JP2020139972A - Wavelength selection filter, and method of manufacturing wavelength selection filter - Google Patents

Abstract

To provide a wavelength selection filter capable of increasing wavelength selectability, and a method of manufacturing the wavelength selection filter.SOLUTION: When, in wavelength selection filter 10, a thickness of a first high refractive index part 13a is represented by T1, a thickness of a second high refractive index part 15a is represented by T2, a refractive index of a material of a high refractive index layer 18 is represented by n1, a refractive index of a material of a rugged structure layer 17 is represented by n2, a refractive index of a material of an embedded layer 19 is represented by n3, an area ratio of a first high refractive index part 13a is represented by R1, and an area ratio of a second high refractive index part 15a is represented by R2, n1>n2, n1>n3, and R1+R2>1 are satisfied, and a ratio of a second parameter represented by T2×{n1×R2+n3×(1-R2)} to a first parameter represented by T1×{n1×R1+n2×(1-R1)} is 0.7 or more and 1.3 or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wavelength selection filter and a method for manufacturing the wavelength selection filter.

A wavelength selection filter using a waveguide mode resonance phenomenon has been proposed as a filter for selecting light by utilizing an optical phenomenon caused by a fine structure of an object. This wavelength selection filter has a sub-wavelength grating that is a diffraction grating with a period smaller than the wavelength of light. When light is incident on the sub-wavelength lattice, the emission of diffracted light into the space on the incident side is suppressed, while light in a specific wavelength range propagates while being multiple-reflected due to the difference in refractive index from the surroundings. This causes resonance and is strongly emitted as reflected light.

For example, the color filter described in Patent Document 1 has a structure in which a plurality of convex portions forming a sub-wavelength lattice are arranged on a substrate. However, in such a structure, in order to increase the intensity of the extracted light, that is, to obtain the reflected light having excellent wavelength selectivity, as described in Patent Document 1, the substrate is formed from synthetic quartz and the substrate is formed. It is desirable to secure a large difference in refractive index between the substrate and the convex portion by forming the convex portion from silicon and reduce the loss due to multiple reflection of light. For that purpose, it is necessary to use an SOQ (Silicon on Quartz) substrate in which single crystal Si is formed on a substrate made of synthetic quartz, which causes an increase in manufacturing cost.

On the other hand, the wavelength selection element described in Patent Document 2 has a waveguide layer formed of a material having a higher refractive index than the material constituting the substrate between the substrate and the convex portion constituting the sub-wavelength lattice. have. According to such a structure, even when the convex portion and the waveguide layer are formed of a resin, the wavelength selectivity of the reflected light is enhanced by propagating the multiple-reflected light into the waveguide layer. Further, since the nanoimprint method can be used as a method for forming the convex portion and the waveguide layer from the resin, it can be easily manufactured while reducing the material cost, and the manufacturing cost can also be reduced.

Japanese Patent No. 5023324 Japanese Unexamined Patent Publication No. 2009-25558

However, in the structure of Patent Document 2, since the light propagation mode in the waveguide layer is mainly determined by the thickness of the waveguide layer and the wavelength of light, light in a desired wavelength range is multiplely reflected in the waveguide layer. In order to cause resonance, it is necessary to precisely control the film thickness of the waveguide layer. Forming a waveguide layer having a precise film thickness in addition to a convex portion having a fine period imposes a heavy load on the production of a wavelength selection filter. For example, when the convex portion and the waveguide layer are formed by the nanoimprint method, the concave plate pressed against the resin material in order to form the convex portion in the resin material coated on the base material. Since the residual film portion sandwiched between the substrate and the substrate serves as the waveguide layer, it is difficult to precisely control the thickness of the waveguide layer. Therefore, in the wavelength selection filter utilizing the waveguide mode resonance phenomenon, there is still room for improvement in the structure for enhancing the wavelength selectivity.

An object of the present invention is to provide a wavelength selection filter capable of increasing the intensity of the extracted light and a method for manufacturing the wavelength selection filter.

The wavelength selection filter that solves the above-mentioned problems is a concave-convex element that is a convex portion or a concave portion, and has a concave-convex structure on the surface formed by a plurality of the concave-convex elements arranged in a two-dimensional lattice while being separated from each other in a sub-wavelength period. An uneven structure layer, a first high refractive index portion located on the uneven structure and having a surface shape following the uneven structure, and a first high refractive index portion located at the bottom of the uneven structure, and the uneven structure. The high refractive index layer including the second high refractive index portion located at the top of the structure and the embedded layer for filling the irregularities on the surface of the high refractive index layer are provided, and the first high refractive index portion includes. The thickness is T1, the thickness of the second high refractive index portion is T2, the refractive index of the material of the high refractive index layer is n1, the refractive index of the material of the concave-convex structure layer is n2, and the material of the embedded layer is n2. The refractive index is n3, the area ratio occupied by the first high refractive index portion in a cross section including the first high refractive index portion and orthogonal to the thickness direction thereof is R1, and the thickness thereof includes the second high refractive index portion. When the area ratio occupied by the second high refractive index portion in the cross section orthogonal to the direction is R2, n1> n2, n1> n3, and R1 + R2> 1, and T1 × {n1 × R1 + n2 × ( The ratio of the second parameter represented by T2 × {n1 × R2 + n3 × (1-R2)} to the first parameter represented by 1-R1)} is 0.7 or more and 1.3 or less.

According to the above configuration, it is a lattice region along a cross section orthogonal to the thickness direction, and the waveguide mode resonance occurs in the lattice region including the first high refractive index portion and the lattice region including the second high refractive index portion. The wavelength range of light that causes resonance becomes closer due to the phenomenon. Therefore, since the light in the close wavelength range enhanced in each of the two lattice regions is obtained as the reflected light, the intensity of the light extracted as the reflected light is higher than that of the wavelength selection filter having only one lattice region. Be done.

In the above configuration, the high refractive index layer includes a side high refractive index portion extending along the side surface of the uneven element between the first high refractive index portion and the second high refractive index portion, and the side thereof. When the area ratio occupied by the side high-refractive index portion in the cross section including the portion high-refractive index portion and perpendicular to the thickness direction is R3, R3 ≦ R1 + R2-1 may be satisfied.

In the above configuration, the high refractive index layer includes a side high refractive index portion extending along the side surface of the uneven element between the first high refractive index portion and the second high refractive index portion, and the high refractive index portion is included. The second high refractive index portion may extend to the outside of the side high refractive index portion when viewed from a direction along the thickness direction of the refractive index layer.

According to each of the above configurations, the width of the side high refractive index portion is suppressed to be small, so that the average refractive index of the region between the two lattice regions is suppressed to be excessively large. Therefore, since the difference in the average refractive index between the lattice region and the adjacent region thereof is well secured, the intensity of the reflected light from each lattice region obtained by the waveguide mode resonance phenomenon becomes good.

In the above configuration, T1 = T2, n2 = n3, and R1 = R2 may be satisfied.
According to the above configuration, the wavelength ranges of light that resonate due to the waveguide mode resonance phenomenon coincide in the two lattice regions. Therefore, the intensity of the light extracted as the reflected light is particularly enhanced.

In the above configuration, a portion composed of the first high refractive index portion, the second high refractive index portion, and a low refractive index region surrounding these high refractive index portions is a resonance structure portion, and the wavelength selection filter. May include a plurality of the resonance structure portions arranged along the thickness direction of the resonance structure portion.

According to the above configuration, since the wavelength selection filter includes four or more lattice regions, the intensity of the light extracted as the reflected light is further increased, and the degree of freedom in adjusting the wavelength range included in the reflected light and the transmitted light is high. It is possible to increase.

In the above configuration, the plurality of resonance structure portions include a first resonance structure portion and a second resonance structure portion, and the period of the arrangement of the uneven elements of the first resonance structure portion and the second resonance The period of the arrangement of the uneven elements included in the structural portion may be the same.

According to the above configuration, the wavelength range of light that resonates due to the waveguide mode resonance phenomenon becomes close to each other in the lattice region included in the first resonance structure portion and the lattice region included in the second resonance structure portion. Therefore, since the light in the close wavelength range enhanced in each of the four lattice regions is obtained as the reflected light, the intensity of the light extracted as the reflected light is further increased.

In the above configuration, the ratio of the second parameter to the first parameter in the first resonance structure part and the ratio of the second parameter to the first parameter in the second resonance structure part are in agreement. You may.

According to the above configuration, the variation in the optical film thickness, which is the parameter, becomes small in the four lattice regions, that is, the wavelength range of the light causing resonance in each lattice region becomes closer. Therefore, the intensity of the light extracted as the reflected light is further increased.

In the above configuration, the plurality of resonance structure portions include a first resonance structure portion and a second resonance structure portion, and the period of the arrangement of the uneven elements of the first resonance structure portion and the second resonance The period of the arrangement of the uneven elements included in the structural portion may be different from each other.

According to the above configuration, the wavelength range of light that resonates due to the waveguide mode resonance phenomenon is different from each other in the lattice region included in the first resonance structure portion and the lattice region included in the second resonance structure portion. Therefore, in the wavelength selection filter, the wavelength range included in the reflected light is expanded and the wavelength range included in the transmitted light is narrowed while increasing the intensity of the reflected light as compared with the case where there is only one lattice region. Is possible.

A method for manufacturing a wavelength selection filter that solves the above problems is a method of manufacturing a concave-convex element which is a plurality of convex portions or concave portions arranged in a two-dimensional lattice pattern on the surface of a layer made of a first low refractive index material while being separated from each other in a sub-frequency period. Along the surface of the concave-convex structure layer, the first step of forming the concave-convex structure layer and a high-refractive index material having a higher refractive index than the first low-refractive index material are used. A second step of forming a high refractive index layer including a first high refractive index portion located at the bottom of the concave-convex structure of the concave-convex structure layer and a second high refractive index portion located at the top of the concave-convex structure, and the above-mentioned The third step of forming an embedded layer by filling the irregularities on the surface of the high refractive index layer with a second low refractive index material having a refractive index lower than that of the high refractive index material is included. 1 The thickness of the high refractive index portion is T1, the thickness of the second high refractive index portion is T2, the refractive index of the high refractive index material is n1, the refractive index of the first low refractive index material is n2, and the first 2 The refractive index of the low refractive index material is n3, the area ratio occupied by the first high refractive index portion in the cross section including the first high refractive index portion and orthogonal to the thickness direction thereof is R1, and the second high refractive index portion. When the area ratio occupied by the second high refractive index portion in the cross section including the portion and orthogonal to the thickness direction is R2, n1> n2, n1> n3, and R1 + R2> 1, and T1 × The ratio of the second parameter represented by T2 × {n1 × R2 + n3 × (1-R2)} to the first parameter represented by {n1 × R1 + n2 × (1-R1)} is 0.7 or more. Each layer is formed so as to be 3 or less.

According to the above manufacturing method, it is possible to manufacture a wavelength selection filter having an increased intensity of light extracted as reflected light without requiring precise control of the thickness of the layer in contact with the lattice region. Therefore, such a wavelength selection filter can be easily manufactured.

In the above manufacturing method, in the second step, the side high refractive index in which the high refractive index layer extends along the side surface of the uneven element between the first high refractive index portion and the second high refractive index portion. A physical vapor phase growth method is used so that the second high refractive index portion extends to the outside of the side high refractive index portion when viewed from the direction along the thickness direction of the high refractive index layer. The high refractive index layer may be formed.

According to the above manufacturing method, although the method of forming the side high refractive index portion on the side surface of the uneven element is adopted, the width of the side high refractive index portion can be suppressed to be small, so that the region between the two lattice regions is used. It is possible to prevent the average refractive index of the above from becoming excessively large. Therefore, since the difference in the average refractive index between the lattice region and the adjacent region thereof is well secured, the intensity of the reflected light from each lattice region obtained by the waveguide mode resonance phenomenon becomes good.

According to the present invention, the intensity of the extracted light can be increased in the wavelength selection filter.

The figure which shows the cross-sectional structure of the wavelength selection filter about the 1st Embodiment of a wavelength selection filter. (A) is a diagram showing the cross-sectional structure of the first grid region in the wavelength selection filter of the first embodiment together with the cross-sectional structure of the wavelength selection filter, and (b) is the second grid in the wavelength selection filter of the first embodiment. The figure which shows the cross-sectional structure of a region together with the cross-sectional structure of a wavelength selection filter. The figure which shows the cross-sectional structure of the intermediate region in the wavelength selection filter of 1st Embodiment together with the cross-sectional structure of a wavelength selection filter. The figure which shows the formation process of the concavo-convex structure layer about the manufacturing method of the wavelength selection filter of 1st Embodiment. The figure which shows the process of forming the high refractive index layer about the manufacturing method of the wavelength selection filter of 1st Embodiment. The figure which shows the forming process of the embedded layer about the manufacturing method of the wavelength selection filter of 1st Embodiment. The figure which shows the cross-sectional structure of the modification of the wavelength selection filter of 1st Embodiment. The figure which shows the action of the wavelength selection device which is an application example of the wavelength selection filter of 1st Embodiment. The figure which shows the planar structure of the display body which is an application example of the wavelength selection filter of 1st Embodiment. The figure which shows the action of the display body which is an application example of the wavelength selection filter of 1st Embodiment. The figure which shows the planar structure of the color filter which is an application example of the wavelength selection filter of 1st Embodiment. The figure which shows the action of the color filter which is an application example of the wavelength selection filter of 1st Embodiment. The figure which shows an example of the cross-sectional structure of the wavelength selection filter about the 2nd Embodiment of a wavelength selection filter. The figure which shows an example of the cross-sectional structure of the wavelength selection filter about the 2nd Embodiment of a wavelength selection filter. The figure which shows the state which the concavo-convex structure faces each other about the manufacturing method of the wavelength selection filter of 2nd Embodiment. The figure which shows the formation process of the embedded layer about the manufacturing method of the wavelength selection filter of 2nd Embodiment.

(First Embodiment)
A wavelength selection filter and a first embodiment of a method for manufacturing the wavelength selection filter will be described with reference to FIGS. 1 to 13. The wavelength selection filter has a function of extracting light in a specific wavelength range from the light incident on the wavelength selection filter by reflecting or transmitting it. The wavelength range to be selected by the wavelength selection filter is not particularly limited, but for example, the wavelength selection filter extracts light in a specific wavelength range from light that can be visually recognized by the human eye, that is, light in the visible region. In the following, the wavelength of light in the visible region is 400 nm or more and 800 nm or less.

[Overall configuration of wavelength selection filter]
As shown in FIG. 1, the wavelength selection filter 10 includes a base material 11, a first low refractive index region 12, a first lattice region 13, an intermediate region 14, a second lattice region 15, and a second low refractive index region 16. It has. Each of the first low refractive index region 12, the first lattice region 13, the intermediate region 14, the second lattice region 15, and the second low refractive index region 16 spreads in a layered manner from a position close to the base material 11. They are arranged in this order. The direction in which each region is arranged is the first direction, and the first direction is, that is, the thickness direction of each region and the wavelength selection filter 10. Further, the side where the second low refractive index region 16 is located with respect to the base material 11 is the surface side of the wavelength selection filter 10, and the side where the base material 11 is located with respect to the second low refractive index region 16 is the wavelength selection filter. It is the back side of 10.

The base material 11 has a plate shape, and among the surfaces of the base material 11, the surface located on the surface side of the wavelength selection filter 10 is the surface of the base material 11. When the selection target of the wavelength selection filter 10 is light in the visible region, for example, a synthetic quartz substrate or a film made of a resin such as polyethylene terephthalate or polyethylene naphthalate is used as the base material 11.

The first low refractive index region 12 is in contact with the surface of the base material 11 and extends along the surface of the base material 11. The first lattice region 13 has a first high refractive index portion 13a and a first low refractive index portion 13b. When viewed from the direction facing the surface of the base material 11, that is, from the direction along the first direction, the plurality of first low refractive index portions 13b are arranged in a two-dimensional lattice pattern, and the first high refractive index portions 13b are arranged. The 13a fills the space between the plurality of first low refractive index portions 13b.

The intermediate region 14 has a side high refractive index portion 14a, an isolated low refractive index portion 14b, and an outer peripheral low refractive index portion 14c. When viewed from the direction along the first direction, the plurality of isolated low refractive index portions 14b are arranged in a two-dimensional lattice, and the side high refractive index portions 14a surround each isolated low refractive index portion 14b. Then, the outer peripheral low refractive index portion 14c fills the space between the plurality of side portion high refractive index portions 14a. The isolated low refractive index portion 14b is located on the first low refractive index portion 13b. The side high refractive index portion 14a is located on the end portion in the width direction of the first high refractive index portion 13a, and the outer peripheral low refractive index portion 14c is located on the central portion in the width direction of the first high refractive index portion 13a. To position.

The second lattice region 15 has a second high refractive index portion 15a and a second low refractive index portion 15b. When viewed from the direction along the first direction, the plurality of second high refractive index portions 15a are arranged in a two-dimensional lattice, and the second low refractive index portion 15b fills the space between the plurality of second high refractive index portions 15a. ing. The second high refractive index portion 15a is located on the isolated low refractive index portion 14b and the side high refractive index portion 14a, and the second low refractive index portion 15b is located on the outer peripheral low refractive index portion 14c.

The second low refractive index region 16 covers the second lattice region 15 on the side opposite to the intermediate region 14 with respect to the second lattice region 15.
In each of the above-mentioned regions constituting the wavelength selection filter 10, the regions adjacent to each other along the first direction are continuous with each other in a part thereof. Specifically, the first low refractive index region 12 and the first low refractive index portion 13b are continuous with each other, and further, the first low refractive index portion 13b and the isolated low refractive index portion 14b are continuous with each other. These are made of the same material as each other. Further, the first high-refractive index portion 13a and the side high-refractive index portion 14a are continuous with each other, and the side high-refractive index portion 14a and the second high-refractive index portion 15a are continuous with each other. It is composed of the same material as each other. Further, the outer peripheral low refractive index portion 14c and the second low refractive index portion 15b are continuous with each other, and the second low refractive index portion 15b and the second low refractive index region 16 are continuous with each other. It is composed of the same material.

That is, the wavelength selection filter 10 includes a base material 11, a concavo-convex structure layer 17 located on the base material 11 and having a concavo-convex structure composed of a plurality of convex portions 17a arranged in a two-dimensional lattice on the surface, and concavo-convex. It is a structure including a high refractive index layer 18 arranged along the surface of the structural layer 17 and having a surface shape following the uneven structure, and an embedded layer 19 for filling the unevenness on the surface of the high refractive index layer 18. It can also be regarded as.

The uneven structure layer 17 is composed of a first low refractive index region 12, a first low refractive index portion 13b, and an isolated low refractive index portion 14b, and the convex portion 17a is composed of a first low refractive index portion 13b and an isolated low refractive index. It is composed of a part 14b.

The high refractive index layer 18 is composed of a first high refractive index portion 13a, a side high refractive index portion 14a, and a second high refractive index portion 15a. The first high refractive index portion 13a is located between the plurality of convex portions 17a, that is, at the bottom of the concave-convex structure. The side high-refractive index portion 14a is between the ends of the first high-refractive index portion 13a and the second high-refractive index portion 15a, which are in contact with the side surface of the convex portion 17a and are adjacent to each other when viewed from the direction along the first direction. It extends in the thickness direction of the intermediate region 14 so as to connect the two. The second high refractive index portion 15a covers the top surface of the convex portion 17a, that is, is located at the top of the uneven structure.

The embedded layer 19 is composed of an outer peripheral low refractive index portion 14c, a second low refractive index portion 15b, and a second low refractive index region 16, and has an outer peripheral low refractive index from the second low refractive index region 16 toward the base material 11. The rate portion 14c and the second low refractive index portion 15b have a protruding shape.

The refractive index of the material of the high refractive index layer 18 is larger than the refractive index of each of the materials of the concave-convex structure layer 17 and the embedded layer 19. That is, the refractive indexes of the first high refractive index portion 13a, the side high refractive index portion 14a, and the second high refractive index portion 15a are the first low refractive index region 12, the first low refractive index portion 13b, and the isolated low. It is larger than the refractive index of each of the refractive index portion 14b, the outer peripheral low refractive index portion 14c, the second low refractive index portion 15b, and the second low refractive index region 16. The uneven structure layer 17 and the embedded layer 19 may be made of the same material or may be made of different materials.

When the selection target of the wavelength selection filter 10 is light in the visible region, the low refractive index material constituting the concave-convex structure layer 17 and the embedded layer 19 includes an inorganic substance such as synthetic quartz, an ultraviolet curable resin, and heat. It is possible to use a resin material such as a plastic resin or a thermosetting resin. In this case, the high refractive index materials constituting the high refractive index layer 18 include TiO ₂ (titanium oxide), Nb ₂ O ₅ (niobium oxide), Ta ₂ O ₅ (tantalum oxide), ZrO (zirconium oxide), and ZnS. Inorganic compound materials such as (zinc sulfide), ITO (indium tin oxide), and AlN (aluminum nitride) can be used.

[Action of wavelength selection filter]
The period of the lattice structure in the first lattice region 13, that is, the period of the arrangement of the first low refractive index portion 13b is the first period P1, and the first period P1 is smaller than the wavelength of light in the visible region. Similarly, the period of the lattice structure in the second lattice region 15, that is, the period of the arrangement of the second high refractive index portion 15a is the second period P2, and the second period P2 is larger than the wavelength of light in the visible region. small. That is, the first period P1 and the second period P2 are sub-wavelength periods, and each of the first lattice region 13 and the second lattice region 15 includes a sub-wavelength lattice.

In the wavelength selection filter 10, the average refractive index for each region is the refractive index of the high refractive index portion and the refractive index of the low refractive index portion, depending on the volume ratio of the high refractive index portion and the low refractive index portion in each region. Is approximated to the averaged value. The side high refractive index portion 14a in the intermediate region 14 is larger than the ratio of the first high refractive index portion 13a in the first lattice region 13 and the ratio of the second high refractive index portion 15a in the second lattice region 15. The proportion is small. Therefore, the average refractive index of the intermediate region 14 is smaller than the average refractive index of the first lattice region 13 and the average refractive index of the second lattice region 15. That is, the wavelength selection filter 10 has a structure in which sub-wavelength lattices located in each of the first lattice region 13 and the second lattice region 15 are embedded in a region having a low refractive index.

When light is incident on the wavelength selection filter 10 from the surface side of the wavelength selection filter 10, the sub-wavelength lattice of the second lattice region 15 is embedded in the region having a low refractive index. Therefore, in the second lattice region 15, the surface is The emission of diffracted light to the side is suppressed, and a waveguide mode resonance phenomenon occurs. That is, light in a specific wavelength region propagates while being multiple-reflected in the second lattice region 15 to cause resonance, and the light in this specific wavelength region is emitted as reflected light to the surface side of the wavelength selection filter 10.

The light transmitted through the second lattice region 15 and further transmitted through the intermediate region 14 enters the first lattice region 13. When light is incident on the first lattice region 13, the sub-wavelength lattice of the first lattice region 13 is embedded in the region having a low refractive index, so that the waveguide mode resonance phenomenon also occurs in the first lattice region 13. That is, light in a specific wavelength region propagates while being multiple-reflected in the first lattice region 13 to cause resonance, and the light in this specific wavelength region is emitted as reflected light to the surface side of the wavelength selection filter 10.

The light transmitted through the first lattice region 13 is transmitted through the first low refractive index region 12 and the base material 11 and exits to the back surface side of the wavelength selection filter 10.
As a result, the light in the wavelength region enhanced in the second lattice region 15 and the light in the wavelength region enhanced in the first lattice region 13 are emitted to the surface side of the wavelength selection filter 10. Then, in the wavelength range included in the incident light to the wavelength selection filter 10, the light in the wavelength range other than the wavelength range emitted as the reflected light is emitted to the back surface side of the wavelength selection filter 10 as transmitted light. ..

When light is incident on the wavelength selection filter 10 from the back surface side of the wavelength selection filter 10, the reflected light in the wavelength range strengthened in the second lattice region 15 and the wavelength range strengthened in the first lattice region 13 are used. The reflected light of the above is emitted to the back surface side of the wavelength selection filter 10. Then, among the wavelength ranges included in the incident light, the light in the wavelength range other than the wavelength range emitted as the reflected light is emitted to the surface side of the wavelength selection filter 10 as transmitted light.

[Detailed configuration of wavelength selection filter]
The configuration for enhancing the wavelength selectivity, that is, for enhancing the intensity of the wavelength range of a specific range in the reflected light, will be described in the wavelength selection filter 10 described above.

In the wavelength selection filter 10, if the wavelength range of the light that causes resonance in the first lattice region 13 and the wavelength range of the light that causes resonance in the second lattice region 15 match, the wavelength selection filter 10 determines the reflected light. The intensity of the emitted light in the wavelength range is increased, and the wavelength selectivity of the reflected light is enhanced.

For example, when light in a specific wavelength region resonates in the second lattice region 15, when the difference in refractive index between the second lattice region 15 and the intermediate region 14 is small, the light in the specific wavelength region is described. A portion of the light leaks into the intermediate region 14 for each reflection within the second grid region 15. Even in such a case, if the wavelength regions of the light causing resonance in the first grid region 13 and the second grid region 15 are the same, the light in the specific wavelength region leaked to the intermediate region 14 is the first grid. It enters the region 13 and causes resonance, and is emitted as reflected light. Therefore, as compared with the wavelength selection filter having only one lattice region, the intensity of the light in the specific wavelength region emitted from the wavelength selection filter 10 as the reflected light is increased, and the wavelength selectivity of the reflected light is enhanced. ..

In order to match the wavelength regions of light that cause resonance in the first grid region 13 and the second grid region 15, the average refractive index and the film thickness are multiplied in the first grid region 13 and the second grid region 15. It suffices to match the optical film thickness, which is a parameter expressed as a value. That is, in the first lattice region 13 and the second lattice region 15, the closer the optical film thickness is, the closer the wavelength region of the light that causes resonance becomes, and the wavelength selectivity of the reflected light is enhanced. The inventor of the present application has found a range of the ratio of the optical film thickness of the first lattice region 13 and the second lattice region 15 to obtain good wavelength selectivity for reflected light by simulation. This content will be described in detail below.

In FIG. 2, (a) is a diagram showing a cross section orthogonal to the first direction in the first lattice region 13 together with a cross section of the wavelength selection filter 10, and (b) is a diagram orthogonal to the first direction in the second lattice region 15. It is a figure which shows the cross section to be performed together with the cross section of the wavelength selection filter 10. The second direction and the third direction are directions along the surface of the base material 11, and each of the second direction and the third direction is orthogonal to the first direction. The second direction and the third direction are orthogonal to each other.

As shown in FIG. 2A, in the first lattice region 13, the plurality of first low refractive index portions 13b are arranged in a two-dimensional lattice pattern. The type of the two-dimensional lattice is not particularly limited, and the first low refractive index portion 13b may be located at the lattice point of the lattice formed by the intersection of two parallel line groups extending in different directions. For example, the two-dimensional lattice formed by the first low refractive index unit 13b may be a square lattice or a hexagonal lattice. The first period P1, which is the period of the lattice structure in the first lattice region 13, coincides with each other in each direction in which the two-dimensional lattice extends.

The shape of the first low refractive index portion 13b is not particularly limited when viewed from the direction along the first direction. For example, when the first low refractive index portion 13b is square, the average refractive index of the first lattice region 13 is increased. It is easy to set the specified volume ratio.

The volume ratio of the first high refractive index portion 13a to the entire first lattice region 13 is the volume ratio of the first high refractive index portion 13a to the entire first lattice region 13 in a plan view seen from the direction along the first direction. Equal to the area ratio. In other words, the area ratio is the area ratio occupied by the first high refractive index portion 13a in the cross section including the first high refractive index portion 13a and orthogonal to the thickness direction thereof. When the area of the first high refractive index portion 13a changes depending on the position of the cross section, the area ratio of the first high refractive index portion 13a in the cross section where the area of the first high refractive index portion 13a is maximized is adopted. ..

When the area ratio of the first high refractive index portion 13a is R1, the area ratio of the first low refractive index portion 13b in the cross section is represented by 1-R1.
When the refractive index of the material of the high refractive index layer 18 is n1 and the refractive index of the material of the concave-convex structure layer 17 is n2 (n1> n2), the average refractive index NA1 of the first lattice region 13 is the following equation (1). Represented by.

NA1 = n1 × R1 + n2 × (1-R1) ・ ・ ・ (1)
The optical film thickness OT1 of the first lattice region 13 is represented by the following equation (2).
OT1 = T1 x NA1
= T1 × {n1 × R1 + n2 × (1-R1)} ・ ・ ・ (2)
As shown in FIG. 2B, in the second lattice region 15, the plurality of second high refractive index portions 15a are arranged in a two-dimensional lattice pattern that coincides with the first lattice region 13. The second period P2, which is the period of the lattice structure in the second lattice area 15, coincides with the first period P1 in the first lattice area 13.

However, when viewed from the direction along the first direction, the second high refractive index portions 15a scattered in the second lattice region 15 are larger than the first low refractive index portions 13b scattered in the first lattice region 13. .. In other words, the width of the second high refractive index portion 15a is larger than the width of the first low refractive index portion 13b in each of the second direction and the third direction. Therefore, the width of the second low refractive index portion 15b is smaller than the width of the first high refractive index portion 13a. The second high refractive index portion 15a has a shape similar to the shape of the first low refractive index portion 13b when viewed from the direction along the first direction.

The volume ratio of the second high refractive index portion 15a to the entire second lattice region 15 is the volume ratio of the second high refractive index portion 15a to the entire second lattice region 15 in a plan view seen from the direction along the first direction. Equal to the area ratio. In other words, the area ratio is the area ratio occupied by the second high refractive index portion 15a in the cross section including the second high refractive index portion 15a and orthogonal to the thickness direction thereof. When the area of the second high refractive index portion 15a changes depending on the position of the cross section, the area ratio of the second high refractive index portion 15a in the cross section where the area of the second high refractive index portion 15a is maximized is adopted. ..

When the area ratio of the second high refractive index portion 15a is R2, the area ratio of the second low refractive index portion 15b in the cross section is represented by 1-R2.
When the refractive index of the material of the high refractive index layer 18 is n1 and the refractive index of the material of the embedded layer 19 is n3 (n1> n3), the average refractive index NA2 of the second lattice region 15 is the following equation (3). Represented by.

NA2 = n1 × R2 + n3 × (1-R2) ・ ・ ・ (3)
The optical film thickness OT2 of the second lattice region 15 is represented by the following equation (4).
OT2 = T2 x NA2
= T2 × {n1 × R2 + n3 × (1-R2)} ・ ・ ・ (4)
When the ratio (OT2 / OT1) of the optical film thickness OT2 of the second lattice region 15 to the optical film thickness OT1 of the first lattice region 13 is 0.7 or more and 1.3 or less, the reflected light in the wavelength selection filter 10 It was confirmed that good wavelength selectivity for the above was obtained.

In particular, when the thickness T1 of the first lattice region 13 and the thickness T2 of the second lattice region 15 are equal, and the refractive index n2 of the material of the concave-convex structure layer 17 and the refractive index n3 of the material of the embedded layer 19 are equal. It is preferable that the area ratio R1 of the first high refractive index portion 13a and the area ratio R2 of the second high refractive index portion 15a are equal to each other because the optical film thickness OT1 and the optical film thickness OT2 match.

As described above, the second high refractive index portion 15a is larger than the first low refractive index portion 13b when viewed from the direction along the first direction. Therefore, in the present embodiment, in order to bring the area ratio R1 of the first high refractive index portion 13a and the area ratio R2 of the second high refractive index portion 15a close to each other, the first low refractive index portion 13 in the first lattice region 13 The area ratio of 13b is made smaller than the area ratio of the first high refractive index portion 13a, and the area ratio of the second high refractive index portion 15a in the second lattice region 15 is smaller than the area ratio of the second low refractive index portion 15b. It's getting bigger. Therefore, each of the area ratio R1 of the first high refractive index portion 13a and the area ratio R2 of the second high refractive index portion 15a is larger than 0.5, and R1 + R2 is larger than 1.

Since the area ratios R1 and R2 are larger than 0.5, the average refractive index of the lattice regions 13 and 15 is higher than that in the form in which the area ratios R1 and R2 are 0.5 or less. Since the difference in the average refractive index between the 13 and 15 and the adjacent regions 12, 14 and 16 becomes large, and as a result, the loss due to the multiple reflections generated in the respective lattice regions 13 and 15 becomes small, the lattice region 13, The intensity of the reflected light emitted from 15 is increased.

FIG. 3 is a diagram showing a cross section orthogonal to the first direction in the intermediate region 14 together with a cross section of the wavelength selection filter 10. As shown in FIG. 3, in the intermediate region 14, the plurality of isolated low refractive index portions 14b are arranged in a two-dimensional lattice pattern that coincides with the first lattice region 13. The third period P3, which is the period of the arrangement of the isolated low refractive index portion 14b in the intermediate region 14, coincides with the first period P1 in the first lattice region 13. The size of the isolated low refractive index portion 14b is the same as that of the first low refractive index portion 13b when viewed from the direction along the first direction. The side high-refractive index portion 14a surrounds the isolated low-refractive index portion 14b one by one, and the outer peripheral low-refractive index portion 14c fills the space between the side high-refractive index portions 14a adjacent to each other.

Here, the area ratio of the side high refractive index portion 14a to the entire intermediate region 14 in the plan view seen from the direction along the first direction is the first low with the area ratio of the second high refractive index portion 15a. It is preferably equal to or less than the difference from the area ratio of the refractive index portion 13b. That is, when the area ratio of the side high refractive index portion 14a is R3, it is preferable that R3 satisfies the following formula (5). In other words, the area ratio is the area ratio occupied by the side high refractive index portion 14a in the cross section including the side high refractive index portion 14a and orthogonal to the thickness direction thereof. When the area of the side high refractive index portion 14a changes depending on the position of the cross section, the area ratio of the side high refractive index portion 14a in the cross section where the area of the side high refractive index portion 14a is maximized is adopted. ..

R3 ≤ R2- (1-R1) = R1 + R2-1 ... (5)
When the above formula (5) is satisfied, the second high refractive index portion 15a extends to the outside of the isolated low refractive index portion 14b and the side high refractive index portion 14a when viewed from the direction along the first direction. ing. Specifically, when the region where the second high refractive index portion 15a is located coincides with the region where the isolated low refractive index portion 14b and the side high refractive index portion 14a are located when viewed from the direction along the first direction. The area ratio R3 of the side high refractive index portion 14a coincides with the right side and becomes R1 + R2-1. Then, when the region where the second high refractive index portion 15a is located is larger than the region where the isolated low refractive index portion 14b and the side high refractive index portion 14a are located when viewed from the direction along the first direction, in other words. For example, when the side high-refractive index portion 14a is located in a region inside the outer edge of the second high-refractive index portion 15a, the area ratio R3 is smaller than R1 + R2-1.

As described above, in order to increase the intensity of the reflected light emitted from the lattice regions 13 and 15 by the waveguide mode resonance phenomenon, the average refractive index of the lattice regions 13 and 15 and the lattice are used for each of the lattice regions 13 and 15. It is desirable that the difference from the average refractive index of the regions 12, 14 and 16 sandwiching the regions 13 and 15 is large. Therefore, the smaller the average refractive index of the intermediate region 14, the more preferable, that is, the smaller the area ratio of the side high refractive index portion 14a, the more preferable. If the configuration (5) is satisfied, the width of the side high-refractive index portion 14a is suppressed to the extent that it does not extend to the outside of the second high-refractive index portion 15a, so that the side high-refractive index The area ratio of the portion 14a does not become too large. Therefore, the intensity of the reflected light from each of the lattice regions 13 and 15 becomes good.

In order to increase the intensity of the reflected light, the difference between the average refractive index of the first lattice region 13 and the average refractive index of each of the first low refractive index region 12 and the intermediate region 14 is more than 0.1. Is also preferable. Similarly, the difference between the average refractive index of the second lattice region 15 and the average refractive index of each of the intermediate region 14 and the second low refractive index region 16 is preferably larger than 0.1.

In the present embodiment, the elements constituting the sub-wavelength grid are arranged in a two-dimensional grid pattern. For example, the elements constituting the sub-wavelength grid extend in a band shape in the second or third direction. However, it is possible to cause a waveguide mode resonance phenomenon. However, when the element extends in one direction, in the lattice region having the element, only the light polarized in a specific direction depending on the arrangement direction of the element is multiple-reflected and resonates, and is used as reflected light. Be ejected. On the other hand, as in the present embodiment, when the above elements are arranged in a two-dimensional lattice pattern, light polarized in different directions can be resonated. Therefore, the reflected light is efficiently emitted with respect to the incident light containing the polarized light components in various directions, so that the intensity of the reflected light is further increased.

In particular, in the case where the elements are arranged in a hexagonal lattice pattern, the directions of polarization that can be resonated in the lattice region are larger than in the form in which the elements are arranged in a square lattice pattern, so that the polarized light is polarized in various directions. The reflected light can be emitted more efficiently with respect to the incident light containing the component.

[Manufacturing method of wavelength selection filter]
A method for manufacturing the wavelength selection filter 10 will be described with reference to FIGS. 4 to 6.
As shown in FIG. 4, first, a layer made of a low refractive index material is formed on the surface of the base material 11, and a concavo-convex structure is formed on the surface of this layer to form the concavo-convex structure layer 17. The uneven structure layer 17 has a flat portion 17c extending along the base material 11 and a plurality of convex portions 17a protruding from the flat portion 17c, and also has a plurality of concave portions 17b which are portions located between the convex portions 17a. .. The plurality of convex portions 17a are separated from each other, and the concave portions 17b form one continuous concave portion.

A known microfabrication technique such as a nanoimprint method or a dry etching method is used to form the uneven structure. Among them, the nanoimprint method is preferable because fine convex portions 17a and concave portions 17b can be easily formed.

For example, when an ultraviolet curable resin is used as a low refractive index material and the concave-convex structure layer 17 is formed by the optical nanoimprint method, the surface of the base material 11 is first coated with the ultraviolet curable resin. Next, a synthetic quartz mold, which is a concave plate having inverted unevenness of unevenness composed of convex portions 17a and concave portions 17b to be formed, is pressed against the surface of the coating layer made of an ultraviolet curable resin, and the coating layer and the concave plate are pressed. Irradiate with ultraviolet rays. Subsequently, the intaglio is released from the cured ultraviolet curable resin. As a result, the unevenness of the intaglio is transferred to the ultraviolet curable resin to form the convex portion 17a and the concave portion 17b, and the convex portion 17a and the concave portion 17b and the base material 11 are made of an ultraviolet curable resin. A flat portion 17c is formed as a residual film.

Next, as shown in FIG. 5, a high refractive index layer 18 made of a high refractive index material is formed on the surface of the concave-convex structure layer 17. As a method for forming the high refractive index layer 18, a known film forming technique such as a vacuum vapor deposition method or a sputtering method is used. The thickness of the high refractive index layer 18 is smaller than the height of the convex portion 17a, and is set according to the desired thickness T1 and thickness T2.

When the high refractive index layer 18 is formed by a physical vapor deposition method including a vacuum vapor deposition method or a sputtering method, a film is formed on the convex portion 17a of the concave-convex structure layer 17 so as to spread more than the convex portion 17a. To. That is, the width of the second high refractive index portion 15a is formed larger than the width of the first low refractive index portion 13b and the isolated low refractive index portion 14b, which are the convex portions 17a. Therefore, when the physical vapor deposition method is adopted, even if the area ratio of the convex portion 17a and the concave portion 17b on the surface of the concave-convex structure layer 17 is set to 1: 1, the first high refractive index portion 13a and the first high refractive index portion 13a 2 The area ratio with the high refractive index portion 15a is deviated.

Further, if the width of the second high refractive index portion 15a is expanded during the film formation, it becomes difficult for the particles of the vapor deposition material to adhere to the recess 17b, so that the thickness T1 of the first high refractive index portion 13a and the first 2 There may be a deviation from the thickness T2 of the high refractive index portion 15a.

The ratio of the optical film thickness OT2 to the optical film thickness OT1 is 0.7 or more and 1.3 or less while compensating for the deviation in the area ratio and the thickness caused by the expansion of the width of the second high refractive index portion 15a. Therefore, it is desirable to set the area ratio between the convex portion 17a and the concave portion 17b. In the case where the convex portions 17a are arranged in a two-dimensional lattice pattern as in the present embodiment, the degree of freedom regarding the size and arrangement of the convex portions 17a is high, so when setting the area ratio between the convex portions 17a and the concave portions 17b. It is easy to make fine adjustments.

Further, when the high refractive index layer 18 is formed by the physical vapor deposition method, the high refractive index material often adheres to the side surface of the convex portion 17a of the concave-convex structure layer 17, and the side high refractive index portion 14a The formation of is inevitable. Therefore, as described above, while adopting a manufacturing method in which the side high refractive index portion 14a is formed by controlling the width of the side high refractive index portion 14a so that the above formula (5) is satisfied. In addition, the intensity of the reflected light from the lattice regions 13 and 15 can be obtained satisfactorily.

The width of the side high refractive index portion 14a can be controlled by the film forming method and the film forming conditions. For example, since the vacuum vapor deposition method and the sputtering method have different angular dependences on the flying direction of the particles, the width of the side high refractive index portion 14a can be changed depending on which method is used. Further, the width of the side high refractive index portion 14a may be reduced by performing etching after the formation of the high refractive index layer 18.

Next, as shown in FIG. 6, an embedded layer 19 made of a low refractive index material is formed so as to cover the surface of the structure composed of the concave-convex structure layer 17 and the high refractive index layer 18, and the high refractive index is formed. The unevenness of the surface of the layer 18 is filled up to the second high refractive index portion 15a.

As a method for forming the embedded layer 19, known film forming techniques such as various coating methods are used. For example, when an ultraviolet curable resin is used as the low refractive index material, first, the surface of the high refractive index layer 18 is coated with the ultraviolet curable resin. Next, a flat plate made of a material that transmits ultraviolet rays is pressed against the surface of the coating layer made of an ultraviolet curable resin, and the coating layer is irradiated with ultraviolet rays. Subsequently, the flat plate is released from the cured ultraviolet curable resin.

As described above, in the wavelength selection filter 10, the reflection obtained by emitting the light in the wavelength region enhanced in the first lattice region 13 and the light in the wavelength region enhanced in the second lattice region 15 is emitted. The intensity of light increases. Therefore, specifically, when the wavelength selection filter 10 is formed by using the nanoimprint method without requiring precise control of the film thickness of the layer in contact with the first lattice region 13 and the second lattice region 15, The wavelength selection filter 10 with improved wavelength selectivity can be manufactured without requiring precise control of the film thickness of the residual film. Therefore, the wavelength selection filter 10 can be easily manufactured.

Further, since the wavelength selection filter 10 can be formed by a manufacturing method that combines an optical nanoimprint method, a vacuum vapor deposition method, or the like, it is suitable for manufacturing by a roll-to-roll method. Therefore, the configuration of the wavelength selection filter 10 is also suitable for mass production.

In the above-mentioned manufacturing method, the concave-convex structure layer 17 may be formed by the nanoimprint method using a thermosetting resin or a thermoplastic resin instead of the ultraviolet curable resin. When a thermosetting resin is used, the irradiation of ultraviolet rays may be changed to heating, and when a thermoplastic resin is used, the irradiation of ultraviolet rays may be changed to heating and cooling.

However, when the concave-convex structure layer 17 is formed by using the thermoplastic resin, a material different from the thermoplastic resin is used in order to prevent the concave-convex structure layer 17 from being heated and deformed when the embedded layer 19 is formed. It is preferable to form the embedded layer 19. For example, the concavo-convex structure layer 17 may be formed of a thermoplastic resin, and the embedded layer 19 may be formed of an ultraviolet curable resin.

Further, as shown in FIG. 7, the wavelength selection filter 10 does not have to include the base material 11. In this case, the uneven structure layer 17 is formed by forming the uneven structure on the surface of the base material made of the low refractive index material. For example, a sheet made of a thermoplastic resin may be used to form an uneven structure on the surface of the sheet, or a substrate made of synthetic quartz may be used to form an uneven structure on the surface of the substrate. A known technique such as a dry etching method may be used for forming the uneven structure on the synthetic quartz substrate.

[Application example of wavelength selection filter]
A specific application example of the wavelength selection filter 10 described above will be described.
<Wavelength selection device>
The first application example of the wavelength selection filter 10 is a form in which the wavelength selection filter 10 is used as a wavelength selection device. As shown in FIG. 8, when the wavelength selection device 50 receives incident light I1 containing light having a plurality of wavelengths, it reflects light I2 in a specific wavelength range and excludes light in this specific wavelength range. It transmits light I3 in the region. The configuration of the wavelength selection filter 10 is applied to the wavelength selection device 50, and the wavelength selection device 50 is arranged so that light is incident from the surface side of the wavelength selection filter 10, for example. The wavelength regions of light I2 and light I3 can be adjusted by setting the period and thickness of the sub-wavelength grids of the first grid region 13 and the second grid region 15.

The wavelength selection device 50 may be used in a form of utilizing light I2 which is reflected light, may be used in a form of utilizing light I3 which is transmitted light, or both light I2 and light I3. It may be used in the form of utilizing. For example, the wavelength selection device 50 is used as a device that requires color separation, a member that constitutes lighting, and the like.

As described above, the wavelength selection filter 10 of the first embodiment enhances the wavelength selectivity. Therefore, by applying the configuration of the wavelength selection filter 10, the wavelength selection device 50 with enhanced wavelength selectivity can be obtained. realizable.

As an example, the wavelength selection device 50 may be used in a display device that displays each color by converting blue light from a light source. This display device includes sub-pixels of three colors of red, green, and blue. In each of the sub-pixels of red and green, for example, using quantum dots, blue light from a light source is used as red light and green light, respectively. Convert to. The wavelength selection device 50 is arranged on the surface side of the display device, that is, on the side opposite to the light source with respect to the layer having the sub-pixels. In the wavelength selection device 50, the configuration of the wavelength selection filter 10 is applied to a region facing each of the red and green sub-pixels, and in this region, blue light is reflected and red and green light is transmitted. The wavelength selection device 50 is configured. According to such a configuration, even when a part of the blue light from the light source passes through the red and green sub-pixels, the blue light leaked from the sub-pixels is reflected by the wavelength selection device 50. Therefore, it is possible to prevent blue light from leaking to the surface side of the display device in the region corresponding to each of the red and green sub-pixels. Therefore, it is possible to enhance the sharpness of the color exhibited by each sub-pixel, and it is possible to display a vivid image.

<Display body>
A second application example of the wavelength selection filter 10 is a form in which the wavelength selection filter 10 is used as a display body. The display body may be used for the purpose of increasing the difficulty of counterfeiting the article, may be used for the purpose of enhancing the design of the article, or may be used for these purposes in combination. For the purpose of increasing the difficulty of counterfeiting goods, the display body is, for example, authentication documents such as passports and driver's licenses, securities such as gift certificates and checks, cards such as credit cards and cash cards, banknotes, etc. It can be pasted. In addition, for the purpose of enhancing the design of the article, the display body is, for example, a decorative object to be worn, an article carried by a user, an article to be stationary such as furniture or a home appliance, a wall, a door, or the like. It can be attached to structures, etc.

As shown in FIG. 9, the display body 60 has a front surface 60F and a back surface 60R which is a surface opposite to the front surface 60F, and the display body 60 is the first display body 60 when viewed from the direction facing the front surface 60F. The display area 61A, the second display area 61B, and the third display area 61C are included. The first display area 61A is an area in which a plurality of first pixels 62A are arranged, the second display area 61B is an area in which a plurality of second pixels 62B are arranged, and the third display area 61C is an area in which a plurality of second pixels 62B are arranged. , This is an area in which a plurality of third pixels 62C are arranged. In other words, the first display area 61A is composed of a set of a plurality of first pixels 62A, and the second display area 61B is composed of a set of a plurality of second pixels 62B, and is a third display area. The 61C is composed of a set of a plurality of third pixels 62C.

Each of the first display area 61A, the second display area 61B, and the third display area 61C may be a character, a symbol, a figure, a pattern, a pattern, or a combination of these areas alone or two or more of these areas. Express the background of. As an example, in the configuration shown in FIG. 9, a circular figure is represented by the first display area 61A, a triangular figure is represented by the second display area 61B, and a background is represented by the third display area 61C.

The configuration of the wavelength selection filter 10 is applied to each of the first pixel 62A, the second pixel 62B, and the third pixel 62C. The first pixel 62A, the second pixel 62B, and the third pixel 62C are arranged so that the second direction and the third direction are along the surface 60F of the display body 60. For example, these pixels 62A, 62B, and 62C are arranged so that the surface side of the wavelength selection filter 10 is the surface side of the display body 60.

The wavelength ranges in which resonance due to the waveguide mode resonance phenomenon occurs in the first pixel 62A, the second pixel 62B, and the third pixel 62C are different from each other. The wavelength range in which resonance occurs in each pixel 62A, 62B, 62C is a desired wavelength for each pixel 62A, 62B, 62C by adjusting the period of the sub-wavelength grids of the first grid region 13 and the second grid region 15. It is set in the area. Therefore, when incident light including light of a plurality of wavelengths is received, the wavelength range of the reflected light emitted from the first pixel 62A, the wavelength range of the reflected light emitted from the second pixel 62B, and the third pixel 62C The wavelength range of the light emitted from is different from each other. Further, when the incident light is received, the wavelength range of the transmitted light emitted from the first pixel 62A, the wavelength range of the transmitted light emitted from the second pixel 62B, and the transmitted light emitted from the third pixel 62C. Wavelength range is different from each other.

That is, as shown in FIG. 10, when the incident light I1 is irradiated from the outside of the display body 60 toward the surface 60F of the display body 60, the surface side of the display body 60 is reflected light from the first pixel 62A. I4 is emitted, reflected light I5 is emitted from the second pixel 62B, and reflected light I6 is emitted from the third pixel 62C. Therefore, when the surface 60F of the display body 60 is viewed from the surface side, the hue color corresponding to the wavelength range of the reflected light I4 is visually recognized in the first display area 61A, and the wavelength of the reflected light I5 is recognized in the second display area 61B. The hue color corresponding to the region is visually recognized, and the hue color corresponding to the wavelength region of the reflected light I6 is visually recognized in the third display region 61C. Since the wavelength range of the reflected light I4, the wavelength range of the reflected light I5, and the wavelength range of the reflected light I6 are different from each other, the first display area 61A, the second display area 61B, and the third display area 61C have different hues. Looks like the color of.

As a result, according to surface reflection observation in which the surface 60F is observed from the surface side of the display body 60 in a state where the incident light I1 is irradiated from the outside of the display body 60 toward the surface 60F, the first colors having different colors are the first. An image composed of the display area 61A, the second display area 61B, and the third display area 61C is visually recognized.

Further, when the incident light I1 is irradiated from the outside of the display body 60 toward the surface 60F of the display body 60, the transmitted light I7 is emitted from the first pixel 62A to the back surface side of the display body 60, and the second The transmitted light I8 is emitted from the pixel 62B, and the transmitted light I9 is emitted from the third pixel 62C. Therefore, when the back surface 60R of the display body 60 is viewed from the back surface side, the hue color corresponding to the wavelength range of the transmitted light I7 is visually recognized in the first display area 61A, and the wavelength of the transmitted light I8 is displayed in the second display area 61B. The hue color corresponding to the region is visually recognized, and the hue color corresponding to the wavelength region of the transmitted light I9 is visually recognized in the third display region 61C. Since the wavelength range of the transmitted light I7, the wavelength range of the transmitted light I8, and the wavelength range of the transmitted light I9 are different from each other, the first display area 61A, the second display area 61B, and the third display area 61C have different hues. Looks like the color of.

As a result, even in the backside transmission observation in which the back surface 60R is observed from the back surface side of the display body 60 in a state where the incident light I1 is irradiated from the outside of the display body 60 toward the front surface 60F, the first display of different colors is also performed. An image composed of the area 61A, the second display area 61B, and the third display area 61C is visually recognized.

Further, since the wavelength range of the reflected light I4 and the wavelength range of the transmitted light I7 are different, the first display area 61A is obtained when the display body 60 is viewed from the front surface side and when the display body 60 is viewed from the back surface side. The hue of the color visually recognized is different. The color seen from the back surface side is a color corresponding to the complementary color of the color seen from the front surface side. Similarly, when the display body 60 is viewed from the front surface side and when the display body 60 is viewed from the back surface side, the hue of the color visually recognized in the second display area 61B is different, and the display body 60 is visually recognized in the third display area 61C. The hue of the color to be produced is also different.

Therefore, in the front surface reflection observation and the back surface transmission observation, images of different colors are visually recognized on the display body 60. Therefore, in the article provided with the display body 60, the difficulty of counterfeiting and the designability are further enhanced. In addition, it is easy to identify the front and back sides of the display body 60.

Then, as described above, since the wavelength selection filter 10 of the first embodiment enhances the wavelength selectivity, the configuration of the wavelength selection filter 10 is applied to each of the pixels 62A, 62B, 62C to display each display. The sharpness and brightness of the colors visually recognized in the regions 61A, 61B, and 61C are enhanced. Therefore, the visibility of the image formed by the display body 60 is enhanced. Further, in the wavelength selection filter 10 of the first embodiment, since a flexible base material 11 such as a resin film can be used, it is possible to realize a display body 60 having a high degree of freedom in shape deformation. It is possible.

Between the first pixel 62A, the second pixel 62B, and the third pixel 62C, the base material 11, the first low refractive index region 12, the first lattice region 13, the intermediate region 14, the second lattice region 15, and the first 2 Each of the low refractive index regions 16 is continuous. That is, the first pixel 62A, the second pixel 62B, and the third pixel 62C have a common base material 11, a concavo-convex structure layer 17 that is mutually continuous between these pixels, and each other between these pixels. It has a continuous high refractive index layer 18 and an embedded layer 19 which is continuous with each other between these pixels.

The concavo-convex structure layer 17 in each of the first pixel 62A, the second pixel 62B, and the third pixel 62C uses, for example, the nanoimprint method to change the concavo-convex cycle at the portion corresponding to each pixel 62A, 62B, 62C. It can be formed at the same time by using a synthetic quartz mold. Further, the high refractive index layer 18 and the embedded layer 19 can also simultaneously form portions corresponding to the pixels 62A, 62B, and 62C. Therefore, the pixels 62A, 62B, and 62C that exhibit different colors can be easily formed.

The number of display areas included in the display body 60, that is, the number of display areas in which pixels to which the configuration of the wavelength selection filter 10 is applied are arranged and exhibit colors having different hues from each other is not particularly limited, and the number of display areas is not particularly limited. The number may be one or four or more. Further, the display body 60 has a region having a configuration different from that of the wavelength selection filter 10, for example, a region having a structure in which only a flat layer made of a low refractive index material is laminated on the base material 11. You may.

Further, the display area may include a display element to which the configuration of the wavelength selection filter 10 is applied, and the display element is not limited to a pixel, which is the minimum unit of repetition for forming a raster image, and a vector image. It may be a region connecting anchors for forming.

<Color filter>
A third application example of the wavelength selection filter 10 is a form in which the wavelength selection filter 10 is used as a color filter.

As shown in FIG. 11, the color filter 70 includes a plurality of pixels 71 arranged in a matrix, and each pixel 71 has three sub-pixels 71R for red, sub-pixels 71G for green, and sub-pixels 71B for blue. It is composed of two sub-pixels.

The color filter 70 is a reflective color filter and is provided in the display device. The side of the color filter 70 where the observer looking at the display surface of the display device is located is the front side of the color filter 70, and the side opposite to the front side of the color filter 70 is the back side of the color filter 70. Is. The color filter 70 is irradiated with light from the surface side. The intensity of the light applied to the color filter 70 can be changed for each sub-pixel by a liquid crystal device or the like.

The red sub-pixel 71R converts the light incident on the red sub-pixel 71R into red light and reflects the light. The green sub-pixel 71G converts the light incident on the green sub-pixel 71G into green light and reflects it. The blue sub-pixel 71B converts the light incident on the blue sub-pixel 71B into blue light and reflects it.

The configuration of the wavelength selection filter 10 is applied to each of the red sub-pixel 71R, the green sub-pixel 71G, and the blue sub-pixel 71B. The red sub-pixel 71R, the green sub-pixel 71G, and the blue sub-pixel 71B are arranged so that the second direction and the third direction are along the surface of the color filter 70. .. For example, these sub-pixels 71R, 71G, and 71B are arranged so that the surface side of the wavelength selection filter 10 is the surface side of the color filter 70.

As shown in FIG. 12, when the red sub-pixel 71R receives the incident light I1 containing light of a plurality of wavelengths from the surface side of the color filter 70, the red reflected light Ir is emitted to the surface side. The period of the sub-wavelength lattice is set. When the green sub-pixel 71G receives the incident light I1, the period of the sub-wavelength grid or the like is set so as to emit the green reflected light Ig toward the surface side. When the blue sub-pixel 71B receives the incident light I1, the period of the sub-wavelength lattice or the like is set so as to emit the blue reflected light Ib to the surface side. By changing the intensity of the incident light for each of the sub-pixels 71R, 71G, and 71B, the color visually recognized as the pixel 71 is changed, and the image displayed by the display device is formed by the set of the pixels 71.

As described above, the wavelength selection filter 10 of the first embodiment enhances the wavelength selectivity. Therefore, by applying the configuration of the wavelength selection filter 10 to the sub-pixels 71R, 71G, 71B, each sub-pixel The sharpness and brightness of colors in 71R, 71G, and 71B are enhanced.

Further, similarly to the form of the display body 60 described above, between the red sub-pixel 71R, the green sub-pixel 71G, and the blue sub-pixel 71B, the base material 11, the first low refractive index region 12, and the first lattice Each of the region 13, the intermediate region 14, the second lattice region 15, and the second low refractive index region 16 is continuous. That is, the red sub-pixel 71R, the green sub-pixel 71G, and the blue sub-pixel 71B have a common base material 11, a concavo-convex structure layer 17 that is continuous between these sub-pixels, and their sub-pixels. It has a high refractive index layer 18 that is continuous with each other between pixels, and an embedded layer 19 that is continuous with each other between these sub-pixels.

The concavo-convex structure layer 17 in each of the red sub-pixel 71R, the green sub-pixel 71G, and the blue sub-pixel 71B is concavo-convex at a portion corresponding to each sub-pixel 71R, 71G, 71B by using, for example, the nanoimprint method. By using synthetic quartz molds with different cycles, they can be formed at the same time. Further, the high refractive index layer 18 and the embedded layer 19 can also simultaneously form portions corresponding to the sub-pixels 71R, 71G, and 71B. Therefore, the color filter 70 having the sub-pixels 71R, 71G, and 71B of three kinds of colors can be easily formed.

As described above, according to the first embodiment, the effects listed below can be obtained.
(1) When the ratio of the optical film thickness OT2 of the second lattice region 15 to the optical film thickness OT1 of the first lattice region 13 is 0.7 or more and 1.3 or less, each of the two lattice regions 13 and 15 Light in the near wavelength range enhanced by is obtained as reflected light. Therefore, the intensity of the light extracted as the reflected light is increased and the wavelength selectivity is enhanced as compared with the wavelength selection filter having only one lattice region.

(2) With respect to the area ratio R3 of the side high refractive index portion 14a in the intermediate region 14, the width of the side high refractive index portion 14a can be suppressed to be small by satisfying R3 ≦ R1 + R2-1. It is possible to prevent the average refractive index from becoming excessively large. Therefore, since the difference in the average refractive index between the lattice regions 13 and 15 and the adjacent regions thereof is satisfactorily secured, the intensity of the reflected light from the lattice regions 13 and 15 obtained by the waveguide mode resonance phenomenon becomes good. ..

Further, if the second high refractive index portion 15a extends to the outside of the side high refractive index portion 14a when viewed from the direction along the first direction, the width of the side high refractive index portion 14a can be suppressed to be small. Therefore, similarly to the above, the intensity of the reflected light from the lattice regions 13 and 15 becomes good.

(3) The thickness T1 of the first lattice region 13 and the thickness T2 of the second lattice region 15 are equal, and the refractive index n2 of the material of the concave-convex structure layer 17 and the refractive index n3 of the material of the embedded layer 19 are equal. In this case, if the area ratio R1 of the first high-refractive index portion 13a and the area ratio R2 of the second high-refractive index portion 15a are equal to each other, the optical film thickness OT1 and the optical film thickness OT2 match. Selectivity is especially enhanced.

(4) A step of forming the concavo-convex structure layer 17 made of a low refractive index material, a step of forming a high refractive index layer 18 on the surface of the concavo-convex structure layer 17, and a low refractive index material on the surface of the high refractive index layer 18. The wavelength selection filter 10 is formed by the step of forming the embedded layer 19 made of the above. Therefore, since the wavelength selectivity of the wavelength selection filter 10 is enhanced without requiring precise control of the film thickness of the layer in contact with the sub-wavelength lattice, the wavelength selection filter 10 can be easily manufactured.

In particular, in a manufacturing method in which a resin is used as a low refractive index material and a concave plate is pressed against a coating layer made of the resin to form the concavo-convex structure layer 17 by curing the resin, the concavo-convex structure layer 17 is formed by using the nanoimprint method. Therefore, the concavo-convex structure layer 17 having fine concavities and convexities can be preferably and easily formed.

(5) When the vacuum vapor deposition method is used to form the high refractive index layer 18, the second high refractive index portion 15a extends to the outside of the side high refractive index portion 14a when viewed from the direction along the first direction. , The high refractive index layer 18 is formed. According to such a manufacturing method, although the method of forming the side high-refractive index portion 14a on the side surface of the convex portion 17a is adopted, the width of the side high-refractive index portion 14a can be suppressed to be small, so that each lattice region 13, The intensity of the reflected light from 15 becomes good.

(Second Embodiment)
A second embodiment of the wavelength selection filter and the method for manufacturing the wavelength selection filter will be described with reference to FIGS. 13 to 16. Hereinafter, the differences between the second embodiment and the first embodiment will be mainly described, and the same reference numerals will be given to the same configurations as those of the first embodiment, and the description thereof will be omitted.

[Structure of wavelength selection filter]
The configuration of the wavelength selection filter of the second embodiment will be described with reference to FIGS. 13 and 14. As shown in FIG. 13, the wavelength selection filter 20 of the second embodiment has the first low refractive index region 12, the first lattice region 13, the intermediate region 14, and the second lattice region 15 described in the first embodiment. It also includes two resonance structure portions 21, which are structures composed of the second low refractive index region 16.

The first resonance structure portion 21A and the second resonance structure portion 21B, which are the two resonance structure portions 21, are adjacent to each other in the first direction, and the two resonance structure portions 21A and 21B are sandwiched between the two base materials 11. It has been. In other words, the wavelength selection filter 20 of the second embodiment has a structure in which two wavelength selection filters 10 having the configuration of the first embodiment are joined so that the second low refractive index regions 16 face each other. That is, the wavelength selection filter 20 of the second embodiment has four sub-wavelength grids arranged with a gap in the first direction, and these sub-wavelength grids have a structure embedded in a low refractive index material. There is. The side of the other base material 11 with respect to one base material 11 is the front surface side of the wavelength selection filter 20, and the side of one base material 11 with respect to the other base material 11 is the back surface side of the wavelength selection filter 20.

The first resonance structure portion 21A and the second resonance structure portion 21B may share a low refractive index region at their boundary portions. For example, in the example shown in FIG. 13, the second low refractive index region 16 included in the first resonance structure portion 21A and the second low refractive index region 16 included in the second resonance structure portion 21B are continuous, and these There are no region boundaries.

As shown in FIG. 13, the structural period Pk, which is the period of the arrangement of the convex portions 17a in the first resonance structure portion 21A, and the structural period Pk, which is the period of the arrangement of the convex portions 17a in the second resonance structure portion 21B, are the same. It may be different from each other as shown in FIG. The structural period Pk coincides with the first period P1 in the first lattice region 13.

In each of the first resonance structure portion 21A and the second resonance structure portion 21B, the ratio of the optical film thickness OT2 of the second lattice region 15 to the optical film thickness OT1 of the first lattice region 13 is 0.7 or more and 1.3. It is as follows. In the form in which the two resonance structure portions 21A and 21B have the same structural period Pk, it is preferable that the first resonance structure portion 21A and the second resonance structure portion 21B have the same ratio.

In the two resonance structure portions 21A and 21B, the directions in which the elements constituting the sub-wavelength lattice are arranged, in other words, the extending directions of the two-dimensional lattice may be the same or different. In the configuration in which the two-dimensional lattices in the two resonance structure portions 21A and 21B extend in different directions, the reflected light can be emitted corresponding to more directions with respect to polarized light.

[Action of wavelength selection filter]
In the configuration in which the two resonance structure portions 21A and 21B have the same structural period Pk, the wavelength regions of the light that causes resonance are close to each other in the four lattice regions 13 and 15 of the wavelength selection filter 20. By emitting the reflected light in the wavelength region enhanced in each of the four lattice regions 13 and 15 onto the surface side of the wavelength selection filter 20, the wavelength selection filter is compared with the wavelength selection filter 10 of the first embodiment. In the reflected light from 20, the intensity of the wavelength range in a specific range becomes higher, and the wavelength selectivity of the reflected light is further enhanced. At this time, as described above, if the ratio of the optical film thickness OT2 to the optical film thickness OT1 is the same in the first resonance structure portion 21A and the second resonance structure portion 21B, the four lattice regions 13 , 15 the variation in the optical film thickness is small, and the wavelength range of the light causing resonance in each of the lattice regions 13 and 15 becomes closer, which is preferable.

On the other hand, in the configuration in which the two resonance structure portions 21A and 21B have different structural periods Pk, the wavelength region of light that causes resonance in the lattice regions 13 and 15 of the first resonance structure portion 21A and the second resonance structure portion 21B The wavelength ranges of light that resonate in the lattice regions 13 and 15 of the above are different from each other. As a result, on the surface side of the wavelength selection filter 20, the light in the wavelength region enhanced in the lattice regions 13 and 15 of the first resonance structure portion 21A and the lattice regions 13 and 15 of the second resonance structure portion 21B Reflected light including light in the enhanced wavelength range is emitted.

Then, on the back surface side of the wavelength selection filter 20, light in a wavelength range other than the wavelength range emitted as the reflected light in the wavelength range included in the incident light on the wavelength selection filter 20 is emitted as transmitted light. To. According to such a configuration, the wavelength selection filter 20 expands the wavelength range included in the reflected light while increasing the intensity of the reflected light as compared with the case where the lattice region is one, and is included in the transmitted light. It is possible to narrow the wavelength range. Therefore, the degree of freedom in adjusting the hue observed as reflected light or transmitted light can be increased.

[Application example of wavelength selection filter]
The configuration of the wavelength selection filter 20 of the second embodiment may be applied to the wavelength selection device 50 or the display element included in the display body 60 as in the application example shown in the first embodiment. Alternatively, it may be applied to the sub-pixels included in the color filter 70.

For example, when a configuration in which the two resonance structure portions 21A and 21B have the same structural period Pk is applied, the wavelength selectivity of the reflected light is further enhanced in the wavelength selection device 50. Further, in the display body 60, the visibility of the image is enhanced by increasing the sharpness and brightness of the colors visually recognized in the display areas 61A, 61B, and 61C by surface reflection observation. Further, in the color filter 70, the color sharpness and brightness of the sub-pixels 71R, 71G, 71B are enhanced, and the reflection type color including the sub-pixels 71R, 71B, 71G that emit the reflected light having high monochromaticity. The filter 70 is realized.

Further, for example, when a configuration in which the two resonance structure portions 21A and 21B have different structural periods Pk is applied, the degree of freedom in adjusting the hue observed as reflected light or transmitted light is increased in the wavelength selection device 50. Be done. Further, in the display body 60, the degree of freedom in adjusting the hue of the image visually recognized in the front surface reflection observation and the back surface transmission observation is increased. Further, as the color filter 70, a transmission type color filter, that is, the color filter is irradiated with light from the back surface side of the color filter, and the observer sees the transmitted light transmitted through the color filter from the front surface side of the color filter. It is possible to realize a color filter used in the form.

Specifically, in the green sub-pixel 71G, the light in the red wavelength region is strengthened by the first resonance structure portion 21A and emitted as reflected light to the back surface side, and the blue wavelength is emitted by the second resonance structure portion 21B. It is configured so that the light in the region is strengthened and emitted as reflected light to the back surface side. According to such a configuration, when white incident light is received from the back surface side of the color filter 70, green transmitted light is emitted to the front surface side of the color filter 70, so that it is viewed from the front surface side of the color filter 70. , Green is visually recognized on the green sub-pixel 71G. Similarly, the red sub-pixel 71R is configured to emit transmitted light in the red wavelength region, and the blue sub-pixel 71B is configured to emit transmitted light in the blue wavelength region. As a result, a transmissive color filter 70 having sub-pixels 71R, 71B, and 71G that emit transmitted light having high monochromaticity is realized.

[Manufacturing method of wavelength selection filter]
A method for manufacturing the wavelength selection filter 20 of the second embodiment will be described with reference to FIGS. 15 and 16. First, in the production of the wavelength selection filter 20 of the second embodiment, the uneven structure layer 17 and the high refractive index layer 18 are sequentially formed on the base material 11 as in the first embodiment.

Subsequently, as shown in FIG. 15, the two concave-convex structures 22, which are structures composed of the base material 11, the concave-convex structure layer 17, and the high-refractive index layer 18, face each other so that the high-refractive index layers 18 face each other. Then, as shown in FIG. 16, these uneven structures 22 are joined by filling the region between the two concave-convex structures 22 with a low refractive index material. As a result, the wavelength selection filter 20 is formed.

As shown in FIG. 16, the portion formed between the two concave-convex structures 22 by embedding with a low refractive index material is the embedding layer 19. Similar to the first embodiment, if the low refractive index material constituting the embedded layer 19 is a material having a lower refractive index than the high refractive index material constituting the high refractive index layer 18, the concave-convex structure layer 17 is formed. It may be a material different from the material to be used. Further, in the two concave-convex structures 22, the low-refractive index material constituting the concave-convex structure layer 17 and the high-refractive index material forming the high refractive index layer 18 may be different from each other.

The second high-refractive index portions 15a may face each other in a state where the two concave-convex structures 22 face each other, or the first high-refractive index portion 13a in one concave-convex structure 22 and the other concave-convex structure. The second high refractive index portion 15a in the body 22 may face each other. Alternatively, the first high refractive index portion 13a in one concave-convex structure 22 faces a part of the first high refractive index portion 13a and a part of the second high refractive index portion 15a in the other concave-convex structure 22. May be good.

For example, by joining the concavo-convex structures 22 having the same period of the convex portions 17a as the two concavo-convex structures 22, the wavelength selection filter 20 in which the two resonance structure portions 21A and 21B have the same structural period Pk can be obtained. Can be formed. Further, for example, as two concave-convex structures 22, by joining the concave-convex structures 22 having different periods of the convex portions 17a, a wavelength selection filter 20 in which the two resonance structure portions 21A and 21B have structural periods Pk different from each other can be obtained. Can be formed.

The wavelength selection filter 20 may include three or more resonance structure portions 21 arranged in the first direction. In a configuration in which the wavelength selection filter 20 includes a plurality of resonance structure portions 21, if the structural period Pk in these resonance structure portions 21 is the same, the larger the number of resonance structure portions 21, the higher the intensity of the reflected light. Further, the plurality of resonance structure portions 21 may include a resonance structure portion 21 having the same structural period Pk and a resonance structure portion 21 having different structural periods Pk. According to such a configuration, it is possible to finely adjust the color of the reflected light and the transmitted light emitted from the wavelength selection filter 20.

In the production of the wavelength selection filter 20 having three or more resonance structure portions 21, the base material 11 and the uneven structure layer 17 of the concave-convex structure 22 are formed of a material capable of peeling the base material 11 from the concave-convex structure layer 17. To. Then, after the two concave-convex structures 22 are joined by the low-refractive index material, one base material 11 is peeled off, and the exposed concave-convex structure layer 17 and the other uneven structure 22 further form a low-refractive index material. By repeating the sandwiching and joining, the wavelength selection filter 20 having 6 or more sub-wavelength grids is formed.

As described above, according to the second embodiment, the following effects can be obtained in addition to the effects (1) to (5) of the first embodiment.
(6) According to the configuration in which the wavelength selection filter 20 includes a plurality of resonance structure portions 21 arranged in the first direction, the wavelength selection filter 10 includes four or more lattice regions 13 and 15, so that the wavelength selection filter 20 includes the wavelength selection filter 20. It is possible to further enhance the wavelength selectivity and increase the degree of freedom in adjusting the wavelength range included in the reflected light and the transmitted light.

(7) According to the configuration in which the structural periods Pk are equal in the plurality of resonance structure portions 21, the wavelength regions of the light causing resonance in the lattice regions 13 and 15 of each resonance structure portion 21 are close to each other. Therefore, since the light in the close wavelength range enhanced in the lattice regions 13 and 15 of each resonance structure portion 21 is emitted as the reflected light, the intensity of the wavelength range in a specific range becomes larger in the reflected light, and the reflected light. Wavelength selectivity is further enhanced.

(8) According to the configuration in which the ratio of the optical film thickness OT2 to the optical film thickness OT1 is the same in the first resonance structure portion 21A and the second resonance structure portion 21B, the optical film thickness is formed in the four lattice regions 13 and 15. That is, the wavelength range of the light that causes resonance in each of the lattice regions 13 and 15 becomes closer. Therefore, the wavelength selectivity of the reflected light is further enhanced.

(9) According to the configuration in which the structural period Pk of the first resonance structure portion 21A and the structural period Pk of the second resonance structure portion 21B are different from each other, resonance occurs in the lattice regions 13 and 15 of the first resonance structure portion 21A. The wavelength range of the light that causes resonance and the wavelength range of the light that causes resonance in the lattice regions 13 and 15 of the second resonance structure portion 21B are different from each other. Therefore, in the wavelength selection filter 20, the wavelength range included in the reflected light is expanded and the wavelength range included in the transmitted light is narrowed while increasing the intensity of the reflected light as compared with the case where the lattice region is one. It is possible. Therefore, the degree of freedom in adjusting the hue observed as reflected light or transmitted light can be increased.

(10) The wavelength selection filter 20 is formed by having two concave-convex structures 22 face each other so that the high-refractive index layers 18 face each other, and filling a region between the two concave-convex structures 22 with a low-refractive index material. Will be done. According to this, the wavelength selection filter 20 including a plurality of resonance structure portions 21 can be easily formed.

[Modification example]
Each of the above embodiments can be modified and implemented as follows.
-In each of the lattice regions 13 and 15, the period of the lattice structure may be different depending on the direction in which the two-dimensional lattice extends. According to such a configuration, it is possible to adjust the responsiveness to the wavelength range included in the reflected light and the polarized light by making the wavelength range in which resonance occurs different depending on the direction in which the two-dimensional lattice extends.

In the above embodiment, the concave-convex structure of the concave-convex structure layer 17 is composed of a plurality of convex portions 17a separated from each other and a single concave portion 17b continuous between the convex portions 17a. Instead, the concave-convex structure of the concave-convex structure layer 17 may be composed of a plurality of concave portions separated from each other and a single convex portion continuous between these concave portions. That is, the concave-convex structure of the concave-convex structure layer 17 may be formed by arranging a plurality of concave-convex elements, which are convex portions or concave portions, in a two-dimensional lattice pattern while being separated from each other.

[Example]
The above-mentioned wavelength selection filter and its manufacturing method will be described with reference to specific examples.

<Manufacturing of wavelength selection filter>
First, a mold, which is an intaglio plate used in the optical nanoimprint method, was prepared. Specifically, since light having a wavelength of 365 nm was used as the light to be irradiated in the optical nanoimprint method, synthetic quartz that transmits light of this wavelength was used as the material for the mold. In forming the mold, first, a film made of Cr was formed on the surface of the synthetic quartz substrate by a sputtering method, and an electron beam resist pattern was formed on the Cr film by an electron beam lithography method. The resist used was a positive type, and the film thickness was 150 nm. The pattern drawn by the electron beam is a pattern in which squares having a side of 210 nm are arranged in a square grid with a period of 300 nm in a square region having a side of 3 cm, and the region in which the electron beam is drawn is an inner region of the square. .. Next, the Cr film in the region exposed from the resist was etched by plasma generated by applying a high frequency to a mixed gas of chlorine and oxygen. Subsequently, the synthetic quartz substrate in the region exposed from the resist and the Cr film was etched by the plasma generated by applying a high frequency to the hexafluorinated ethane gas. The depth of the synthetic quartz substrate etched by this was 200 nm. The remaining resist and Cr film were removed, and Optool HD-1100 (manufactured by Daikin Industries, Ltd.) was applied as a mold release agent to obtain a mold in which a grid pattern in which squares were arranged in a square grid pattern was formed in the square region.

Next, an ultraviolet curable resin was applied to the square region where the lattice pattern was formed on the mold, and the mold surface was covered with a polyethylene terephthalate film which had been subjected to an easy-adhesion treatment. The ultraviolet curable resin was stretched using a roller so as to spread over the entire surface of the square region, irradiated with ultraviolet rays of 365 nm to cure the ultraviolet curable resin, and then the polyethylene terephthalate film was peeled off from the mold. As a result, a laminate of an uneven structure layer made of an ultraviolet curable resin having a lattice pattern formed on the surface and a base material which is a polyethylene terephthalate film was obtained. The above steps were repeated to prepare two laminates of the concave-convex structure layer and the base material. The irradiation amount of ultraviolet rays at 365 nm was set to 50 mJ / cm ² .

Next, a high refractive index layer made of TiO ₂ was formed by forming a TiO ₂ film having a film thickness of 100 nm on the surfaces of the above two laminated bodies by a vacuum vapor deposition method. Subsequently, the ultraviolet curable resin is applied to the region of the two laminates where the lattice pattern on the surface of one laminate is located, and the surface of the other laminate is applied to the coated ultraviolet curable resin. The two laminates were faced to each other so that they were in contact with each other and the regions where the grid patterns were located overlapped. The ultraviolet curable resin was spread using a roller so as to spread over the entire surface in the region where the lattice pattern was located, and was irradiated with ultraviolet rays of 365 nm to cure the ultraviolet curable resin to form an embedded layer. As a result, the wavelength selection filter of the example was obtained. The irradiation amount of ultraviolet rays at 365 nm was set to 50 mJ / cm ² .

<Evaluation of wavelength selection filter>
When the reflection spectroscopy of the wavelength selection filter of the example was measured, a reflection spectrum having a center wavelength of about 450 nm was observed.

10, 20 ... Wavelength selection filter, 11 ... Substrate, 12 ... First low refractive index region, 13 ... First lattice region, 13a ... First high refractive index section, 13b ... First low refractive index section, 14 ... Intermediate Region, 14a ... side high refractive index part, 14b ... isolated low refractive index part, 14c ... outer peripheral low refractive index part, 15 ... second lattice region, 15a ... second high refractive index part, 15b ... second low refractive index Part, 16 ... 2nd low refractive index region, 17 ... Concavo-convex structure layer, 17a ... Convex part, 18 ... High refractive index layer, 19 ... Embedded layer, 21 ... Resonance structure part, 22 ... Concavo-convex structure, 50 ... Wavelength Selected device, 60 ... Display body, 60F ... Front surface, 60R ... Back surface, 61A ... First display area, 61B ... Second display area, 61C ... Third display area, 62A ... First pixel, 62B ... Second pixel, 62C ... 3rd pixel, 70 ... color filter, 71 ... pixel, 71R ... red sub-pixel, 71G ... green sub-pixel, 71B ... blue sub-pixel.

Claims (10)

A concavo-convex structure layer having a concavo-convex structure, which is a concavo-convex element that is a convex portion or a concave portion and is composed of a plurality of the concavo-convex elements arranged in a two-dimensional lattice while being separated from each other in a sub-wavelength period.
A high-refractive index layer that is located on the uneven structure and has a surface shape that follows the uneven structure, and is located at the first high-refractive index portion located at the bottom of the uneven structure and at the top of the uneven structure. With the high refractive index layer including the second high refractive index portion
An embedded layer that fills the irregularities on the surface of the high refractive index layer is provided.
The thickness of the first high refractive index portion is T1, and the thickness of the second high refractive index portion is T2.
The refractive index of the material of the high refractive index layer is n1, the refractive index of the material of the concave-convex structure layer is n2, and the refractive index of the material of the embedded layer is n3.
The area ratio occupied by the first high refractive index portion in the cross section including the first high refractive index portion and orthogonal to the thickness direction is R1, and the cross section including the second high refractive index portion and orthogonal to the thickness direction thereof. When the area ratio occupied by the second high refractive index portion is R2,
n1> n2, n1> n3, and R1 + R2> 1.
The ratio of the second parameter represented by T2 × {n1 × R2 + n3 × (1-R2)} to the first parameter represented by T1 × {n1 × R1 + n2 × (1-R1)} is 0.7 or more. A wavelength selection filter that is 1.3 or less. The high refractive index layer includes a side high refractive index portion extending along the side surface of the uneven element between the first high refractive index portion and the second high refractive index portion.
The first aspect of the present invention, wherein R3 ≦ R1 + R2-1 is satisfied when the area ratio occupied by the side high refractive index portion in the cross section including the side high refractive index portion and orthogonal to the thickness direction thereof is R3. Wavelength selection filter. The high refractive index layer includes a side high refractive index portion extending along the side surface of the uneven element between the first high refractive index portion and the second high refractive index portion.
The wavelength selection filter according to claim 1 or 2, wherein the second high refractive index portion extends to the outside of the side high refractive index portion when viewed from a direction along the thickness direction of the high refractive index layer. The wavelength selection filter according to any one of claims 1 to 3, wherein T1 = T2, n2 = n3, and R1 = R2 are satisfied. The portion composed of the first high refractive index portion, the second high refractive index portion, and the low refractive index region surrounding these high refractive index portions is a resonance structure portion.
The wavelength selection filter according to any one of claims 1 to 4, wherein the wavelength selection filter includes a plurality of the resonance structure portions arranged along the thickness direction of the resonance structure portion. The plurality of resonance structure portions include a first resonance structure portion and a second resonance structure portion, and the first resonance structure portion has a period of arrangement of the uneven elements and the second resonance structure portion has. The wavelength selection filter according to claim 5, wherein the period of the arrangement of the uneven elements is the same. Claim 6 that the ratio of the second parameter to the first parameter in the first resonance structure part and the ratio of the second parameter to the first parameter in the second resonance structure part are in agreement. The wavelength selection filter described in. The plurality of resonance structure portions include a first resonance structure portion and a second resonance structure portion, and the first resonance structure portion has a period of arrangement of the uneven elements and the second resonance structure portion has. The wavelength selection filter according to claim 5, wherein the period of the arrangement of the uneven elements is different from each other. A concavo-convex structure layer is formed by forming concavo-convex elements, which are a plurality of convex or concave parts arranged in a two-dimensional lattice pattern while being separated from each other in a sub-wavelength period, on the surface of a layer made of a first low refractive index material. 1 step and
Using a high refractive index material having a higher refractive index than the first low refractive index material, the first high refractive index is located at the bottom of the concave-convex structure of the concave-convex structure layer along the surface of the concave-convex structure layer. A second step of forming a high refractive index layer including a portion and a second high refractive index portion located at the top of the uneven structure.
A third step of forming an embedded layer by filling the irregularities on the surface of the high refractive index layer with a second low refractive index material having a refractive index lower than that of the high refractive index material is included.
The thickness of the first high refractive index portion is T1, and the thickness of the second high refractive index portion is T2.
The refractive index of the high refractive index material is n1, the refractive index of the first low refractive index material is n2, and the refractive index of the second low refractive index material is n3.
The area ratio occupied by the first high refractive index portion in the cross section including the first high refractive index portion and orthogonal to the thickness direction is R1, and the cross section including the second high refractive index portion and orthogonal to the thickness direction thereof. When the area ratio occupied by the second high refractive index portion is R2,
n1> n2, n1> n3, and R1 + R2> 1.
The ratio of the second parameter represented by T2 × {n1 × R2 + n3 × (1-R2)} to the first parameter represented by T1 × {n1 × R1 + n2 × (1-R1)} is 0.7 or more. A method for manufacturing a wavelength selection filter that forms each layer so as to be 1.3 or less. In the second step, the high refractive index layer includes a side high refractive index portion extending along the side surface of the uneven element between the first high refractive index portion and the second high refractive index portion. The high refractive index is increased by using the physical vapor phase growth method so that the second high refractive index portion extends to the outside of the side high refractive index portion when viewed from the direction along the thickness direction of the high refractive index layer. The method for manufacturing a wavelength selection filter according to claim 9, wherein the rate layer is formed.