WO2013103037A1 - 光学装置、光学素子および画像表示装置 - Google Patents
光学装置、光学素子および画像表示装置 Download PDFInfo
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- WO2013103037A1 WO2013103037A1 PCT/JP2012/075695 JP2012075695W WO2013103037A1 WO 2013103037 A1 WO2013103037 A1 WO 2013103037A1 JP 2012075695 W JP2012075695 W JP 2012075695W WO 2013103037 A1 WO2013103037 A1 WO 2013103037A1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/008—Surface plasmon devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F21—LIGHTING
- F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
- F21V9/00—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters
- F21V9/14—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters for producing polarised light
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/20—Lamp housings
- G03B21/2006—Lamp housings characterised by the light source
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/20—Lamp housings
- G03B21/2073—Polarisers in the lamp house
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/10—Beam splitting or combining systems
- G02B27/1006—Beam splitting or combining systems for splitting or combining different wavelengths
- G02B27/102—Beam splitting or combining systems for splitting or combining different wavelengths for generating a colour image from monochromatic image signal sources
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/10—Beam splitting or combining systems
- G02B27/14—Beam splitting or combining systems operating by reflection only
- G02B27/141—Beam splitting or combining systems operating by reflection only using dichroic mirrors
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/0004—Devices characterised by their operation
Definitions
- the present invention relates to an optical device, an optical element, and an image display device.
- an image display device such as a projector
- a light emitting element a light guide that receives light (excitation light) from the light emitting element, and light provided from the light guide.
- An optical device has been developed that includes a plasmon excitation layer to be excited, and an emission layer that is laminated on the plasmon excitation layer and that converts light incident from the plasmon excitation layer into light having a predetermined emission angle and emits the light. (Patent Document 1).
- Such an optical device emits light on the following principle. That is, first, carriers are generated in the carrier generation layer by absorbing the excitation light irradiated from the light emitting element into the carrier generation layer. These carriers combine with free electrons in the plasmon excitation layer to excite surface plasmons. Then, the excited surface plasmon is emitted as light.
- An object of the present invention is to provide an optical device, an optical element, and an image display device capable of improving the absorption efficiency of excitation light.
- the optical device of the present invention comprises: 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 that is laminated on the carrier generation layer and has a plasma frequency higher than a frequency of light generated when the carrier generation layer is excited by light of the light emitting element; The light generated on the surface of the plasmon excitation layer or the surface plasmon is converted into light having a predetermined emission angle and is emitted, Furthermore, a polarization conversion layer is provided below the carrier generation layer.
- the optical element of the present invention is A carrier generation layer in which light from the light emitting element is incident and carriers are generated; A plasmon excitation layer that is laminated on the carrier generation layer and has a plasma frequency higher than the frequency of light generated when the carrier generation layer is excited with the light, and that excites plasmons; The light generated on the surface of the plasmon excitation layer or the surface plasmon is converted into light having a predetermined emission angle and is emitted, Furthermore, a polarization conversion layer is provided below the carrier generation layer.
- the image display device of the present invention is The optical device of the present invention, or the optical element of the present invention, An image display unit capable of displaying an image.
- an optical device an optical element, and an image display device capable of improving the absorption efficiency of excitation light.
- FIG. 1 is a perspective view schematically showing a configuration of an example (Embodiment 1) of an optical device of the present invention.
- FIG. 2 is a diagram showing the incident angle and polarization dependence of the absorption rate of excitation light in the carrier generation layer.
- FIG. 3 is a diagram showing the dependency of the excitation light absorption rate on the thickness of the carrier generation layer.
- FIG. 4 is a diagram showing an emission spectrum from the optical device when the thickness of the carrier generation layer is 50 nm.
- FIG. 5 is a diagram showing an emission spectrum from the optical device when the thickness of the carrier generation layer is 100 nm.
- FIG. 6 is a diagram illustrating the excitation light incident angle dependence of the emission spectrum from the optical device.
- FIG. 1 is a perspective view schematically showing a configuration of an example (Embodiment 1) of an optical device of the present invention.
- FIG. 2 is a diagram showing the incident angle and polarization dependence of the absorption rate of excitation light in the carrier generation layer.
- FIG. 7 is a perspective view schematically showing the configuration of another example (Embodiment 2) of the optical apparatus of the present invention.
- FIG. 8 is a perspective view schematically showing the configuration of still another example (Embodiment 3) of the optical apparatus of the present invention.
- FIG. 9 is a schematic diagram showing the configuration of an example (Embodiment 6) of the image display device (LED projector) of the present invention.
- FIG. 10 is a diagram for explaining the emission wavelength of the optical device used in the LED projector of Embodiment 6 and the excitation wavelength and emission wavelength of the phosphor.
- FIG. 11 is a perspective view schematically showing the configuration of still another example (Embodiment 4) of the optical apparatus of the present invention.
- the optical device of the present embodiment is an example of an optical device in which the polarization conversion layer is a quarter wavelength plate.
- the configuration of the optical device of the present embodiment is shown in the perspective view of FIG.
- the optical device 1 of this embodiment includes a light source unit 2 and a light control unit 3 as main components.
- the light source unit 2 includes a light emitting element 101 and a quarter wavelength plate 102, and the quarter wavelength plate 102 is stacked on the light emitting element 101.
- the light control unit 3 includes a carrier generation layer 103, a dielectric layer 104 stacked on the carrier generation layer 103, a plasmon excitation layer 105 stacked on the dielectric layer 104, and a stack on the plasmon excitation layer 105.
- the wave vector conversion layer 107 functions as the “outgoing layer” in the present invention.
- the light control unit 3 is stacked on the light source unit 2 such that the surface of the light control unit 3 on the carrier generation layer 103 side and the surface of the light source unit 2 on the quarter wavelength plate 102 side face each other.
- the effective dielectric constant of the excitation light incident side portion (hereinafter also referred to as “incident side portion”) has an effective light output side portion (hereinafter also referred to as “output side portion”). It is comprised so that it may become lower than a dielectric constant.
- the incident side portion includes the entire structure laminated on the light emitting element 101 side of the plasmon excitation layer 105 and an ambient atmosphere medium (hereinafter sometimes referred to as “medium”) in contact with the light emitting element 101.
- the entire structure includes the dielectric layer 104, the carrier generation layer 103, the quarter wavelength plate 102, and the light emitting element 101.
- the emission side portion includes the entire structure laminated on the wave vector conversion layer 107 side of the plasmon excitation layer 105 and a medium in contact with the wave vector conversion layer 107.
- the entire structure includes a dielectric layer 106 and a wave vector conversion layer 107.
- the dielectric layer 104 and the dielectric layer 106 are excluded, when 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.
- the effective dielectric constant ( ⁇ eff ) is an x-axis, y-axis direction parallel to the interface of the plasmon excitation layer 105, and a direction perpendicular to the interface of the plasmon excitation layer 105 (the surface of the plasmon excitation layer 105 has irregularities).
- the z axis is the direction perpendicular to the average plane), and when the carrier generation layer 103 alone is excited with excitation light, the angular frequency of light emitted from the carrier generation layer 103 is ⁇ , and plasmon excitation
- the dielectric constant distribution of the dielectric in the incident side portion or the emission side portion with respect to the layer 105 is ⁇ ( ⁇ , x, y, z), the z component of the wave number of the surface plasmon is k spp, z , the imaginary unit is 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 ⁇ eff may be calculated using an expression represented by the following expression (7). However, it is particularly desirable to use the formula (1).
- 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.
- the ranges in the x-axis and y-axis directions in the integration range D are ranges that do not include the medium up 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, This is the range up to the outer edge in the plane parallel to the surface of the plasmon excitation layer 105 on the wave vector conversion layer 107 side.
- 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 effective dielectric can be calculated from the above equations (1) and (7).
- a rate is required.
- ⁇ ( ⁇ , x, y, z) is a vector, and is different for each radial direction perpendicular to the z axis.
- 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 emission side portion.
- ⁇ ( ⁇ , x, y, z) is a dielectric constant with respect to the direction parallel to the radial direction perpendicular to the z axis. Therefore, all phenomena related to effective permittivity such as k spp, z , k spp , and d eff described later have different values for 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 components k spp of the wave number of the surface plasmon are ⁇ metal as the real part of the dielectric constant of the plasmon excitation layer 105, and the wave number of light in vacuum if a and k 0, represented by the following formula (2) and (3).
- the distance from the surface of the plasmon excitation layer 105 on the carrier generation layer 103 side to the surface of the carrier generation layer 103 on the plasmon excitation layer 105 side is set to be shorter than the effective interaction distance d eff of the surface plasmon.
- the effective interaction distance of the surface plasmon is a distance at which the intensity of the surface plasmon is e ⁇ 2 .
- ⁇ ( ⁇ , x, y, z) is used as the incident side portion of the plasmon excitation layer 105.
- the effective dielectric constant ⁇ effin of the incident side portion and the effective dielectric constant ⁇ effout of the emission side portion with respect to the plasmon excitation layer 105 are respectively obtained by calculation .
- the z component k spp, z of the wave number of the surface plasmon represented by the above equation (2) is 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 later-described embodiments is also defined in the same manner as the formula (1) or the formula (7).
- the quarter wavelength plate 102 is disposed between the light emitting element 101 and the carrier generation layer 103.
- the optical device 1 may be referred to as an absorption efficiency of excitation light, that is, a waveguide composed of the carrier generation layer 103, the dielectric layer 104, and the plasmon excitation layer 105 (hereinafter referred to as “waveguide”). .))
- the coupling efficiency has been improved. The fact that the optical device 1 has such an effect will be described in detail below.
- the present inventors In order to improve the luminous efficiency of the optical device, it is important to improve the absorption rate of excitation light from the light emitting element. As a result of intensive studies from the viewpoint of improving the absorption efficiency of the excitation light, the present inventors have found that the absorption efficiency of the excitation light in the carrier generation layer remarkably depends on the polarization characteristics of the excitation light. Furthermore, the present inventors have found that the absorption efficiency also depends on the incident angle of the excitation light. These findings have been found for the first time by the present inventors. The polarization dependency and incident angle dependency of the absorption efficiency will be further described based on the optical device 1 of the present embodiment.
- FIG. 2 shows the incident angle and polarization dependency of the absorption rate of the excitation light in the carrier generation layer 103.
- the optical device 1 is set under the following conditions.
- the light reflected by the plasmon excitation layer 105 is not reused.
- the “incident angle” is the incident surface of the light beam and the carrier generation layer 103 when the light (light beam) emitted from the light emitting element 101 enters the carrier generation layer 103 (light control unit 3).
- the “incident angle” is represented 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 + 0.03j), thickness: 50 nm
- 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
- the absorptance increases remarkably when the polarization of the excitation light is s-polarized light, and the polarization of the excitation light is p-polarized light.
- the absorption rate is significantly reduced.
- the absorption efficiency depends on the polarization and incident angle of the excitation light.
- FIG. 3 shows the relationship between the absorption rate of the excitation light and the thickness of the carrier generation layer 103.
- the conditions are the same as those in the example shown in FIG. 2, except that the thickness of the carrier generation layer 103 is 50 nm or 100 nm and the incident angle of the excitation light is 70 degrees.
- the horizontal axis indicates the ratio of the s-polarized component in the excitation light, 100% indicates that the excitation light is only s-polarized light, and 0% indicates that the excitation light is only p-polarized light. Show. As shown in FIG.
- the absorption rate of the excitation light is improved.
- the thickness of the carrier generation layer 103 is 100 nm, the absorption rate of the excitation light is improved as the s-polarized component is reduced in the excitation light, that is, as the p-polarized component is increased.
- the maximum absorptance is obtained for s-polarized light or p-polarized light.
- the absorptance does not become the maximum value for polarized light between s-polarized light and p-polarized light, that is, intermediate polarized light.
- FIG. 4 shows an emission spectrum from the optical device 1 when the thickness of the carrier generation layer 103 in the example shown in FIG. 3 is 50 nm.
- “0%”, “33%”, “66%”, and “100%” in FIG. 4 indicate the proportion of the s-polarized component in the excitation light.
- the vertical axis is normalized assuming that the emission spectrum when the excitation light is p-polarized light (“0%” in FIG. 4) is 1.
- the light emission power was maximum when the excitation light was s-polarized light (100%), and was 8 times that when the excitation light was 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. 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. 3 is 100 nm.
- “0%”, “33%”, “66%”, and “100%” in FIG. 5 indicate the proportion of the s-polarized component in the excitation light.
- the vertical axis is normalized assuming that the emission spectrum when the excitation light is s-polarized light (“100%” in FIG. 5) is 1.
- the emission power was maximum when the excitation light was p-polarized light (0%), and was four times that when the excitation light was s-polarized light (100%). From the comparison with FIG. 3, 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, as in the case where the thickness of the carrier generation layer 103 is 50 nm. I understand.
- the absorption efficiency of the excitation light in the carrier generation layer depends on the polarization of the excitation light, and becomes maximum in either s-polarized light or p-polarized light depending on the thickness of the carrier generation layer. Therefore, it has been found that if only s-polarized light or p-polarized light is incident on the carrier generation layer according to the thickness of the carrier generation layer, the absorption efficiency of the excitation light can be improved.
- the present inventors have arranged that the polarization conversion layer is disposed at the predetermined position so that polarized light (s-polarized light or p-polarized light) is absorbed in the carrier generation layer as will be described later. And the present invention has been completed. According to the present invention, by improving the absorption efficiency of excitation light, for example, an optical device having high luminous efficiency and high light output rating can be realized.
- FIG. 6 shows the relationship between the emission spectrum from the optical device 1 shown in the example of FIG. 2 and the incident angle of the excitation light.
- “0 °”, “10 °”, “20 °”, “30 °”, “40 °”, “50 °”, “60 °”, “70 °”, and “80 °” indicate incident angles of the excitation light.
- the vertical axis is normalized assuming that the emission spectrum when the incident angle of the excitation light is 0 degree is 1.
- the emission power was improved as the incident angle of the excitation light to the carrier generation layer 103 was increased. From the comparison with FIG. 2, 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.
- the incident angle of light incident on the carrier generation layer 103 is relatively large, the polarization dependency of the excitation light absorptance increases.
- the excitation light absorptance in the carrier generation layer 103 can be improved as compared with the case where the incident angle is small.
- excitation light light emitted from the light emitting element 101 enters the light control unit 3 and is transmitted from the wave vector conversion layer 107 of the light control unit 3. An operation of emitting light will be described.
- the excitation light emitted from the light emitting element 101 passes through the quarter wavelength plate 102 and enters the light control unit 3.
- the excitation light is coupled to the waveguide and confined therein.
- the carrier generation layer 103 is excited by the trapped excitation light, and carriers are generated in the carrier generation layer 103.
- This carrier couples with free electrons in the plasmon excitation layer 105 across the dielectric layer 104 and excites surface plasmons at the interface between the dielectric layer 104 and the plasmon excitation layer 105.
- the excited surface plasmon is emitted as light from the interface between the plasmon excitation layer 105 and the dielectric layer 106 (hereinafter sometimes referred to as “emitted light”).
- the light emission occurs when the effective permittivity of the incident side portion is lower than the effective permittivity of the exit side portion.
- the wavelength of the emitted light is equal to the wavelength of the light generated when the carrier generation layer 103 is excited alone.
- the emission angle ⁇ out of the emitted light is expressed by the following formula (5), where n out is the refractive index of the dielectric layer 106.
- the wave number of the excited surface plasmon exists only in the vicinity that is uniquely set by the equation (2).
- the emitted light is only converted from the wave number vector of the surface plasmon. Therefore, the emission angle of the emitted light is uniquely determined, and its polarization state is always p-polarized light. 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.
- the absorption efficiency of the excitation light in the carrier generation layer depends on the polarization of the excitation light. Therefore, of the excitation light incident on the carrier generation layer 103, polarized light (s-polarized light or p-polarized light) that has not been absorbed by the carrier generation layer 103 is transmitted through the carrier generation layer 103. The polarized light is reflected by the plasmon excitation layer 105. The reflected light passes through the dielectric layer 104, the carrier generation layer 103 and the quarter wavelength plate 102 and is reflected by the light emitting element 101. The reflected light passes through the quarter-wave plate 102 and enters the carrier generation layer 103 again.
- polarized light s-polarized light or p-polarized light
- the optical device 1 can improve the absorption efficiency of the excitation light.
- the above-described operation is repeated until all of the excitation light is absorbed by the carrier generation layer 103 or is extracted from the light source unit 2 without passing through the light control unit 3.
- the light emitting element 101 emits light having a wavelength that can be absorbed by the carrier generation layer 103 (excitation light).
- excitation light a wavelength that can be absorbed by the carrier generation layer 103
- a light emitting diode (LED), a laser diode, a super luminescent diode, etc. are mentioned, for example.
- the absorption efficiency of the excitation light increases as the incident angle of the excitation light to the carrier generation layer 103 increases. Therefore, the incident angle is preferably 40 degrees or more, more preferably 60 degrees or more, and further preferably 70 degrees or more.
- a conventionally known one can be used, for example, one using a birefringent material such as quartz or polymer, one using structural birefringence by a structure finer than the wavelength of the excitation light. Etc.
- 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.
- the phosphor include organic phosphors, inorganic phosphors, quantum dot phosphors, and semiconductor phosphors.
- the organic phosphor include rhodamine (Rhodamine 6G) and sulforhodamine (Sulforhodamine 101).
- 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 an inorganic material semiconductor or an organic material semiconductor phosphor.
- 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 composed 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 preferably 1 ⁇ m or less, particularly preferably 100 nm or less, for example.
- the carrier generation layer 103 may include, for example, metal particles.
- the metal particles excite surface plasmons on the surface of the metal particles by interaction with the excitation light, and induce an enhanced electric field in the vicinity of the surface near 100 times the electric field intensity of the excitation light. With this enhanced electric field, the number of carriers generated in the carrier generation layer 103 can be increased. For example, the use 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 alloys thereof.
- the metal is preferably gold, silver, copper, platinum, aluminum, or an alloy containing these as the main component, and gold, silver, aluminum, or an alloy containing these as the main component is particularly preferable.
- the metal particles include, for example, a core-shell structure in which metal species are different in the peripheral part and the central part; a hemispherical union structure in which two metal hemispheres are combined; a cluster-in-cluster structure in which different clusters are aggregated to form particles Or the like.
- the resonance wavelength can be controlled without changing the size, shape, etc. of the metal particles.
- the shape of the metal particles may be a shape having a closed surface, and examples thereof include a rectangular parallelepiped, a cube, an ellipsoid, a sphere, a triangular pyramid, and a triangular prism.
- the metal particles include those obtained by processing a metal thin film into a structure including a closed surface having a side of less than 10 ⁇ m by fine processing typified 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 when the carrier generation layer 103 alone is excited with excitation light (hereinafter sometimes referred to as “emission frequency”).
- optical A part of the dielectric layer having anisotropy may be disposed.
- This dielectric layer has optical anisotropy having a different dielectric constant depending on, for example, a direction perpendicular to the stacking direction of the components of the light control unit 3, in other words, a direction parallel to the interface of each layer. . That is, the dielectric layer has a dielectric constant relationship between a certain direction and a direction perpendicular thereto in a plane perpendicular to the stacking direction of the components of the light control unit 3. Due to this dielectric layer, the effective dielectric constant of the incident side portion differs between a certain direction and a direction perpendicular thereto in a plane perpendicular to the stacking direction of the components of the optical device 1.
- the effective permittivity of the incident side portion is set so high that plasmon coupling does not occur in a certain direction and low enough that plasmon coupling occurs in a direction orthogonal thereto, for example, light incident on the wave vector conversion layer 107
- the incident angle and polarization can be further limited. For this reason, for example, the light extraction efficiency by the wave vector conversion layer 107 can be further improved.
- the above-described effective dielectric constant that is high enough not to generate plasmon 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 is positive.
- the effective dielectric constant that is 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 is negative or zero.
- the efficiency with which carriers generated in the carrier generation layer 103 are coupled to the surface plasmon is a condition in which the effective dielectric constant of the incident side portion and the sum of the dielectric constants of the plasmon excitation layer 105 are zero. Therefore, the condition that the sum of the dielectric constant of the plasmon excitation layer 105 and the minimum value of the effective dielectric constant of the incident side portion is 0 is most preferable from the viewpoint of increasing the directivity with respect to the azimuth.
- 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 dielectric obliquely deposited film and an obliquely sputtered film.
- 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 alloys thereof.
- the constituent material is preferably gold, silver, copper, platinum, aluminum, and a mixture with a dielectric containing these as a main component, and gold, silver, aluminum, and a dielectric containing these as a main component. A mixture with is particularly preferred.
- the thickness of the plasmon excitation layer 105 is not particularly limited, is preferably 200 nm or less, and particularly preferably about 10 to 100 nm.
- the surface of the plasmon excitation layer 105 on the carrier generation layer 103 side may be roughened, for example.
- the rough surface causes, for example, scattering of the excitation light and excitation of localized plasmons at the sharpened portion of the rough surface, and increases 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, specifically, for example, an SiO 2 nanorod array film; SiO 2 , AlF 3 , MgF 2 , Na 3 AlF 6 , NaF, LiF, CaF 2 , BaF 2. And a thin film such as a low dielectric constant plastic or a porous film.
- 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, Examples thereof include high dielectric constant materials such as Nb 2 O 5 .
- 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 thereof.
- the wave vector conversion layer 107 has a function of emitting the emitted light from the optical device 1 in a direction substantially orthogonal to the interface between the plasmon excitation layer 105 and the dielectric layer 106.
- the shape of the wave 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 (for example, a rough structure) Surface structure constituted by surfaces); hologram; microlens array and the like.
- the quasi-periodic structure indicates, for example, an incomplete periodic structure in which a part of the periodic structure is missing.
- the shape is preferably a periodic structure typified 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 vector conversion layer 107 may have a structure in which a convex portion is provided on a flat base, for example.
- the distance from the surface of the plasmon excitation layer 105 on the carrier generation layer 103 side to the surface of the carrier generation layer 103 on the plasmon excitation layer 105 side is set shorter than the effective interaction distance d eff of the surface plasmon.
- d eff the effective interaction distance
- the region where the coupling efficiency is high is, for example, from the position where carriers are generated in the carrier generation layer 103 (for example, the position where the phosphor is present in the carrier generation layer 103) to the surface of the plasmon excitation layer 105 side of the carrier generation layer 103 It is an area up to.
- the region is very narrow, for example, about 200 nm, and is, for example, in the range of 1 to 200 nm or in the range of 10 to 100 nm.
- the carrier generation layer 103 is preferably disposed in the range of 1 to 200 nm from the plasmon excitation layer 105.
- the carrier generation layer 103 is preferably disposed within the range of 10 to 100 nm from the plasmon excitation layer 105.
- the thickness of the dielectric layer 104 is 10 nm, and the thickness of the carrier generation layer 103 is 90 nm.
- the carrier generation layer 103 is preferably as thin as possible.
- the carrier generation layer 103 is preferably as thick as possible. Therefore, the thickness of the carrier generation layer 103 is determined based on, for example, required light extraction efficiency and 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. What is necessary is just to set the thickness of a layer, the thickness of the said carrier production
- the quarter-wave plate is disposed between the light emitting element and the carrier generation layer, but the present invention is not limited to this example.
- the quarter-wave plate may be disposed below the carrier generation layer (that is, on the light emitting element side of the carrier generation layer) because the excitation light is multiply reflected. As a result, the excitation light passes through the quarter-wave plate twice or more, so that the above-described effect can be obtained.
- the arrangement position of the 1 ⁇ 4 wavelength plate may be, for example, the opposite side of the light emitting element from the carrier generation layer side, or, for example, the 1 ⁇ 4 wavelength plate may be included in the light emitting element.
- the quarter wave plate is used as the polarization conversion layer, the present invention is not limited to this example.
- the polarization conversion layer only needs to convert the polarization of the excitation light into s-polarized light and p-polarized light into s-polarized light. For example, by using two 1/8 wavelength plates, The same effect as the quarter wavelength plate can be obtained.
- the plasmon excitation layer is sandwiched between the two dielectric layers.
- the dielectric layer is not essential in the present invention.
- the plasmon excitation layer is formed on the carrier generation layer.
- the plasmon excitation layer may be disposed.
- the dielectric layer may be laminated only on one surface of the plasmon excitation layer.
- the said light source part and the said light control part are contact
- the light source unit may include a plurality of the light emitting elements, for example.
- the excitation light is incident on the quarter-wave plate from the light emitting element, but the present invention is not limited to this example.
- the excitation light may be incident on the quarter-wave plate via a light guide.
- the shape of the light guide include a rectangular parallelepiped or a wedge; those having a light output portion or a structure for extracting light inside the light guide, and the like.
- the light extraction structure preferably has a function of converting the incident angle of the excitation light to the carrier generation layer into an angle at which the absorption rate of the excitation light is increased.
- the surface excluding the light emitting portion of the light guide is preferably subjected to a treatment that does not emit the excitation light from the surface using, for example, a reflective material or a dielectric multilayer film.
- the optical device of the present embodiment is an example of an optical device in which the polarization conversion layer is a quarter wavelength plate.
- the configuration of the optical device according to 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.
- the optical device 11 of the present embodiment includes a light source unit 2 and a light control unit 13 as main components.
- the light source unit 2 includes a light emitting element 101 and a quarter wavelength plate 102, and the quarter wavelength plate 102 is stacked on the light emitting element 101.
- 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 vector conversion layer (emission layer) 207 stacked on the plasmon excitation layer 105.
- the light control unit 13 is stacked on the light source unit 2 such that the surface of the light control unit 13 on the carrier generation layer 103 side and the surface of the light source unit 2 on the quarter wavelength plate 102 side face each other.
- 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 output side portion.
- the incident side portion includes the entire structure laminated on the light emitting element 101 side of the plasmon excitation layer 105 and a medium in contact with the light emitting element 101.
- the entire structure includes the carrier generation layer 103, the quarter-wave plate 102, and the light emitting element 101.
- the emission side portion includes the entire structure laminated on the wave vector conversion layer 207 side of the plasmon excitation layer 105 and a medium in contact with the wave vector conversion layer 207.
- the entire structure includes a wave vector conversion layer 207.
- the excitation light emitted from the light emitting element 101 passes through the quarter wavelength plate 102 and enters the carrier generation layer 103 of the light control unit 13.
- the excitation light is coupled to the waveguide and confined therein. Due to the trapped excitation light, part of the excitation light incident on the carrier generation layer 103 is absorbed by the carrier generation layer 103 and carriers are generated in the carrier generation layer 103.
- This carrier is combined with free electrons in the plasmon excitation layer 105 to 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 is transmitted through the plasmon excitation layer 105 and propagates to the interface between the plasmon excitation layer 105 and the wave vector conversion layer 207.
- 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 vector conversion layer 207 is formed.
- the distance from the surface of the wave vector conversion layer 207 of the plasmon excitation layer 105 is disposed within the range of the effective interaction distance of the surface plasmon at the end portion on the 105 side.
- the wave vector conversion layer 207 when the wave vector conversion layer 207 is a flat dielectric layer, it is not converted into light at the interface.
- the surface plasmon at the interface is emitted (radiated) as light to the outside of the optical device 11 because the wave vector conversion layer 207 has a function of taking out the surface plasmon as light, for example, a diffraction action.
- the wavelength of the emitted light is equal to the wavelength of the light generated when the carrier generation layer 103 is excited alone.
- the emission angle ⁇ rad of the emitted light is a refractive index on the light extraction side of the wave vector conversion layer 207 (that is, a medium in contact with the wave vector conversion layer 207), where ⁇ is the pitch of the periodic structure of the wave vector conversion layer 207. Is represented by the following formula (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 that is 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-polarized light. That is, the emitted light is p-polarized light having very high directivity.
- polarized light (s-polarized light or p-polarized light) that has not been absorbed by the carrier generation layer 103 is transmitted through the carrier generation layer 103.
- the polarized light is reflected by the plasmon excitation layer 105.
- the reflected light passes through the carrier generation layer 103 and the quarter-wave plate 102 and is reflected by the light emitting element 101.
- the reflected light passes through the quarter-wave plate 102 and enters the carrier generation layer 103 again.
- the quarter-wave plate 102 twice its polarization is orthogonal to that when it enters the carrier generation layer 103 before being reflected by the plasmon excitation layer 105. .
- the optical device 11 can improve the absorption efficiency of the excitation light. In the optical device 11, for example, the above-described operation is repeated until all of the excitation light is absorbed by the carrier generation layer 103 or extracted outside from the light source unit 2 without passing through the light control unit 13.
- the wave vector conversion layer 207 extracts surface plasmons excited at the interface between the plasmon excitation layer 105 and the wave vector conversion layer 207 as light from the interface by converting the wave vector, and radiates it from the optical device 11. It is an emission part. That is, the wave vector conversion layer 207 converts the surface plasmon into light having a predetermined radiation angle, and emits the light from the optical device 11. Furthermore, the wave vector conversion layer 207 has a function of radiating emitted light from the optical device 11 so as to be substantially orthogonal to the interface between the plasmon excitation layer 105 and the wave vector conversion layer 207, for example. As the wave vector conversion layer 207, for example, the same one as the wave vector conversion layer 107 of the first embodiment can be used.
- the carrier generation layer is disposed in contact with the plasmon excitation layer, but the present invention is not limited to this example.
- a dielectric layer having a thickness smaller than the effective interaction distance d eff of the surface plasmon represented by the formula (4) may be disposed between the carrier generation layer and the plasmon excitation layer.
- the wave vector conversion layer is disposed in contact with the plasmon excitation layer.
- the present invention is not limited to this example.
- the wave vector conversion layer is interposed between the wave vector conversion layer and the plasmon excitation layer.
- a dielectric layer having a thickness smaller than the effective interaction distance d eff of the surface plasmon represented by the formula (4) may be disposed.
- the optical device of this embodiment is an example of an optical device in which the polarization conversion layer is a quarter-wave plate and includes a light guide.
- the configuration of the optical device according to the present embodiment is shown in the perspective view of FIG. In FIG. 8, in order to show all the components, a portion that is obstructed by the quarter-wave plate 102 and the conductor light 308 is indicated by a broken line.
- the optical device 21 of the present embodiment includes a light source unit 22 and a light control unit 23 as main components.
- the light source unit 22 includes a light emitting element 301, a quarter wavelength plate 102, and a light guide 308.
- the quarter wave plate 102 is stacked on the light guide 308.
- the light emitting element 301 is disposed around the side of the light guide 308.
- 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 control unit 23 is stacked on the light source unit 22 so that the surface of the light control unit 23 on the dielectric layer 306 side and the surface of the light source unit 22 on the light guide 308 side face each other.
- the distance from the surface of the plasmon excitation layer 305 on the carrier generation unit 303 side to the surface of the carrier generation unit 303 on the plasmon excitation layer 305 side is the effective interaction of the surface plasmon represented by the above formula (4). It is set shorter than the distance d eff .
- excitation light from the light emitting element 301 enters the light control unit 23, and from a surface opposite to the surface on the carrier generation unit 303 side of the light guide 308 (light emission surface 309). An operation of emitting light will be described.
- the excitation light emitted from the light emitting element 301 enters the light guide 308 and is guided while being subjected to multiple reflections from the quarter wavelength plate 102 to the plasmon excitation layer 305.
- a part of the excitation light that has entered the carrier generation unit 303 is absorbed by the carrier generation unit 303, and carriers are generated in the carrier generation unit 303.
- the absorption rate of the excitation light in the carrier generation unit 303 has a significant dependency on the polarization state and the incident angle of the excitation light, as in the first embodiment. It selectively absorbs polarized excitation light.
- the polarization component hardly absorbed in the carrier generation unit 303 passes through the quarter-wave plate 102 twice, and is converted into a polarization state having a high absorption rate by the carrier generation unit 303.
- Some of the carriers are combined with free electrons in the plasmon excitation layer 305 to excite surface plasmons at the interface between the dielectric layer 306 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, passes through the light exit surface 309, and is emitted as light to the outside of the optical device 21.
- the wavelength of the emitted light is equal to the wavelength of the light generated when the carrier generation unit 303 is excited alone.
- the emission angle ⁇ rad of the emitted light is expressed by the above formula (6).
- the light guide body 308 side portion of the plasmon excitation layer 305 also serves as the excitation light incident side portion and the light emission side portion defined in the first embodiment.
- 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 that is uniquely set by the equation (2). Therefore, the emission angle of the emitted light is uniquely determined, and its polarization state is always p-polarized light. That is, the emitted light is p-polarized light having very high directivity.
- the light distribution of the propagating light due to the carriers that have not been combined with the surface plasmon is superimposed on the light distribution of the emitted light.
- the above-described operation is repeated until all of the excitation light is absorbed by the carrier generation unit 303 or extracted from the light source unit 22 without passing through the light control unit 23.
- the light emitting element 301 can be the same as the light emitting element 101 of the first embodiment, for example.
- the shape of the light guide 308 is, for example, a rectangular parallelepiped and a wedge; the light exit surface 309 side of the light guide 308, the surface facing the light exit surface 309 side, or the inside of the light guide 308 for extracting light
- the light extraction structure may be provided on both of the both surfaces and the inside.
- the surface on the light emitting surface 309 side of the light guide 308 and the surface other than the surface facing the light emitting body 308 are subjected to a treatment that does not emit the excitation light from the surface using, for example, a reflective material or a dielectric multilayer film. It is preferable.
- the carrier generation unit 303 is a layer that absorbs excitation light to generate carriers, and its function and constituent materials are the same as, for example, the carrier generation layer 103 of the first embodiment.
- 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, Examples thereof include high dielectric constant materials such as Nb 2 O 5 .
- the thickness of the dielectric layer 306 is not particularly limited, and is, for example, in the range of 1 to 1000 nm, preferably in the range of 5 to 50 nm, and more preferably in the range of 5 to 10 nm.
- the high dielectric constant material for example, among the carriers generated in the carrier generation unit 303, the number of carriers combined with the surface plasmon can be increased, and light with higher directivity and higher polarization degree can be obtained. Can be emitted from the optical device 21.
- the function, constituent material, shape, and the like are 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 between the light guide 308 and the plasmon excitation layer 305. The configuration and effects of this dielectric layer are the same as those shown in the first embodiment.
- the light source unit and the light control unit are stacked in contact with each other.
- the present invention is not limited to this example, and the light source unit and the light control unit are not limited to this example.
- the section may be arranged separately.
- the quarter wavelength plate is disposed on the light guide, but the present invention is not limited to this example.
- the 1 ⁇ 4 wavelength plate may be disposed on the light guide side from the plasmon excitation layer because the excitation light is multiply reflected, and thus the 1 ⁇ 4 wavelength plate is disposed. Since the excitation light passes through the plate twice or more, the above-described effect can be obtained.
- the arrangement position of the quarter-wave plate may be, for example, between the plasmon excitation layer and the dielectric layer, or between the dielectric layer and the light guide.
- the carrier generation unit is embedded in the dielectric layer.
- the dielectric layer and the carrier generation are performed.
- the dielectric part may be periodically embedded in the carrier generation layer by reversing the relationship with the part. Even with such a configuration, the same effect as described above can be obtained.
- the surface on the light guide body side of the dielectric layer and the surface on the light guide body side of the carrier generation unit are set to the same height, the present invention is not limited to this example, It does not necessarily have to be the same height.
- the carrier generation unit may be connected 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.
- the optical device of the present embodiment is an example of an optical device that includes a half-wave plate as a polarization conversion element.
- the schematic diagram of FIG. 11 shows the configuration of the optical device of the present embodiment.
- the optical device 31 of this embodiment includes the optical device 1 and a half-wave plate 410 as main components.
- the optical device 1 is the optical device according to Embodiment 1 shown in FIG.
- the half-wave plate 410 is disposed on the wave vector conversion layer 107 side of the optical device 1.
- the half-wave plate 410 is indicated by a two-dot chain line.
- the light is emitted from the wave vector conversion layer 107. Since the light is p-polarized light as described above, the polarization direction of the light field pattern is radial. For this reason, the light is axially symmetric polarized light (for example, refer to [0104] of International Publication No. 2011/040528).
- the light (axisymmetric polarization) is incident on the half-wave plate 410. At this time, the axially symmetric polarized light is converted into linearly polarized light by the half-wave plate 410.
- the polarization state of the light can be made uniform (for example, refer to [0105] of 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 plates disclosed in International Publication No. 2011/040528 are listed.
- the half-wave plate disclosed in the publication includes, for example, a pair of glass substrates each formed with an alignment film, a liquid crystal layer disposed between the glass substrates with the alignment films of these substrates facing each other, and glass 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 liquid crystal molecules are arranged concentrically with respect to the center of the half-wave plate.
- the axially symmetric polarized light is converted into linearly polarized light by the 1 ⁇ 2 wavelength plate.
- the present invention is not limited to this example. It may be converted into polarized light.
- the optical device according to the present embodiment the optical device according to the first embodiment is used.
- the present invention is not limited to this example.
- the optical device according to the second or third embodiment is used. Also good.
- the optical element of the present embodiment is laminated on the carrier generation layer on which light from the light emitting element is incident and carriers are generated, and the carrier generation layer is excited by the light of the light emitting element.
- a plasmon excitation layer that excites a plasmon having a plasma frequency higher than the frequency of the light that is sometimes generated, and the light generated on the surface of the plasmon excitation layer or the surface plasmon is converted into light having a predetermined emission angle and emitted.
- a polarization conversion layer below the carrier generation layer.
- the polarization conversion layer is preferably a quarter wavelength plate.
- the image display device of this embodiment is an example of a three-plate projection display device (LED projector).
- FIG. 9 shows the configuration of the LED projector of this embodiment.
- FIG. 9A is a schematic perspective view of the LED projector of the present embodiment
- FIG. 9B is a top view of the LED projector.
- the LED projector 10 includes three optical devices 1r, 1g, and 1b according to the first to fourth embodiments, three liquid crystal panels 502r, 502g, and 502b, and color synthesis.
- the optical element 503 and the 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 optical paths, respectively.
- Optical devices 1r, 1g, and 1b are made of different materials for red (R) light, green (G) light, and blue (B) light, respectively.
- the liquid crystal panels 502r, 502g, and 502b modulate the light intensity according to the image to be displayed.
- the color synthesis optical element 503 synthesizes light transmitted through the liquid crystal panels 502r, 502g, and 502b.
- the projection optical system 504 includes a projection lens that projects light emitted from the color synthesis optical element 503 onto a projection surface such as a screen.
- FIG. 10 shows the emission wavelength (Rs, Gs, Bs) of the optical device used in the LED projector 10, the excitation wavelength (Ra, Ga, Ba) and the emission wavelength (Rr, Gr, Br) of the carrier generation layer.
- the emission wavelengths Rs, Gs, and Bs of the optical device for R light, the optical device for G light, and the optical device for B light are substantially equal to the excitation wavelengths Ra, Ga, and Ba of the carrier generation layer.
- the emission wavelengths Rs, Gs, Bs of the optical device and the excitation wavelengths Ra, Ga, Ba of the carrier generation layer and the emission wavelengths Rr, Gr, Br of the carrier generation layer do not overlap each other. Is set.
- the emission spectra of the R light optical device, the G light optical device, and the B light optical device are set so as to match the excitation spectrum of each carrier generation layer or to be within the excitation spectrum. Yes.
- the emission spectrum of the carrier generation layer is set so as not to overlap with any excitation spectrum of the carrier generation layer.
- the LED projector 10 modulates an image on the liquid crystal panel for each optical path by a control circuit unit (not shown).
- the LED projector 10 can improve the brightness of the projected image by including any one of the optical devices according to the first to fourth embodiments.
- the optical device since the optical device exhibits very high directivity, for example, the optical device can be miniaturized without using an illumination optical system.
- the LED projector of this embodiment shown in FIG. 9 is a three-plate liquid crystal projector, but the present invention is not limited to this example, and may be, for example, a single-plate liquid crystal projector.
- the image display device of the present invention is not limited to the above-described LED projector, but may be a projector using a light emitting element other than an LED (for example, a laser diode, a super luminescent diode, etc.), or a liquid crystal display device.
- An image display device combined with a backlight or a backlight using MEMS may be used.
- the image display apparatus of the present invention may include only the optical element of the present invention such as the fifth embodiment, and the light emitting element may be disposed outside the image display apparatus.
- the image display device using the optical device or the optical element of the present invention can be used as a projector or the like.
- the projector is, for example, a mobile projector, a next-generation rear projection TV (rear projection TV), a digital cinema, a retina scanning display (RSD), a head-up display (HUD: Head Up Display), or a mobile phone, digital.
- Embedded projectors for cameras, laptop computers, etc. can be mentioned and can be applied to a wide range of markets. However, its use is not limited and can be applied to a wide range of fields.
- Light control unit 10 LED projector (image display device) 101, 301 Light-emitting element 102 1/4 wavelength plate (polarization conversion layer) 103 Carrier generation layer 104 Dielectric layer 105, 305 Plasmon excitation layer 106, 306 Dielectric layer 107, 207 Wave vector conversion layer (outgoing layer) 303 Carrier generator (outgoing layer) 308 Light guide 309 Light exit surface 410 1/2 wavelength plate (polarization conversion element) 502r, 502g, 502b Liquid crystal panel 503 Color composition optical element 504 Projection optical system
Abstract
Description
発光素子と、
前記発光素子からの光が入射し、キャリアが生成されるキャリア生成層と、
前記キャリア生成層の上側に積層され、前記キャリア生成層を前記発光素子の光で励起したときに発生する光の周波数よりも高いプラズマ周波数を有する、プラズモンを励起するプラズモン励起層と、
前記プラズモン励起層の表面に発生する光または表面プラズモンを、所定の出射角の光に変換して出射する出射層とを備え、
さらに、前記キャリア生成層の下側に、偏光変換層を備える。
発光素子からの光が入射し、キャリアが生成されるキャリア生成層と、
前記キャリア生成層の上側に積層され、前記キャリア生成層を前記光で励起したときに発生する光の周波数よりも高いプラズマ周波数を有する、プラズモンを励起するプラズモン励起層と、
前記プラズモン励起層の表面に発生する光または表面プラズモンを、所定の出射角の光に変換して出射する出射層とを備え、
さらに、前記キャリア生成層の下側に、偏光変換層を備える。
前記本発明の光学装置、または、前記本発明の光学素子と、
画像を表示可能な画像表示部とを含む。
本実施形態の光学装置は、前記偏光変換層が1/4波長板である光学装置の一例である。図1の斜視図に、本実施形態の光学装置の構成を示す。
発光素子101:レーザダイオード(発光波長:460nm)
キャリア生成層103:形成材料:蛍光体(屈折率:1.7+0.03j)、厚み:50nm
誘電体層104:形成材料:SiO2、厚み:10nm
プラズモン励起層105:形成材料:Ag、厚み:50nm
誘電体層106:形成材料:TiO2、厚み:0.5mm
波数ベクトル変換層107:半球レンズ、直径:10mm
本実施形態の光学装置は、前記偏光変換層が1/4波長板である光学装置の一例である。図7の斜視図に、本実施形態の光学装置の構成を示す。本実施形態の光学装置は、前記光制御部が誘電体層を含まないこと以外は、前記実施形態1の光学装置と同様の構成を有する。図7に示すように、本実施形態の光学装置11は、光源部2と、光制御部13とを、主要な構成要素として含む。光源部2は、発光素子101と、1/4波長板102を含み、1/4波長板102は、発光素子101上に積層されている。光制御部13は、キャリア生成層103と、キャリア生成層103上に積層されたプラズモン励起層105と、プラズモン励起層105上に積層された波数ベクトル変換層(出射層)207とを含む。光制御部13は、光制御部13のキャリア生成層103側の面と光源部2の1/4波長板102側の面とが対向するようにして、光源部2に積層されている。
本実施形態の光学装置は、前記偏光変換層が1/4波長板であり、導光体を備える光学装置の一例である。図8の斜視図に、本実施形態の光学装置の構成を示す。図8において、全構成要素を示すため、1/4波長板102および導体光308で遮られて見えない部分を破線で示す。図8に示すように、本実施形態の光学装置21は、光源部22と、光制御部23とを、主要な構成要素として含む。光源部22は、発光素子301と、1/4波長板102と、導光体308とを含む。1/4波長板102は、導光体308上に積層されている。発光素子301は、導光体308の側方周囲に配置されている。光制御部23は、キャリア生成部303と、プラズモン励起層305と、誘電体層306とを含む。誘電体層306は、プラズモン励起層305に積層されている。キャリア生成部303は、誘電体層306に周期的に埋め込まれ、誘電体層306を貫通し、その一端部がプラズモン励起層305と接している。キャリア生成部303は、前記本発明における「出射層」としての機能を有する。光制御部23は、光制御部23の誘電体層306側の面と光源部22の導光体308側の面とが対向するようにして、光源部22に積層されている。
本実施形態の光学装置は、偏光変換素子として1/2波長板を備える光学装置の一例である。図11の模式図に、本実施形態の光学装置の構成を示す。
本実施形態の光学素子は、発光素子からの光が入射し、キャリアが生成されるキャリア生成層と、前記キャリア生成層の上側に積層され、前記キャリア生成層を前記発光素子の光で励起したときに発生する光の周波数よりも高いプラズマ周波数を有する、プラズモンを励起するプラズモン励起層と、前記プラズモン励起層の表面に発生する光または表面プラズモンを、所定の出射角の光に変換して出射する出射層とを備え、さらに、前記キャリア生成層の下側に、偏光変換層を備える。前記偏光変換層は、1/4波長板であることが好ましい。本実施形態における、各構成および励起光の吸収率向上等は、前記実施形態1等の記載を引用できる。
本実施形態の画像表示装置は、3板式の投射型表示装置(LEDプロジェクタ)の一例である。図9に、本実施形態のLEDプロジェクタの構成を示す。図9(a)は、本実施形態のLEDプロジェクタの概略斜視図であり、図9(b)は、同LEDプロジェクタの上面図である。
2、22 光源部
3、13、23 光制御部
10 LEDプロジェクタ(画像表示装置)
101、301 発光素子
102 1/4波長板(偏光変換層)
103 キャリア生成層
104 誘電体層
105、305 プラズモン励起層
106、306 誘電体層
107、207 波数ベクトル変換層(出射層)
303 キャリア生成部(出射層)
308 導光体
309 光出射面
410 1/2波長板(偏光変換素子)
502r、502g、502b 液晶パネル
503 色合成光学素子
504 投射光学系
Claims (18)
- 発光素子と、
前記発光素子からの光が入射し、キャリアが生成されるキャリア生成層と、
前記キャリア生成層の上側に積層され、前記キャリア生成層を前記発光素子の光で励起したときに発生する光の周波数よりも高いプラズマ周波数を有する、プラズモンを励起するプラズモン励起層と、
前記プラズモン励起層の表面に発生する光または表面プラズモンを、所定の出射角の光に変換して出射する出射層とを備え、
さらに、前記キャリア生成層の下側に、偏光変換層を備える、光学装置。 - 前記偏光変換層は、1/4波長板である、請求項1記載の光学装置。
- 前記プラズモン励起層の少なくとも一方の面に、誘電体層が積層されている、請求項1または2記載の光学装置。
- 前記プラズモン励起層の前記キャリア生成層側表面と、前記キャリア生成層の前記プラズモン励起層側表面との距離は、前記プラズモン励起層の前記キャリア生成層側表面に励起される表面プラズモンの有効相互作用距離よりも短い、請求項1から3のいずれか一項に記載の光学装置。
- 前記キャリア生成層は、前記プラズモン励起層からの距離が、1~200nmの範囲内に配置されている、請求項4記載の光学装置。
- 前記出射層は、表面周期構造を有する、請求項1から5のいずれか一項に記載の光学装置。
- 前記表面周期構造は、フォトニック結晶である、請求項6記載の光学装置。
- 前記キャリア生成層は、表面周期構造を有し、かつ、前記出射層を兼ねる、請求項1から7のいずれか一項に記載の光学装置。
- さらに、前記出射層から出射される軸対称偏光を所定の偏光状態に揃える偏光変換素子を備える、請求項1から8のいずれか一項に記載の光学装置。
- 前記プラズモン励起層の前記発光素子側に積層された構造全体と前記発光素子に接する媒質とを含む入射側部分の実効誘電率は、前記プラズモン励起層の前記出射層側に積層された構造全体と前記出射層に接する媒質とを含む出射側部分の実効誘電率より、低い、請求項1から9のいずれか一項に記載の光学装置。
- 前記プラズモン励起層の前記発光素子側に積層された構造全体と前記発光素子に接する媒質とを含む入射側部分の実効誘電率は、前記プラズモン励起層の前記出射層側に積層された構造全体と前記出射層に接する媒質とを含む出射側部分の実効誘電率より、高いまたは等しく、
前記出射層の前記プラズモン励起層側の端部は、前記プラズモン励起層の前記出射層側の面からの距離が、表面プラズモンの有効相互作用距離の範囲内に配置されている、請求項1から9のいずれか一項に記載の光学装置。 - 前記実効誘電率(εeff)は、前記プラズモン励起層の界面に平行な方向をx軸、y軸、前記プラズモン励起層の界面に垂直な方向をz軸、前記キャリア生成層から出射する光の角周波数をω、前記入射側部分または前記出射側部分の誘電体の誘電率分布をε(ω,x,y,z)、積分範囲Dを前記入射側部分または前記出射側部分の三次元座標の範囲、表面プラズモンの波数のz成分をkspp,z、虚数単位をj、Re[ ]を[ ]内の数値の実部を示す記号とすれば、下記式(1)または式(7)のいずれか一方で表され、
かつ、前記表面プラズモンの波数のz成分kspp,z、および前記表面プラズモンの波数のx、y成分ksppは、前記プラズモン励起層の誘電率の実部をεmetal、真空中での光の波数をk0とすれば、下記式(2)および式(3)で表される、請求項10または11記載の光学装置。
- 前記キャリア生成層に入射する光の入射角を、40度以上とする、請求項1から13のいずれか一項に記載の光学装置。
- 発光素子からの光が入射し、キャリアが生成されるキャリア生成層と、
前記キャリア生成層の上側に積層され、前記キャリア生成層を前記光で励起したときに発生する光の周波数よりも高いプラズマ周波数を有する、プラズモンを励起するプラズモン励起層と、
前記プラズモン励起層の表面に発生する光または表面プラズモンを、所定の出射角の光に変換して出射する出射層とを備え、
さらに、前記キャリア生成層の下側に、偏光変換層を備える、光学素子。 - 前記偏光変換層は、1/4波長板である、請求項15記載の光学素子。
- 請求項1から14のいずれか一項に記載の光学装置、または、請求項15もしくは16記載の光学素子と、
画像を表示可能な画像表示部とを含む、画像表示装置。 - さらに、前記画像表示部からの出射光により投射映像を投射する投射光学系を含む、請求項17記載の画像表示装置。
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