion layer 207 is Λ. _Is given by the following equation (6).

The wave number of the surface plasmon excited at the interface between the carrier generation layer 103 and the plasmon excitation layer 105 exists only in the vicinity uniquely set by the equation (2). The same applies to the wave number of the surface plasmon excited at the interface between the plasmon excitation layer 105 and the wave vector conversion layer 207. Therefore, the emission angle of the emitted light is uniquely determined, and its polarization state is always p-polarization. That is, the emitted light is p-polarized light having very high directivity. Of the excitation light incident on the carrier generation layer 103, the one not coupled to the waveguide is reflected by the light control unit 13 (for example, the plasmon excitation layer 105). The reflected light is reflected by a reflector such as, for example, a metal mirror, a dielectric mirror, or a prism, and the light is incident on the light control unit 3 again to further improve the utilization efficiency of the excitation light. The incident angle of the excitation light to the carrier generation layer 103 is the same as that of the first embodiment.

The wave number vector conversion layer 207 extracts surface plasmons excited at the interface between the plasmon excitation layer 105 and the wave number vector conversion layer 207 as light from the interface by converting the wave number vector, and emits the light from the optical device 11 It is an emitting part. That is, the wave vector conversion layer 207 converts the surface plasmon into light of a predetermined radiation angle, and causes the light to be emitted from the optical device 11. Furthermore, the wave number vector conversion layer 207 has a function of emitting radiation light from the optical device 11 so as to be substantially orthogonal to the interface between the plasmon excitation layer 105 and the wave number vector conversion layer 207, for example. The wave number vector conversion layer 207 can use, for example, the same one as the wave number vector conversion layer 107 of the first embodiment.

In the optical device of the present embodiment shown in FIG. 7, the carrier generation layer is disposed in contact with the plasmon excitation layer, but the present invention is not limited to this example. Even if, for example, a dielectric layer having a thickness smaller than the effective interaction distance d _{eff of the} surface plasmon represented by the formula (4) is disposed between the carrier generation layer and the plasmon excitation layer. Good. Moreover, although the said wave number vector conversion layer is arrange | positioned in contact with the said plasmon excitation layer, this invention is not limited to this example, For example, between the said wave number vector conversion layer and the said plasmon excitation layer The dielectric layer may have a thickness smaller than the effective interaction distance d _{eff of the} surface plasmon represented by the formula (4).

Further, in the optical device of this embodiment, for example, as in the first embodiment, a dielectric layer having optical anisotropy may be disposed between the carrier generation layer and the plasmon excitation layer. In this case, if the effective dielectric constant of the incident side portion is set high enough not to cause plasmon coupling in a certain direction, and low enough to cause plasmon coupling in the direction orthogonal thereto, for example, light enters the wave number vector conversion layer The angle of incidence and polarization of the light can be further limited. Thus, for example, the light extraction efficiency of the wave number vector conversion layer can be further improved.

(Embodiment 3)
The configuration of the optical device of the present embodiment is shown in the perspective view of FIG. As shown in FIG. 8, the optical device 21 of the present embodiment includes

light emitting elements

101 a and 101 b and a light control unit 23 as main components. The light control unit 23 includes a carrier generation unit 303, a plasmon excitation layer 305, and a dielectric layer 306. The dielectric layer 306 is stacked on the plasmon excitation layer 305. The carrier generation unit 303 is periodically embedded in the dielectric layer 306, penetrates the dielectric layer 306, and one end thereof is in contact with the plasmon excitation layer 305. The carrier generation unit 303 has a function as the “emission layer” in the present invention. The

light emitting elements

101 a and 101 b are disposed around the side surface of the light control unit 23.

Furthermore, in the optical device 21, the distance from the surface on the carrier generation unit 303 side of the plasmon excitation layer 305 to the surface on the plasmon excitation layer 305 side of the carrier generation unit 303 is an effective interaction of surface plasmons represented by the equation (4). It is set shorter than the distance d _eff .

Next, in the optical device 21, excitation light from the

light emitting elements

101 a and 101 b enters the light control unit 23, and the surface of the carrier generation unit 303 and the surface of the dielectric layer 306 opposite to the plasmon excitation layer 305 side The operation of emitting light from the (light emitting surface 309) will be described.

The excitation light emitted from the

light emitting elements

101a and 101b enters the carrier generation unit 303 at the predetermined incident angle (and polarization). Then, the carrier generation unit 303 is excited by the excitation light, and carriers are generated in the carrier generation unit 303. The carriers couple with free electrons in the plasmon excitation layer 305, and excite surface plasmons at the interface between the carrier generation unit 303 and the plasmon excitation layer 305. The excited surface plasmon is diffracted by the periodic structure formed by the carrier generation unit 303 and the dielectric layer 306, and is emitted as light through the light emitting surface 309 to the outside of the optical device 21. The wavelength of the emitted light is equal to the wavelength of light generated when the carrier generation unit 303 is excited alone. Among the carriers generated in the carrier generation unit 303, those not coupled to the surface plasmons are emitted from the optical device 21 as, for example, general light and propagating light. The emission angle θ _rad of the emitted light is expressed by the equation (6). Here, in the present embodiment, the portion including the entire structure stacked on the dielectric layer 306 side of the plasmon excitation layer 305 and the medium in contact with the carrier generation unit 303 (and the dielectric layer 306) It serves both as the excitation light incident side portion and the light emission side portion defined. The wave number of the surface plasmon excited at the interface between the dielectric layer 306 and the plasmon excitation layer 305 exists only in the vicinity uniquely set by the equation (2). Therefore, the emission angle of the emitted light is uniquely determined, and its polarization state is always p-polarization. That is, the emitted light is p-polarized light having very high directivity. The light distribution distribution of the propagation light by the carriers not coupled with the surface plasmons is superimposed on the light distribution distribution of the emitted light.

The carrier generation unit 303 is a layer that absorbs excitation light to generate carriers, and the functions, constituent materials, and the like thereof are the same as, for example, the carrier generation layer 103 of the first embodiment. The carrier generation unit 303 may include, for example, the metal particles as in the carrier generation layer 103 of the first embodiment. The metal and the effect etc. which comprise the said metal particle are the same as that of what was shown in the said Embodiment 1. FIG.

The constituent material of the dielectric layer 306 is, for example, diamond, TiO ₂ , CeO ₂ , Ta ₂ O ₅ , ZrO ₂ , Sb ₂ O ₃ , HfO ₂ , La ₂ O ₃ , NdO ₃ , Y ₂ O ₃ , ZnO, A high dielectric constant material such as Nb ₂ O ₅ can be mentioned. By using the high dielectric constant material, for example, among the carriers generated in the carrier generation unit 303, the number of carriers coupled to surface plasmons can be increased, and light having higher directivity and higher degree of polarization can be obtained. Can be emitted from the optical device 21. The thickness of the dielectric layer 306 is not particularly limited, and is, for example, in the range of 1 to 100 nm, preferably in the range of 5 to 50 nm, and more preferably in the range of 5 to 10 nm.

The function, constituent material, shape, and the like of the plasmon excitation layer 305 are, for example, the same as those of the plasmon excitation layer 105 of the first embodiment. For example, a dielectric layer having optical anisotropy may be disposed on the side of the plasmon excitation layer 305 on which the dielectric layer 306 is stacked. The configuration, effects and the like of this dielectric layer are the same as those shown in the first embodiment.

In the optical device of the present embodiment shown in FIG. 8, the carrier generation unit is embedded in the dielectric layer, but the present invention is not limited to this example, for example, the dielectric layer and the dielectric layer The dielectric portion may be periodically embedded in the carrier generation layer by reversing the relationship with the carrier generation portion. Even with such a configuration, the same effect as described above can be obtained. Moreover, although the side surface where the said plasmon excitation layer of the said dielectric material layer is not laminated | stacked and the surface on the opposite side to the said plasmon excitation layer of the said carrier production | generation part are set to the same height, this invention The present invention is not limited to this example, and does not necessarily have to have the same height. The carrier generation unit may be connected, for example, over the entire surface of the dielectric layer, or one end of the carrier generation unit may not be in contact with the plasmon excitation layer.

(Embodiment 4)
The optical device of the present embodiment is an example of an optical device provided with a half wave plate as a polarization conversion element. The structure of the optical apparatus of this embodiment is shown in the schematic diagram of FIG.

As shown in FIG. 11, the optical device 31 of the present embodiment includes the optical device 1 and a half wave plate 410 as main components. The optical device 1 is the optical device of the first embodiment shown in FIG. The half-wave plate 410 is disposed on the side of the wave number vector conversion layer 107 of the optical device 1. In FIG. 11, for convenience of explanation, the half-wave plate 410 is indicated by a two-dot chain line.

As shown in the first embodiment, light is emitted from the wave number vector conversion layer 107. Since the light is p-polarized as described above, the field pattern of the light has a radial polarization direction. For this reason, the light is axisymmetrically polarized (see, for example, [0104] of WO 2011/040528). Then, the light (axisymmetric polarization) is incident on the half wave plate 410. At this time, the axisymmetric polarization is converted into linearly polarized light by the half wave plate 410. As described above, in the optical device of the present embodiment, the polarization state of the light can be aligned (see, for example, [0105] in the same International Publication).

The half-wave plate 410 is not particularly limited, and examples thereof include conventionally known ones. Specifically, for example, the following half-wave plate disclosed in WO 2011/040528 may be mentioned.

The half-wave plate disclosed in the above publication includes, for example, a pair of glass substrates each having an alignment film formed thereon, a liquid crystal layer disposed with the alignment films of these substrates facing each other, and the glass substrate, And a spacer provided between the substrates. The liquid crystal layer, n ₀ the refractive index for the ordinary _light, the refractive index when the n _e for extraordinary light, a refractive index greater than n ₀ the refractive index n _e is. The thickness d of the liquid crystal layer satisfies (n _e −n ₀ ) × d = λ / 2. Here, λ is the wavelength of incident light in vacuum.

In the liquid crystal layer, liquid crystal molecules are arranged concentrically with respect to the center of the half wave plate. The liquid crystal molecule has an angle of θ between the main axis of the liquid crystal molecule and the coordinate axis in the vicinity of the main axis, and the angle between the coordinate axis and the polarization direction is θ. It is oriented in a direction satisfying any of the relational expressions of 2φ-180.

In the optical device of the present embodiment shown in FIG. 11, axisymmetric polarization is converted into linearly polarized light by the 1⁄2 wavelength plate, but the present invention is not limited to this example. For example, the axisymmetric polarization is circular It may be converted to polarized light. In addition, although the optical device of the first embodiment is used in the optical device of the present embodiment, the present invention is not limited to this example, for example, using the optical device of the second or third embodiment. It is also good.

Embodiment 5
The image display device of the present embodiment is an example of a three-panel projection display device (LED projector). FIG. 9 shows the configuration of the LED projector of this embodiment. Fig.9 (a) is a schematic perspective view of the LED projector of this embodiment, FIG.9 (b) is a top view of the same LED projector.

As shown in FIG. 9, the LED projector 10 according to this embodiment includes the

optical devices

1r, 1g, 1b of any of the three embodiments 1 to 4, three

liquid crystal panels

502r, 502g, 502b, and color synthesis. An optical element 503 and a projection optical system 504 are included as main components. The optical device 1r and the liquid crystal panel 502r, the optical device 1g and the liquid crystal panel 502g, and the optical device 1b and the liquid crystal panel 502b form an optical path, respectively.

The

optical devices

1r, 1g, and 1b are respectively made of different materials for red (R) light, green (G) light, and blue (B) light. The

liquid crystal panels

502r, 502g, and 502b receive the light emitted from the optical device and modulate the light intensity in accordance with the image to be displayed. The color combining optical element 503 combines the light modulated by the

liquid crystal panels

502r, 502g, and 502b. The projection optical system 504 includes a projection lens that projects the light emitted from the color combining optical element 503 onto a projection surface such as a screen.

FIG. 10 shows the light emission wavelengths (Rs, Gs, Bs) of the optical device used for the LED projector 10, and the excitation wavelengths (Ra, Ga, Ba) and the light emission wavelengths (Rr, Gr, Br) of the carrier generation layer. It shows the relationship with the strength. As shown in FIG. 10, the emission wavelengths Rs, Gs, Bs of the optical device for R light, the optical device for G light, and the optical device for B light, and the excitation wavelengths Ra, Ga, Ba of the carrier generation layer are approximately the same. It is set equally. In addition, the emission wavelengths Rs, Gs, and Bs of the optical device, the excitation wavelengths Ra, Ga, and Ba of the carrier generation layer, and the emission wavelengths Rr, Gr, and Br of the carrier generation layer do not overlap with each other. It is set. In addition, the emission spectra of the R optical device, the G optical device, and the B optical device are set to match the excitation spectrum of each carrier generation layer or to be within the excitation spectrum. There is. In addition, the emission spectrum of the carrier generation layer is set so as not to almost overlap with any excitation spectrum of the carrier generation layer.

The LED projector 10 modulates the image on the liquid crystal panel for each of the light paths by a control circuit unit (not shown). The LED projector 10 can improve the brightness of the projection image by including the optical device according to any one of the first to fourth embodiments. In addition, since the optical device exhibits very high directivity, it can be miniaturized, for example, without using an illumination optical system.

Although the LED projector of the present embodiment shown in FIG. 9 is a three-plate type liquid crystal projector, the present invention is not limited to this example, and may be, for example, a single-plate type liquid crystal projector. Further, the image display device of the present invention may be a projector using not only the above-described LED projector but also, for example, a light emitting element other than an LED (for example, a laser diode, a super luminescent diode, etc.) It may be an image display device combined with a backlight or a backlight using MEMS.

As described above, the optical device of the present invention has an improved absorption efficiency of excitation light. Therefore, the image display device using the optical device of the present invention can be used as a projector or the like. The projector may be, for example, a mobile projector, a next-generation rear projection TV, a digital cinema, a retinal scanning display (RSD), a head up display (HUD), or a mobile phone, digital There are a camera, a built-in projector (embedded projector) in a notebook personal computer and the like, and application to a wide range of markets is possible. However, the application is not limited and can be applied to a wide range of fields.

Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

This application claims priority based on Japanese Patent Application No. 2012-1693 filed on Jan. 7, 2012, the entire disclosure of which is incorporated herein.

1, 1 r, 1 g, 1 b, 11, 21, 31

Optical devices

3, 13, 23 Light control unit 10 LED projector (image display device)
101a, 101b Light emitting element 103 Carrier generation layer 104

Dielectric layer

105, 305

Plasmon excitation layer

106, 306

Dielectric layer

107, 207 Wavenumber vector conversion layer (emission layer)
303 Carrier generation unit (emission layer)
309 Light emitting surface 410 1/2 wavelength plate (polarization conversion element)
502r, 502g, 502b liquid crystal panel 503 color combining optical element 504 projection optical system

Claims

A light emitting element,
A carrier generation layer in which light from the light emitting element is incident and carriers are generated;
A plasmon excitation layer for exciting plasmons, which is stacked on the carrier generation layer and has a plasma frequency higher than the frequency of light generated when the carrier generation layer is excited by the light of the light emitting element;
And an emission layer for converting light or surface plasmon generated on the surface of the plasmon excitation layer into light of a predetermined emission angle and emitting the light.
The optical apparatus which makes the incident angle of the light which injects into the said carrier production | generation layer 40 degrees or more.
The optical device according to claim 1, wherein the incident angle is 60 degrees or more.
The optical device according to claim 1, wherein a dielectric layer is laminated on at least one surface of the plasmon excitation layer.
The distance between the carrier generation layer side surface of the plasmon excitation layer and the plasmon excitation layer side surface of the carrier generation layer is an effective interaction of surface plasmons excited on the carrier generation layer side surface of the plasmon excitation layer The optical device according to any one of claims 1 to 3, which is shorter than the distance.
The optical device according to claim 4, wherein the carrier generation layer is disposed within a range of 1 to 200 nm from the plasmon excitation layer.
The optical device according to any one of claims 1 to 5, wherein the exit layer has a surface periodic structure.
The optical device according to any one of claims 1 to 6, wherein the carrier generation layer has a surface periodic structure and doubles as the exit layer.
The optical device according to any one of claims 1 to 7, further comprising a polarization conversion element for aligning the axially symmetric polarized light emitted from the output layer into a predetermined polarization state.
The effective dielectric constant of the incident side portion including the entire structure stacked on the light emitting element side of the plasmon excitation layer and the medium in contact with the light emitting element is the entire structure stacked on the output layer side of the plasmon excitation layer The optical device according to any one of claims 1 to 8, which is lower than an effective dielectric constant of an output side portion including a medium in contact with the output layer.
The effective dielectric constant of the incident side portion including the entire structure stacked on the light emitting element side of the plasmon excitation layer and the medium in contact with the light emitting element is the entire structure stacked on the output layer side of the plasmon excitation layer Higher than or equal to the effective dielectric constant of the emission side portion including the medium in contact with the emission layer,
The end of the emission layer on the plasmon excitation layer side is located within the range of the effective interaction distance of surface plasmons from the surface of the plasmon excitation layer on the emission layer side. 8. The optical device according to any one of 8.
The effective dielectric constant (ε eff ) is such that a direction parallel to the interface of the plasmon excitation layer is x-axis, y-axis, a direction perpendicular to the interface of the plasmon excitation layer is z-axis, of the light emitted from the carrier generation layer The angular frequency is ω, the dielectric constant distribution of the dielectric of the incident side or the emission side is ε (ω, x, y, z), the integration range D is three dimensional coordinates of the incident side or the emission side If the z component of the wave number of the surface plasmon is k spp, z , the imaginary unit is j, and Re [] is a symbol indicating the real part of the numerical value in [], the following equation (1) or (7) Represented by either
The z component k spp, z of the wave number of the surface plasmon and the x, y component k spp of the wave number of the surface plasmon are ε metal of the real part of the dielectric constant of the plasmon excitation layer. The optical device according to claim 9 or 10, which is represented by the following formula (2) and formula (3), assuming that the wave number is k 0 .
12. The effective interaction distance d eff according to any one of claims 4 to 11, wherein Im [] is a symbol indicating an imaginary part of a numerical value in []. Optical device.
An optical device according to any one of the preceding claims,
An image display device including an image display unit capable of displaying an image.
The image display device according to claim 13, further comprising a projection optical system that projects a projection image by light emitted from the image display unit.