JPWO2013046865A1 - Optical element, light source device and projection display device - Google Patents

Abstract

The present invention reduces the etendue of light emitted from an optical element without depending on the etendue of the optical element. The carrier generation layer generates carriers by light, and is laminated on the carrier generation layer. A plasmon excitation layer having a plasma frequency higher than the frequency of the light generated when the generation layer is excited by light from the light emitting element, and the plasmon excitation layer are stacked on the plasmon excitation layer, and are stacked on the plasmon excitation layer. And a surface on the carrier generation layer side of the plasmon excitation layer is a rough surface.

Description

  The present invention relates to an optical element, a light source device, and a projection display device that use surface plasmons to emit light.

  There has been proposed an LED projector in which a light emitting diode (LED) is used as a light emitting element of a light source device. In this type of LED projector, a light source device having an LED, an illumination optical system into which light from the light source device is incident, a light valve having a liquid crystal display panel into which light from the illumination optical system is incident, and light from the light valve And a projection optical system for projecting onto the projection surface.

  In the LED projector, in order to increase the brightness of the projected image, it is required to prevent light loss as much as possible in the optical path from the light source device to the light valve.

  In addition, as described in Non-Patent Document 1, there is a restriction due to Etendue determined by the product of the area of the light source device and the radiation angle. That is, if the product value of the light emitting area and the emission angle of the light source device is not less than or equal to the product value of the area of the incident surface of the light valve and the capture angle (solid angle) determined by the F number of the projection lens, the light source The light from the device is not used as projection light.

  Therefore, in a light source device having an LED and an optical element on which light from the LED is incident, it is a concern to reduce the above-described light loss by reducing etendue of light emitted from the optical element. Yes.

  In a light source device provided in an LED projector, it is indispensable to realize a projection light beam of about several thousand lumens by using a plurality of LEDs in order to make up for a shortage of light quantity of a single LED.

  As an example of a light source device using a plurality of LEDs, Patent Document 1 discloses a plurality of single color light source devices 203a to 203f having LEDs 204a to 204f and these single color light source devices 203a to 203f as shown in FIG. Optical axis alignment members 202a to 202d for matching the optical axes of the emitted light from the light sources, light source sets 201a and 201b from which light enters from these optical axis alignment members 202a to 202d, and light from the light source sets 201a and 201b are incident A light source unit including the light guide device 200 is disclosed. In this light source unit, light from a plurality of monochromatic light source devices 203 a to 203 f is combined, and light whose emission angle is narrowed by the light source sets 201 a and 201 b is incident on the light guide device 200. In this configuration, the light loss is reduced by narrowing the radiation angle of the light incident on the light guide device 200 by the light source sets 201a and 201b.

  As another example of a light source device using a plurality of LEDs, Patent Document 2 discloses a light source device including a light source substrate 301 in which a plurality of LEDs 300 are arranged on a plane as shown in FIG. Yes. This light source device includes an optical element composed of two prism sheets 304 and 305 arranged on one surface with a prism row formed so as to intersect each other and a frame 303 that supports the prism sheets 304 and 305. I have. In this light source device, light from the plurality of LEDs 300 is synthesized by two prism sheets 304 and 305.

JP 2008-145510 A JP 2009-87695 A

PhlatLight ™ Photonic Lattice LEDs for RPTV Light Engineers Christian Hoefner, SID Symposium Digest 37, 1808 (2006)

  However, in the configuration described in Patent Document 1 described above, the light emission areas on the dichroic reflection surfaces of the optical axis alignment members 202a to 202d are larger than the light emission areas of the LEDs 204a to 204f. For this reason, when the etendue of light incident on the light guide device 200 is compared with the etendue of light from the LEDs 204a to 204f, the etendue does not change as a result.

  Therefore, in the configuration described in Patent Document 1, the etendue of the emitted light from the light guide device 200 depends on the etendue of the LEDs 204a to 204f, and the etendue of the emitted light from the light guide device 200 can be reduced. There wasn't.

  Further, in the configuration described in Patent Document 2, since the light emitting area of the entire light source is increased by arranging a plurality of LEDs 300 on a plane, there is a problem in that the etendue of the light source itself increases.

  That is, in the configuration disclosed in Patent Documents 1 and 2 described above, the etendue of the light emitted from the light source unit and the light source device depends on the etendue of the light from the LED, and the etendue of the light emitted from the optical element is reduced. It could not be reduced.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the related art and to reduce the etendue of light emitted from the optical element without depending on the etendue of the light emitting element, and a light source device and a projection display device including the same Is to provide.

In order to achieve the above-described object, the optical element according to the present invention includes:
A carrier generation layer in which carriers are generated by light;
A plasmon excitation layer stacked on the carrier generation layer and having a plasma frequency higher than the frequency of light generated when the carrier generation layer is excited by light of the light emitting element;
An emission layer that is laminated on the plasmon excitation layer, converts the light emitted from the plasmon excitation layer or the surface plasmon into light of a predetermined emission angle, and emits the light;
The surface of the plasmon excitation layer on the carrier generation layer side is a rough surface.

  In addition, a light source device according to the present invention includes the optical element of the present invention, a light guide, and a light emitting element disposed on the outer periphery of the light guide.

  A projection display device according to the present invention includes the light source device of the present invention, a display element that modulates light emitted from the light source device, and a projection optical system that projects a projected image by the light emitted from the display element. Prepare.

  In addition, the optical element according to the present invention includes a carrier generation layer in which carriers are generated by light and a frequency of light that is disposed on the carrier generation layer and is generated when the carrier generation layer is excited by light from the light emitting element. A surface of the plasmon excitation layer on the carrier generation layer side is a rough surface.

  ADVANTAGE OF THE INVENTION According to this invention, the etendue of the emitted light from an optical element can be reduced without depending on the etendue of a light emitting element.

10 is a schematic diagram for explaining a configuration of Patent Document 1. FIG. It is a disassembled perspective view for demonstrating the structure of patent document 2. FIG. It is a perspective view which shows typically the light source device by this invention. It is sectional drawing for demonstrating the behavior of the light in the light source device by this invention. It is a perspective view which shows typically the directivity control layer with which the light source device of 1st Embodiment is provided. It is a perspective view which shows typically the directivity control layer with which the light source device of 2nd Embodiment is provided. It is sectional drawing which shows the state of the joint surface of the plasmon excitation layer 17 and the carrier production | generation layer 16 in FIG. 5A. It is a figure which shows the normalization photon number with respect to the radiation angle with which 1st Embodiment is provided. It is sectional drawing which shows the state of the joint surface of the plasmon excitation layer 17 and the carrier production | generation layer 16 in FIG. 5A. It is sectional drawing for demonstrating the manufacturing process in the light source device of 1st Embodiment. It is sectional drawing for demonstrating the manufacturing process in the light source device of 1st Embodiment. It is sectional drawing for demonstrating the manufacturing process in the light source device of 1st Embodiment. It is sectional drawing for demonstrating the manufacturing process in the light source device of 1st Embodiment. It is sectional drawing for demonstrating the manufacturing process in the light source device of 1st Embodiment. It is sectional drawing for demonstrating the manufacturing process in the light source device of 1st Embodiment. It is sectional drawing for demonstrating the manufacturing process in the light source device of 1st Embodiment. It is sectional drawing for demonstrating a manufacturing process in the light source device of 2nd Embodiment. It is sectional drawing for demonstrating a manufacturing process in the light source device of 2nd Embodiment. It is sectional drawing for demonstrating a manufacturing process in the light source device of 2nd Embodiment. It is sectional drawing for demonstrating a manufacturing process in the light source device of 2nd Embodiment. It is sectional drawing for demonstrating a manufacturing process in the light source device of 2nd Embodiment. It is sectional drawing for demonstrating the formation process of a photonic crystal in the light source device of 2nd Embodiment. It is sectional drawing for demonstrating the formation process of a photonic crystal in the light source device of 2nd Embodiment. It is sectional drawing for demonstrating the formation process of a photonic crystal in the light source device of 2nd Embodiment. It is sectional drawing for demonstrating the formation process of a photonic crystal in the light source device of 2nd Embodiment. In the light source device of 2nd Embodiment, it is sectional drawing for demonstrating the other example of the formation process of a photonic crystal. In the light source device of 2nd Embodiment, it is sectional drawing for demonstrating the other example of the formation process of a photonic crystal. In the light source device of 2nd Embodiment, it is sectional drawing for demonstrating the other example of the formation process of a photonic crystal. In the light source device of 2nd Embodiment, it is sectional drawing for demonstrating the other example of the formation process of a photonic crystal. In the light source device of 2nd Embodiment, it is sectional drawing for demonstrating the other example of the formation process of a photonic crystal. In the light source device of 2nd Embodiment, it is sectional drawing for demonstrating the other example of the formation process of a photonic crystal. In the light source device of 2nd Embodiment, it is sectional drawing for demonstrating the other example of the formation process of a photonic crystal. In the light source device of 2nd Embodiment, it is sectional drawing for demonstrating the other example of the formation process of a photonic crystal. It is a perspective view which shows typically the light source device of 3rd Embodiment. It is sectional drawing for demonstrating the formation process of the micro lens array in the light source device of 3rd Embodiment. It is sectional drawing for demonstrating the formation process of the micro lens array in the light source device of 3rd Embodiment. It is a perspective view which shows typically the directivity control layer with which the light source device of 4th Embodiment is provided. It is a perspective view which shows typically the directivity control layer with which the light source device of 5th Embodiment is provided. It is a perspective view which shows typically the directivity control layer with which the light source device of 6th Embodiment is provided. It is a perspective view which shows typically the directivity control layer with which the light source device of 7th Embodiment is provided. It is a perspective view which shows typically the directivity control layer with which the light source device of 8th Embodiment is provided. It is a perspective view which shows typically the directivity control layer with which the light source device of 9th Embodiment is provided. It is a perspective view which shows typically the directivity control layer with which the light source device of 10th Embodiment is provided. In 11th Embodiment, it is a perspective view which shows the structure by which the micro lens array was provided in the surface of the directivity control layer. It is sectional drawing for demonstrating the formation process of a micro lens array in the light source device of 11th Embodiment. It is sectional drawing for demonstrating the formation process of a micro lens array in the light source device of 11th Embodiment. It is a perspective view which shows typically the directivity control layer with which the light source device of 12th Embodiment is provided. It is a perspective view which shows typically the directivity control layer with which the light source device of 13th Embodiment is provided. It is a perspective view which shows typically the directivity control layer with which the light source device of 14th Embodiment is provided. It is a perspective view which shows typically the directivity control layer with which the light source device of 15th Embodiment is provided. It is a perspective view which shows typically the directivity control layer with which the light source device of 16th Embodiment is provided. It is a perspective view which shows typically the directivity control layer with which the light source device of 17th Embodiment is provided. It is a perspective view which shows typically the directivity control layer with which the light source device of 18th Embodiment is provided. It is a perspective view which shows the light source device of 19th Embodiment. It is a longitudinal cross-sectional view which shows the structure of the half-wave plate for axial symmetry polarization | polarized-light with which the light source device of 19th Embodiment is provided. It is a schematic diagram shown in order to demonstrate the half-wave plate for axial symmetry polarization | polarized-light with which the light source device of 19th Embodiment is provided. It is a schematic diagram shown in order to demonstrate the half-wave plate for axial symmetry polarization | polarized-light with which the light source device of 19th Embodiment is provided. In the light source device of an embodiment, it is a mimetic diagram showing the far field pattern and polarization direction of outgoing light in the case of composition which is not provided with an axisymmetric polarization half wave plate. In the light source device of an embodiment, it is a mimetic diagram showing the far field pattern and polarization direction of outgoing light in the case of the composition provided with the axially symmetric polarization half-wave plate. It is a schematic diagram which shows the LED projector to which the light source device of embodiment is applied. It is a figure for demonstrating the wavelength of the light source used for the LED projector to which the light source device of embodiment is applied, the excitation wavelength of a fluorescent substance, and the light emission wavelength. It is a figure which shows the rough surface shape of a plasmon excitation layer. It is a figure which shows the rough surface shape of a plasmon excitation layer. It is a figure which shows the rough surface shape of a plasmon excitation layer. It is a figure which shows the rough surface shape of a plasmon excitation layer. It is a figure which shows the rough surface shape of a plasmon excitation layer. It is a figure which shows the rough surface shape of a plasmon excitation layer.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 3 is a perspective view of a schematic configuration of the light source device according to the present invention. FIG. 4 shows a cross-sectional view for explaining the behavior of light in the light source device according to the present invention. In the light source device, the actual thickness of each individual layer is very thin, and the difference in the thickness of each layer is large. Therefore, it is difficult to draw each layer with an accurate scale and ratio. For this reason, in the drawings, the layers are not drawn in actual proportions, and the layers are schematically shown.

  As shown in FIGS. 3 and 4, the light source device 2 of the present embodiment includes a plurality of light emitting elements 11 (11 a to 11 n) and an optical element 1 on which light emitted from these light emitting elements 11 is incident. Yes. The optical element 1 includes a light guide 12 on which light emitted from the light emitting element 11 enters, and a directivity control layer 13 that emits emitted light by the light from the light guide 12.

  The directivity control layer 13 is a layer for enhancing the directivity of the emitted light from the light source device 2, and is provided on the light guide 12 as in the first embodiment shown in FIG. 5A, for example. A carrier generation layer 16 in which carriers are generated by a part of light incident from 12, and a frequency of light that is laminated on the carrier generation layer 16 and is generated when the carrier generation layer 16 is excited by light from the light emitting element 11. A plasmon excitation layer 17 having a higher plasma frequency, and an emission layer that is laminated on the plasmon excitation layer 17 and converts the wave number vector of the surface plasmon generated by the plasmon excitation layer 17 to emit light having a predetermined emission angle. The wave vector conversion layer 18 is provided. The upper surface of the carrier generation layer 16 is subjected to a roughening process, and the bonding surface of the plasmon excitation layer 17 laminated on the carrier generation layer 16 with the carrier generation layer 16 is roughened.

  The light guide in the present embodiment has a light emitting element in which the light emitted from the light emitting element 11 can be sufficiently absorbed in the carrier generation layer 16 when the light emitted from the light emitting element 11 does not damage the directivity control layer 13. 11 is not necessary when the uniformity of the light intensity on the light emitting surface is not a problem.

The carrier generation layer 16 in the present embodiment is disposed immediately below the plasmon excitation layer 17, but the thickness of the surface plasmon represented by the following expression 4 is between the carrier generation layer 16 and the plasmon excitation layer 17. It may be configured with a dielectric layer thinner than the effective interaction distance d _eff .

The wave vector conversion layer 18 in the present embodiment is disposed immediately above the plasmon excitation layer 17, but the surface between the wave vector conversion layer 18 and the plasmon excitation layer 17 has a thickness represented by Equation 4 described later. A dielectric layer thinner than the effective interaction distance d _{eff of} plasmons may be provided.

  The plasmon excitation layer 17 is sandwiched between two layers having dielectric properties. In the present embodiment, these two layers correspond to the carrier generation layer 16 and the wave vector conversion layer 18. The optical element 1 according to the present embodiment includes the entire structure laminated on the light guide 12 side of the plasmon excitation layer 17 and an ambient atmosphere medium (hereinafter simply referred to as a medium) in contact with the light guide 12. The output side portion including the entire structure in which the effective dielectric constant of the portion (hereinafter simply referred to as the incident side portion) is laminated on the wave vector conversion layer 18 side of the plasmon excitation layer 17 and the medium in contact with the wave vector conversion layer 18 It is configured so as to be higher than the effective dielectric constant (hereinafter simply referred to as the emission side portion). The entire structure laminated on the light guide 12 side of the plasmon excitation layer 17 includes the carrier generation layer 16 and the light guide 12. The entire structure stacked on the wave vector conversion layer 18 side of the plasmon excitation layer 17 includes the wave vector conversion layer 18.

  That is, in the first embodiment, the effective dielectric constant of the incident side portion including the light guide 12, the carrier generation layer 16, and the medium with respect to the plasmon excitation layer 17 is equal to the wave vector conversion layer 18 with respect to the plasmon excitation layer 17. It is higher than the effective dielectric constant of the exit side portion including the medium.

  Specifically, the effective dielectric constant of the incident side portion (the light emitting element 11 side) of the plasmon excitation layer 17 is set higher than the effective dielectric constant of the emission side portion (the wave vector conversion layer 18 side) of the plasmon excitation layer 17. Yes.

Here, the effective dielectric constant ε _eff is an x-axis, y-axis direction parallel to the interface of the plasmon excitation layer 17, and a direction perpendicular to the interface of the plasmon excitation layer 17 (if the plasmon excitation layer 17 has irregularities, The z axis is the direction perpendicular to the average plane), the angular frequency of light emitted from the carrier generation layer 16 is ω, and the real part of the dielectric constant distribution of the dielectric in the incident side portion and the emission side portion with respect to the plasmon excitation layer 17 is ε. (Ω, x, y, z), where the z component of the wave number of the surface plasmon is k _{spp, z} and the imaginary unit is j,

  It is determined based on the dielectric constant distribution of the incident side portion or the emission side portion and the distribution of surface plasmons with respect to the direction perpendicular to the interface of the plasmon excitation layer 17,

It is represented by Here, 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 17. In other words, the x-axis and y-axis direction ranges in the integration range D are ranges that do not include the medium up to the outer peripheral surface of the structure included in the incident side portion or the outer peripheral surface of the structure included in the output side portion. It ranges up to the outer edge of the plane parallel to the plane of the wave number vector conversion layer 18 side of the excitation layer 17. 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 (including the medium). Regarding the range in the z-axis direction in the integration range D, the interface between the plasmon excitation layer 17 and the dielectric layer adjacent to the plasmon excitation layer 17 is a position where z = 0, and from this interface, The plasmon excitation layer 17 is a range from the adjacent layer side to infinity, and the direction away from this interface is the (+) z direction in the equation (1). Therefore, when obtaining the effective dielectric constant for the plasmon excitation layer 17 having a rough surface, the origin of the z coordinate is changed with respect to the height of the raised portion and the settled portion of the rough surface, and the frequency of occurrence of each height is changed. , And the effective dielectric constant needs to be obtained as an average value. If there is a material with optical anisotropy in the effective permittivity calculation range, ε (ω, x, y, z) is a vector and has a different value for each radial direction perpendicular to the z axis. . 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. At this time, the value of ε (ω, x, y, z) is a dielectric constant with respect to a 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 effective dielectric constant ε _eff may be calculated using the following equation. However, it is particularly desirable to use the formula (1).

Further, the z component k _{spp, z} of the wave number of the surface plasmon, the x and y components k _spp of the wave number of the surface plasmon are set such that the dielectric constant of the plasmon excitation layer 17 is ε _metal and the wave number of light in vacuum is k _0. If

It is represented by

  Here, Re [] represents taking a real part in [].

Therefore, the real part ε _in (ω of the dielectric constant distribution of the incident side portion of the plasmon excitation layer 17 is expressed as ε (ω, x, y, z) using Equations (1), (2), and (3). , X, y, z) and the real part ε _out (ω, x, y, z) of the permittivity distribution of the emission side portion of the plasmon excitation layer 17 are respectively substituted and calculated, whereby the plasmon excitation layer 17 is calculated. effective permittivity epsilon _Effout effective permittivity layer epsilon _effin, and the exit-side portion of the incident side portion is obtained, respectively. In fact, given an appropriate initial value as the effective dielectric constant epsilon _eff, equation (1), equation (2), by calculating repeatedly Equation (3) is obtained easily effective dielectric constant epsilon _eff. When the real part of the dielectric constant of the layer in contact with the plasmon excitation layer 17 is very large, the z component k _{spp, z} of the surface plasmon wave number at the interface 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 17 corresponds to the effective dielectric constant in this case. The effective dielectric constant in the other embodiments is also defined in the same manner as Equation (1).

Here, if the effective interaction distance of the surface plasmon is a distance where the intensity of the surface plasmon is e ⁻² , the effective interaction distance d _eff of the surface plasmon is

It is represented by

  FIG. 5C is a cross-sectional view showing a state of the carrier generation layer 16 and the plasmon excitation layer 17 shown in FIG. 5A.

  As shown in FIG. 5C, when the plasmon excitation layer 17 and the carrier generation layer 16 are roughened, the excitation light incident from the carrier generation layer 16 side is incident on the plasmon excitation layer 17. Scattered light is generated and the rate of absorption by the carrier generation layer 16 increases. Further, localized plasmons are generated at the sharpened portion of the rough surface, and the ratio of the excitation light absorbed by the carrier generation layer 16 is increased around the sharpened portion of the rough surface. The light emission intensity is increased by the above mechanism.

  Table 1 shows the emission enhancement when the joining surface of the plasmon excitation layer 17 and the carrier generation layer 16 is a flat surface and a rough surface, and FIG. 5D shows the normalized photon number (= detected photon number / (absorption) with respect to the radiation angle. Photon number x uptake rate)).

  Table 1 shows that the emission intensity increases, and it is confirmed from FIG. 5D that the emission intensity increases and radiation with high directivity is performed.

The unevenness depth and unevenness width of the rough surface are preferably 5 nm or more and λ or less, where λ is the emission wavelength when the carrier generation layer 16 is excited independently. The reason is that when the roughness depth and the width of the rough surface are less than 5 nm, the excitation intensity of the surface plasmon and the light scattering intensity are low, and when λ or more, the surface plasmon excited by the plasmon excitation layer 17 is uneven. This is because the ratio of being scattered and extracted as highly directional radiation is reduced. More preferably, it is 5 nm or more and d _eff or less. In this case, scattering of surface plasmons can be further suppressed.

  The rough surface in the present invention has a sharp shape in FIG. 5C, but the tip of the sharp portion may be rounded as shown in FIG. 5E. The curvature radius R of the tip is preferably 100 nm or less, and more preferably about 20 nm to 50 nm. If the radius of curvature R is 100 nm or less, the effect of confining the excitation light in the carrier generation layer 16 by the sharply generated localized plasmons and the effect of promoting the generation rate of carriers can be obtained. High directional radiation. If the radius of curvature R is about 20 nm to 50 nm, the above effect can be obtained more strongly, so that highly directional radiation with further increased emission intensity can be obtained.

  The formation range of the rough surface is provided on the entire surface of the plasmon excitation layer 17 in the present invention, but it goes without saying that it can be designed as necessary. That is, even when a rough surface is formed on a part of the plasmon excitation layer 17 on the carrier generation layer 16 side, highly directional radiation with increased emission intensity can be obtained as compared with the case where the plasmon excitation layer 17 has no rough surface.

  As shown in FIG. 35, the rough surface on the carrier generation layer side 3502 of the plasmon excitation layer 3501 may have a rectangular structure.

  As shown in FIG. 36, the rough surface on the carrier generation layer side 3602 of the plasmon excitation layer 3601 may have a rounded structure.

  As shown in FIGS. 37 and 38, the rough surfaces of the plasmon excitation layers 3701 and 3801 on the carrier generation layers 3702 and 3802 side may have a trapezoidal structure.

As shown in FIGS. 39 and 40, dielectric layers 3902 and 4002 may be disposed between the plasmon excitation layers 3901 and 4001 and the carrier generation layers 3903 and 4003. Note that the surface of the dielectric layer on the carrier generation layer side may be a rough surface as shown in FIG. 39 or a flat surface as shown in FIG. Here, the thickness of the dielectric layer is preferably such that the closest distance between the carrier generation layer and the plasmon excitation layer is equal to or less than the effective interaction distance d _{eff of the} surface plasmon.

  Further, the rough surface does not need to have periodicity as shown in FIG. 5C, and may have various uneven depth, uneven width, and radius of curvature.

  It goes without saying that the same rough surface can be applied to other embodiments.

  In the case of the present embodiment, any layer including the light guide 12 or a medium in contact with the wave vector conversion layer 18 at the frequency of light generated when the carrier generation layer 16 is excited by the light of the light emitting element 11. However, the imaginary part of the complex dielectric constant is preferably as low as possible. By making the imaginary part of the complex dielectric constant as low as possible, plasmon coupling can be easily generated and light loss can be reduced.

  The medium around the light source device 2, that is, the medium in contact with the light guide 12 and the wave vector conversion layer 18 may be solid, liquid, or gas, and the light guide 12 side and the wave vector conversion layer 18 side May be different media.

  In the present embodiment, the plurality of light emitting elements 11 a to 11 n are arranged on the four side surfaces of the flat light guide 12 with predetermined intervals, respectively. Here, a surface where the light emitting elements 11 a to 11 n are connected to the side surfaces is referred to as a light incident surface 14. As the light emitting element 11, for example, a light emitting diode (LED) that emits light having a wavelength that can be absorbed by the carrier generation layers 16 and 2006, a laser diode, a super luminescent diode, or the like is used. The light emitting element 11 may be disposed away from the light incident surface 14 of the light guide 12. For example, the light emitting element 11 is configured to be optically connected to the light guide 12 by a light guide member such as a light pipe. Also good.

  In the present embodiment, the light guide 12 is formed in a flat plate shape, but the shape of the light guide 12 is not limited to a rectangular parallelepiped. A structure body that controls light distribution characteristics such as a microprism may be provided inside the light guide body 12. The light guide 12 may be provided with a reflective film on the entire outer peripheral surface excluding the light emitting portion 15 and the light incident surface 14 or on a part of the outer peripheral surface. Similarly, the light source device 2 may be provided with a reflective film (not shown) on the entire or a part of the outer peripheral surface excluding the light emitting portion 15 and the light incident surface 14. As the reflective film, for example, a metal material such as silver or aluminum, or a dielectric multilayer film is used.

  Examples of the carrier generation layer 16 include organic phosphors such as rhodamine (Rhodamine 6G) and sulforhodamine (sulfodamine 101), phosphors such as quantum dot phosphors such as CdSe and CdSe / ZnS quantum dots, and GaN and GaAs. Inorganic materials (semiconductors) such as (thiophene / phenylene) co-oligomer, and organic materials (semiconductor materials) such as Alq3 are used. When using a phosphor, the carrier generation layer 16 may include a mixture of materials that emit a plurality of wavelengths having the same or different emission wavelengths. The thickness of the carrier generation layer 16 is preferably 1 μm or less.

  The plasmon excitation layer 17 is a fine particle layer or a thin film layer formed of a material having a plasma frequency higher than the frequency (light emission frequency) of light generated when the carrier generation layer 16 alone is excited by light of the light emitting element 11. . In other words, the dielectric constant of the plasmon excitation layer 17 is negative in the real part of the dielectric constant at the emission frequency generated when the carrier generation layer 16 alone is excited by the light of the light emitting element 11.

  Examples of the material of the plasmon excitation layer 17 include gold, silver, copper, platinum, palladium, rhodium, osmium, ruthenium, iridium, iron, tin, zinc, cobalt, nickel, chromium, titanium, tantalum, tungsten, indium, and aluminum. Or alloys thereof. Among these, as a material of the plasmon excitation layer 17, gold, silver, copper, platinum, aluminum and alloys containing these as main components are preferable, and gold, silver, aluminum and alloys containing these as main components are particularly preferable. Further, the thickness of the plasmon excitation layer 17 is preferably 50 nm or less, particularly preferably about 0 nm to 30 nm, excluding the rough surface portion. That is, there may be a hole in a part of the plasmon excitation layer 17 and the layers around the plasmon excitation layer 17 may be in contact with each other. The wave vector conversion layer 18 converts the surface plasmon excited at the interface between the plasmon excitation layer 17 and the wave vector conversion layer 18 into a wave vector of the surface plasmon, whereby the plasmon excitation layer 17 and the wave vector conversion layer 18 are converted. This is an emission layer for taking out light from the interface with the optical element 1 and emitting light from the optical element 1.

  Examples of the wave vector conversion layer 18 include a surface relief grating, a periodic structure represented by a photonic crystal, a quasi-periodic structure, or a quasi-crystal structure, a texture structure larger than the wavelength of light from the optical element 1, such as a rough surface. And the like using a surface structure on which is formed, a hologram, a microlens array, and the like. The quasi-periodic structure refers to, for example, an incomplete periodic structure in which a part of the periodic structure is missing. Among these, it is preferable to use a periodic structure represented by a photonic crystal, a quasi-periodic structure, a quasicrystalline structure, or a microlens array. This is because not only the light extraction efficiency can be increased, but also the directivity can be controlled. When using a photonic crystal, it is desirable that the crystal structure has a triangular lattice structure. The wave vector conversion layer 18 may have a structure in which a convex portion is provided on a flat plate-like base portion or a structure in which a concave portion is provided on a flat plate-like base portion. In the embodiment described later, only the configuration in which the wave vector conversion layer 18 is made of a photonic crystal is shown, but other structures described above may be used.

  In the light source device 2 configured as described above, an operation in which light incident on the directivity control layer 13 from the light emitting element 11 is emitted from the light emitting unit 15 of the directivity control layer 13 will be described.

  As shown in FIG. 4, among the plurality of light emitting elements 11, for example, light emitted from the light emitting element 11 f passes through the light incident surface 14 of the light guide 12 and propagates while totally reflecting inside the light guide 12. To do. At this time, a part of the light incident on the interface between the light guide 12 and the directivity control layer 13 is converted by the directivity control layer 13 into a direction and a wavelength shown in Expression (5) to be described later, from the light emitting unit 15. Emitted. Of the light emitted from the light emitting element 11f, the light that has not been used in the directivity control layer 13 is returned to the light guide body 12, and is again returned to the interface between the light guide body 12 and the directivity control layer 13. Are converted into directions and wavelengths according to the characteristics of the directivity control layer 13 and emitted from the light emitting unit 15. By repeating these steps, most of the light incident on the light guide 12 is emitted from the light emitting unit 15. Similarly, among the plurality of light emitting elements 11, the light emitted from the light emitting element 11 m disposed at the position facing the light emitting element 11 f with the light guide 12 interposed therebetween and similarly transmitted through the light incident surface 14. The direction and wavelength are converted and emitted from the light emitting unit 15. The direction and wavelength of the light emitted from the light emitting portion 15 depend only on the characteristics of the directivity control layer 13, and the incident angle to the position of the light emitting element 11 and the interface between the light guide 12 and the directivity control layer 13. Is independent. Hereinafter, unless otherwise specified, a configuration including the wave vector conversion layer 18 made of a photonic crystal will be described.

  Next, characteristics of the directivity control layer 13 will be described. Carriers are generated in the carrier generation layer 16 by light from the light emitting element 11 propagating in the light guide 12. The generated carriers cause plasmon coupling with free electrons in the plasmon excitation layer 17. Through this plasmon coupling, surface plasmons are excited at the interface between the plasmon excitation layer 17 and the wave vector conversion layer 18. The excited surface plasmon is diffracted by the wave vector conversion layer 18 and emitted to the outside of the light source device 2.

  When the dielectric constant at the interface between the plasmon excitation layer 17 and the wave vector conversion layer 18 is spatially uniform, that is, a flat surface, surface plasmons generated at this interface cannot be extracted. For this reason, in the present invention, by providing the wave vector conversion layer 18, the surface plasmon is diffracted and extracted as light. The light emitted from one point of the wave vector conversion layer 18 has an annular intensity distribution that spreads concentrically as it propagates. Under the condition that formula (5) described later is 0, the intensity distribution of the single peak having the strongest light intensity is provided in the direction along the z-axis.

When the emission angle having the highest intensity is set as the central emission angle, the central emission angle θ _rad of light emitted from the wave vector conversion layer 18 is Λ, and the pitch of the periodic structure of the wave vector conversion layer 18 is Λ. If the refractive index of the light extraction side (that is, the medium in contact with the wave vector conversion layer) is n _rad ,

It is represented by Here, i is a positive or negative integer. At the interface between the plasmon excitation layer 17 and the wave vector conversion layer 18, only surface plasmons in the vicinity of the wave number determined by the equation (3) exist, and therefore the angular distribution of the emitted light determined by the equation (5) becomes narrow.

  The manufacturing process of the optical element 1 with which the light source device 2 is provided is shown to FIG. 6A-FIG. 6G. This is merely an example, and the present invention is not limited to this manufacturing method. First, as shown in FIGS. 6A and 6B, a carrier generation layer 16 is applied on the light guide 12 by a spin coating method. Subsequently, a rough surface is formed on the carrier generation layer 16 by etching. Thereafter, as shown in FIG. 6C, the plasmon excitation layer 17 is formed on the carrier generation layer 16 by, for example, physical vapor deposition, electron beam vapor deposition, sputtering, or the like.

  Next, as shown in FIG. 6D, a wave vector conversion layer 18 is formed on the carrier generation layer 16 by a photonic crystal. Subsequently, as shown in FIG. 6E, a resist film 21 is applied onto the wave vector conversion layer 18 by spin coating, and a negative pattern of the photonic crystal is transferred to the resist film 21 by nanoimprinting as shown in FIG. 6F. To do. As shown in FIG. 6G, the wave vector conversion layer 18 is etched to a desired depth by dry etching, and then the resist film 21 is peeled from the wave vector conversion layer 18. Finally, the light source device 2 is completed by arranging the plurality of light emitting elements 11 on the outer periphery of the light guide 12.

  As described above, the light source device 2 of the present embodiment has a relatively simple configuration in which the light guide 12 is provided with the directivity control layer 13, so that the light source device 2 as a whole can be downsized. In the light source device 2 according to the present embodiment, the incident angle of light incident on the wave vector conversion layer 18 is such that the complex dielectric constant of the plasmon excitation layer 17 and the effective dielectric constant of the incident side portion sandwiching the plasmon excitation layer 17 are. And the effective dielectric constant of the emission side portion and the emission spectrum of the light generated in the light source device 2. For this reason, the directivity of the emitted light from the optical element 1 is not limited to the directivity of the light emitting element 11. In addition, the light source device 2 according to each embodiment can apply the plasmon coupling in the radiation process, thereby narrowing the radiation angle of the emitted light from the optical element 1 and improving the directivity of the emitted light. That is, according to the present embodiment, the etendue of the emitted light from the light source device 2 can be reduced without depending on the etendue of the light emitting element 11. Further, since the etendue of the emitted light from the light source device 2 is not limited by the etendue of the light emitting element 11, the incident light from the plurality of light emitting elements 11 is synthesized while keeping the etendue of the emitted light from the light source device 2 small. be able to.

  In addition, the configuration disclosed in Patent Document 1 described above has a problem that the entire light source unit is increased in size by including the optical axis alignment members 202a to 202d and the light source sets 201a and 201b. However, according to the optical element 1 in the present embodiment, the entire optical element 1 can be reduced in size.

  Further, in the configuration disclosed in Patent Document 2 described above, there is a problem in that light from the plurality of LEDs 300 is bent in various directions by the prism sheets 304 and 305 arranged to intersect each other, thereby causing light loss. . However, according to the optical element 1 according to each embodiment, the utilization efficiency of light from the plurality of light emitting elements 11 can be improved.

  This embodiment can be manufactured by a structure forming technique in a general semiconductor field.

(Second Embodiment)
FIG. 5B is a diagram showing a main configuration of the second embodiment of the present invention. Since the present embodiment is obtained by changing only the configuration of the directivity control layer 13 of the first embodiment, only the directivity control layer 13 ′ is shown in FIG. 5B. The directivity control layer 13 ′ is provided on the light guide 12, and a carrier generation layer 2006 in which carriers are generated by a part of light incident from the light guide 12, and is laminated on the carrier generation layer 2006. A plasmon excitation layer 2008 having a plasma frequency higher than the frequency of light generated when the generation layer 2006 is excited by light of the light emitting element 11, and a wave vector of the incident light that is stacked on the plasmon excitation layer 2008 and converted. And a wave vector conversion layer 2010 as an emission layer that emits light.

  The plasmon excitation layer 2008 is sandwiched between two layers having dielectric properties. As two layers having dielectric properties, the directivity control layer 13 ′ according to this configuration example includes a high dielectric constant layer 2009 provided between the plasmon excitation layer 2008 and the wave vector conversion layer 2010, and carrier generation. A low dielectric constant layer 2007 provided between the layer 2006 and the plasmon excitation layer 2008 and having a dielectric constant lower than that of the high dielectric constant layer 2009. Even if the high dielectric constant layer 2009 and the low dielectric constant layer 2007 are not included, when the effective dielectric constant of the incident side portion described later is lower than the effective dielectric constant of the output side portion, the high dielectric constant layer 2009 and the low dielectric constant layer 2007 are provided. Is not an essential component in the operation of this embodiment.

  In the optical element 11 in this configuration example, the effective dielectric constant of the incident side portion (hereinafter simply referred to as the incident side portion) including the entire structure laminated on the light guide 12 side of the plasmon excitation layer 2008 is plasmon excitation. The effective dielectric constant of the emission side portion (hereinafter, simply referred to as the emission side portion) including the entire structure stacked on the wave vector conversion layer 2010 side of the layer 2008 and the medium in contact with the wave vector conversion layer 10 is reduced. It is configured. The entire structure stacked on the light guide 12 side of the plasmon excitation layer 2008 includes the light guide 12. The entire structure laminated on the wave vector conversion layer 2010 side of the plasmon excitation layer 2008 includes the wave vector conversion layer 2010.

  In other words, in this configuration example, the effective dielectric constant of the incident side portion including the light guide 12 and the carrier generation layer 2006 with respect to the plasmon excitation layer 2008 is an emission including the wave vector conversion layer 2010 and the medium with respect to the plasmon excitation layer 2008. It is lower than the effective dielectric constant of the side portion.

  Specifically, the effective dielectric constant of the incident side portion (light emitting element 11 side) of the plasmon excitation layer 2008 is set lower than the effective dielectric constant of the emission side portion (wave number vector conversion layer 2010 side) of the plasmon excitation layer 2008. Yes.

  The upper surface of the low dielectric constant layer 2007 shown in FIG. 5B is subjected to a roughening treatment, and the bonding surface of the plasmon excitation layer 2008 laminated on the low dielectric constant layer 2007 with the low dielectric constant layer 2007 is a rough surface. Is done. In the case of the present embodiment, any layer including the light guide 12 or a medium in contact with the wave vector conversion layer 2010 at the frequency of light generated when the carrier generation layer 16 is excited by the light of the light emitting element 11. However, the imaginary part of the complex dielectric constant is preferably as low as possible. By making the imaginary part of the complex dielectric constant as low as possible, plasmon coupling can be easily generated and light loss can be reduced.

  The medium around the light source device 50, that is, the medium in contact with the light guide 12 and the wave vector conversion layer 2010 may be solid, liquid, or gas. The light guide 12 side and the wave vector conversion layer 2010 side May be different media.

In the case of the second embodiment, examples of the low dielectric constant layer 2007 include an SiO ₂ nanorod array film, SiO ₂ , AlF ₃ , MgF ₂ , Na ₃ AlF ₆ , NaF, LiF, CaF ₂ , BaF ₂ , low It is preferable to use a thin film such as a dielectric constant plastic or a porous film. The thickness of the low dielectric constant layer 2007 is desirably as thin as possible.

Examples of the high dielectric constant layer 2009 include 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, and Nb. _It is preferable to use a high dielectric constant material such as ₂ O ₅ .

  The plasmon excitation layer 2008 is a fine particle layer or a thin film layer formed of a material having a plasma frequency higher than the frequency (light emission frequency) of light generated when the carrier generation layer 2006 alone is excited by light of the light emitting element 1. . In other words, the plasmon excitation layer 2008 has a negative dielectric constant at an emission frequency that is generated when the carrier generation layer 2006 is excited by the light of the light emitting element 1.

  The wave vector conversion layer 2010 is an emission layer for extracting light from the high dielectric constant layer 2009 and emitting light from the optical element 1 by converting the wave vector of incident light incident on the wave vector conversion layer 2010. is there. In other words, the wave vector conversion layer 2010 converts light emitted from the interface between the high dielectric constant layer 2009 and the plasmon excitation layer 2008 into light having a predetermined emission angle and emits the light from the optical element 1. That is, the wave vector conversion layer 2010 has a function of emitting outgoing light from the optical element 1 so as to be substantially orthogonal to the interface between the plasmon excitation layer 2008 and the wave vector conversion layer 2010.

  The surface of the high dielectric constant layer 2009 on the side opposite to the light guide 12 is configured such that a microlens array is disposed instead of a photonic crystal as the wave vector conversion layer 2010, or a rough surface is formed. It may be.

  In the light source device 2 configured as described above, an operation in which light incident on the directivity control layer 13 ′ from the light emitting element 11 is emitted from the light emitting unit 15 of the directivity control layer 13 ′ will be described.

  The operation of this embodiment will be described with reference to FIG. As shown in FIG. 4, among the plurality of light emitting elements 11, for example, light emitted from the light emitting element 11 f passes through the light incident surface 14 of the light guide 12 and propagates while totally reflecting inside the light guide 12. To do. At this time, a part of the light incident on the interface between the light guide 12 and the directivity control layer 13 ′ is converted into the direction and wavelength of the formula (6) described later by the directivity control layer 13 ′, and wave vector conversion is performed. The light is emitted from the layer 2010. Of the light emitted from the light emitting element 11f, the light that has not been used in the directivity control layer 13 ′ is returned to the light guide 12 and is again incident on the interface between the light guide 12 and the directivity control layer 13 ′. Is converted into a direction and a wavelength according to the characteristics of the directivity control layer 13 ′ and emitted from the light emitting unit 15. By repeating these steps, most of the light incident on the light guide 12 is emitted from the light emitting unit 15. Similarly, among the plurality of light emitting elements 11, the light emitted from the light emitting element 11 m disposed at the position facing the light emitting element 11 f with the light guide 12 interposed therebetween and similarly transmitted through the light incident surface 14. The direction and wavelength are converted and emitted from the light emitting unit 15. The direction and wavelength of the light emitted from the light emitting portion 15 depend only on the characteristics of the directivity control layer 13 ′, and the position of the light emitting element 11 and the interface between the light guide 12 and the directivity control layer 13 ′. It is independent of the incident angle. Hereinafter, unless otherwise specified, a configuration including the wave vector conversion layer 2010 made of a photonic crystal will be described with reference to FIG. 5B.

  Next, characteristics of the directivity control layer 13 'will be described. Carriers are generated in the carrier generation layer 2006 by light from the light emitting element 11 propagating in the light guide 12. The generated carriers cause plasmon coupling with free electrons in the plasmon excitation layer 2008. Light is emitted from the interface between the plasmon excitation layer 2008 and the wave vector conversion layer 2010 via this plasmon coupling. This light is diffracted by the wave vector conversion layer 2010 and emitted to the outside of the light source device 2.

When the wave vector conversion layer 2010 is not provided, the light emitted from this interface cannot be extracted because it is light having a total reflection angle or more at the interface between the light source device 2 and the air. Therefore, in the present invention, by providing the wave vector conversion layer 2010, this light is diffracted and extracted. The light emitted from one point of the wave vector conversion layer 2010 has an annular intensity distribution that spreads concentrically as it propagates. When the incident angle with the highest intensity of the light incident on the wave vector conversion layer 18 is the central incident angle, the central incident angle θ _out of the light incident on the wave vector conversion layer 18 is the refractive index of the high dielectric constant layer 2009. n _out ,

It is represented by At the interface between the plasmon excitation layer 2008 and the low dielectric constant layer 2007, there are only surface plasmons in the vicinity of the wave number determined by the equation (3), so the angle distribution of the light incident on the wave vector conversion layer 2010 determined by the equation (6) Becomes narrower. Therefore, the angular distribution of the light diffracted and extracted by the wave vector conversion layer 2010 is also narrowed.

  7A to 7E show manufacturing steps of the optical element 1 according to the second embodiment. This is merely an example, and the present invention is not limited to this manufacturing method. First, as shown in FIGS. 7A and 7B, a carrier generation layer 2006 is applied on the light guide 12 by a spin coating method. Subsequently, as shown in FIGS. 7C to 7E, for example, by physical vapor deposition, electron beam vapor deposition, sputtering, or the like, the low dielectric constant layer 2007, the plasmon excitation layer 2008, and the high dielectric constant layer 2009 are formed on the carrier generation layer 2006. Are stacked in the order of. After the low dielectric constant layer 2007 is laminated and before the plasmon excitation layer 2008 is laminated, the surface of the low dielectric constant layer 2007 is etched to form a rough surface on the surface of the low dielectric constant layer 2007.

  A manufacturing process for forming the wave vector conversion layer 2010 by a photonic crystal is shown in FIGS. 8A to 8D. A wave vector conversion layer 2010 is formed on the high dielectric constant layer 2009 as shown in FIG. 8A, a resist film 2011 is applied on the wave vector conversion layer 2010 by a spin coating method, and nano imprint is applied as shown in FIG. 8B. The negative pattern of the photonic crystal is transferred to the resist film 2011. The wave vector conversion layer 2010 is etched to a desired depth by dry etching as shown in FIG. 8C, and then the resist film 2011 is peeled off as shown in FIG. 8D. Finally, the light source device 2 is completed by arranging the plurality of light emitting elements 1 on the outer periphery of the light guide 12.

  9A to 9H show another manufacturing process in which the wave vector conversion layer 2010 is formed by a photonic crystal on the surface of the high dielectric constant layer 2009 of the light source device 2. This is merely an example and is not limited to this manufacturing method.

  First, as shown in FIG. 9A, a resist film 2011 is applied on the substrate 12 by spin coating, and as shown in FIG. 9B, a negative pattern of a photonic crystal is transferred to the resist film 2011 by nanoimprinting. Subsequently, as shown in FIGS. 9C to 9E, a high dielectric constant layer 2009, a plasmon excitation layer 2008, and a low dielectric constant layer 2007 are sequentially laminated by physical vapor deposition, electron beam vapor deposition, and sputtering. As shown in FIG. 9F, a carrier generation layer 2006 is applied on the low dielectric constant layer 2007 by a spin coating method, and as shown in FIG. 9G, the light guide 12 is pressure-bonded to the carrier generation layer 2006 and dried. Finally, as shown in FIG. 9H, after the resist film 2011 is peeled from the substrate 2012, the light source device 2 is completed by disposing the plurality of light emitting elements 1 on the outer periphery of the light guide 12.

  As described above, the light source device 2 of the present embodiment has a relatively simple configuration in which the light guide 12 is provided with the directivity control layer 13, so that the light source device 2 as a whole can be downsized. In the light source device 2 according to the present embodiment, the incident angle of light incident on the wave vector conversion layer 18 is such that the complex dielectric constant of the plasmon excitation layer 17 and the effective dielectric constant of the incident side portion sandwiching the plasmon excitation layer 17 are. And the effective dielectric constant of the emission side portion and the emission spectrum of the light generated in the light source device 2. For this reason, the directivity of the emitted light from the optical element 1 is not limited to the directivity of the light emitting element 11. In addition, the light source device 2 according to each embodiment can apply the plasmon coupling in the radiation process, thereby narrowing the radiation angle of the emitted light from the optical element 1 and improving the directivity of the emitted light. That is, according to the present embodiment, the etendue of the emitted light from the light source device 2 can be reduced without depending on the etendue of the light emitting element 11. Further, since the etendue of the emitted light from the light source device 2 is not limited by the etendue of the light emitting element 11, the incident light from the plurality of light emitting elements 11 is synthesized while keeping the etendue of the emitted light from the light source device 2 small. be able to.

  In addition, the configuration disclosed in Patent Document 1 described above has a problem that the entire light source unit is increased in size by including the optical axis alignment members 202a to 202d and the light source sets 201a and 201b. However, according to the optical element 1 in the present embodiment, the entire optical element 1 can be reduced in size.

  Further, in the configuration disclosed in Patent Document 2 described above, there is a problem in that light from the plurality of LEDs 300 is bent in various directions by the prism sheets 304 and 305 arranged to intersect each other, thereby causing light loss. . However, according to the optical element 1 according to each embodiment, the utilization efficiency of light from the plurality of light emitting elements 11 can be improved.

(Third embodiment)
Hereinafter, light source devices according to other embodiments will be described. Since the light source device of other embodiment differs only in the structure of the directivity control layer 13 compared with the light source device 2 of 1st Embodiment, only a directivity control layer is demonstrated. In the directivity control layers of the following embodiments, the same reference numerals as those in the first embodiment are assigned to the same layers as the directivity control layer 13 in the first embodiment, and the description thereof is omitted.

  In the present embodiment, the configuration of the wave vector conversion layer 18 in the first embodiment shown in FIG. 5A is different. The wave vector conversion layer 18 may have a configuration in which a microlens array is disposed instead of a photonic crystal, or a layer in which a rough surface is formed. In FIG. 10, the typical perspective view of the directivity control layer with which the light source device of 3rd Embodiment is provided is shown.

  As shown in FIG. 10, the directivity control layer 23 is provided with a wave vector conversion layer 28 made of a microlens array on the surface of the plasmon excitation layer 17. Even if the directivity control layer 23 is configured to include the wave vector conversion layer 28 formed of a microlens array, the same effect as that of the configuration including the wave vector conversion layer 18 formed of a photonic crystal can be obtained.

  11A and 11B are cross-sectional views for explaining the manufacturing process of the configuration in which the microlens array is laminated on the plasmon excitation layer 17. Even in the configuration including the microlens array, the carrier generation layer 16 and the plasmon excitation layer 17 are laminated on the light guide 12 in the same manner as in the manufacturing method shown in FIGS. 6A to 6G. Omitted.

  As shown in FIGS. 11A and 11B, the carrier generation layer 16 and the plasmon excitation layer 17 are laminated on the light guide 12 using the manufacturing method shown in FIGS. 6A to 6G, and then the surface of the plasmon excitation layer 17 is obtained. In addition, the wave vector conversion layer 28 is formed by a microlens array. This manufacturing method is merely an example, and the present invention is not limited to this. As shown in FIG. 11A, after a UV curable resin 31 is applied to the surface of the plasmon excitation layer 17 by a spin coating method or the like, a desired lens array pattern is formed on the UV curable resin 31 using nanoimprint, and then UV cured. The resin 31 is irradiated with light and cured to form a microlens array.

  Also in the directivity control layer 23 in the second embodiment configured as described above, the same effect as in the first embodiment can be obtained by including the wave vector conversion layer 28 formed of a microlens array.

  In the embodiment described later, a configuration in which the wave vector conversion layer 18 is made of a photonic crystal is also shown. However, as described above, the wave vector conversion layer 18 may be replaced with the wave vector conversion layer 28 made of a microlens array. The same effect as each embodiment is acquired.

(Fourth embodiment)
In FIG. 12, the perspective view of the directivity control layer with which the light source device of 4th Embodiment is provided is shown. As shown in FIG. 12, the directivity control layer 33 in the fourth embodiment includes a carrier generation layer 16, a plasmon excitation layer 17, a dielectric constant layer 19, and a wave vector conversion layer 18 in this order on the light guide 12. It is configured by stacking.

  Therefore, the fourth embodiment is different from the first embodiment in that a dielectric constant layer 19 is independently provided between the plasmon excitation layer 17 and the wave vector conversion layer 18. Since this dielectric constant layer 19 is set to have a dielectric constant lower than that of a dielectric constant layer 20 (high dielectric constant layer 20) in a fifth embodiment to be described later, it will be referred to as a low dielectric constant layer 19 hereinafter. As the dielectric constant of the low dielectric constant layer 19, a range in which the effective dielectric constant of the emission side portion with respect to the plasmon excitation layer 17 is kept lower than the effective dielectric constant of the incident side portion is allowed. That is, the dielectric constant of the low dielectric constant layer 19 need not be smaller than the effective dielectric constant of the incident side portion with respect to the plasmon excitation layer 17.

  The low dielectric constant layer 19 may be formed of a material different from that of the wave vector conversion layer 18. For this reason, this embodiment can raise the freedom degree of the material selection of the wave vector conversion layer 18.

As the low dielectric constant layer 19, for example, a thin film or a porous film made of SiO ₂ , AlF ₃ , MgF ₂ , Na ₃ AlF ₆ , NaF, LiF, CaF ₂ , BaF ₂ , low dielectric constant plastic or the like is used. preferable. The thickness of the low dielectric constant layer 19 is desirably as thin as possible. Note that this allowable maximum value of the thickness corresponds to the oozing length of the surface plasmon generated in the thickness direction of the low dielectric constant layer 19 calculated using Expression (4). When the thickness of the low dielectric constant layer 19 exceeds the value calculated from the equation (4), it is difficult to extract surface plasmons as light.

  Also in the directivity control layer 33 in the fourth embodiment, in order to cause plasmon coupling in the plasmon excitation layer 17, the effective dielectric constant of the incident side portion including the light guide 12 and the carrier generation layer 16 is wave vector conversion. It is set to be higher than the effective dielectric constant of the emission side portion including the layer 18 and the low dielectric constant layer 19 and the medium in contact with the wave vector conversion layer 18.

  According to the directivity control layer 33 in the fourth embodiment configured as described above, the same effects as in the first embodiment can be obtained, and the plasmon excitation can be achieved by including the independent low dielectric constant layer 19. It becomes possible to easily adjust the effective dielectric constant of the emission side portion of the layer 17.

(Fifth embodiment)
In FIG. 13, the perspective view of the directivity control layer with which the light source device of 5th Embodiment is provided is shown. As shown in FIG. 13, the directivity control layer 43 in the fifth embodiment is a wave vector composed of the carrier generation layer 16, the dielectric constant layer 20, the plasmon excitation layer 17, and the photonic crystal on the light guide 12. The conversion layer 18 is laminated in this order.

  Therefore, the fifth embodiment is different from the first embodiment in that the dielectric constant layer 20 is independently provided between the plasmon excitation layer 17 and the carrier generation layer 16. Since the dielectric constant layer 20 is set to have a higher dielectric constant than the low dielectric constant layer 19 in the above-described fourth embodiment, it is hereinafter referred to as a high dielectric constant layer 20. The dielectric constant of the high dielectric constant layer 20 allows a range in which the effective dielectric constant of the exit side portion is kept lower than the effective dielectric constant of the entrance side portion with respect to the plasmon excitation layer 17. That is, the dielectric constant of the high dielectric constant layer 20 does not need to be larger than the effective dielectric constant of the emission side portion with respect to the plasmon excitation layer 17.

  The high dielectric constant layer 20 may be formed of a material different from that of the carrier generation layer 16. For this reason, this embodiment can raise the freedom degree of material selection of the carrier production | generation layer 16. FIG.

Examples of the high dielectric constant layer 20 include 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, and Nb ₂ O _5. It is preferable to use a thin film or a porous film made of a high dielectric constant material such as. The high dielectric constant layer 20 is preferably formed of a conductive material. The thickness of the high dielectric constant layer 20 is desirably as thin as possible. The allowable maximum value of the thickness corresponds to the distance at which plasmon coupling occurs between the carrier generation layer 16 and the plasmon excitation layer 17 and is calculated from the equation (4).

  Also in the directivity control layer 43 in the fifth embodiment, in order to generate plasmon coupling in the plasmon excitation layer 17, the effective dielectric of the incident side portion including the light guide 12, the carrier generation layer 16, and the high dielectric constant layer 20 is used. The rate is set to be higher than the effective dielectric constant of the emission side portion including the wave vector conversion layer 18 and the medium in contact with the wave vector conversion layer 18.

  According to the directivity control layer 43 in the fifth embodiment configured as described above, the same effects as in the first embodiment can be obtained, and the plasmon excitation can be achieved by including the independent high dielectric constant layer 20. It is possible to easily adjust the effective dielectric constant of the incident side portion of the layer 17. Furthermore, since the rate at which the carriers generated in the carrier generation layer 16 are thermally lost in the plasmon excitation layer 17 can be reduced, light with higher directivity can be obtained with higher efficiency than in the first embodiment. It is possible to take it out.

(Sixth embodiment)
In FIG. 14, the perspective view of the directivity control layer with which the light source device of 6th Embodiment is provided is shown. As shown in FIG. 14, the directivity control layer 53 includes a low dielectric constant layer 19 provided between the plasmon excitation layer 17 and the wave vector conversion layer 18, a carrier generation layer 16, and a plasmon excitation layer 17. And a high dielectric constant layer 20 having a dielectric constant higher than that of the low dielectric constant layer 19.

  Also in the directivity control layer 53 in the sixth embodiment, in order to cause plasmon coupling in the plasmon excitation layer 17, the effective dielectric of the incident side portion including the light guide 12, the carrier generation layer 16, and the high dielectric constant layer 20 is used. The rate is set to be higher than the effective dielectric constant of the emission side portion including the wave vector conversion layer 18 and the low dielectric constant layer 19 and the medium in contact with the wave vector conversion layer 18.

  According to the directivity control layer 53 in the sixth embodiment configured as described above, the same effects as in the first embodiment can be obtained, and the independent low dielectric constant layer 19 and high dielectric constant layer 20 can be provided. By providing, it is possible to easily adjust the effective dielectric constant of the emission side portion of the plasmon excitation layer 17 and the effective dielectric constant of the incident side portion of the plasmon excitation layer 17. The directivity control layer 53 in the sixth embodiment can also obtain the same effects as those in the first embodiment. Furthermore, since the rate at which the carriers generated in the carrier generation layer 16 are thermally lost in the plasmon excitation layer 17 can be reduced, light with higher directivity can be obtained with higher efficiency than in the first embodiment. It is possible to take it out.

  In the sixth embodiment, the low dielectric constant layer 19 is disposed on the wave vector conversion layer 18 side of the plasmon excitation layer 17, and the high dielectric constant layer 20 is disposed on the carrier generation layer 16 side of the plasmon excitation layer 17. However, it is not limited to this configuration. What is the low dielectric constant layer 19 and the high dielectric constant layer 20 as long as the effective dielectric constant of the incident side portion of the plasmon excitation layer 17 is higher than the effective dielectric constant of the emission side portion of the plasmon excitation layer 17? A material having a dielectric constant may be used. That is, depending on the dielectric constant of the layers other than the low dielectric constant layer 19 and the high dielectric constant layer 20, the dielectric constant of the high dielectric constant layer 20 may be lower than that of the low dielectric constant layer 19.

(Seventh embodiment)
FIG. 15 is a perspective view of the directivity control layer included in the light source device of the seventh embodiment. As shown in FIG. 15, the directivity control layer 63 in the seventh embodiment has the same configuration as the directivity control layer 53 in the sixth embodiment, and the low dielectric constant layer 19 in the sixth embodiment and The high dielectric constant layer 20 is different in that it is formed by laminating a plurality of dielectric layers.

  In other words, the directivity control layer 63 in the seventh embodiment is a high dielectric layer 29 in which a plurality of dielectric layers 29a to 29c are stacked and a plurality of dielectric layers 30a to 30c are stacked. And a dielectric constant layer group 30.

  In the low dielectric constant layer group 29, a plurality of dielectric layers 29a to 29c are arranged so that the dielectric constant decreases monotonously from the side closer to the plasmon excitation layer 17 toward the wave vector conversion layer 18 side. Similarly, in the high dielectric constant layer group 30, a plurality of dielectric layers 30 a to 30 c are arranged so that the dielectric constant increases monotonously from the side closer to the carrier generation layer 16 toward the plasmon excitation layer 17.

  The entire thickness of the low dielectric constant layer group 29 is formed to be equal to the thickness of the low dielectric constant layer in the embodiment in which the directivity control layer includes the low dielectric constant layer independently. Similarly, the entire thickness of the high dielectric constant layer group 30 is formed to the same thickness as the high dielectric constant layer in the embodiment in which the directivity control layer includes the high dielectric constant layer independently. In addition, although the low dielectric constant layer group 29 and the high dielectric constant layer group 30 are each shown with a three-layer structure, they can be configured with a layer structure of about 2 to 5 layers, for example. If necessary, the number of dielectric layers constituting the low dielectric constant layer group and the high dielectric constant layer group may be different, or only one of the low dielectric constant layer and the high dielectric constant layer may include a plurality of dielectric constant layers. It is good also as composition which consists of.

  Thus, the high dielectric constant layer and the low dielectric constant layer are composed of a plurality of dielectric layers, so that the dielectric constant of each dielectric layer adjacent to the interface of the plasmon excitation layer 17 can be set satisfactorily and carrier generation can be performed. It is possible to match the refractive index of the layer 16, the wave vector conversion layer 18 or a medium such as external air in contact with the wave vector conversion layer 18 and the dielectric layers adjacent to each other. That is, the high dielectric constant layer group 30 reduces the refractive index difference at the interface with the wave vector conversion layer 18 or a medium such as air, and the low dielectric constant layer group 29 is refracted at the interface with the carrier generation layer 16. It becomes possible to reduce the rate difference.

  According to the directivity control layer 63 of the sixth embodiment configured as described above, the dielectric constant of each dielectric layer adjacent to the plasmon excitation layer 17 is satisfactorily set, and the carrier generation layer 16 and the wave vector are set. It becomes possible to set the difference in refractive index at the interface with the conversion layer 18 to be small. For this reason, light loss can be further reduced, and the utilization efficiency of light from the light emitting element 11 can be further increased.

  Instead of the low dielectric constant layer group 29 and the high dielectric constant layer group 30, a single layer film whose dielectric constant changes monotonously inside may be used. In the case of this configuration, the high dielectric constant layer has a distribution in which the dielectric constant gradually increases from the carrier generation layer 16 side toward the plasmon excitation layer 17 side. Similarly, the low dielectric constant layer has a distribution in which the dielectric constant gradually decreases from the plasmon excitation layer 17 side toward the wave vector conversion layer 18 side.

(Eighth embodiment)
FIG. 16 is a perspective view of the directivity control layer provided in the light source device of the eighth embodiment. As shown in FIG. 16, the directivity control layer 73 in the eighth embodiment has the same configuration as the directivity control layer 13 in the first embodiment, and a plurality of plasmon excitation layer groups 37 are stacked. The difference is that the metal layers 37a and 37b are formed.

  In the plasmon excitation layer group 37 of the directivity control layer 73 in the eighth embodiment, the metal layers 37a and 37b are respectively formed and stacked with different metal materials. Thereby, the plasmon excitation layer group 37 can adjust the plasma frequency.

  When adjusting the plasma frequency in the plasmon excitation layer group 37 to be high, for example, the metal layers 37a and 37b are formed of Ag and Al, respectively. Further, when adjusting the plasma frequency in the plasmon excitation layer group 37 to be low, for example, different metal layers 37a and 37b are formed of Ag and Au, respectively.

  Note that the plasmon excitation layer group 37 has shown a two-layer structure as an example, but it is needless to say that the plasmon excitation layer group 37 may be composed of three or more metal layers as necessary. In addition, the thickness of the plasmon excitation layer group 37 is preferably formed to 200 nm or less, and particularly preferably about 10 nm to 100 nm.

  According to the directivity control layer 73 of the eighth embodiment configured as described above, the plasmon excitation layer group 37 is configured by the plurality of metal layers 37a and 37b, so that the effective plasmon excitation layer group 37 is effective. It is possible to adjust the plasma frequency to be close to the frequency of light incident on the plasmon excitation layer group 37 from the carrier generation layer 16. For this reason, the utilization efficiency of the light which injects into the optical element 1 from the light emitting element 11 can further be improved.

(Ninth embodiment)
In FIG. 17, the perspective view of the directivity control layer with which the light source device of 9th Embodiment is provided is shown. As shown in FIG. 17, in the directivity control layer 83 in the eighth embodiment, in addition to the plasmon excitation layer 17 in the first embodiment, a plasmon excitation layer 27 as another plasmon excitation layer is further arranged. Yes.

  In the directivity control layer 83 in the ninth embodiment, the plasmon excitation layer 27 is disposed between the carrier generation layer 16 and the light guide 12. In the directivity control layer 83, plasmons are excited in the plasmon excitation layer 27 by light incident from the light guide 12, and carriers are generated in the carrier generation layer 16 by the excited plasmons.

  At this time, in order to cause plasmon resonance in the plasmon excitation layer 27, the dielectric constant of the carrier generation layer 16 is set lower than that of the light guide 12. Further, in order to widen the material selection range of the carrier generation layer 16, a dielectric constant layer whose real part of the complex dielectric constant is lower than that of the light guide 12 is sandwiched between the plasmon excitation layer 27 and the carrier generation layer 16. It may be provided.

  Note that the plasmon excitation layer 27 has a plasma frequency higher than the emission frequency generated when the carrier generation layer 16 is excited alone by the light of the light emitting element 11. The plasmon excitation layer 27 has a plasma frequency higher than the light emission frequency of the light emitting element 11. In addition, when the carrier generation layer 16 having a plurality of different emission frequencies is used, the plasmon excitation layer 27 is one of the different frequencies of the light generated when the carrier generation layer 16 is excited alone with the light of the light emitting element 11. Has a higher plasma frequency. Similarly, when a plurality of types of light emitting elements having different emission frequencies are used, the plasmon excitation layer 27 has a plasma frequency higher than any of the different emission frequencies of the light emitting elements.

  In such a configuration, carriers are generated by plasmons in the carrier generation layer 16, so that the fluorescence enhancement effect by plasmons can be used.

  According to the ninth embodiment configured as described above, carriers can be efficiently generated in the carrier generation layer 16 due to the fluorescence enhancement effect by plasmons, and the number of carriers can be increased. Utilization efficiency can be further increased.

  The plasmon excitation layer 27 may be configured by stacking a plurality of metal layers, like the plasmon excitation layer group 37 in the above-described eighth embodiment.

(Tenth embodiment)
FIG. 18 is a perspective view of the directivity control layer included in the light source device of the tenth embodiment. As shown in FIG. 18, the directivity control layer 93 in the tenth embodiment has the same configuration as the directivity control layer 13 in the first embodiment, and is between the carrier generation layer 16 and the light guide 12. The difference is that a low dielectric constant layer 39 having an action different from that of the low dielectric constant layer 19 in the above-described embodiment is provided.

  In the directivity control layer 93 in the tenth embodiment, a low dielectric constant layer 39 is disposed immediately below the carrier generation layer 16. The dielectric constant of the low dielectric constant layer 39 is set lower than that of the light guide 12. Incident light from the light emitting element 11 is set to a predetermined angle with respect to the light incident surface 14 of the light guide 12 so that total reflection occurs at the interface between the light guide 12 and the low dielectric constant layer 39. Yes.

  Incident light that has entered the light guide 12 from the light emitting element 11 undergoes total reflection at the interface between the light guide 12 and the low dielectric constant layer 39, and an evanescent wave is generated along with this total reflection. The evanescent wave acts on the carrier generation layer 16 to generate carriers in the carrier generation layer 16.

  By the way, in the light source devices of the first, third to ninth embodiments described above, part of the light emitted from the light emitting element 11 is transmitted through each layer and emitted. For this reason, two types of light corresponding to the emission wavelength of the light emitting element 11 and the emission wavelength of the carrier generation layer 16 are emitted, each having a wavelength different by about 30 nm to 300 nm. However, as in the present embodiment, by generating carriers only with the evanescent wave, the light corresponding to the emission wavelength of the light emitting element 11 among the light emitted from the light source device is reduced. It becomes possible to increase the light corresponding to the emission wavelength. Therefore, according to the ninth embodiment, the utilization efficiency of the light from the light emitting element 11 can be further increased.

(Eleventh embodiment)
In the directivity control layers of the following embodiments, the same layers as those of the directivity control layer 13 ′ in the second embodiment are denoted by the same reference numerals as those in the second embodiment, and description thereof is omitted.

  The directivity control layer in the present embodiment is obtained by providing a microlens array on the surface of the high dielectric constant layer 2009 in the second embodiment shown in FIG. 5B. As shown in FIG. 19, even if the directivity control layer 2014 has a configuration including a microlens array 2013, the same effects as those obtained when a photonic crystal is used as the wave vector conversion layer 2010 can be obtained.

  20A and 20B are cross-sectional views for explaining the manufacturing process of the configuration in which the microlens array 2013 is stacked on the high dielectric constant layer 2009. FIG. Even in the configuration including the microlens array 2013, each layer from the carrier generation layer 2006 to the high dielectric constant layer 2009 is laminated on the light guide 12 as in the manufacturing method illustrated in FIGS. 7A to 7E. Description of the manufacturing process is omitted.

  As shown in FIGS. 20A and 20B, after the layers from the carrier generation layer 2006 to the high dielectric constant layer 2009 are stacked on the light guide 12 using the manufacturing method shown in FIGS. A microlens array 2013 is formed on the surface of the rate layer 2009. This is merely an example, and the present invention is not limited to this manufacturing method. After the UV curable resin 2015 is applied to the surface of the high dielectric constant layer 2009 by a spin coat method or the like, a desired lens array pattern is formed on the UV curable resin 2015 using nanoimprint, and the UV curable resin 2015 is irradiated with light. Then, the microlens array 2013 is formed by curing.

(Twelfth embodiment)
In FIG. 21, the perspective view of the directivity control layer with which the light source device of 12th Embodiment is provided is shown. As shown in FIG. 21, in the directivity control layer 2018 in the sixth embodiment, on the light guide 12, a carrier generation layer 2016, a plasmon excitation layer 2008, and a wave vector conversion layer 2017 made of a photonic crystal are arranged in this order. Are stacked.

  In the directivity control layer 2018 in the twelfth embodiment, the wave vector conversion layer 2017 also serves as the high dielectric constant layer 2009 in the second embodiment, and the carrier generation layer 2016 is the low dielectric constant layer in the second embodiment. Also serves as 2007. Therefore, in order to generate plasmon coupling in the plasmon excitation layer 2008, the dielectric constant of the wave vector conversion layer 2017, which is a layer disposed adjacent to the emission side interface of the plasmon excitation layer 2008, is the incident side of the plasmon excitation layer 2008. It is set higher than the dielectric constant of the carrier generation layer 2016 which is a layer disposed adjacent to the interface.

  According to the light source device of the twelfth embodiment configured as described above, the same effects as those of the second embodiment can be obtained, and further downsizing can be achieved as compared with the second embodiment.

(13th Embodiment)
In FIG. 22, the perspective view of the directivity control layer with which the light source device of 13th Embodiment is provided is shown. As shown in FIG. 22, in the directivity control layer 2019 according to the eighth embodiment, the wave number of the carrier generation layer 2006, the low dielectric constant layer 2007, the plasmon excitation layer 2008, and the photonic crystal on the light guide 12. The vector conversion layers 2017 are stacked in this order.

  In the directivity control layer 2019 in the thirteenth embodiment, the wave vector conversion layer 2017 also serves as the high dielectric constant layer 2009 in the second embodiment. Therefore, in order to cause plasmon coupling in the plasmon excitation layer 2008, the dielectric constant of the wave vector conversion layer 2017 is set higher than that of the low dielectric constant layer 2007. However, even when the dielectric constant of the wave vector conversion layer 2017 is lower than that of the low dielectric constant layer 2007, the real part of the effective dielectric constant on the wave vector conversion layer 2017 side of the plasmon excitation layer 2008 is the plasmon excitation layer. The directivity control layer 2019 operates if it is higher than the real part of the effective dielectric constant on the low dielectric constant layer 2007 side of 2008. In other words, the real part of the effective dielectric constant of the emission side portion of the plasmon excitation layer 2008 is kept higher than the real part of the effective dielectric constant of the incident side portion of the plasmon excitation layer 2008 in the dielectric constant of the wave vector conversion layer 2017. Range is acceptable.

  According to the light source device of the thirteenth embodiment configured as described above, the same effects as those of the second embodiment can be obtained, and further downsizing can be achieved as compared with the second embodiment.

(Fourteenth embodiment)
FIG. 23 is a perspective view of the directivity control layer provided in the light source device of the fourteenth embodiment. As shown in FIG. 23, in the directivity control layer 2020 according to the fourteenth embodiment, the wave number of the carrier generation layer 2016, the plasmon excitation layer 2008, the high dielectric constant layer 2009, and the photonic crystal on the light guide 12. The vector conversion layers 2010 are stacked in this order.

  In the directivity control layer 2020 in the fourteenth embodiment, the carrier generation layer 2016 also serves as the low dielectric constant layer 2007 in the second embodiment. Therefore, in order to generate plasmon coupling in the plasmon excitation layer 2008, the dielectric constant of the carrier generation layer 2016 is set lower than that of the high dielectric constant layer 2009. However, even when the dielectric constant of the carrier generation layer 2016 is higher than that of the high dielectric constant layer 2009, the real part of the effective dielectric constant of the plasmon excitation layer 2008 on the carrier generation layer 2016 side is the same as that of the plasmon excitation layer 2008. The directivity control layer 2020 operates if it is lower than the real part of the effective dielectric constant on the high dielectric constant layer 2009 side. That is, the dielectric constant of the carrier generation layer 2016 is a range in which the real part of the effective dielectric constant of the emission side portion of the plasmon excitation layer 2008 is kept higher than the real part of the effective dielectric constant of the incident side portion of the plasmon excitation layer 2008. Is acceptable.

  According to the light source device of the fourteenth embodiment configured as described above, the same effects as those of the second embodiment can be obtained, and the size can be further reduced as compared with the second embodiment.

(Fifteenth embodiment)
In FIG. 24, the perspective view of the directivity control layer with which the light source device of 15th Embodiment is provided is shown. As shown in FIG. 24, in the directivity control layer 2037 in the fifteenth embodiment, in addition to the plasmon excitation layer 2008 in the second embodiment, a plasmon excitation layer 2036 as another plasmon excitation layer is further arranged. Yes.

  In the directivity control layer 2037 in the fifteenth embodiment, the plasmon excitation layer 2036 is disposed between the carrier generation layer 2006 and the light guide 12. In the directivity control layer 2037, plasmons are excited in the plasmon excitation layer 2036 by light incident from the light guide 12, and carriers are generated in the carrier generation layer 2006 by the excited plasmons.

  At this time, in order to generate plasmon resonance in the plasmon excitation layer 2036, the dielectric constant of the carrier generation layer 2006 is set lower than that of the light guide 12. Further, in order to widen the material selection range of the carrier generation layer 2006, a dielectric constant layer having a real part of a complex dielectric constant lower than that of the light guide 12 is sandwiched between the plasmon excitation layer 2036 and the carrier generation layer 2006. It may be provided. Here, the effective dielectric constant of the plasmon excitation layer 2036 on the light guide 12 side needs to be higher than the effective dielectric constant of the plasmon excitation layer 2036 on the carrier generation layer 2006 side.

  Note that the plasmon excitation layer 2008 has a plasma frequency higher than the frequency of light generated when the carrier generation layer 2006 is excited alone with the light of the light emitting element 1. The plasmon excitation layer 2036 has a plasma frequency higher than the light emission frequency of the light emitting element 1. In the case where the carrier generation layer 2006 having a plurality of different emission frequencies is used, the plasmon excitation layer 2008 can be any one of the different frequencies of light generated when the carrier generation layer 2006 is excited by the light of the light emitting element 1 alone. Has a higher plasma frequency. Similarly, when a plurality of types of light emitting elements having different emission frequencies are used, the plasmon excitation layer 2036 has a plasma frequency higher than any of the different emission frequencies of the light emitting elements.

  Here, in order for light from the light emitting element 1 to be coupled with plasmons at the interface of the plasmon excitation layer 2036, there is a condition on an incident angle of light incident on the plasmon excitation layer 2036 from the light emitting element 1. Of the wave number vector of incident light on the carrier generation layer 2006 side of the plasmon excitation layer 2036, the incident angle at which the component parallel to the interface coincides with the component parallel to the surface plasmon interface on the carrier generation layer 2006 side of the plasmon excitation layer 2036. Therefore, it is necessary to make light incident.

  With such a configuration, carriers are generated by plasmons in the carrier generation layer 2006, so that the fluorescence enhancement effect by plasmons can be used.

  According to the fifth embodiment configured as described above, carriers can be efficiently generated in the carrier generation layer 2006 due to the fluorescence enhancement effect by plasmons, and the number of carriers can be increased. Utilization efficiency can be further increased.

(Sixteenth embodiment)
FIG. 25 is a perspective view of the directivity control layer included in the light source device of the sixteenth embodiment. As shown in FIG. 25, the directivity control layer 2040 in the sixteenth embodiment has the same configuration as the directivity control layer 13 ′ in the second embodiment, and the low dielectric constant layer 2007 in the second embodiment. And the high dielectric constant layer 2009 is configured by a plurality of laminated dielectric layers.

  That is, the directivity control layer 2040 in the sixteenth embodiment is a high dielectric layer 2038c in which a plurality of dielectric layers 2038a to 2038c are stacked and a plurality of dielectric layers 2039a to 2039c are stacked. And a dielectric constant layer group 2039.

  In the low dielectric constant layer group 2038, a plurality of dielectric layers 2038a to 2038c are arranged so that the dielectric constant decreases monotonously from the side closer to the carrier generation layer 2006 toward the plasmon excitation layer 2008. Similarly, in the high dielectric constant layer group 2039, a plurality of dielectric layers 2039a to 2039a are arranged so that the dielectric constant decreases monotonously from the side closer to the plasmon excitation layer 2008 toward the wave vector conversion layer 2010 made of photonic crystal. 2039c is arranged.

  The total thickness of the low dielectric constant layer group 2038 is equal to the thickness of the low dielectric constant layer in the embodiment in which the directivity control layer includes the low dielectric constant layer independently. Similarly, the total thickness of the high dielectric constant layer group 2039 is the same as that of the high dielectric constant layer in the embodiment in which the directivity control layer includes the high dielectric constant layer independently. Note that the low dielectric constant layer group 2038 and the high dielectric constant layer group 2039 are each shown in a three-layer structure, but can be formed in a layer structure of about 2 to 5 layers, for example. If necessary, the number of dielectric layers constituting the low dielectric constant layer group and the high dielectric constant layer group may be different, or only one of the low dielectric constant layer and the high dielectric constant layer may include a plurality of dielectric constant layers. It is good also as composition which consists of.

  In this way, the high dielectric constant layer and the low dielectric constant layer are composed of a plurality of dielectric layers, so that the dielectric constant of each dielectric layer adjacent to the interface of the plasmon excitation layer 2008 can be set satisfactorily and carrier generation can be performed. It becomes possible to match the refractive index of the layer 2006, the wave vector conversion layer 2010, or a medium such as external air, and the dielectric layers adjacent to them. That is, the high dielectric layer group 2039 reduces the refractive index difference at the interface with the wave vector conversion layer 2010 or a medium such as air, and the low dielectric layer group 2038 is refracted at the interface with the carrier generation layer 2006. It becomes possible to reduce the rate difference.

  According to the directivity control layer 2040 of the sixteenth embodiment configured as described above, the dielectric constant of each dielectric layer adjacent to the plasmon excitation layer 2008 is set satisfactorily, and the carrier generation layer 2006 and the wave vector are set. The refractive index difference at the interface with the conversion layer 2010 can be set small. For this reason, the optical loss can be further reduced, and the utilization efficiency of the light from the light emitting element 1 can be further increased.

  Instead of the low dielectric constant layer group 2038 and the high dielectric constant layer group 2039, a single layer film whose dielectric constant changes monotonously inside may be used. In this configuration, the high dielectric constant layer has a distribution in which the dielectric constant gradually decreases from the plasmon excitation layer 2007 side toward the wave vector conversion layer 2010 side. Similarly, the low dielectric constant layer has a distribution in which the dielectric constant gradually decreases from the carrier generation layer 2006 side toward the plasmon excitation layer 2007 side.

(Seventeenth embodiment)
In FIG. 26, the perspective view of the directivity control layer with which the light source device of 17th Embodiment is provided is shown. As shown in FIG. 26, the directivity control layer 2042 in the seventh embodiment has the same configuration as the directivity control layer 13 ′ in the second embodiment, and includes the carrier generation layer 2006 and the light guide body 12. The difference is that another low dielectric constant layer 2041 is provided therebetween.

  In the directivity control layer 2042 in the seventeenth embodiment, the low dielectric constant layer 2041 is disposed immediately below the carrier generation layer 2006. The dielectric constant of the low dielectric constant layer 2041 is set lower than the dielectric constant of the light guide 12. Incident light from the light emitting element 1 is set to a predetermined angle with respect to the light incident surface 14 of the light guide 12 so that total reflection occurs at the interface between the light guide 12 and the low dielectric constant layer 2041. Yes.

  Incident light that has entered the light guide 12 from the light emitting element 1 undergoes total reflection at the interface between the light guide 12 and the low dielectric constant layer 2041, and an evanescent wave is generated along with this total reflection. Carriers are generated in the carrier generation layer 2006 by the evanescent wave acting on the carrier generation layer 2006.

  By the way, in the light source devices of the second, eleventh to fifteenth embodiments described above, part of the light emitted from the light emitting element 1 is transmitted through each layer and emitted. For this reason, two types of light corresponding to the emission wavelength of the light-emitting element 1 and the emission wavelength of the carrier generation layer 2006 are emitted, each having a wavelength different by about 30 nm to 300 nm. However, as in the present embodiment, by generating carriers only with the evanescent wave, the light corresponding to the emission wavelength of the light emitting element 1 among the light emitted from the light source device 2 is reduced, and the carrier generation layer 2006 is reduced. It becomes possible to increase the light corresponding to the emission wavelength. Therefore, according to the seventeenth embodiment, the utilization efficiency of light from the light emitting element 1 can be further increased.

(Eighteenth embodiment)
FIG. 27 is a perspective view of the directivity control layer provided in the light source device of the eighteenth embodiment. As shown in FIG. 27, the directivity control layer 45 in the eighth embodiment has the same configuration as that of the directivity control layer 13 ′ in the second embodiment, and a plurality of plasmon excitation layer groups 2044 are stacked. The metal layers 2044a and 2044b are different.

  In the plasmon excitation layer group 2044 of the directivity control layer 2045 in the eighteenth embodiment, the metal layers 2044a and 2044b are formed of different metal materials and stacked. Thereby, the plasmon excitation layer group 2044 can adjust the plasma frequency.

  In the case of adjusting the plasma frequency in the plasmon excitation layer 2044 to be high, for example, the metal layers 2044a and 2044b are formed of Ag and Al, respectively. Further, when adjusting the plasma frequency in the plasmon excitation layer 2044 to be low, for example, different metal layers 2044a and 2044b are formed of Ag and Au, respectively. Although the plasmon excitation layer 2044 has a two-layer structure as an example, it is needless to say that the plasmon excitation layer 2044 may be formed of three or more metal layers as necessary.

  According to the directivity control layer 2045 of the eighth embodiment configured as described above, since the plasmon excitation layer 2044 is configured by the plurality of metal layers 2044a and 2044b, effective plasma in the plasmon excitation layer 2044 is obtained. The frequency can be adjusted to be close to the frequency of light incident on the plasmon excitation layer 2044 from the carrier generation layer 2006. For this reason, the utilization efficiency of the light which injects into the optical element 1 from the light emitting element 1 can further be improved.

(Nineteenth embodiment)
FIG. 28 is a perspective view of the light source device of the nineteenth embodiment. As shown in FIG. 28, in the light source device of the nineteenth embodiment, an axis that linearly polarizes incident light from the optical element 11 as a polarization conversion element that aligns axially symmetric polarized light incident from the optical element 1 in a predetermined polarization state. A symmetric polarizing half-wave plate 226 is provided. The light emitted from the light source device 2 is linearly polarized by the axisymmetric polarization half-wave plate 226, thereby realizing a light source device in which the polarization state of the emitted light is uniform. Note that aligning axially symmetric polarized light in a predetermined polarization state by the polarization conversion element is not limited to linearly polarized light but also includes circularly polarized light. Of course, any of the directivity control layers in the first to eighteenth embodiments described above may be applied as the directivity control layer.

  FIG. 29 is a longitudinal sectional view of the structure of the half-wave plate 226 for axially symmetric polarization. The configuration of the axially symmetric polarizing half-wave plate is merely an example, and is not limited to this configuration. As shown in FIG. 29, the axially symmetric polarizing half-wave plate 226 includes a pair of glass substrates 227 and 232 on which alignment films 228 and 231 are formed, and alignment films 228 and 231 of the glass substrates 227 and 232, respectively. And a spacer 229 disposed between the glass substrates 227 and 232, and a liquid crystal layer 230 disposed between the glass substrates 227 and 232.

  The liquid crystal layer 230 has a refractive index ne larger than the refractive index no, where no is the refractive index for ordinary light and ne is the refractive index for extraordinary light. Further, the thickness d of the liquid crystal layer 230 satisfies (ne−no) × d = λ / 2. Note that λ is the wavelength of incident light in a vacuum.

  30A and 30B are schematic views for explaining the axially symmetric polarizing half-wave plate 226. FIG. 30A shows a cross-sectional view of a state in which the liquid crystal layer 230 of the half-wave plate 36 for axially symmetric polarization is cut parallel to the main surface of the glass substrate 232. FIG. 30B is a schematic diagram for explaining the alignment direction of the liquid crystal molecules 233.

  As shown in FIG. 30A, the liquid crystal molecules 233 are arranged concentrically with respect to the center of the axially symmetric polarizing half-wave plate 226. In addition, as shown in FIG. 30B, the liquid crystal molecule 233 has an angle formed between the principal axis of the liquid crystal molecule 233 and a coordinate axis in the vicinity of the principal axis as Φ, and an angle formed between the coordinate axis and the polarization direction as θ. , Θ = 2Φ, or θ = 2Φ-180. Here, FIG. 30A and FIG. 30B show the same plane.

  FIG. 31 shows a far-field pattern 235 of emitted light in a case where the light source device does not include an axisymmetric polarizing half-wave plate. In the above-described first to eighteenth embodiments, the polarization in which plasmon coupling occurs in the plasmon excitation layers 8 and 2008 is only P-polarized light. Therefore, the far-field pattern 235 of the emitted light from the light source device is shown in FIG. Thus, it becomes an axially symmetric polarization in which the polarization direction is radial.

  FIG. 32 shows a far field pattern 238 of the emitted light that has passed through the half-wave plate 226 for axially symmetric polarization. According to the present embodiment, by using the above-described half-wave plate for axially symmetric polarization 226, as shown in FIG. 32, emitted light with the polarization direction 237 aligned can be obtained.

  The light source device of this embodiment is suitable for use as a light source device of an image display device, and is used as a light source device provided in a projection display device, a direct light source device of a liquid crystal panel (LCD), a so-called backlight. You may use for electronic devices, such as a portable telephone and PDA (Personal Data Assistant).

  Finally, an LED projector as a projection display device to which the light source device of the above-described embodiment is applied will be briefly described. FIG. 33 is a schematic diagram of the projection display device of the embodiment.

  As shown in FIG. 33, the LED projector according to the embodiment includes the optical element 2 according to the above-described embodiment, a liquid crystal panel 252 on which light emitted from the optical element 2 is incident, and light emitted from the liquid crystal panel 252 on a screen. And a projection optical system 253 including a projection lens that projects onto the projection surface 255.

  The light source device 1 included in the LED projector has a red (R) light LED 257R, a green (G) light LED 257G, and a blue (B) light LED 257B on one side surface of the light guide 12 provided with the directivity control layer. Are arranged respectively. The carrier generation layer included in the directivity control layer of the light source device 2 includes phosphors for red (R) light, green (G) light, and blue (B) light.

  FIG. 34 shows the relationship between the wavelength of the light-emitting element 1 used in the LED projector of the embodiment and the intensity of the excitation wavelength and emission wavelength of the phosphor. As shown in FIG. 34, the emission wavelengths Rs, Gs, and Bs of the R light LED 257R, the G light LED 257G, and the B light LED 257B and the excitation wavelengths Ra, Ga, and Ba of the phosphor are set to be approximately equal to each other. The emission wavelengths Rs, Gs, and Bs and the excitation wavelengths Ra, Ga, and Ba are set so that the emission wavelengths Rr, Gr, and Gr of the phosphor do not overlap each other. In addition, the emission spectrum of each of the R light LED 257R, the G light LED 257G, and the B light LED 257B is set to match the excitation spectrum of each phosphor or to be within the excitation spectrum. Further, the emission spectrum of the phosphor is set so as not to overlap with any excitation spectrum of the phosphor.

  The LED projector employs a time-sharing method, and is switched so that only one of the R light LED 257R, the G light LED 257G, and the B light LED 257B emits light by a control circuit unit (not shown).

  According to the LED projector of the present embodiment, the luminance of the projected video can be improved by including the light source device 2 of the above-described embodiment.

  In addition, although the structural example of the single plate type liquid crystal projector was given as the LED projector of the embodiment, it is needless to say that the present invention may be applied to a three plate type liquid crystal projector including a liquid crystal panel for each of R, G, and B.

  Each embodiment has been described with reference to a light guide. However, the light guide is not an essential component, and instead of the light guide, the light emitting surface of the light emitting element is arranged close to the carrier generation layer. May be. Further, the light-emitting element may be arranged with a space therebetween, and the light from the light-emitting element may be applied to the carrier generation layer, and the light-emitting element is not an essential component.

  The optical element is disposed on the carrier generation layer where carriers are generated by light, and a plasma frequency higher than the frequency of light generated when the carrier generation layer is excited by light from the light emitting element. The surface of the plasmon excitation layer on the carrier generation layer side may be a rough surface.

The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments. Various changes 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. 2011-212586 filed on September 27, 2011 and Japanese Patent Application No. 2012-1323 filed on January 6, 2012 The entire disclosure of which is incorporated herein.

DESCRIPTION OF SYMBOLS 1 Optical element 2 Light source device 11 Light emitting element

Claims (31)

A carrier generation layer in which carriers are generated by light;
A plasmon excitation layer disposed on the carrier generation layer and having a plasma frequency higher than a frequency of light generated when the carrier generation layer is excited by light of the light emitting element;
An emission layer that is disposed on the plasmon excitation layer and converts the light emitted from the plasmon excitation layer or the surface plasmon into light of a predetermined emission angle and emits the light, and
An optical element having a rough surface on the carrier generation layer side of the plasmon excitation layer. A light emitting element;
A light guide for receiving light from the light emitting element,
The optical element according to claim 1, wherein the carrier generation layer is provided on the light guide, and carriers are generated by light from the light guide.   The optical element according to claim 2, further comprising a dielectric constant layer provided adjacent to at least one side of the emission layer side of the plasmon excitation layer and the light guide side of the plasmon excitation layer.   The optical element according to claim 2, further comprising another plasmon excitation layer provided between the light guide and the carrier generation layer and having a plasma frequency higher than the frequency of the light emitting element. Provided adjacent to the carrier generation layer side of the light guide, comprising a low dielectric constant layer having a lower dielectric constant than the light guide,
5. The carrier generation layer according to claim 2, wherein the carrier generation layer generates carriers by an evanescent wave generated when light from the light guide is totally reflected at an interface with the carrier generation layer. 6. Optical elements.   The optical element according to claim 1, wherein the emission layer has a surface periodic structure.   The optical element according to claim 1, wherein the emission layer is made of a photonic crystal.   The optical element according to claim 1, wherein the plasmon excitation layer is configured by laminating a plurality of metal layers made of different metal materials.   The plasmon excitation layer is made of any one of Ag, Au, Cu, Pt, and Al, or an alloy containing at least one of these, 8. 2. The optical element according to item 1. The optical element according to any one of claims 2 to 9,
The plasmon excitation layer is sandwiched between two layers having dielectric properties,
The effective dielectric constant of the incident side portion including the entire structure laminated on the light guide body side of the plasmon excitation layer is the entire structure laminated on the emission layer side of the plasmon excitation layer, and a medium in contact with the emission layer An optical element that is higher than the effective dielectric constant of the exit side portion including The plasmon excitation layer is sandwiched between a pair of dielectric layers,
The optical element according to claim 10, wherein the dielectric constant layer adjacent to the light guide body side of the plasmon excitation layer has a higher dielectric constant than the dielectric constant layer adjacent to the emission layer side of the plasmon excitation layer.   The dielectric constant layer provided adjacent to the emission layer side of the plasmon excitation layer is configured by laminating a plurality of dielectric layers having different dielectric constants, and the plurality of dielectric layers are formed of the plasmon excitation layer. The optical element according to claim 10, wherein the optical element is arranged so that a dielectric constant decreases in order from the side toward the emission layer side.   The dielectric constant layer provided adjacent to the light guide body side of the plasmon excitation layer is configured by laminating a plurality of dielectric layers having different dielectric constants, and the plurality of dielectric layers are formed by the carrier generation layer. The optical element of Claim 10 arrange | positioned so that a dielectric constant may become high in order from the side to the said plasmon excitation layer side.   The dielectric constant layer provided adjacent to the emission layer side of the plasmon excitation layer has a distribution in which a dielectric constant gradually decreases from the plasmon excitation layer side toward the emission layer side. The optical element according to 10.   The dielectric constant layer provided adjacent to the light guide body side of the plasmon excitation layer has a distribution in which a dielectric constant gradually increases from the carrier generation layer side toward the plasmon excitation layer side. The optical element described.   The optical element according to claim 10, wherein the dielectric constant layer provided adjacent to the emission layer side of the plasmon excitation layer is a porous layer. The optical element according to any one of claims 2 to 9,
The plasmon excitation layer is sandwiched between two layers having dielectric properties,
The effective dielectric constant of the incident side portion including the entire structure laminated on the light guide body side of the plasmon excitation layer is the entire structure laminated on the emission layer side of the plasmon excitation layer, and a medium in contact with the emission layer An optical element that is lower than the effective dielectric constant of the exit side portion including The plasmon excitation layer is sandwiched between a pair of dielectric layers,
The optical element according to claim 17, wherein the dielectric constant layer adjacent to the light guide body side of the plasmon excitation layer has a lower dielectric constant than the dielectric constant layer adjacent to the emission layer side of the plasmon excitation layer.   The dielectric constant layer provided adjacent to the light guide body side of the plasmon excitation layer is a low dielectric constant layer having a lower dielectric constant than a layer adjacent to the emission layer side of the plasmon excitation layer. The optical element according to 17.   The dielectric constant layer provided adjacent to the emission layer side of the plasmon excitation layer is a high dielectric constant layer having a higher dielectric constant than a layer adjacent to the light guide side of the plasmon excitation layer. The optical element according to 17.   The low dielectric constant layer is formed by laminating a plurality of dielectric layers having different dielectric constants, and the dielectric constant of the plurality of dielectric layers decreases from the carrier generation layer side toward the plasmon excitation layer side. The optical element according to claim 19, arranged as follows.   The high dielectric constant layer is formed by laminating a plurality of dielectric layers having different dielectric constants, and the dielectric constant of the plurality of dielectric layers decreases in order from the plasmon excitation layer side to the emission layer side. The optical element according to claim 20, which is disposed in   The optical element according to claim 19, wherein the low dielectric constant layer has a distribution in which a dielectric constant gradually decreases from the carrier generation layer side toward the plasmon excitation layer side.   The optical element according to claim 20, wherein the high dielectric constant layer has a distribution in which a dielectric constant gradually decreases from the plasmon excitation layer side toward the emission layer side.   The optical element according to any one of claims 19, 21, and 23, wherein the low dielectric constant layer is a porous layer. The effective dielectric constant is
Dielectric constant distribution of the dielectric of the incident side portion or the emission side portion;
A distribution of surface plasmons in a direction perpendicular to the interface of the plasmon excitation layer at the incident side portion or the emission side portion;
The optical element according to claim 10, wherein the optical element is determined based on the above. The optical element according to any one of claims 10 to 26,
The effective dielectric constant is an effective dielectric constant ε _eff , and the effective dielectric constant ε _eff is
The direction parallel to the interface of the plasmon excitation layer is the x axis and the y axis, the direction perpendicular to the interface of the plasmon excitation layer is the z axis, the angular frequency of light emitted from the carrier generation layer is ω, the incident side portion or The dielectric constant distribution of the dielectric on the exit side is ε (ω, x, y, z), the integration range D is the range of the three-dimensional coordinates of the entrance side or the exit side, and the z component of the wave number of the surface plasmon _Is k _{spp, z} and the imaginary unit is j,

Or

The filling,
And the z-component k _{spp, z} of the wave number of the surface plasmon, the x- and y-components k _spp of the wave number of the surface plasmon,
If the dielectric constant of the plasmon excitation layer is ε _metal and the wave number of light in vacuum is k ₀ ,

An optical element that meets the requirements. An optical element according to any one of claims 2 to 27;
A light source device comprising: a light emitting element disposed on an outer periphery of the light guide.   The light source device according to claim 28, further comprising a polarization conversion element that aligns axially symmetric polarized light incident from the optical element in a predetermined polarization state. A light source device according to claim 28 or 29;
A display element that modulates light emitted from the light source device;
A projection display system comprising: a projection optical system that projects a projected image by light emitted from the display element. A carrier generation layer in which carriers are generated by light;
A plasmon excitation layer disposed on the carrier generation layer and having a plasma frequency higher than a frequency of light generated when the carrier generation layer is excited by light of the light emitting element, and
An optical element having a rough surface on the carrier generation layer side of the plasmon excitation layer.

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