JP2009139411A - Polarization and wavelength separation element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarization and wavelength separation element having wire grids, and having a polarization separation function and a wavelength separation function in combination. <P>SOLUTION: The polarization and wavelength separation element includes: a plurality of first metallic layers 13 and a plurality of second metallic layers 14 as the first and second wire grids. The first and the second metallic layers 13, 14 are composed of any one of a metallic material being any one selected from among gold, silver, copper, lithium and aluminum, a metallic material satisfying a condition 25<(εr/εi)<SP>2</SP><120 wherein the real part and imaginary part of a complex dielectric constant near a wavelength to be subjected to polarization separation are denoted as εr and εi, respectively and a metallic material satisfying a condition 0.l3<nr<0.28 wherein the real part of a refractive index near a wavelength to be subjected to the polarization separation denotes as nr. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polarization wavelength separation element having a polarization separation function and a wavelength separation function.

Conventionally, for example, as disclosed in Patent Document 1, it is known that predetermined polarized light can be separated by a wire grid. The wire grid generally has a structure in which a plurality of metal wires extending in one direction are arranged at equal intervals. The wire diameter and the wire interval of the metal wires in the wire grid depend on the wavelength of the target light. Usually, the wire interval is smaller than the wavelength of the target light, for example, the wavelength of the target light. The wire diameter is, for example, about 1/4 of the wire interval. Such a wire grid reflects light of a polarization component that vibrates in a direction parallel to the one direction, and transmits light of a polarization component that vibrates in a direction orthogonal to the one direction. For this reason, for example, when non-polarized light is incident on the wire grid, light separated from predetermined polarized light is emitted from the wire grid.
JP 2006-330616 A

  As described above, the wire grid conventionally has a function of separating the polarization, but cannot perform wavelength separation. If the wire grid has not only the polarization separation function but also the wavelength separation function, not only will the applicable range of the wire grid be expanded, but in the case of polarization separation and wavelength separation, for example, wavelength separation such as a filter separately from the wire grid. No element is required, and for example, reduction in cost and size can be expected.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a polarized light having a wire grid and having a polarization separation function for separating a predetermined polarization component and a wavelength separation function for separating a predetermined wavelength. It is to provide a wavelength separation element.

As a result of various studies, the present inventor has found that the above object is achieved by the present invention described below. That is, according to one aspect of the present invention, the apparatus includes first and second wire grids in which a plurality of metal wires extending in one direction are arranged at predetermined first intervals in a direction that is linearly independent of the one direction. In the normal direction of the surface formed by the one direction and the linearly independent direction so that the metal wire of the second wire grid faces the gap between the metal wires in the first wire grid. The first and second wire grids are arranged at a predetermined second interval from the first wire grid, and the metal wires of the first and second wire grids are made of any one of gold, silver, copper, lithium, and aluminum. If the real part and the imaginary part of the complex permittivity in the vicinity of the wavelength to be used are εr and εi, a metal material satisfying the condition of 25 <(εr / εi) ² <120, In addition, when the real part of the refractive index in the vicinity of the wavelength to be polarized light is nr, it is made of any one of the metal materials satisfying the condition of 0.13 <nr <0.28. In the polarization wavelength separation element described above, preferably, a substrate and a plurality of concave and convex portions formed on one main surface of the substrate, extending in one direction and arranged in a direction linearly independent of the one direction, A plurality of first metal layers respectively formed on the top surfaces of the plurality of convex portions in the plurality of concave and convex portions, and a plurality of second metal layers respectively formed on the bottom surfaces of the plurality of concave portions in the plurality of concave and convex portions, The first wire grid is composed of the plurality of first metal layers, and the second wire grid is composed of the plurality of second metal layers.

The optical element having such a configuration is such that the metal wires of the first and second wire grids are at least one of gold, silver, copper, lithium, and aluminum, as will be demonstrated by examples described later. A metal material satisfying at least “25 <(εr / εi) ² <120” and a metal material satisfying at least “0.13 <nr <0.28”. By being formed, light having a predetermined polarization component can be separated and light having a predetermined wavelength can be separated. In the present invention, a transmittance of 50% or more is defined as “transmission”.

  In the polarization wavelength separation element described above, the ratio S1: S2 between the first area S1 of the metal wire in the first wire grid and the second area S2 of the metal wire in the second wire grid should be polarization wavelength separated. In this wavelength, the light transmittance of the polarization component to be polarized and separated is 50% or more, and the light transmittance of the polarization component orthogonal to the polarization component to be polarized and separated is less than 50%. It is preferable. In the polarization wavelength separation element according to the preferred aspect described above, the ratio S1: S2 between the first area S1 of the first metal layer and the second area S2 of the second metal layer is a wavelength to be subjected to polarization wavelength separation. It is preferable that the light transmittance of the polarization component to be polarized and separated is 50% or more and the light transmittance of the polarization component orthogonal to the polarization component to be polarized and separated is less than 50%. .

  According to this configuration, polarization wavelength separation can be more reliably performed at a wavelength at which polarization wavelength separation is to be performed. In particular, in the case where the area ratio S1: S2 is 1: 1, the polarization component orthogonal to the predetermined polarization component while keeping the transmittance of light of the predetermined polarization component better at the wavelength to be polarized wavelength separation. The reflectance of the light can also be improved, and the polarization wavelength can be separated in a balanced manner between the transmittance and the reflectance.

  In the polarization wavelength separation element described above, the repetitive pitch P of the metal wires in the first and second wire grids is 0.1 μm ≦ P ≦ 0 when the shortest wavelength in the light to be incident is λmin. It is preferable to satisfy the condition of 5 × λmin. In the polarization wavelength separation element according to the above-described preferred embodiment, the repetitive pitch P of the concavo-convex portion is a condition of 0.1 μm ≦ P ≦ 0.5 × λmin, where λmin is the shortest wavelength in light to be incident It is preferable to satisfy.

  According to this configuration, the polarization wavelength separation element 1 can be manufactured relatively easily by a general thin film forming technique, and the diffraction effect on incident light is suppressed, and the proportion of incident light that is transmitted straight is further increased. Is possible.

In the polarization wavelength separation element described above, the distance from the center position of the metal wire in the first wire grid to the center position of the metal wire in the second wire grid is h, and the wavelength at which the polarization is to be separated is λpb, When the real part and the imaginary part of the complex permittivity are εr and εi, the condition of 490 <((εr / εi) ² −8500 × (h / λpb) ² + 4000 × (h / λpb)) <530 is satisfied. It is preferable. In the polarization wavelength separation element according to the preferred embodiment described above, the height from the bottom surface of the concave portion to the top surface of the convex portion is h, the wavelength at which the polarized light is to be separated is λpb, and the real and imaginary parts of the complex permittivity Εr and εi, it is preferable that the condition of 490 <((εr / εi) ² -8500 × (h / λpb) ² + 4000 × (h / λpb)) <530 is satisfied.

  According to this configuration, when h satisfies the conditional expression, the difference between the transmittance of certain polarized light and the transmittance of polarized light orthogonal to the wavelength λpb to be polarization-separated can be maximized. In addition, the polarization wavelength can be reliably separated at the wavelength at which the polarization wavelength is to be separated.

  In the polarization wavelength separation element described above, when the thickness in the normal direction of the metal wires in the first and second wire grids is t and the imaginary part of the complex refractive index is ni, 3.6 <( It is preferable that the condition of ni + 4.6 × t) <4.3 is satisfied. In the polarization wavelength separation element according to the preferred aspect described above, when the thickness of the first and second metal layers is t and the imaginary part of the complex refractive index is ni, 3.6 <(ni + 4.6 × t It is preferable that the condition <4.3 is satisfied.

  According to this configuration, when t satisfies the conditional expression, the bottom of the transmittance characteristic of a certain polarization at the wavelength λpb to be polarization-separated and the peak of the transmittance characteristic of the polarized light orthogonal thereto are matched. Can do. In addition, the polarization wavelength can be reliably separated at the wavelength at which the polarization wavelength is to be separated.

  The optical element of the present invention can separate a predetermined polarization component and a predetermined wavelength.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.
(Embodiment)
The polarization wavelength separation element according to the embodiment includes first and second wire grids in which a plurality of metal wires extending in one direction are arranged at a predetermined first interval in a direction linearly independent of the one direction. In the normal direction of the surface formed by the one direction and the linearly independent direction, the two-wire grid has the metal wire of the second wire grid facing the gap between the metal wires in the first wire grid. The first wire grid is disposed at a predetermined second interval. The metal wires of the first and second wire grids may be any metal material selected from gold (Au), silver (Ag), copper (Cu), lithium (Li), and aluminum (Al), and polarized light separation. A metal material that satisfies the condition of “25 <(εr / εi) ² <120” when the real part and the imaginary part of the complex permittivity in the vicinity of the wavelength to be used are εr and εi, and When the real part of the refractive index is nr, it is made of any one of the metal materials satisfying the condition of “0.13 <nr <0.28”.

  As a more specific embodiment of such a polarization wavelength separation element, the case where the first and second wire grids are formed on a substrate will be described below.

  FIG. 1 is a diagram illustrating a configuration of a polarization wavelength separation element in the embodiment. FIG. 1A is a perspective view, and FIG. 1B is a cross-sectional view.

  In FIG. 1, a polarization wavelength separation element 1 is formed on a substrate 11 and one main surface of the substrate 11, and extends in one direction and is arranged in a direction linearly independent of the one direction (12a, 12a, 12b), a plurality of first metal layers 13 formed on the top surfaces of the plurality of convex portions 12a in the plurality of concave and convex portions 12, and a plurality of surfaces formed on the bottom surfaces of the plurality of concave portions 12b in the plurality of concave and convex portions 12, respectively. And a second metal layer 14.

  The substrate 11 is a parallel plate-like member, and is formed of a material having high translucency with respect to the wavelength of the light to be polarized wavelength separated, for example, in order to transmit the light (electromagnetic wave) to be polarized wavelength separated. . Examples of the material (substrate material) of the substrate 11 include glass, transparent inorganic crystals, and transparent plastic (resin). Examples of the glass include quartz glass and various optical glasses. Examples of the optical glass include crown glass such as BK, FK, BaK, and LaK, and flint glass such as LF, SF, LaF, and LaSF. Can be mentioned. Examples of the transparent inorganic crystal include quartz, sapphire, calcite, fluorite, alkali halide, silicon, gallium, and arsenic. Examples of the transparent plastic include polyethylene, polystyrene, polyvinyl alcohol, polyimide, polyester, polycarbonate, and polymethyl methacrylate (PMMA).

  The concavo-convex portion 12 includes a convex portion 12a extending in one direction and a concave portion 12b extending in the one direction, and a plurality of the concave and convex portions 12 are arranged on one main surface of the substrate 11 in a direction linearly independent of the one direction. In the example shown in FIG. 1, the plurality of uneven portions 12 are arranged in a direction orthogonal to the one direction. That is, a one-dimensional lattice composed of a plurality of concave and convex portions 12 is formed on one main surface of the substrate 11. The repetitive pitch (lattice pitch) P of the plurality of concavo-convex portions 12 is shorter than the wavelength of the light to be polarized wavelength separated.

The first and second metal layers 13 and 14 are thin films made of a metal material (including an alloy). The first metal layer 13 is formed on the upper surface of the convex portion 12a, and the second metal layer 14 is formed on the bottom surface of the concave portion 12b, thereby forming a two-layer wire grid. The first wire grid is composed of a plurality of first metal layers 13, and the second wire grid is composed of the plurality of second metal layers 14. The first and second metal layers 13 and 14 are made of any metal material of gold, silver, copper, lithium and aluminum (first case), and the real part of the complex dielectric constant in the vicinity of the wavelength to be polarized and separated. When the imaginary part is εr and εi, the metal material satisfying the condition of “25 <(εr / εi) ² <120” (second case) and the refractive index in the vicinity of the wavelength to be polarized light separated When the part is nr, it is made of any one of the metal materials satisfying the condition of “0.13 <nr <0.28” (third case).

The inventor evaluated whether it was possible to form two-layer first and second wire grids with various metal materials and to separate the polarization wavelength. The results are shown in Table 1. In Table 1, in order from left to right, the metal wire material, the polarization wavelength separation wavelength λpb, the real part nr of the complex refractive index, the imaginary part ni of the complex refractive index, the real part εr of the complex dielectric constant, and the imaginary of the complex dielectric constant The part εi, (εr / εi) ² , and the sum nr + ni of the real part nr of the complex refractive index and the imaginary part ni of the complex refractive index are shown.

  As shown in Table 1, in the optical element having the structure shown in FIG. 1, the metal materials of the first and second metal layers 13 and 14 (metal wire) are lead (Pb), chromium (Cr), and platinum (Pt). In some cases, the polarization wavelength cannot be separated, while the metal materials of the first and second metal layers 13 and 14 can be separated at any wavelength in the case of gold, silver, copper, lithium, and aluminum. . Therefore, when the metal material of the first and second metal layers 13 and 14 is at least one of gold, silver, copper, lithium, and aluminum, polarization wavelength separation can be performed. In addition, although silver has shown three cases, in each case, the height h of the uneven | corrugated | grooved part 12 and the thickness t of the 1st and 2nd metal layers 13 and 14 differ.

  These metals are those that are relatively easy to cause surface plasmon resonance. For this reason, the inventor speculates that the surface plasmon resonance in the metal wire is involved in the polarization wavelength separation action by the two-layer first and second wire grids. Surface plasmon resonance is a phenomenon in which reflected light is attenuated at a specific incident angle in a total reflection angle region when light is applied to a metal. It is known that surface plasmon resonance occurs in a metal (metal film, metal layer) within a predetermined thickness according to the type of material.

In general, a metal that easily causes surface plasmon resonance has a large value of (εr / εi) ² . Therefore, (εr / εi) ² is obtained for each metal, and when this (εr / εi) ² is compared with a metal that separates the polarization wavelength and a metal that does not separate the polarization wavelength, the polarization wavelength is separated as shown in Table 1. The metal satisfies the condition of at least 25 <(εr / εi) ² <120.

  Surface plasmon resonance occurs when light enters (immerses) a metal surface. Therefore, the real part nr of the refractive index is obtained for each metal, and when this nr is compared between the metal that separates the polarization wavelength and the metal that does not separate the polarization wavelength, as shown in Table 1, the metal that separates the polarization wavelength is at least 0. The condition of .13 <nr <0.28 is satisfied.

  The first and second metal layers 13 and 14 may satisfy a plurality of cases among the first to third cases.

  In the polarization wavelength separation element 1 having such a configuration, when incident light is incident, the first and second metal layers 13 and 14 (the first and second wire grids) formed on the concavo-convex portion 12 are formed. , And emitted light of a predetermined wavelength component having a predetermined polarization component is emitted. As described above, the polarization wavelength separation element 1 having the two-layer wire grid can not only perform polarization separation but also wavelength separation. That is, the polarization wavelength separation element 1 having such a configuration has a polarization separation function and a wavelength separation function.

  As described above, the inventor speculates that the surface plasmon resonance in the metal wire is involved in the polarization wavelength separation action by the two-layer first and second wire grids. For this reason, it is necessary to adjust each area of the metal wires in the first and second wire grids. In the present invention, a transmittance of 50% or more is defined as “transmission”.

  Accordingly, in the polarization wavelength separation element 1 described above, the ratio S1: S2 between the first area S1 of the first metal layer 13 and the second area S2 of the second metal layer 14 is the polarization separation at the wavelength to be polarized wavelength separated. It is preferable that the light transmittance of the polarization component to be reduced is 50% or more and that the light transmittance of the polarization component orthogonal to the polarization component to be polarization-separated is smaller than 50%.

  FIG. 2 is a diagram illustrating wavelength transmission characteristics depending on the difference in area ratio. 2A shows a case where the area ratio is 50:50 (= 1: 1), and FIG. 2B shows a case where the area ratio is 62:38 (≈1.63: 1). In FIG. 2, the horizontal axis is the wavelength expressed in nm, and the vertical axis is the transmittance. In FIG. 2, ▪ indicates the characteristics in the case of 90-degree polarized light, and ▲ indicates the characteristics in the case of 0-degree polarized light.

The wavelength transmission characteristics shown in FIG. 2 are obtained by an optical element having the following specifications. This optical element is configured similarly to the structure shown in FIG. The substrate 11 is made of a material that is transparent to light having a wavelength of at least about 395 nm to about 800 nm, and its refractive index N is 1.5. The repetition pitch P of the concavo-convex portion 12A is 0.08 μm. The first and second metal layers 13 and 14 have a complex refractive index real part nr and imaginary part ni of 0.157 and 2.4, respectively, and a complex dielectric constant real part and imaginary part of εr and εi, respectively. In this case, (εr / εi) ² is made of silver (Ag) having 57.92. The thickness t of the first and second metal layers 13 and 14 is 0.025 μm. The ratio S1: S2 between the first area S1 of the first metal layer 13 and the second area S2 of the second metal layer 14 is 50:50 in the case of FIG. 2A, whereas FIG. In the case of B), it is 62:38. The height h from the bottom surface of the concave portion 12b to the top surface of the convex portion 12a in the concavo-convex portion 12 is 0.115 mm in the case of FIG. 2A and 0.08 mm in the case of FIG. 2B. . Thus, the height h is optimized according to the area ratio S1: S2. These specifications are summarized in Table 2.

  In the case of FIG. 2A where the area ratio S1: S2 is 50:50, the wavelength transmission characteristics of the 0-degree polarized light increase from about 0.75 as the wavelength increases from about 395 nm to about 440 nm. The profile gradually increases from about 0.8, and the transmittance gradually decreases from about 0.8 to about 0.07 as the wavelength increases from about 440 nm to about 800 nm. The wavelength transmission characteristics of 90-degree polarized light gradually decrease from about 0.035 to about 0.015 as the wavelength increases from about 395 nm to about 440 nm, and the wavelength from about 440 nm to about 620 nm. As the length increases, the transmittance gradually increases from about 0.015 to about 0.75, and as the wavelength increases from about 620 nm to about 800 nm, the transmittance increases from about 0.75 to about 0.9. The profile increases gradually.

  On the other hand, in the case of FIG. 2B in which the area ratio S1: S2 is 62:38, the wavelength transmission characteristics of the 0-degree polarized light are about 0. 0 as the wavelength increases from about 395 nm to about 800 nm. The profile gradually decreases from 57 to about 0.07. The wavelength transmission characteristics of 90-degree polarized light gradually decreases from about 0.03 to about 0.02 as the wavelength increases from about 395 nm to about 440 nm, and the wavelength from about 440 nm to about 530 nm. As the length increases, the transmittance gradually increases from about 0.02 to about 0.78, and as the wavelength increases from about 530 nm to about 800 nm, the transmittance increases from about 0.78 to about 0.84. The profile increases gradually.

  As described above, the wavelength transmission characteristics change according to the area ratio S1: S2. Therefore, as described above, in the polarization wavelength separation element 1 described above, the area ratio S1: S2 is such that the light transmittance of the polarization component to be polarization separated is 50% or more at the wavelength to be polarization wavelength separation, and It is preferable that the light transmittance of the polarized light component orthogonal to the polarized light component to be separated is less than 50%.

  For example, assuming that polarization wavelength separation is performed at a wavelength at which the transmittance of 90-degree polarized light is lowest, when the area ratio S1: S2 is 50:50, as shown in FIG. At a wavelength of about 440 nm at which the transmittance is lowest, the transmittance of 0-degree polarized light is about 0.8, and polarization separation is excellent. On the other hand, when the area ratio S1: S2 is 62:38, as shown in FIG. 2B, the transmittance of the 0-degree polarized light is about 0 at the wavelength of about 440 nm where the transmittance of the 90-degree polarized light is the lowest. .42, and polarization separation is not good.

  When the area ratio is 50:50, surface plasmon resonance is generated in a balanced manner by the two layers of the first and second wire grids, and polarization separation is performed in a balanced manner. Therefore, in the polarization wavelength separation element 1 described above, the ratio S1: S2 between the first area S1 of the metal wire in the first wire grid and the second area S2 of the metal wire in the second wire grid is about 1: 1 ( = About 50:50). That is, in the polarization wavelength separation element 1 described above, the ratio S1: S2 between the first area S1 of the first metal layer 13 and the second area S2 of the second metal layer 14 is about 1: 1 (= about 50:50). ) Is more preferable.

  In the polarization wavelength separation element 1 described above, it is preferable that the condition “0.1 μm ≦ P ≦ 0.5 × λmin” is satisfied when the shortest wavelength in the light to be incident is λmin.

  If the above condition is not satisfied, that is, if the repetitive pitch (lattice pitch) P is shorter than 0.1 μm, it becomes difficult to embed a metal material in the recess 12b, so that the formation of the second metal layer 14 becomes difficult. It is not preferable. In general, since the incident light is diffracted when the repetition pitch P is approximately the same as the wavelength, the proportion of the incident light that is transmitted straight decreases. On the other hand, if the repetition pitch P is about half the wavelength, the influence of diffraction is almost eliminated. For this reason, if it exceeds the said conditions, the ratio which the incident light permeate | transmits straight will reduce, and it is not preferable. Therefore, in such a configuration, the polarization wavelength separation element 1 can be manufactured relatively easily by a thin film forming technique such as vapor deposition or sputtering, and the ratio of incident light that is transmitted straight is suppressed because of the diffraction effect on incident light. Can be further increased.

In the polarization wavelength separation element 1 described above, preferably, the height from the bottom surface of the concave portion 12b to the top surface of the convex portion 12a is h, the wavelength at which the polarized light is to be separated is λpb, the real part and the imaginary part of the complex dielectric constant When the parts are εr and εi, the condition of “490 <((εr / εi) ² −8500 × (h / λpb) ² + 4000 × (h / λpb)) <530” is satisfied.

As described above, the inventors speculate that this polarization wavelength separation action involves surface plasmon resonance in a metal wire. For this reason, when first to eighth examples described later are evaluated by (εr / εi) ² and (h / λpb) for evaluating surface plasmon resonance, at least “490 <((εr / εi) ² −8500 × ( When the condition of h / λpb) ² + 4000 × (h / λpb)) <530 ”is satisfied, the polarization wavelength separation element 1 can perform polarization wavelength separation.

  In the polarization wavelength separation element 1 described above, preferably, when the thickness of the first and second metal layers 13 and 14 is t and the imaginary part of the complex refractive index is ni, “3.6 <(ni + 4 .6 × t) <4.3 ”.

  Further, the surface plasmon resonance depends on the size of the minute metal. For this reason, first to eighth embodiments described later are used as an index of the size of the metal with the imaginary part ni of the complex refractive index that varies depending on the thickness t of the first and second metal layers 13 and 14 and the size of the minute metal. When evaluated, the polarization wavelength separation element 1 can perform polarization wavelength separation when at least the condition of “3.6 <(ni + 4.6 × t) <4.3” is satisfied.

  Further, in the polarization wavelength separation element 1 described above, in order to improve the adhesion between the first and second metal layers 13 and 14 and the substrate 11, the metal material of the first and second metal layers 13 and 14 and the substrate 11. An underlayer made of a metal material (including an alloy) determined according to the substrate material may be formed between the first and second metal layers 13 and 14 and the substrate 11. For example, when the metal material of the first and second metal layers 13 and 14 is gold and the substrate material of the substrate 11 is glass, titanium (Ti) is used as the metal material of the base layer, for example.

  The polarization wavelength separation element 1 having such a configuration can be manufactured, for example, by the following steps.

  FIG. 3 is a diagram for explaining a manufacturing process of the polarization wavelength separation element shown in FIG. First, a parallel plate substrate 11 is prepared, and a resist film 21 is formed on one main surface of the substrate 11 (FIG. 3A). Next, in order to form the concavo-convex portion 12 described above, a mask pattern (not shown) is overlaid on the resist film 21, the resist film 21 is exposed through the mask pattern, and the resist film 21 is developed. As a result, portions of the resist film corresponding to the plurality of convex portions 12a remain and portions of the resist film corresponding to the plurality of concave portions 12b are removed (FIG. 3B). Next, the portion of the substrate 11 from which the resist film has been removed is anisotropically etched in the thickness direction of the substrate 11 (FIG. 3C), and the remaining resist film is removed (FIG. 3D). )). As a result, a plurality of convex portions 12 a are formed on the substrate 11 and a plurality of concave portions 12 b are formed, whereby a plurality of concave and convex portions 12 are formed. Next, for example, a plurality of first metal layers 13 are formed on the top surfaces of the plurality of convex portions 12a by a thin film forming technique such as vacuum deposition or sputtering, and a plurality of second metal layers are formed on the bottom surfaces of the plurality of concave portions 12b. A metal layer 14 is formed (FIG. 3E). The polarization wavelength separation element 1 is manufactured by such steps.

  In the manufacturing process described above, the resist film 21 is formed, exposed and developed, and the substrate 11 is etched to form the plurality of concavo-convex portions 12 on the substrate 11. However, the present invention is not limited to this. . For example, the plurality of concave and convex portions 12 may be formed on the substrate 11 by molding (pressing) a mold member corresponding to the concave and convex portions 12 on the parallel plate-shaped substrate 11. Further, for example, the plurality of uneven portions 12 may be formed by injection-molding a substrate material. Further, for example, a plurality of uneven portions 12 may be formed on the substrate 11 by excavating the substrate 11 by irradiating laser light. Further, for example, after a metal layer is formed on one main surface of the substrate 11 made of a heat-formable plastic material, a mold member corresponding to the concavo-convex portion 12 is molded on the plastic material substrate 11 on which the metal layer is formed ( A plurality of concave and convex portions 12 may be formed on the substrate 11 by embossing. Since the metal layer does not extend as compared with the substrate 11 made of plastic material, the two-layer wire grid can be formed.

  Such a polarization wavelength separation element 1 according to this embodiment includes a light source that needs to irradiate a specific wavelength and polarized light, a measurement device that needs to receive a specific wavelength and polarized light from incident light, and the like. It is applicable to various devices. Here, as an example, a case where the present invention is applied to a white light source that emits white light by mixing three colors of R (red), G (green), and B (blue) will be described below.

(First white light source)
FIG. 4 is a diagram illustrating a configuration of the first white light source. In FIG. 4, the first white light source 3 is a light source suitably applied to a backlight of a liquid crystal display device (LCD), for example, and includes a semiconductor laser array 31 and an optical multiplexer 32. .

  The semiconductor laser array 31 includes a semiconductor laser element 31a that emits red laser light, a semiconductor laser element 31b that emits blue laser light, a semiconductor laser element 31c that emits green laser light, and semiconductor lasers of these colors. And a circuit board 31d on which the elements 31a to 31c are arranged. The red semiconductor laser element 31a and the blue semiconductor laser element 31b emit laser beams having the same polarization component, and the green semiconductor laser element 31c is the polarization of the red semiconductor laser element 31a and the blue semiconductor laser element 31b. A laser beam having a polarization component orthogonal to the component is irradiated. For example, the red semiconductor laser element 31a and the blue semiconductor laser element 31b emit 90-degree polarized laser light, and the green semiconductor laser element 31c emits 0-degree polarized laser light. Here, 0 degree polarization means light whose vibration surface (wavefront) is in the direction along the wires of the wire grid (long direction), and 90 degree polarization means that the vibration surface is a vibration surface of 0 degree polarization. The light that is orthogonal, that is, the light whose vibration plane is orthogonal to the direction along the wires of the wire grid.

  The optical multiplexer 32 is an optical element that combines the laser beams of a plurality of colors with the red laser beam, the blue laser beam, and the green laser beam in the present embodiment, and includes, for example, a light guide plate 32a and a mirror 32b. The polarization wavelength separation element 32c and the polarization separation element 32d are provided.

  The light guide plate 32a is a parallel plate-shaped member that guides red, blue, and green color lights as will be described later and is transparent to at least light of each wavelength. The mirror 32b is an optical element that reflects at least each color light of red, blue, and green, and is, for example, a metal film. The polarization wavelength separation element 32c is configured in the same manner as the above-described polarization wavelength separation element (including the above-described modified form) 1 shown in FIG. 1. In the example shown in FIG. (In the above example, 90-degree polarized light) has a characteristic of transmitting light in the blue wavelength band and reflecting light in the red wavelength band. The polarization separation element 32d is an optical element that separates and emits a predetermined polarization component from incident light. In the example shown in FIG. 4, light of red and blue polarization components (in the above example, light of 90-degree polarization). ) Is separated and injected. That is, the polarization separation element 32d transmits the light of the red and blue polarization components, and the light of the polarization component orthogonal to the red and blue polarization components, that is, in the example shown in FIG. Light (0-degree polarized light in the above example) is reflected.

  A polarization wavelength separation element 32c and a polarization separation element 32d are formed on one surface of the light guide plate 32a, and a mirror 32b is formed on the other substantially entire surface. The circuit board 31d of the semiconductor laser array 31 and the light guide plate 32a of the optical multiplexer 32 have the semiconductor laser elements 31a to 31c on the circuit board 31d so that the distance between the surfaces gradually increases from one end to the other end. The main surface to be arranged and the one surface of the light guide plate 32a are arranged so as to form a predetermined angle θ. The semiconductor laser elements 31a to 31c of the respective colors are arranged on the main surface of the circuit board 31d from the one end to the other end in the order of the red semiconductor laser element 31a, the blue semiconductor laser element 31b, and the green semiconductor laser element 31c. Yes. The polarization wavelength separation element 32c is formed on the light guide plate 32a at a position where the optical axis AX1 of the red semiconductor laser element 31a folded from the other surface to the one surface by the mirror 32b and the optical axis AX2 of the blue semiconductor laser element 31b intersect. It is arranged on one side. The polarization separation element 32d is an optical axis AX2 of the blue semiconductor laser element 31b folded from the other surface to the one surface by the mirror 32b (a red semiconductor laser folded from the one surface to the other surface by the polarization wavelength separation element 1). The optical axis AX1) of the element 31a and the optical axis AX3 of the blue semiconductor laser element 31b are arranged on one surface of the light guide plate 32a.

  In the first white light source 3 having such a configuration, the red laser light emitted from the semiconductor laser element 31a is incident on one surface of the light guide plate 32a. The incident red laser light guides the light guide plate 32a from one surface to the other surface and is reflected by the mirror 32b. The red laser light reflected by the mirror 32b guides the light guide plate 32a from the other surface to one surface and reaches the polarization wavelength separation element 32c. On the other hand, the blue laser light emitted from the semiconductor laser element 31b is incident on the polarization wavelength separation element 32c. The blue laser light incident on the polarization wavelength separation element 32c is transmitted through the polarization wavelength separation element 32c, while the red laser light reaching the polarization wavelength separation element 32c is reflected by the polarization wavelength separation element 32c, The blue laser beam and the red laser beam are combined by the polarization wavelength separation element 32c. The combined red and blue laser light guides the light guide plate 32a from one surface to the other surface and is reflected by the mirror 32b. The red and blue laser beams reflected by the mirror 32b guide the light guide plate 32a from the other surface to the one surface and reach the polarization separation element 32d. On the other hand, the green laser light emitted from the semiconductor laser element 31c is incident on the polarization separation element 32d. The green laser light incident on the polarization separation element 32d is reflected by the polarization separation element 32d, while the red and blue laser lights reaching the polarization separation element 32d pass through the polarization separation element 32d and are green. And the red and blue laser lights are combined by the polarization separation element 32d to be emitted from the first white light source 3 as white laser light.

  In this way, the first white light source 3 combines the polarization components of the respective colors and the red, blue, and green laser beams by the polarization wavelength separation action of the polarization wavelength separation element 32c and the polarization separation action of the polarization separation element 32d. It is possible to emit white laser light whose optical axes are substantially coincident.

(Second white light source)
FIG. 5 is a diagram showing a configuration of the second white light source. In FIG. 5, the second white light source 5 is a light source suitably applied to, for example, a backlight of a liquid crystal display device, and includes first to third semiconductor laser elements 51 to 53 and first and second optical multiplexers. 54 and 55.

  The first to third semiconductor laser elements 51 to 53 are light sources that emit red laser light, green laser light, and blue laser light, respectively. These first to third semiconductor laser elements 51 to 53 emit laser beams having the same polarization component.

  The first and second optical multiplexers 54 and 55 are optical elements that multiplex laser beams of a plurality of colors, respectively. In the present embodiment, the first optical multiplexer 54 is an element that combines the red laser light and the green laser light with the same polarization component, and the second optical multiplexer 55 is the red laser light, the green laser light This element combines laser light and blue laser light with the same polarization component. Each of the first and second optical multiplexers 54 and 55 includes, for example, first prisms 54a and 55a, polarization wavelength separation elements 54b and 55b, and second prisms 54c and 55c. The first and second prisms 54a, 55a: 54c, 55c have a triangular prism shape whose cross section is a right-angled isosceles triangle. The first prism 54a is formed of a member that guides red light as described later and is transparent to at least light of this wavelength. The second prisms 54c and 55c guide the red and green light beams as described later, and are formed of a member that is transparent to at least the light of each wavelength. The first prism 55a guides red, green, and blue color lights as described later, and is formed of a member that is at least transparent to light of each wavelength. The first prisms 54a, 55a and the second prisms 54c, 55c are layered (film-like, plate-like) such that their bottom surfaces (surfaces including unequal sides of right-angled isosceles triangles in the cross section) face each other. The polarization wavelength separation elements 54b and 55b are in close contact with each other. The polarization wavelength separation elements 54b and 55b are configured in the same manner as the polarization wavelength separation element 1 (including the above-described modification) 1 shown in FIG. In the example shown in FIG. 5, the polarization wavelength separation element 54 b has characteristics of transmitting light in the red wavelength band and reflecting light in the green wavelength band in the light of the polarization components of each color. In the example shown in FIG. 5, the polarization wavelength separation element 55b has characteristics of transmitting light in the red and green wavelength bands and reflecting light in the blue wavelength band in the light of the polarization components of each color. Yes.

  The first semiconductor laser element 51 is arranged so that red laser light is incident on the first side surface of the first optical multiplexer 54. More specifically, the first semiconductor laser element 51 faces the first side surface of the first prism 54a in the first optical multiplexer 54 (a surface including one side of equal sides of a right isosceles triangle in the cross section). To be arranged. The second semiconductor laser element 52 has an optical axis AX5 that substantially intersects the optical axis AX4 of the first semiconductor laser element 51 at the polarization wavelength separation element 54b of the first optical multiplexer 54, and the first optical multiplexer. The green laser beam is arranged so as to enter the second side surface orthogonal to the first side surface in 54. More specifically, the second semiconductor laser element 52 has its optical axis AX5 substantially orthogonal to the optical axis AX4 of the first semiconductor laser element 51 at the polarization wavelength separation element 54b of the first optical multiplexer 54, and The second prism 54c of the first optical multiplexer 54 opposes the second side surface orthogonal to the first side surface of the first prism 54a (a surface including one side of equal sides of a right isosceles triangle in the cross section). Are arranged as follows. The first optical multiplexer 54 and the second optical multiplexer 55 are arranged so that their polarization wavelength separation elements 54b and 55b are orthogonal to each other, and their optical axes coincide with each other. More specifically, a third side surface (a third side surface orthogonal to the second side surface of the second prism 54c (an equal side of a right-angled isosceles triangle in the cross section) facing the first side surface of the first optical multiplexer 54. And the third side surface of the second optical multiplexer 55 (the third side surface of the second prism 55c (the surface including the other side of the equal side of the right isosceles triangle in the cross section)). The first optical multiplexer 54 and the second optical multiplexer 55 are arranged so as to face each other, and the third semiconductor laser element 53 is a second orthogonal to the third side surface of the second optical multiplexer 55. It arrange | positions so that a blue laser beam may inject into a side surface.The 2nd side surface of this 2nd optical multiplexer 55 is located in the opposite side to the 2nd side surface of the 1st optical multiplexer 54. More concretely. The third semiconductor laser element 53 includes the first prism in the second optical multiplexer 55. (In cross-section plane including the one side of the equal sides of the isosceles right triangle) second side of 55a are disposed so as to face the.

  In the second white light source 5 having such a configuration, the red laser light emitted from the semiconductor laser element 51 is incident on the first side surface of the first optical multiplexer 54 (the first side surface of the first prism 54a). . The incident red laser light guides the first prism 54a of the first optical multiplexer 54 from the first side surface toward the third side surface (the third side surface of the second prism 54c), and the polarization wavelength separation element 54b. To reach. On the other hand, the green laser light emitted from the semiconductor laser element 52 is incident on the second side surface of the first optical multiplexer 54 (the second side surface of the second prism 54c). The incident green laser light guides the second prism 54c of the first optical multiplexer 54 from the second side surface toward the fourth side surface, and reaches the polarization wavelength separation element 54b. The fourth side surface is a fourth side surface orthogonal to the first side surface of the first prism 54c of the first optical multiplexer 54 (a surface including the other side of the equal sides of the right isosceles triangle in the cross section). The red laser light reaching the polarization wavelength separation element 54b is transmitted through the polarization wavelength separation element 54b, while the green laser light reaching the polarization wavelength separation element 54b is reflected by the polarization wavelength separation element 54b, The laser beam and the green laser beam are combined by the polarization wavelength separation element 54b. The combined red and green laser light guides the second prism 54c of the first optical multiplexer 54 from the polarization wavelength separation element 54b toward the third side surface from the first side surface toward the third side surface, Injected from the third side. The red and green laser beams emitted from the third side face are incident on the third side face of the second optical multiplexer 55 (the third side face of the second prism 55c). The incident red and green laser light guides the second prism 55c of the second optical multiplexer 55 from the third side surface toward the first side surface (first side surface of the first prism 55a), and polarization wavelength separation. The element 55b is reached. On the other hand, the blue laser light emitted from the semiconductor laser element 53 is incident on the second side surface of the second optical multiplexer 55 (the second side surface of the second prism 54c). The incident blue laser light guides the second prism 55c of the second optical multiplexer 55 from the second side surface toward the fourth side surface, and reaches the polarization wavelength separation element 55b. The fourth side surface of the second optical multiplexer 55 is a fourth side surface orthogonal to the first side surface of the first prism 55a of the second optical multiplexer 55 (in the cross section, the other side of the equal side of the right isosceles triangle is Including the surface). The red and green laser beams that have reached the polarization wavelength separation element 55b are transmitted through the polarization wavelength separation element 55b, while the blue laser light that has reached the polarization wavelength separation element 55b is reflected by the polarization wavelength separation element 55b, The red and green laser lights and the blue laser light are combined by the polarization wavelength separation element 55b. The combined red, green, and blue laser beams are guided from the polarization wavelength separation element 55b to the first side surface through the first prism 55a of the second optical multiplexer 55 from the third side surface toward the first side surface. Then, it is emitted from the first side surface as white laser light.

  In this way, by combining the red, blue, and green laser lights by the polarization wavelength separation action of the polarization wavelength separation elements 54b and 55b, the second white light source 5 is white in which the polarization components and the optical axes of the respective colors are substantially the same. The laser beam can be emitted.

  Next, the polarization wavelength separation element according to the present invention will be described more specifically with reference to examples.

  6 to 13 are diagrams showing the wavelength transmission characteristics of the polarization wavelength separation elements in the first to eighth embodiments. 6 to 13, the horizontal axis represents the wavelength in nm, and the vertical axis represents the transmittance. In FIGS. 6 to 13, ■ indicates the characteristics in the case of 90-degree polarized light and an incident angle of 0 degrees, □ indicates the characteristics in the case of 90-degree polarized light and an incident angle of 20 degrees, and ▲ Indicates a characteristic in the case of 0 degree polarization and an incident angle of 0 degree, and Δ indicates a characteristic in the case of 0 degree polarization and an incident angle of 20 degrees. The incident angle is set to 0 degrees as the normal direction of the surface formed by the plurality of first metal layers 13 (or the plurality of second metal layers 14), and the repeating direction in which the plurality of first metal layers 13 are arranged is 90 degrees. It is an angle between the normal direction and the repeat direction, in degrees.

(First embodiment)
The polarization wavelength separation element 1A in the first embodiment is configured in the same manner as the structure shown in FIG. The substrate 11A is made of a material that transmits light with a wavelength of at least about 395 nm to about 800 nm, and its refractive index N is 1.45. The height h from the bottom surface of the concave portion 12Ab to the top surface of the convex portion 12Aa in the concavo-convex portion 12A is 0.07 nm, and the repetition pitch P of the concavo-convex portion 12A is 0.15 μm. In the first and second metal layers 13A and 14A, the real part nr and the imaginary part ni of the complex refractive index are 0.13025 and 2.79813, respectively, and the real part and the imaginary part of the complex dielectric constant are respectively εr and εi. In this case, (εr / εi) ² is formed of silver (Ag) having 114.88. The ratio SA1: SA2 between the first area SA1 of the first metal layer 13A and the second area SA2 of the second metal layer 14A is 50:50, and the thickness t of the first and second metal layers 13A, 14A is: 0.02 μm. In the first and second metal layers 13A and 14A, ni + 4.6 × t is 3.698, and when the wavelength at which polarized light is to be separated is λpb, ((εr / εi) ² −8500 × ( h / λpb) ² + 4000 × (h / λpb)) is about 515.133.

  Such a polarization wavelength separation element 1A in the first embodiment exhibits the wavelength transmission characteristics shown in FIG. That is, the wavelength transmission characteristic of 0-degree polarized light with an incident angle of 0 degrees is a profile in which the transmittance gradually decreases from about 0.75 to about 0.13 as the wavelength increases from about 395 nm to about 800 nm. The wavelength transmission characteristic of 0-degree polarized light with an incident angle of 20 degrees is a profile in which the transmittance gradually decreases from about 0.70 to about 0.10 as the wavelength increases from about 395 nm to about 800 nm.

  The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 0 degrees gradually decrease from about 0.35 to about 0.02 as the wavelength increases from about 395 nm to about 485 nm. As the wavelength increases from 485 nm to about 620 nm, the transmittance gradually increases from about 0.02 to about 0.55, and as the wavelength increases from about 620 nm to about 800 nm, the transmittance increases to about 0.55. The profile gradually increases from about 0.7 to about 0.7. The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 20 degrees gradually decrease from about 0.37 to about 0.02 as the wavelength increases from about 395 nm to about 485 nm. The transmittance gradually increases from about 0.02 to about 0.50 as it increases to about 620 nm, and the transmittance increases from about 0.50 to about 0.50 as the wavelength increases from about 620 nm to about 800 nm. The profile gradually increases to 0.7.

  In this way, there is almost no difference in wavelength transmission characteristics due to the difference in incident angle between 0 degree polarized light and 90 degree polarized light, and 0 degree polarized light is slightly transmitted when the incident angle is 20 degrees compared to when the incident angle is 0 degrees. The rate is only low. In addition, as described above, the polarization wavelength separation element 1A according to the first embodiment performs polarization separation and wavelength separation at a wavelength of about 485 nm.

(Second embodiment)
The polarization wavelength separation element 1B in the second embodiment is configured in the same manner as the structure shown in FIG. The substrate 11B is made of a material that transmits light with a wavelength of at least about 395 nm to about 800 nm, and its refractive index N is 1.45. The height h from the bottom surface of the concave portion 12Bb to the top surface of the convex portion 12Ba in the concavo-convex portion 12B is 0.13 nm, and the repetition pitch P of the concavo-convex portion 12B is 0.15 μm. In the first and second metal layers 13B and 14B, the real part nr and the imaginary part ni of the complex refractive index are 0.157 and 2.4, respectively, and (εr / εi) ² is 57.92. (Ag). The ratio SB1: SB2 between the first area SB1 of the first metal layer 13B and the second area SB2 of the second metal layer 14B is 50:50, and the thickness t of the first and second metal layers 13B, 14B is: 0.04 μm. In the first and second metal layers 13B and 14B, when ni + 4.6 × t is 4.2 and λpb is a wavelength at which polarized light is to be separated, ((εr / εi) ² −8500 × ( h / λpb) ² + 4000 × (h / λpb)) is about 497.7746.

  Such a polarization wavelength separation element 1B in the second embodiment exhibits the wavelength transmission characteristics shown in FIG. That is, the wavelength transmission characteristics of 0-degree polarized light with an incident angle of 0 degrees gradually increase from about 0.59 to about 0.7 as the wavelength increases from about 395 nm to about 440 nm. As the wavelength increases from 440 nm to about 575 nm, the transmission gradually decreases from about 0.7 to about 0.1, and as the wavelength increases from about 575 nm to about 800 nm, the transmission decreases to about 0.1. The profile gradually decreases from about 0 to about 0. The wavelength transmission characteristics of 0-degree polarized light with an incident angle of 20 degrees gradually decrease from about 0.65 to about 0.07 as the wavelength increases from about 395 nm to about 575 nm, and the wavelength is about As the length increases from 575 nm to about 800 nm, the transmittance gradually decreases from about 0.07 to about 0.

  The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 0 degrees gradually decrease from about 0.02 to about 0 as the wavelength increases from about 395 nm to about 440 nm, and the wavelength starts from about 440 nm. As the wavelength increases from about 710 nm, the transmission gradually increases from about 0 to about 0.77, and as the wavelength increases from about 710 nm to about 800 nm, the transmission increases from about 0.77 to about 0.7. The profile gradually increases to 9. The wavelength transmission characteristic of 90-degree polarized light with an incident angle of 20 degrees gradually decreases from about 0.02 to about 0 as the wavelength increases from about 395 nm to about 440 nm, and the wavelength decreases from about 440 nm to about 710 nm. As the wavelength increases from about 0 to about 0.8, and as the wavelength increases from about 710 nm to about 800 nm, the transmittance increases from about 0.8 to about 0.86. It is a slowly increasing profile.

  Thus, in 0 degree polarized light and 90 degree polarized light, no peak is observed when the incident angle of 0 degree polarized light is 20 degrees, but there is almost no difference in wavelength transmission characteristics due to the difference in incident angle. When the incident angle is 20 degrees, the transmittance is slightly lower than when the incident angle is 0 degrees, and with 90-degree polarized light, the transmittance is slightly higher when the incident angle is 20 degrees than when the incident angle is 0 degrees. Only. In addition, as described above, the polarization wavelength separation element 1B according to the second embodiment performs polarization separation and wavelength separation at a wavelength of about 440 nm.

(Third embodiment)
The polarization wavelength separation element 1C in the third embodiment is configured in the same manner as the structure shown in FIG. The substrate 11C is made of a material that transmits light with a wavelength of at least about 197 nm to about 800 nm, and its refractive index N is 1.45. The height h from the bottom surface of the recess 12Cb to the top surface of the protrusion 12Ca in the uneven portion 12C is 0.105 nm, and the repetition pitch P of the uneven portion 12C is 0.15 μm. In the first and second metal layers 13C and 14C, the real part nr and the imaginary part ni of the complex refractive index are 0.1728 and 1.9838, respectively, and the (εr / εi) ² is 32.45. (Ag). The ratio SC1: SC2 between the first area SC1 of the first metal layer 13C and the second area SC2 of the second metal layer 14C is 50:50, and the thickness t of the first and second metal layers 13C, 14C is 0.04 μm. In the first and second metal layers 13C and 14C, ni + 4.6 × t is 3.784, and ((εr / εi) ² −8500 × ( h / λpb) ² + 4000 × (h / λpb)) is about 497.648.

  The polarization wavelength separation element 1C according to the third embodiment exhibits the wavelength transmission characteristics shown in FIG. That is, the wavelength transmission characteristics of 0-degree polarized light with an incident angle of 0 degrees gradually decrease from about 0.2 to about 0.14 as the wavelength increases from about 197 nm to about 264 nm. As the length increases from 264 nm to about 331 nm, the transmittance gradually increases from about 0.14 to about 0.7, and as the wavelength increases from about 331 nm to about 532 nm, the transmittance increases from about 0.7 to about 331 nm. It is a profile that gradually decreases from 0.1 and gradually decreases in transmittance from about 0.1 to about 0 as the wavelength increases from about 532 nm to about 800 nm. The wavelength transmission characteristics of 0-degree polarized light at an incident angle of 20 degrees gradually decrease from about 0.06 to about 0.1 as the wavelength increases from about 197 nm to about 264 nm. The transmittance gradually increases from about 0.1 to about 0.67 as the wavelength increases from about 331 nm, and the transmittance increases from about 0.67 to about 0.1 as the wavelength increases from about 331 nm to about 532 nm. The profile gradually decreases to 08, and the transmittance gradually decreases from about 0.08 to about 0 as the wavelength increases from about 532 nm to about 800 nm.

  The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 0 degree gradually increase from about 0.08 to about 0.2 as the wavelength increases from about 197 nm to about 331 nm. As the wavelength increases from 331 nm to about 398 nm, the transmittance gradually decreases from about 0.2 to about 0.03, and as the wavelength increases from about 398 nm to about 666 nm, the transmittance increases from about 0.03 to about 366 nm. It is a profile that gradually increases to 0.8 and whose transmittance is approximately constant at about 0.8 as the wavelength increases from about 666 nm to about 800 nm. The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 20 degrees gradually increase from about 0.05 to about 0.15 as the wavelength increases from about 197 nm to about 331 nm. As the wavelength increases from about 398 nm, the transmittance gradually decreases from about 0.15 to about 0.03, and as the wavelength increases from about 398 nm to about 666 nm, the transmittance increases from about 0.03 to about 0.03. The profile gradually decreases to 78, and the transmittance gradually increases from about 0.78 to about 0.8 as the wavelength increases from about 666 nm to about 800 nm.

  In this way, there is almost no difference in wavelength transmission characteristics due to the difference in incident angle between 0 degree polarized light and 90 degree polarized light, and 0 degree polarized light is slightly transmitted when the incident angle is 20 degrees compared to when the incident angle is 0 degrees. The rate is only low. In addition, as described above, the polarization wavelength separation element 1 </ b> C according to the third embodiment performs polarization separation and wavelength separation at a wavelength of about 400 nm.

(Fourth embodiment)
The polarization wavelength separation element 1D in the fourth embodiment is configured in the same manner as the structure shown in FIG. The substrate 11D is made of a material that transmits light with a wavelength of at least about 395 nm to about 800 nm, and its refractive index N is 1.45. The height h from the bottom surface of the concave portion 12Db to the top surface of the convex portion 12Da in the concave / convex portion 12D is 0.15 nm, and the repetition pitch P of the concave / convex portion 12D is 0.15 μm. The first and second metal layers 13D and 14D are gold in which the real part nr and the imaginary part ni of the complex refractive index are 0.21238 and 3.015, respectively, and (εr / εi) ² is 49.89. (Au) is formed. The ratio SD1: SD2 between the first area SD1 of the first metal layer 13D and the second area SD2 of the second metal layer 14D is 50:50, and the thickness t of the first and second metal layers 13D, 14D is: 0.02 μm. The first and second metal layers 13D and 14D have ni + 4.6 × t of 3.915, and ((εr / εi) ² −8500 × ( h / λpb) ² + 4000 × (h / λpb)) is about 518.637.

  Such a polarization wavelength separation element 1D in the fourth embodiment exhibits the wavelength transmission characteristics shown in FIG. That is, the wavelength transmission characteristics of 0-degree polarized light with an incident angle of 0 degrees gradually increase from about 0.29 to about 0.82 as the wavelength increases from about 395 nm to about 620 nm. As the length increases from 620 nm to about 800 nm, the transmittance gradually decreases from about 0.82 to about 0.25. The wavelength transmission characteristics of 0-degree polarized light with an incident angle of 20 degrees gradually increase from about 0.28 to about 0.75 as the wavelength increases from about 395 nm to about 620 nm. It is a profile in which the transmittance gradually decreases from about 0.75 to about 0.16 as it becomes longer to about 800 nm.

  The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 0 degrees gradually increase from about 0.28 to about 0.3 as the wavelength increases from about 395 nm to about 485 nm. As the wavelength increases from 485 nm to about 575 nm, the transmittance gradually decreases from about 0.3 to about 0, and as the wavelength increases from about 575 nm to about 620 nm, the transmittance is approximately constant at about 0; The profile gradually increases from about 0 to about 0.82 as the wavelength increases from about 620 nm to about 800 nm. The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 20 degrees are substantially the same as the profile of 90-degree polarized light with an incident angle of 0 degrees.

  In this way, there is almost no difference in wavelength transmission characteristics due to the difference in incident angle between 0 degree polarized light and 90 degree polarized light, and 0 degree polarized light is slightly transmitted when the incident angle is 20 degrees compared to when the incident angle is 0 degrees. The rate is only low. In addition, as described above, the polarization wavelength separation element 1D according to the fourth embodiment performs polarization separation and wavelength separation at a wavelength of about 600 nm.

(5th Example)
The polarization wavelength separation element 1E in the fifth embodiment is configured in the same manner as the structure shown in FIG. The substrate 11E is made of a material that transmits light having a wavelength of at least about 395 nm to about 800 nm, and its refractive index N is 1.45. The height h from the bottom surface of the concave portion 12Eb to the top surface of the convex portion 12Ea in the concavo-convex portion 12E is 0.14 nm, and the repetition pitch P of the concavo-convex portion 12E is 0.15 μm. In the first and second metal layers 13E and 14E, the real part nr and the imaginary part ni of the complex refractive index are 0.272 and 3.24, respectively, and (εr / εi) ² is 34.97. (Ag). The ratio SE1: SE2 between the first area SE1 of the first metal layer 13E and the second area SE2 of the second metal layer 14E is 50:50, and the thickness t of the first and second metal layers 13E, 14E is: 0.02 μm. In the first and second metal layers 13E and 14E, when ni + 4.6 × t is 4.14 and the wavelength at which polarized light is to be separated is λpb, ((εr / εi) ² -8500 × ( h / λpb) ² + 4000 × (h / λpb)) is about 504.797.

  Such a polarization wavelength separation element 1E in the fifth embodiment exhibits the wavelength transmission characteristics shown in FIG. In other words, the wavelength transmission characteristics of 0-degree polarized light with an incident angle of 0 degrees gradually increase from about 0.38 to about 0.4 as the wavelength increases from about 395 nm to about 530 nm. As the wavelength increases from 530 nm to about 620 nm, the transmittance gradually increases from about 0.4 to about 0.7, and as the wavelength increases from about 620 nm to about 800 nm, the transmittance increases to about 0.7. The profile gradually decreases from about 0.22 to about 0.22. The wavelength transmission characteristics of 0-degree polarized light with an incident angle of 20 degrees are almost constant at about 0.38 as the wavelength increases from about 395 nm to about 530 nm, and the wavelength increases from about 530 nm to about 620 nm. The transmittance gradually increases from about 0.38 to about 0.58, and as the wavelength increases from about 620 nm to about 800 nm, the transmittance gradually increases from about 0.58 to about 0.15. It is a profile that decreases.

  The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 0 degree gradually decrease from about 0.2 to about 0.03 as the wavelength increases from about 395 nm to about 620 nm. As the length increases from 620 nm to about 800 nm, the transmittance gradually increases from about 0.03 to about 0.8. The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 20 degrees are substantially the same as the profile of 90-degree polarized light with an incident angle of 0 degrees.

  In this way, there is almost no difference in wavelength transmission characteristics due to the difference in incident angle between 0 degree polarized light and 90 degree polarized light, and 0 degree polarized light is slightly transmitted when the incident angle is 20 degrees compared to when the incident angle is 0 degrees. The rate is only low. In addition, as described above, the polarization wavelength separation element 1E according to the fifth embodiment performs polarization separation and wavelength separation at a wavelength of about 620 nm.

(Sixth embodiment)
The polarization wavelength separation element 1F in the sixth embodiment is configured in the same manner as the structure shown in FIG. The substrate 11F is made of a material that transmits light with a wavelength of at least about 395 nm to about 800 nm, and its refractive index N is 1.45. The height h from the bottom surface of the concave portion 12Fb to the upper surface of the convex portion 12Fa in the concave and convex portion 12F is 0.12 nm, and the repeating pitch P of the concave and convex portion 12F is 0.15 μm. In the first and second metal layers 13F and 14F, the real part nr and the imaginary part ni of the complex refractive index are 0.21457 and 2.19177, respectively, and (εr / εi) ² is 25.59. (Li) is formed. The ratio SF1: SF2 between the first area SF1 of the first metal layer 13F and the second area SF2 of the second metal layer 14F is 50:50, and the thickness t of the first and second metal layers 13F, 14F is: 0.04 μm. The first and second metal layers 13F and 14F have an (ni + 4.6 × t) of 3.992, and ((εr / εi) ² -8500 × ( h / λpb) ² + 4000 × (h / λpb)) is about 494.925.

  The polarization wavelength separation element 1F according to the sixth embodiment exhibits the wavelength transmission characteristics shown in FIG. That is, the wavelength transmission characteristic of 0-degree polarized light with an incident angle of 0 degrees gradually increases from about 0.6 to about 0.65 as the wavelength increases from about 395 nm to about 440 nm, and the wavelength Is a profile in which the transmittance gradually decreases from about 0.65 to about 0.1 as the length increases from about 440 nm to about 800 nm. The wavelength transmission characteristic of 0-degree polarized light with an incident angle of 20 degrees is a profile in which the transmittance gradually decreases from about 0.6 to about 0.1 as the wavelength increases from about 395 nm to about 800 nm.

  The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 0 degree gradually decrease from about 0.05 to about 0 as the wavelength increases from about 395 nm to about 485 nm, and the wavelength starts from about 485 nm. The transmittance increases slowly from about 0 to about 0.05 as it increases to about 575 nm, and as the wavelength increases from about 575 nm to about 800 nm, the transmittance increases from about 0.05 to about 0.00. The profile gradually increases to 7. The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 20 degrees are substantially the same as the profile of 90-degree polarized light with an incident angle of 0 degrees.

  Thus, in 0 degree polarized light and 90 degree polarized light, no peak is observed when the incident angle of 0 degree polarized light is 20 degrees, but there is almost no difference in wavelength transmission characteristics due to the difference in incident angle. The transmittance is slightly lower when the incident angle is 20 degrees than when the incident angle is 0 degrees. In addition, as described above, the polarization wavelength separation element 1F according to the sixth embodiment performs polarization separation and wavelength separation at a wavelength of about 485 nm.

(Seventh embodiment)
The polarization wavelength separation element 1G in the seventh embodiment is configured similarly to the structure shown in FIG. The substrate 11G is made of a material that transmits light with a wavelength of at least about 197 nm to about 800 nm, and its refractive index N is 1.45. The height h from the bottom surface of the concave portion 12Gb to the top surface of the convex portion 12Ga in the concavo-convex portion 12G is 0.055 nm, and the repetition pitch P of the concavo-convex portion 12G is 0.15 μm. In the first and second metal layers 13G and 14G, the real part nr and the imaginary part ni of the complex refractive index are 0.21788 and 3.185, respectively, and the real part and the imaginary part of the complex dielectric constant are εr and εi, respectively. In this case, (εr / εi) ² is formed of aluminum (Al) having 52.93. The ratio SG1: SG2 between the first area SG1 of the first metal layer 13G and the second area SG2 of the second metal layer 14G is 50:50, and the thickness t of the first and second metal layers 13G, 14G is 0.015 μm. In the first and second metal layers 13G and 14G, when ni + 4.6 × t is 3.86 and the wavelength at which polarized light is to be separated is λpb, ((εr / εi) ² -8500 × ( h / λpb) ² + 4000 × (h / λpb)) is about 516.97.

  Such a polarization wavelength separation element 1G in the seventh embodiment exhibits the wavelength transmission characteristics shown in FIG. That is, the wavelength transmission characteristic of 0-degree polarized light with an incident angle of 0 degrees gradually decreases from about 0.8 to about 0.08 as the wavelength increases from about 197 nm to about 398 nm. Is a profile in which the transmittance gradually decreases from about 0.08 to about 0 as the length increases from about 398 nm to about 800 nm. The wavelength transmission characteristics of 0-degree polarized light at an incident angle of 20 degrees gradually decrease from about 0.75 to about 0.08 as the wavelength increases from about 197 nm to about 398 nm, and the wavelength is about As the length increases from 398 nm to about 800 nm, the transmittance gradually decreases from about 0.08 to about 0.

  The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 0 degrees gradually decrease from about 0.1 to about 0.03 as the wavelength increases from about 197 nm to about 264 nm. As the length increases from 264 nm to about 398 nm, the transmittance gradually increases from about 0.03 to about 0.7, and as the wavelength increases from about 398 nm to about 800 nm, the transmittance increases to about 0.7. The profile gradually increases from about 0.79 to about 0.79. The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 20 degrees gradually decrease from about 0.2 to about 0.03 as the wavelength increases from about 197 nm to about 264 nm. As the wavelength increases from about 398 nm, the transmission gradually increases from about 0.03 to about 0.7, and as the wavelength increases from about 398 nm to about 800 nm, the transmission increases from about 0.7 to about 0.7. The profile gradually increases to 0.8.

  In this way, there is almost no difference in wavelength transmission characteristics due to the difference in incident angle between 0 degree polarized light and 90 degree polarized light, and 0 degree polarized light is slightly transmitted when the incident angle is 20 degrees compared to when the incident angle is 0 degrees. The rate is only low. In addition, as described above, the polarization wavelength separation element 1G according to the seventh embodiment performs polarization separation and wavelength separation at a wavelength of about 265 nm.

(Eighth embodiment)
The polarization wavelength separation element 1H in the eighth embodiment is configured similarly to the structure shown in FIG. The substrate 11H is made of a material that transmits light with a wavelength of at least about 197 nm to about 800 nm, and its refractive index N is 1.45. The height h from the bottom surface of the concave portion 12Hb to the top surface of the convex portion 12Ha in the concavo-convex portion 12H is 0.13 nm, and the repetition pitch P of the concavo-convex portion 12H is 0.15 μm. In the first and second metal layers 13H and 14H, the real part nr and the imaginary part ni of the complex refractive index are 0.1728 and 1.9838, respectively, and (εr / εi) ² is 32.45. (Ag). The ratio SH1: SH2 between the first area SH1 of the first metal layer 13H and the second area SH2 of the second metal layer 14H is 50:50, and the thickness t of the first and second metal layers 13H, 14H is: 0.05 μm. In the first and second metal layers 13H and 14H, when ni + 4.6 × t is 4.234 and the wavelength at which polarized light is to be separated is λpb, ((εr / εi) ² −8500 × ( h / λpb) ² + 4000 × (h / λpb)) is about 434.639.

  Such a polarization wavelength separation element 1H in the eighth embodiment exhibits the wavelength transmission characteristics shown in FIG. That is, the wavelength transmission characteristics of 0-degree polarized light with an incident angle of 0 degrees gradually decrease from about 0.13 to about 0.06 as the wavelength increases from about 197 nm to about 264 nm. As the length increases from 264 nm to about 398 nm, the transmittance gradually increases from about 0.06 to about 0.57, and as the wavelength increases from about 398 nm to about 532 nm, the transmittance increases from about 0.57 to about 532 nm. The profile gradually decreases to 0.09, and the transmittance gradually decreases from about 0.09 to about 0 as the wavelength increases from about 532 nm to about 800 nm. The wavelength transmission characteristics of 0-degree polarized light with an incident angle of 20 degrees gradually increase from about 0 to about 0.58 as the wavelength increases from about 197 nm to about 398 nm, and the wavelength increases from about 398 nm to about 532 nm. The transmittance gradually decreases from about 0.58 to about 0.04, and as the wavelength increases from about 532 nm to about 800 nm, the transmittance decreases from about 0.04 to about 0. The profile gradually decreases.

  In addition, the wavelength transmission characteristics of 90-degree polarized light with an incident angle of 0 degrees gradually increase from about 0.05 to about 0.14 as the wavelength increases from about 197 nm to about 331 nm. As the wavelength increases from 331 nm to about 398 nm, the transmittance gradually decreases from about 0.14 to about 0, and as the wavelength increases from about 398 nm to about 800 nm, it gradually increases from about 0 to about 0.87. It is a profile. The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 20 degrees gradually increase from about 0.02 to about 0.07 as the wavelength increases from about 197 nm to about 331 nm. A profile that gradually decreases from about 0.07 to about 0 as the wavelength increases from about 398 nm, and gradually increases from about 0 to about 0.86 as the wavelength increases from about 398 nm to about 800 nm. is there.

  Thus, in 0 degree polarized light and 90 degree polarized light, there is almost no difference in wavelength transmission characteristics due to a difference in incident angle. In addition, as described above, the polarization wavelength separation element 1H in the eighth embodiment performs polarization separation and wavelength separation at a wavelength of about 400 nm.

(Comparative example)
Next, an optical element of a comparative example for the first to eighth embodiments will be described.

  FIG. 14 is a diagram showing the wavelength transmission characteristics of the optical element in the comparative example. In FIG. 14, the horizontal axis is the wavelength in nm, and the vertical axis is the transmittance. The black square indicates the characteristics when the polarization is 90 degrees and the incident angle is 0 degree, the square indicates the characteristics when the polarization is 90 degrees and the incident angle is 20 degrees, and the solid triangle indicates that the polarization is 0 degrees. The characteristic is obtained when the incident angle is 0 degree, and Δ indicates the characteristic when the incident light is 0 degree polarized light and the incident angle is 20 degrees.

The optical element in the comparative example is configured similarly to the structure shown in FIG. The substrate is made of a material that is transparent to light having a wavelength of at least about 197 nm to about 800 nm, and its refractive index N is 1.45. The height h from the bottom surface of the concave portion to the top surface of the convex portion in the concave and convex portion is 0.075 nm, and the repeating pitch P of the concave and convex portion is 0.15 μm. The first and second metal layers have lead (Pb) in which the real part nr and the imaginary part ni of the complex refractive index are 1.20229 and 2.29904, respectively, and the (εr / εi) ² is 0.48. It is formed with. The ratio of the first area of the first metal layer to the second area of the second metal layer is 50:50, and the thickness t of the first and second metal layers is 0.025 μm. In the first and second metal layers, ni + 4.6 × t is 3.424, and when the wavelength at which polarized light is to be separated is λpb, ((εr / εi) ² -8500 × (h / λpb ) ² + 4000 × (h / λpb)) is about −1530.767.

  The optical element in such a comparative example exhibits the wavelength transmission characteristics shown in FIG. That is, the wavelength transmission characteristic of 0-degree polarized light with an incident angle of 0 degrees is a profile in which the transmittance gradually decreases from about 0.32 to about 0.04 as the wavelength increases from about 197 nm to about 800 nm. The wavelength transmission characteristics of 0-degree polarized light with an incident angle of 20 degrees gradually increase from about 0.14 to about 0.16 as the wavelength increases from about 197 nm to about 264 nm. The profile gradually decreases from about 0.16 to about 0.04 as the transmittance increases to about 800 nm.

  The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 0 degrees gradually decrease from about 0.1 to about 0.04 as the wavelength increases from about 197 nm to about 264 nm. The transmittance from 264 nm to about 331 nm is approximately constant at 0.04 burning, and as the wavelength increases from about 331 nm to about 800 nm, the transmittance gradually increases from about 0.04 to about 0.6. It is a profile. The wavelength transmission characteristics of 90-degree polarized light with an incident angle of 20 degrees are substantially the same as the profile of 90-degree polarized light with an incident angle of 0 degrees.

  Thus, the optical element in the comparative example cannot separate the wavelength while separating the polarization.

  Table 3 summarizes the specifications of the first to eighth examples and the comparative example.

As can be seen from Table 3, the polarization wavelength separation element 1 (1A to 1H) having the structure shown in FIG. 1 has at least the first and second metal layers 13 and 14 serving as the metal wires of the first and second wire grids. , Gold, silver, copper, lithium and aluminum. Alternatively, the first and second metal layers 13 and 14 are made of a metal material that satisfies at least the condition of “25 <(εr / εi) ² <120”. Alternatively, the first and second metal layers 13 and 14 are formed of a metal material that satisfies at least the condition of “0.13 <nr <0.28”. Alternatively, the polarization wavelength separation element 1 (1A to 1H) satisfies at least the condition of “490 <((εr / εi) ² −8500 × (h / λpb) ² + 4000 × (h / λpb)) <530”. ing. Alternatively, the polarization wavelength separation element 1 (1A to 1H) satisfies at least the condition of “3.6 <(ni + 4.6 × t) <4.3”.

  In order to express the present invention, the present invention has been properly and fully described through the embodiments with reference to the drawings. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that this is possible. Accordingly, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not covered by the claims. It is interpreted that it is included in

It is a figure which shows the structure of the polarization wavelength separation element in embodiment. It is a figure which shows the wavelength transmission characteristic by the difference in area ratio. It is a figure for demonstrating the manufacturing process of the polarization wavelength separation element shown in FIG. It is a figure which shows the structure of a 1st white light source. It is a figure which shows the structure of a 2nd white light source. It is a figure which shows the wavelength transmission characteristic of the polarization wavelength separation element in 1st Example. It is a figure which shows the wavelength transmission characteristic of the polarization wavelength separation element in 2nd Example. It is a figure which shows the wavelength transmission characteristic of the polarization wavelength separation element in 3rd Example. It is a figure which shows the wavelength transmission characteristic of the polarization wavelength separation element in 4th Example. It is a figure which shows the wavelength transmission characteristic of the polarization wavelength separation element in 5th Example. It is a figure which shows the wavelength transmission characteristic of the polarization wavelength separation element in 6th Example. It is a figure which shows the wavelength transmission characteristic of the polarization wavelength separation element in 7th Example. It is a figure which shows the wavelength transmission characteristic of the polarization wavelength separation element in 8th Example. It is a figure which shows the wavelength transmission characteristic of the optical element in a comparative example.

Explanation of symbols

1, 1A to 1H, 32c, 54b, 55b Polarization wavelength separation element 3 First white light source 5 Second white light source 11, 11A to 11H Substrate 12, 12A to 12H Uneven portion 13, 13A to 13H First metal layer 14, 14A -14H Second metal layer

Claims (6)

A first and second wire grid in which a plurality of metal wires extending in one direction are arranged at predetermined first intervals in a direction linearly independent of the one direction;
The second wire grid is a normal of a surface formed by the one direction and the linearly independent direction so that the metal wires of the second wire grid face the gap between the metal wires in the first wire grid. Arranged at a predetermined second distance from the first wire grid in a direction,
The metal wires of the first and second wire grids are made of any metal material of gold, silver, copper, lithium and aluminum, and εr is a real part and an imaginary part of a complex dielectric constant in the vicinity of a wavelength to be polarized light separated. A metal material satisfying the condition of 25 <(εr / εi) ² <120 when εi is set, and 0.13 <nr <0. A polarization wavelength separation element comprising any one of metal materials satisfying 28 conditions. The ratio S1: S2 between the first area S1 of the metal wire in the first wire grid and the second area S2 of the metal wire in the second wire grid is the ratio of the polarization component to be polarized and separated at the wavelength to be polarized. The light transmittance is 50% or more, and the light transmittance of the polarized light component orthogonal to the polarized light component to be polarized and separated is a ratio smaller than 50%. Polarization wavelength separation element. The repetition pitch P of the metal wires in the first and second wire grids satisfies the condition of 0.1 μm ≦ P ≦ 0.5 × λmin, where λmin is the shortest wavelength in the light to be incident. The polarization wavelength separation element according to claim 1. The distance from the center position of the metal wire in the first wire grid to the center position of the metal wire in the second wire grid is h, the wavelength at which polarized light is to be separated is λpb, and the real and imaginary parts of the complex permittivity are The condition of 490 <((εr / εi) ² -8500 × (h / λpb) ² + 4000 × (h / λpb)) <530 is satisfied when εr and εi are set forth. Polarization wavelength separation element. When the thickness in the normal direction of the metal wires in the first and second wire grids is t and the imaginary part of the complex refractive index is ni, 3.6 <(ni + 4.6 × t) <4.3 The polarization wavelength separation element according to claim 1, wherein the following condition is satisfied. A substrate,
A plurality of concave and convex portions formed on one main surface of the substrate and extending in one direction and arranged in a direction linearly independent of the one direction;
A plurality of first metal layers respectively formed on upper surfaces of a plurality of convex portions in the plurality of concave and convex portions;
A plurality of second metal layers respectively formed on the bottom surfaces of the plurality of recesses in the plurality of uneven portions,
The first wire grid is composed of the plurality of first metal layers,
The polarization wavelength separation element according to any one of claims 1 to 5, wherein the second wire grid is configured by the plurality of second metal layers.

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