JP5293969B2 - Wavelength demultiplexing optical element - Google Patents

Abstract

A wavelength demultipling optical element of very simple refractive index multilayer transparent structure which can be manufactured at a low cost and used in WDM system near infrared communication for reflecting/demultiplexing wavelength multiplexed light or single wavelength light. In the wavelength demultipling optical element, a plurality of transparent resin layers having different refractive index are laminated, a large number of protrusions are formed, at a predetermined interval, of the resin forming the transparent resin layer on the surface of the uppermost transparent resin layer integrally therewith and the formation period width (P) of adjoining protrusions has a relation shown by the following expression to the wavelength (W<SUB>vmax</SUB>) of the light to be reflected. P=nKOE<SUB>vmax</SUB> ..... (I). In the expression (I), the wavelength W<SUB>vmax</SUB> of the light to be reflected is in the range of 200-2000 nm, n is 1 or 2, and K is 0.5-0.75.

Description

  The present invention relates to a wavelength demultiplexing optical element that reflects and demultiplexes light of a specific wavelength from among light beams including light of many wavelengths or from single wavelength light. More specifically, a wavelength demultiplexing optical element having a remarkably simple structure formed by laminating and forming transparent resin layers having different refractive indexes on a substrate and having a significantly low manufacturing cost. The present invention relates to a wavelength demultiplexing optical element capable of effectively reflecting and demultiplexing light having a specific wavelength from incident light rays.

  With the development of communication technology, the information transmission medium is changing from electricity to light. For example, in the Internet, a network using an optical fiber is constructed instead of an electric signal using a telephone line like ISDN, and information is transmitted as a bundle of light composed of a plurality of lights having different wavelengths through the optical fiber. can do. For example, optical communication technology uses a plurality of pieces of information in such a way that light of a specific wavelength constituting such a bundle of light is used as a transmission medium for image information, and light of another specific wavelength is used as a transmission medium for acoustic information. It is possible to transmit simultaneously using a single optical fiber.

  As a concrete example, in an optical fiber communication network used for Internet communication, wavelength light in the near-infrared to mid-infrared region (wavelength: 760 nm to 2.5 μm, 2.5 to 4 μm) is used. Information is transmitted. This near-infrared to mid-infrared wavelength light is invisible to the naked eye, but it has properties close to visible light as well as light properties. Since it is optical, it has recently been used in the optical communication network of mobile phones and the optical fiber communication network of the Internet, which have spread rapidly. In the future, the amount of information transmission is expected to increase.

Thus, in optical communication, for example, a wavelength division multiplexing WDM (Wavelength Division Multiplexing) method is employed.
The WDM system adopted here uses a plurality of lights having different wavelengths, for example, assigns independent information such as voice, image, video, etc. to light of each wavelength and has a wavelength corresponding to the number of independent information. This is an optical communication system that multiplexes a number of lights and transmits a light beam as an optical signal.

  Therefore, on the side receiving the information transmitted by the WDM system, it is necessary to separate light of a specific wavelength included in the light bundle separately from the light bundle. In order to separate (or demultiplex) an optical signal multiplexed and transmitted in such a WDM communication system, a filter that is selective to a wavelength having wavelength demultiplexing (or wavelength selectivity) is required. In general, such a filter is called a wavelength demultiplexing optical element.

  Regarding such a wavelength demultiplexing optical element, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2006-350126) discloses that “a substrate and a grating member formed on the substrate are periodically arranged with a space therebetween. And a grating layer, wherein an average refractive index of the grating layer is larger than a refractive index of the substrate. The grating layer of this wavelength selection element is composed of a grating and a gap formed between these gratings, and the fill factor value, which is the volume occupied by the grating in this grating layer, is 0.5 or more and 0.7 or less. In addition, it is shown that the period in which the grating is arranged in the grating layer is formed to be smaller than the wavelength in vacuum of the light incident on the wavelength selection element.

  In the wavelength selective element described in the cited document 1, the material for forming the grating provided in the grating layer is different from the material for forming the substrate on which the grating layer is formed. It is very difficult to form a fine lattice with a constant period. In addition, the period of formation of the grating for reflecting the light of the target wavelength from the light bundle is not necessarily clarified.

  Patent Document 2 (Japanese Patent Laid-Open No. 2002-0222918) states that “a resin-molded light-transmitting substrate having an entrance surface and an exit surface that emits light transmitted through the entrance surface is created. A reflection grating, which is a resonance mode grating filter, is formed on the surface by forming a grating pattern layer having a refractive index higher than that of the resin material of the base, and the resonance wavelength of light incident obliquely on the incident surface. The wavelength separation filter is characterized in that the component corresponding to is extracted by reflection, and other components are transmitted and emitted from the exit surface. " In paragraphs [0026], [0027], [0029], and [0034] of Patent Document 2, a resonant mode grating filter (color separation filter) that transmits incident light before entering the light separator 8 is described. ), And it is described that light having a wavelength resonating with the diffraction grating of the resonance mode grating filter is reflected by using the resonance mode grating filter.

And this diffraction grating is “made by transferring a fine shape formed on a resin molding die. For example, a polycarbonate resin is used for resin molding. Alternatively, a plurality of convex portions are arranged in a lattice shape, and this concave portion or convex portion has a mirror-symmetrical and rotationally symmetric shape in order to generate two equivalent resonance wave vectors in the lattice plane, It is preferable to position the incident surface of the incident light on the bisector of the convex portion. Further, “a high refractive index layer for forming a resonance mode grating filter is formed on the incident surface 9. As a method, as shown in FIG. 5 (a), a TiO ₂ film or a SiO ₂ film is formed by vapor deposition on a resin-molded incident surface, and a lattice pattern is formed thereon by an electron beam exposure technique and etching, Mold as shown in Fig. 5 (b) A grid pattern formed by micromachining, after transferring directly to the molded object during resin molding, is described as. "There is a method of uniformly formed by vapor deposition of TiO ₂ film or the like in the concave portion and the convex portion of the transfer surface ing.

Since this resonance mode grating filter is arranged so that the bisector coincides with the grating on the incident surface, this resonance mode grating filter is arranged with the same inclination as the incident surface formed to be inclined. The In Cited Document 2, since the incident light is a light beam parallel to the reflecting surface 10, the light is incident on the incident surface (that is, the resonance mode grating filter) at a predetermined angle. Thus, when light is incident on the resonance mode grating filter with an inclination, light of a specific wavelength resonates and is reflected. In order to resonate the light in this lattice, it is necessary to use a high refractive index TiO ₂ film or SiO ₂ film. When the polymer carbonate resin as described above is used alone, resonance causes a specific wavelength. It is not possible to reflect the light.

  Further, Patent Document 3 (Japanese Patent Laid-Open No. 2005-331582) states that “in the optical waveguide type WDM multiplexer / demultiplexer, demultiplexes or demultiplexes light propagating in the core provided in the middle of the core of the optical waveguide. An optical waveguide type WDM multiplexer / demultiplexer characterized in that a grating part is formed in the part is disclosed. Patent Document 3 discloses that an optical waveguide type WDM multiplexer / demultiplexer is formed of an organic polymer material, the organic polymer material is formed of fluorinated polyimide, polysilane, polymethyl methacrylate, polycarbonate, etc., and further graded. It is disclosed that the part is formed by a hot embossing method. In the example of the cited document 3, “in order to create a Y-branch type multiplexer / demultiplexer in the first embodiment, polysilane which is an organic polymer material in a desired waveguide shape on a Si substrate” Then, the lower clad was formed while controlling the film thickness by spin coating, followed by heat curing, and then polysilane was further applied on the heat-cured lower clad while controlling the film thickness by spin coating. The mask layer was used to irradiate ultraviolet light to give a refractive index difference to form a core layer, and then the ultraviolet light was irradiated to the branched portion to form a grating portion. The upper clad was formed by controlling the film thickness with a coat and performing heat curing. ”The main chain formed of —Si—Si— was formed of —C—C—. Using a polymer with a structure different from that of organic polymer compounds that are generally used, a core is formed with a refractive index difference on a polysilane layer that is laminated in multiple layers by irradiating ultraviolet rays using a mask. After that, it is shown that the branching portion is irradiated with ultraviolet laser light, and polysilane is applied again thereon, and the upper cladding is formed with a leading portion by heat curing.

  In this way, the cited document specifically gives a difference in refractive index to polysilane by irradiation of ultraviolet rays, and from a bundle of light multiplexed by changing the refractive index by changing the structural configuration. There is no description regarding extracting light of a specific wavelength.

Further, the resin specifically used here is polysilane having a main chain of -Si-Si- and the main chain has a -C-C- structure. difficult.
As described above, it is known that it can be selectively separated by a structure having a lattice structure on the surface (surface structure; SWS; Sub Wavelength Structured surface) from the relationship with the wavelength of light to be reflected. For example, attempts have been made to use it as a wavelength separation (or demultiplexing) element, a polarization separation element, a wavelength light conversion element, a diffraction grating light filter, a wavelength selection filter, an optical waveguide layer type wavelength filter, and the like.

  However, the existence of a substance having a high refractive index is indispensable for such an optical element which has been conventionally known, and in a typical organic polymer compound having a —C—C— bond in the main chain, wavelength demultiplexing optics is used. There is no material having a high refractive index and high transparency required for the element.

For this purpose, it is necessary to vacuum deposit metal oxides or use a very special resin such as polysilane whose main chain is -Si-Si-, and the wavelength demultiplexing optical element is expensive. It was. Furthermore, in future optical communication technology, it is predicted that communication information using optical fibers will increase dramatically, and there is an urgent need to develop a high-performance and inexpensive wavelength demultiplexing optical element that can handle such high-speed and mass communication.
JP 2006-350126 A JP 2002-022918 A JP 2005-331582 A

  An object of the present invention is a remarkably simple resin structure, an optical element comprising a transparent structure that demultiplexes near-infrared wavelength light incident on its surface through a fine structure shaped on its surface Is to provide.

  Further, the present invention is a wavelength demultiplexing optical element formed by forming a transparent resin in a multi-layered manner at a very low cost and in a simple manner. It is an object of the present invention to provide a wavelength demultiplexing optical element characterized in that near-infrared wavelength light is efficiently reflected and demultiplexed as desired specific wavelength light.

In the wavelength demultiplexing optical element of the present invention, a plurality of transparent resin layers having different refractive indexes are laminated, and a large number of protrusions formed at predetermined intervals on the surface of the transparent resin top layer in the outermost surface layer are transparent. The resin forming the resin layer is inseparably formed integrally with the transparent resin top layer, and the formation period width (P) of the adjacent protrusions is the following formula with respect to the wavelength (W _vmax ) of the light to be reflected: It is characterized by having the relationship represented by.

However, in the above formula (I), W _vmax is the wavelength of light to be reflected, is in the range of 200 to 2000 nm, n is 1 or 2, and K is 0.5 to 0.75, Preferably it is 0.65-0.69.

  In the wavelength demultiplexing optical element of the present invention, the transparent resin layers having different refractive indexes have at least a three-layer structure of a transparent substrate layer (L0), a transparent resin intermediate layer (L1), and a transparent resin top layer (L2). It is preferable to have.

  Furthermore, the wavelength demultiplexing optical element of the present invention is the difference between the refractive index (n2) of the transparent resin top layer and the refractive index (n1) of the transparent resin intermediate layer of the wavelength demultiplexing optical element having the above three-layer structure ( n2-n1) is preferably in the range of 0.06-0.25, preferably 0.1-0.2.

  Still further, the wavelength demultiplexing optical element of the present invention is the difference (n0−n1) between the refractive index (n0) of the transparent substrate layer and the refractive index (n1) of the transparent resin intermediate layer of the above three-layered wavelength demultiplexing element. ) Is usually in the range of -0.1 to 0.3, preferably in the range of 0 to 0.15.

  In the wavelength demultiplexing optical element, when the period of the lattice structure is shorter than the wavelength of light, it becomes equivalent to a medium having a certain refractive index with respect to light. In addition, since the refractive index can be controlled by the shape of the microstructure, the incident wavelength light is strengthened by the grating layer, the upper radiated wave overlaps with the reflected wave of the incident light, and the light emitted to the substrate side is Since it weakens the transmitted light, strong resonant reflection occurs on the incident grating surface.

  The present inventor has conventionally focused on such an optical technical field, and has formed a concavo-convex microstructure having a size of several hundred nm to several μm on a resin member by using conventional lithography. Patent applications have already been filed as Japanese Patent Application Nos. 2006-190928 and 2006-251975 for new functional members that are transferred by the thermal nanoimprint method instead of the transfer method. That is, a stamper material (or mold) with various ultrafine structures attached to a mold is pressed or impressed on a thermoplastic resin as a stamped member under heat melting, and the stamper member We are proposing nanotechnology materials that exhibit new functions by using ultra-fine structures transferred to the resin surface.

  The basic skeleton of such nanotechnology materials is a resin whose main chain has a —C—C— structure, which can be produced using organic polymer chemistry techniques that have been adopted conventionally, and are further handled Can do.

  In the present invention, a surface structure (SWS: Sub Wavelength Structured Surface) having a specific relationship with the wavelength of light using such a resin and having a period shorter than the wavelength of light is used for the wavelength demultiplexing optical element. By forming inseparably with the upper layer, light of a desired wavelength can be selectively reflected and light of other wavelengths can be transmitted.

  In the present invention, on the surface of the transparent resin top layer in the outermost surface layer of the multi-layered transparent resin, a large number of protrusions formed so as to have a predetermined interval are formed on the transparent resin made of the transparent resin on the outermost surface. By forming inseparable with the top layer, the refractive index of the transparent resin, the protrusions formed indefinitely integral with the transparent resin top layer, and the refractive index difference of the resin layer cooperate to form a specific wavelength. The incident light is selectively reflected. That is, when the near infrared region light is shown as an example, the present inventor has focused on (A) reflection / refraction / transmission of light rays such as near infrared region light irradiated on the member surface, and (B) Two or more types of resin layers having different optical refractive indexes in the infrared region or the like are spin-coated on a transparent substrate to form a multi-layered resin layer having different refractive indexes. On the transparent resin in the resin top layer (outermost surface layer), a thermal nanoimprint method is used to form a fine pattern in which protrusions such as ridges and prisms are formed at a predetermined period. (D) From the resulting protrusion surface When irradiated with light such as light in the infrared region, (E) The reflection intensity of incident light can be selectively changed by the formation period of the protrusion and the difference in refractive index. If you can reflect with high selectivity Findings were obtained. Furthermore, by providing a lattice-like microstructure on the top surface of the transparent resin top layer and changing the refractive index of the layer to be laminated within a predetermined range, it is desired to enter multi-wavelength light or single-wavelength light having an incident near-infrared wavelength. It can be effectively demultiplexed as wavelength light.

  In the wavelength demultiplexing optical element of the present invention, protrusions are formed on the surface of the transparent resin top layer of the multilayer structure composed of transparent resins having different refractive indexes at a period shown by a specific relational expression with respect to the wavelength of incident light. The protrusion is inseparably formed with the transparent resin top layer. In the wavelength demultiplexing optical element of the present invention, the refractive index difference of the transparent resin forming each layer is set within a certain range, whereby the protrusion structure on the surface cooperates with the refractive index difference, thereby forming the protrusion formation period. It is possible to selectively reflect the incident light having the wavelength specified by. In particular, the wavelength demultiplexing optical element of the present invention has a very high wavelength range selectivity when incident light is multi-wavelength light in the near-infrared region, and produces a single wavelength without causing sidebands. Can be selected and reflected.

  Moreover, in the wavelength demultiplexing optical element of the present invention, a transparent resin having a refractive index difference within a predetermined range is laminated, and, for example, protrusions are formed at a predetermined cycle on the outermost surface layer using a nanoprint technique. The structure is remarkably simple and can be manufactured at low cost. Furthermore, the wavelength demultiplexing optical element of the present invention can be effectively used for an infrared communication system having high security with respect to communication data.

FIG. 1 is a perspective view showing an example of a wavelength demultiplexing optical element in which convex protrusions are inseparably integrated with the transparent resin top layer at a specific formation period on the surface of the transparent resin top layer. FIG. 2 is a perspective view showing an example of a wavelength demultiplexing optical element in which prismatic protrusions inseparably integrated with the transparent resin top layer are provided on the surface of the transparent resin top layer at a specific formation period. FIG. 3 is a cross-sectional view showing an example of a cross section of the wavelength demultiplexing optical element of the present invention. FIG. 4 is a diagram illustrating an example of another shape of the protrusion. FIG. 5 shows the reflection / transmission demultiplexing characteristics of multi-wavelength light in the near infrared region perpendicularly incident on the wavelength demultiplexing optical element (D-1) of Embodiment-1 according to the present invention. did. FIG. 5B shows the reflection characteristics of the wavelength-demultiplexed light as a reflection spectrum waveform. FIG. 6 shows the reflection / transmission demultiplexing characteristics of multi-wavelength light in the near-infrared region perpendicularly incident on the wavelength demultiplexing optical element (D-2) of Embodiment-2 according to the present invention. did. Further, in FIG. 6B, the reflection characteristics of the demultiplexed wavelength light are displayed as a reflection spectrum waveform. FIG. 7A shows the demultiplexing characteristics of reflection / transmission of multi-wavelength light in the near infrared region perpendicularly incident on the wavelength demultiplexing optical element (D-3) of Embodiment-3 according to the present invention. did. Further, in FIG. 7B, the reflection characteristics of the demultiplexed wavelength light are displayed as a reflection spectrum waveform. FIG. 8 shows the demultiplexing characteristics of reflection / transmission of multi-wavelength light in the near infrared region perpendicularly incident on the wavelength demultiplexing optical element (D-4) of Embodiment-4 according to the present invention. did. Further, in FIG. 8B, the reflection characteristics of the demultiplexed wavelength light are displayed as a reflection spectrum waveform. FIG. 9 shows the reflection / transmission demultiplexing characteristics of multi-wavelength light in the near infrared region perpendicularly incident on the wavelength demultiplexing optical element (D-5) of Embodiment-5 according to the present invention. did. Further, in FIG. 9B, the reflection characteristics of the demultiplexed wavelength light are displayed as a reflection spectrum waveform. FIG. 10A shows the demultiplexing characteristics of reflection / transmission of multi-wavelength light in the near infrared region perpendicularly incident on the wavelength demultiplexing optical element (D-6) of Embodiment-6 according to the present invention. did. Further, in FIG. 10B, the reflection characteristics of the demultiplexed wavelength light are displayed as a reflection spectrum waveform. FIG. 11 shows the reflection / transmission demultiplexing characteristics of the multi-wavelength light in the near infrared region perpendicularly incident on the wavelength demultiplexing optical element (D-7) of Embodiment-7 according to the present invention. did. Further, in FIG. 11B, the reflection characteristics of the demultiplexed wavelength light are displayed as a reflection spectrum waveform. FIG. 12A shows the reflection / transmission demultiplexing characteristics of the multi-wavelength light in the near-infrared region that is incident on the demultiplexing element (D-1) of Embodiment-1 at 60 °. FIG. 12B shows the reflection characteristics of the wavelength-demultiplexed light as a reflection spectrum waveform. FIG. 13 illustrates the transmission characteristics of multi-wavelength light in the near-infrared region perpendicularly incident on the optical element (H-1) of Embodiment-1 in FIG. Further, FIG. 13B shows the reflected spectrum waveform of the demultiplexed ultra-low wavelength light. FIG. 14 shows that the refractive index difference | n 2 −n 1 | = 0.005, in which the transparent resin intermediate layer (L 1) is not provided or the refractive index of the transparent resin intermediate layer (L 1) is close to the refractive index of the lattice layer (L 2). FIG. 14A shows the transmission characteristics of multi-wavelength light in the near-infrared region perpendicularly incident on the optical element (H-2) of Comparative Embodiment-2. Further, FIG. 14B shows the reflected spectrum waveform of the demultiplexed ultra-low wavelength light. FIG. 15A shows the transmission characteristics of multi-wavelength light in the near infrared region perpendicularly incident on the optical element (H-3) of Comparative Embodiment-3. Further, FIG. 15B shows the reflected spectrum waveform of the demultiplexed ultra-low wavelength light. FIG. 16 illustrates the transmission characteristics of multi-wavelength light in the near-infrared region perpendicularly incident on the optical element (H-4) of Comparative Embodiment-4, as illustrated in FIG. Further, in FIG. 16B, the reflected spectrum waveform of the demultiplexed ultra-low wavelength light is displayed. FIG. 17 shows the optical characteristics of Comparative Experiment Mode-5 in which the grating period (P) is 1.03 μm and the fill factor (FF) is 0.8 in the embodiment-1 shown in FIG. FIG. 17A shows the transmission characteristics of multi-wavelength light in the near infrared region perpendicularly incident on the element (H-5). FIG. 17B shows the reflected spectrum waveform of the demultiplexed ultra-low wavelength light. FIG. 18 is the same as that of the embodiment-1 shown in FIG. 1, wherein the grating period (P) is 1.03 μm within the scope of the claims, and the difference in refractive index between the transparent resin top layer and the transparent resin intermediate layer FIG. 18A shows the transmission characteristics of multi-wavelength light in the near-infrared region perpendicularly incident on the optical element (H-6) of Comparative Embodiment-6 set to 0.35, which is outside the range of the preferred constituents of the invention. As shown in the figure. Further, in FIG. 18B, the reflected spectrum waveform of the demultiplexed very short wavelength light is displayed. FIG. 19 shows a wavelength demultiplexing optical element that does not satisfy the requirements of the present invention in which K is 0.3 in the above-described formula (I), and a reflection spectrum waveform of this element. FIG. 20 shows a wavelength demultiplexing optical element in which K is 2 and does not satisfy the requirements of the present invention in the above-mentioned formula (I), and the reflection spectrum waveform of this element. 21A shows the reflection peak of light in the ultraviolet region with a wavelength of 235 nm, FIG. 21B shows the reflection peak of light in the visible region with a wavelength of 534 nm, and FIG. It is a reflection peak of light in the infrared region. FIG. 22 shows both layers formed by stacking “top layer (lattice layer)” / “intermediate layer” of the demultiplexing element (Db) according to the present invention in Example 3 or 4, and the “top layer”. SEM photographic images of both layer cut surfaces (lamination interface) after the thermal nanoimprint transfer of the lattice-like microstructure are shown in FIGS. 22 (a) and 22 (b), respectively. FIG. 23 is a concept for explaining the transferability of the grating fine structure [period (P), grating width (A)] of the mold to the grating top layer in the third step of manufacturing the wavelength demultiplexing optical element according to the present invention. The figures are shown in FIGS. 23 (a), (b) and (c).

Next, the wavelength demultiplexing optical element of the present invention will be specifically described with reference to the drawings.
FIG. 1 shows a wavelength demultiplexing optical element 10 having a three-layer structure made of transparent resin, and a width A on the upper surface of the transparent resin top layer (outermost surface layer) L ₁₂ of this laminate. The perspective view which shows typically the example of the wavelength demultiplexing optical element 10 in which the three ridges 10b of this with the pitch width P were formed is shown.
FIG. 2 also shows a three-layer structure made of transparent resin, and a prism 20b having a width A _{1 in} the X direction and a width A _{2 in} the Z direction is formed on the uppermost surface L ₂₂ of the laminate. is a perspective view schematically showing an example of the pitch width P _1, Z direction pitch P ₂ in 15 formed wavelength division optical element 20 in the X direction.

As shown in FIG. 1, the wavelength demultiplexing optical element 10 of the present invention includes a transparent substrate L ₁₀ , a transparent resin intermediate layer L ₁₁ laminated on the transparent substrate L ₁₀ , and the transparent resin intermediate layer L ₁₁ . The transparent resin top layer (outermost surface layer) L _{12 has} a three-layer structure laminated thereon, and the transparent resin top layer (outermost surface layer) L _{12 has} an upper surface on the transparent resin top layer L _12. the same resin as the resin forming the convex portion of the integral part of the transparent resin top layer L ₁₂ Sanjo are formed protrusions 10b is.

Each protrusion 10b is formed in the form of a plate-like ridge having a substantially rectangular longitudinal section with a width A. In FIG. 1, such ridges 10b are formed such that the pitch width between adjacent ridges 10b is P. In FIG. The height (thickness) D ₁ of this ridge is usually 50 nm to 1.0 μm, preferably 200 to 500 nm.

The resin forming the ridges 10b and the transparent resin top layer is a highly transparent resin, and the total light transmittance of this resin is usually 80% or more, preferably 90% or more. The refractive index of the resin forming the transparent resin top layer is usually in the range of 1.5 to 1.8, preferably in the range of 1.56 to 1.63. A resin having a relatively high refractive index is used as the resin for forming the transparent resin top layer. This, in wavelength division optical element of the present invention, in order to selectively reflect light of a specific wavelength, a transparent resin intermediate layer which is laminated with the transparent resin top layer L ₁₂ Toko transparent resin top layer L ₁₂ the refractive index difference between the L ₁₁ is taken into consideration. That is, when the refractive index of the transparent resin top layer L ₁₂ is n ₂ and the refractive index of the transparent resin intermediate layer L ₁₁ is n ₁ , in the wavelength demultiplexing optical element of the present invention, the transparent resin top layer L ₁₂ The difference (n ₂ −n ₁ ) between the refractive index n ₂ and the refractive index n ₁ of the transparent resin intermediate layer L ₁₁ is in the range of 0.06 to 0.25, preferably in the range of 0.1 to 0.2. It is desirable to select a resin for forming each layer so that To set the difference between the refractive index n ₁ of the refractive index n ₂ and the transparent resin intermediate layer L ₁₁ of such transparent resin top layer L ₁₂ (n ₂ -n ₁₎ is a transparent resin top layer L ₁₂ This is because by selecting a resin having a high refractive index n _{2 as} the resin to be formed, the range of selection of the resin for forming the transparent resin intermediate layer L ₁₁ is widened, and various resins can be used.

The thickness D ₂ of the transparent resin top layer L ₁₂ is usually in the range of 0.30 to 3.00 μm, preferably 0.6 to 1.5 μm.
On the surface of the transparent resin top layer L _12, it is inseparably formed with transparent resin top layer L ₁₂ ridge (projection) 10b are formed of the same resin as the transparent resin top layer L ₁₂ Therefore, the refractive index of the resin forming this ridge (projection) 10b is usually in the range of 1.5 to 1.8, preferably in the range of 1.56 to 1.63. It is in.

In the wavelength demultiplexing optical elements 10 and 20 of the present invention, as the resins forming the transparent resin top layers L ₁₂ and L ₂₂ , acrylic resins, polystyrene resins, (thio) phenol derivative resins, fluorine-modified acrylic resins Inorganic nanoparticle-added resins and organic-inorganic hybrid resins can be used. Here, examples of the inorganic nanoparticles incorporated in the inorganic nanoparticle-added resin include zircon oxide and titanium oxide, and examples of the base resin at this time include acrylic resins and polystyrene resins. . Examples of organic-inorganic hybrid resins include acrylic resins or polystyrene resins containing metal elements. These can be used alone or in combination. The refractive index can be adjusted by the combination of these resins. In addition, in a resin formed by reacting a plurality of monomers such as an acrylic resin, the refractive index can be adjusted by the combination of monomers used. You can change the rate. Further, the refractive index can be changed by using a monomer having a halogen atom such as a fluorine atom bonded thereto instead of a substituent or a hydrogen atom bonded to a carbon atom. Further, the refractive index can be changed without lowering the transparency by uniformly blending, for example, nanoparticles smaller than the wavelength of light used in the resin. The nanoparticles in this case may be organic particles or inorganic particles.

Examples of the resin forming these transparent resin top layers L ₁₂ and L ₂₂ include acrylic resins, polystyrene resins, (thio) phenol derivative resins, fluorine-modified acrylic resins, inorganic nanoparticle-added resins, and organic-inorganic. Any of the hybrid resins is preferably used alone or in combination.

In the wavelength demultiplexing optical elements 10 and 20 of the present invention, the transparent resin intermediate layers L ₁₁ and L ₂₁ laminated on the transparent resin top layers L ₁₂ and L ₂₂ having the protrusions 10b and 20b formed on the surface are the transparent resin tops. The layers L ₁₂ and L ₂₂ are formed of a resin having a refractive index n _{1 that} is 0.06 to 0.25 lower, preferably 0.1 to 0.2 lower than the refractive index n _{2 of the} layers L ₁₂ and L ₂₂ . Accordingly, the refractive index n ₂ of the resin forming the transparent resin intermediate layers L ₁₁ and L ₂₁ is usually in the range of 1.35 to 1.6, preferably in the range of 1.4 to 1.5. Ordinary acrylic resin, styrene resin, polycarbonate resin, cyclic olefin resin, (thio) phenol derivative resin, fluorine-modified acrylic resin, inorganic nanoparticle added resin and organic-inorganic hybrid resin A transparent resin such as can be used. Here, the transparency required for the transparent resin intermediate layers L ₁₁ and L ₂₁ is a transparency in which the total light transmittance of the resin is usually 80% or more, preferably 90% or more.

The thickness D ₃ of the transparent resin intermediate layers L ₁₁ and L ₂₁ is usually 2.0 μm or more, preferably 2 to 30 μm.
Transparent substrate layers L ₁₀ and L ₂₀ are laminated below the transparent resin intermediate layers L ₁₁ and L ₂₁ as described above.

Refractive index n0 of the resin forming the transparent substrate L _10, L ₂₀ is preferably higher than the refractive index n1 of the resin forming the top layer and is transparent resin intermediate layer L _11, L _21, the refractive index of the transparent substrate The value of the difference (n0-n1) between n0 and the refractive index n1 of the transparent resin intermediate layer is usually (n0-n1) in the range of -0.1 to 0.3, preferably 0 to 0.15. Is in range. Accordingly, the refractive index n0 of the resin forming the transparent substrate layer L _10, L ₂₀ is in the range of usually 1.4 to 1.8, preferably in the range of 1.45 to 1.68. The resin forming such a transparent substrate is a transparent resin having a total light transmittance of usually 80% or more, preferably 90% or more. Examples of such transparent resins include polyethylene terephthalate, polyalkyl ( Mention may be made of (meth) acrylates, cyclic olefin resins, polytetrafluoroethylene (PTFE) resins, polysulfone (PS) resins, and polyether sulfone (PES) resins.

The thickness of L _10, L ₂₀ of such a transparent substrate layer can be set appropriately, usually, 20 to 1000 .mu.m, preferably in the range of 50 to 200 [mu] m.
The wavelength demultiplexing optical element of the present invention usually has a transparent resin intermediate layer L _11,21 and a transparent resin top layer L _12,22 formed thereon. This transparent resin intermediate layer It is preferable to have a three-layer structure having transparent substrate layers L ₁₀ and ₂₀ below, and the wavelength demultiplexing optical element of the present invention may further have a layer structure of three or more layers.

Furthermore, the wavelength demultiplexing optical element of the present invention is formed by forming a certain gap on the surface of the transparent resin top layer L ₁₂ , ₂₂ as described above with the same resin as that forming the transparent resin top layer. A large number of protrusions are inseparably formed.

The wavelength of light to be reflected differs depending on the formation pitch width of such protrusions. In the present invention, when the pitch width is P, the wavelength of light to be reflected is W _VMAX, and K is a constant, the following relationship is established: Projections are formed so as to satisfy the formula (I).

However, in the above formula (I), W _vmax is the wavelength of light to be reflected, and is 200 to 2000 nm in the present invention. N is 1 or 2, and K is 0.5 to 0.75, preferably 0.6 to 0.7. In particular, when the light to be reflected is visible light and the wavelength W _vmax is in the range of ₃₀₀ to 500 nm, the visible light that is incident efficiently can be efficiently obtained even if the value of n is 1 or 2. Can reflect well. However, when the light to be reflected is 200 nm or more and less than 300 nm, and more than 500 nm and 2000 nm or less, the incident light is more efficiently emitted when n is 1 than when 2 is 2. Can be reflected. Therefore, it is preferable to change the pitch width of the protrusions to be formed by changing the value of n in accordance with the wavelength of light incident on the wavelength demultiplexing optical element of the present invention.

  As shown in FIG. 1 of the protrusions formed in this way, the longitudinal section may be formed from a recess formed by a substantially rectangular protrusion 10a and an adjacent protrusion 10a, or as shown in FIG. As described above, a large number of prisms 25 having a substantially rectangular longitudinal section may be used.

  When the protrusion is a prism as shown in FIG. 2, the pitch represented by the above formula (I) occurs in two directions, the Y direction and the X direction. That is, with respect to the prism 28, a pitch width of P1 is generated between the prism 27 adjacent in the X direction, and the prism 27 is adjacent to the prism 27 in the Y direction. A pitch width of P2 occurs between 25 and 25.

  In the wavelength demultiplexing optical element of the present invention, when a pitch width is generated in two directions as described above, at least one of the pitch widths, preferably the relationship between the pitch widths of the two is represented by the above formula (I). Is preferably satisfied.

In the wavelength demultiplexing optical element of the present invention, the shape of the protrusion formed on the surface of the transparent resin top layer L ₁₂ may be a ridge as shown in FIG. 1 or a prism as shown in FIG. Further, the shape may be a combination of prisms with different heights as shown in FIG. 4 (a), or a combination of arcuate protrusions as shown in FIG. 4 (b). Further, although not shown, even a polygonal columnar shape such as a triangular columnar shape can be formed in various shapes such as a cylindrical shape and an elliptical columnar shape. Further, the top of these protrusions does not particularly need to be flat, and for example, as shown in FIG. 4C, it is formed in various shapes such as forming the top in a substantially triangular shape. Can do.

Further, as shown in FIG. 3, the surface of the transparent resin top layer L ₂ of the wavelength demultiplexing optical element of the present invention has projections 6.7.8.9 and gaps 6a, 7a, formed between these projections 6.7.8.9. Protrusions having a predetermined period P are formed by 8a and 9a. However, when the volume of the protrusions 6.7.8.9 occupying this pitch is increased, the ratio of the containers occupied by the gaps 6a, 7a, 8a and 9a inevitably decreases. The volume occupied by the protrusion with respect to the total volume of the protrusion and the gap formed on the surface of the transparent resin top layer (L2) is referred to as a fill factor; FF. In the present invention, this fill factor (FF) is usually in the range of 0.07 to 0.95, preferably in the range of 0.25 to 0.75. As the value of the fill factor (FF) approaches 1, the proportion of the volume occupied by the gap gradually decreases, and projections formed with a predetermined interval gradually approach each other. And the part of the formed projection has a junction point with the adjacent projection, and the projection formed on the surface of the wavelength demultiplexing optical element of the present invention is joined to each other, and the joined projection Forming the convex part may be formed by the group. In this case, the structure of the protrusion on the surface is formed with a recess in a portion where the protrusion does not exist, but in the present invention, a protrusion group having a joint portion between adjacent protrusions may be formed. Good.

  In the wavelength demultiplexing optical element of the present invention as described above, it is substantially parallel (0 °) to the standing direction of the protrusion formed on the surface of the transparent resin top layer L2 of the wavelength demultiplexing optical element of the present invention. Light having a specific wavelength (including single wavelength light) incident at an angle of ˜60 °, particularly light having a specific wavelength in the near infrared region can be independently reflected and demultiplexed with a high reflectance.

Next, the wavelength demultiplexing optical element of the present invention will be described in more detail below with reference to FIGS.
<Embodiment of wavelength demultiplexing optical element according to the present invention>
FIG. 5A shows a transparent resin intermediate layer on a transparent substrate (L0) 13 having a thickness of 120 μm measured using a wavelength of 1.556 μm and a refractive index (n0) = 1.65. The refractive index (n1) = 1.485, the film thickness (m1) = 3 μm, the PMMA (polymethyl methacrylate) transparent resin intermediate layer (L1) 12, and the transparent resin top layer as the refractive index (n2) = 1.565. Then, a sectional view of the refractive index multilayer structure in which the convex lattice 11 is formed on the transparent resin top layer (L2) formed using PSt (polystyrene) with a film thickness (m2) = 0.92 μm is displayed. Has been.

Hereinafter, the refractive index described in the present invention is a refractive index measured using near-infrared wavelength light of 1.556 μm, unless otherwise specified.
That is, the convex lattice 10 having a depth (D2) = 0.25 μm is provided on the transparent resin top layer having a thickness (m2) of 0.92 μm (= 0.67 + 0.25), and the transparent resin Wavelength demultiplexing optical element of Embodiment-1 of the present invention in which the refractive index difference (= n2-n1) between the top layer and the transparent resin intermediate layer is 0.08 [hereinafter simply referred to as demultiplexing element] (D-1 ).

Further, the grating formation period (P; pitch width) = 1.03 μm, the grating width (A) = 0.675 μm, and its fill factor (FF) = 0.655. is there.
That is, in this wavelength demultiplexing optical element, the reflection target light W _vmax in the formula (I) is 1536 nm, the pitch width P is 1.03 μm, n is 1, and K is 0.671. It was.

Therefore, in the present invention, multi-wavelength light in the near-infrared wavelength range of 1.0 to 1.7 μm is incident as vertical light on this demultiplexing element (D-1), and the reflection demultiplexing characteristics are evaluated. .
As a result, in FIG. 5B, a reflected spectrum waveform of the reflected and demultiplexed near-infrared wavelength light having a wavelength of 1.536 μm is displayed with a small half-value width and a sharp waveform.

At the same time, from the reflection spectrum waveform diagram shown in FIG. 5B, it can be seen that most of the other near-infrared wavelength light is almost transmitted and separated.
As described above, the demultiplexing element (D-1) of the present invention effectively reflects the near-infrared wavelength light of the multi-wavelength light incident substantially parallel (0 °) with the projection installation direction with high reflectivity. I can see that it makes waves.

  The demultiplexing element (D-3) of Embodiment-3 of the present invention illustrated in FIG. 7A is the same as the demultiplexing element (D-1) displayed in FIG. A transparent resin top layer 11 having a refractive index (n1) = 1.485 and a transparent resin top layer 11a having a refractive index (n2) = 1.60 and a refractive index (n1) ) = 1.465 In place of the transparent resin intermediate layer 12a, a demultiplexing element (D-3) in which the refractive index difference (= n2-n1) between the transparent resin top layer and the transparent resin layer is expanded to 0.135. is there.

In this wavelength demultiplexing optical element, the reflection target light W _vmax in the formula (I) is 1550 nm, the pitch width P is 1.03 μm, n is 1, and K is 0.665.
As a result, as is apparent from the reflection spectrum waveform diagram shown in FIG. 7B, the reflected near-infrared wavelength of 1.550 μm is demultiplexed with a reflectance of almost 100%. Therefore, it can be seen that all near-infrared wavelength light other than the incident wavelength of 1.550 μm is almost transmitted and separated.

  The demultiplexing element (D-4) of Embodiment-4 of the present invention illustrated in FIG. 8A is the same as the demultiplexing element (D-1) displayed in FIG. Each of the transparent resin top layer 11 of 1.565 and the protrusion 10 having a protrusion width (A) = 0.675 μm, the transparent resin top layer 11a having a refractive index (n2) = 1.60, and the protrusion width (A ) = Instead of the 0.3 μm grating 10a, the demultiplexing element of the present invention has the fill factor (FF) value of the demultiplexing element (D-1) (FF) = lower limit of 0.25 to 0.95 This is a demultiplexing element (D-4) with a fill factor (FF) close to the value = 0.291.

In this wavelength demultiplexing optical element, the reflection target light W _vmax in the formula (I) is 1553 nm, the pitch width P is 1.03 μm, n is 1, and K is 0.664.
As a result, as is apparent from the reflection spectrum waveform diagram shown in FIG. 8B, the near-infrared wavelength of 1.553 μm, which is reflected and demultiplexed, has no sideband at all, and is almost 95%. It is demultiplexed by the reflectance. Therefore, it can be seen that all near-infrared wavelength light other than the incident wavelength of 1.553 μm is almost transmitted and separated.

  The demultiplexing element (D-5) of Embodiment-5 of the present invention illustrated in FIG. 9A is the same as the demultiplexing element (D-1) displayed in FIG. 1. A demultiplexing element (D-5) in which the thickness (m1) of the transparent resin intermediate layer (L1) is 20 μm instead of the transparent resin intermediate layer 12b having a thickness (m1) = 3 μm at 1.485. .

In this wavelength demultiplexing optical element, the light W _{vmax to be} reflected in the formula (I) is 1545 nm, the pitch width P is 1.03 μm, n is 1, and K is 0.667.
As a result, as is apparent from the reflection spectrum waveform diagram shown in FIG. 9B, the near-infrared wavelength of the reflected demultiplexed wavelength of 1.545 μm does not show any sidebands and is almost 100%. Demultiplexed by reflectivity. Therefore, it can be seen that all near infrared wavelength light other than the incident wavelength of 1.545 μm is almost transmitted and separated.

  According to such an embodiment, in the wavelength demultiplexing optical element that is the refractive index multilayer structure of the present invention, the film thickness (m1) of the intermediate layer, the film thickness (m2) of the top layer, and the film thickness of the substrate layer Compared with (m0), it can be made thicker. In the present invention, the film thickness (m1) of the transparent intermediate layer (L1) is preferably set to film thickness (m1) = 30 μm or less from the viewpoint of forming a film with good smoothness by a spin coating method. .

  The demultiplexing element (D-6) of Embodiment-6 of the present invention shown in FIG. 10A is the same as the demultiplexing element (D-1) displayed in FIG. Instead of the ridge 10 with 0.675 μm and protrusion formation period (P) = 1.03 μm, a protrusion 10 d with protrusion width (A) = 0.55 μm and protrusion formation period (P) = 0.9 μm is provided. As a result, the projection width (A) of the wavelength demultiplexing optical element (D-1) is changed by changing the formation period (P) of the ridges in this way. The fill factor (FF) of the demultiplexing element (D-6) can be changed to 0.611 with respect to the fill factor (FF) of 0.655.

In this branching element, the reflection target light W _vmax in the formula (I) is 1350 nm, the pitch width P is 0.90 μm, n is 1, and K is 0.667.
As a result, as is apparent from the reflection spectrum waveform diagram shown in FIG. 10B, the near-infrared wavelength of the reflected demultiplexed wavelength of 1.35 μm is demultiplexed with a high reflectivity of about 83%. The demultiplexing wavelength band can be effectively shifted with respect to 1.536 μm (1536 nm) of the wavelength demultiplexing optical element (D-1).

  Further, the demultiplexing element (D-7) of Embodiment-7 of the present invention shown in FIG. 11A is similar to the demultiplexing element (D-6) in the protrusion width (A) = 0.25 μm. , A demultiplexing element (D-7) provided with a protrusion 10e having a protrusion formation period (P) = 0.68 μm.

  Similarly, this wavelength is changed with respect to the fill factor (FF) = 0.655 of the width (A) of the protrusion of the wavelength demultiplexing optical element (D-1) by changing the formation period (P) of the ridges. The fill factor (FF) of the demultiplexing optical element (D-7) is changed to 0.368.

In this wavelength demultiplexing optical element, the reflection target light W _vmax in the formula (I) is 1025 nm, the pitch width P is 0.68 μm, n is 1, and K is 0.667.
As a result, as is apparent from the reflection spectrum waveform diagram illustrated in FIG. 7B, the near-infrared wavelength of the reflected and demultiplexed wavelength of 1025 nm is demultiplexed with a high reflectivity of approximately 100%, The demultiplexing wavelength band can be greatly and effectively shifted with respect to the wavelength of 1.536 μm of the demultiplexing element (D-1).

  As described above, in the present invention, as a structural factor for changing the fill factor (FF) value of the grating from the reflection demultiplexing characteristics of the demultiplexing element (D-6) and demultiplexing element (D-7). By changing the formation period (P) of the protrusions, the wavelength band of the desired specific wavelength light to be reflected and demultiplexed can be appropriately and freely shifted in the near infrared region.

  FIG. 12A shows incident near infrared rays when near infrared wavelength light is obliquely incident at an incident angle of 60 ° on the grating surface of the branching element (D-1) according to Embodiment-1 of the present invention. The operations of light incidence / reflection / refraction / transmission are displayed.

In this wavelength demultiplexing optical element, the reflection target light W _vmax in the formula (I) is 1224 nm, the pitch width P is 0.68 μm, n is 1, and K is 0.557.
As a result, as is apparent from the reflection spectrum waveform diagram shown in FIG. 12B, the reflection-demultiplexed near-infrared wavelength light having a wavelength of 1.224 μm has a reflection intensity of about 27% and a low sideband. Although not made, it is possible to reflect and demultiplex almost specific wavelength light.

  An optical element (H-1) shown in FIG. 13A is a transparent resin intermediate having a refractive index (n1) = 1.485 in the demultiplexing element (D-1) of the present invention shown in FIG. In place of the layer (L1) 12, the transparent resin having the refractive index (n1) = 1.535 shown in FIG. 13A, which is close to the refractive index (n2) = 1.565 of the transparent resin top layer 11 In addition to the intermediate layer 12c, and the transparent substrate 13 is a transparent substrate 13 having a refractive index (n0) = 1.65, all the above-described element constituent requirements for the branching element (D-1) of the present invention are as follows. This is the same demultiplexing element (H-1) of Comparative Embodiment-1.

In this wavelength demultiplexing optical element, there is no reflection target light W _vmax in formula (I), and therefore formula (I) does not hold.
As a result, as is apparent from the reflection spectrum waveform diagram shown in FIG. 13B, the reflection is weak over the entire near infrared region, and a very turbulent reflection spectrum waveform diagram is displayed. As is apparent from this waveform diagram, the incident near-infrared wavelength light is not reflected at all and almost all the incident wavelength light is transmitted. In such an optical element (H-1), it is impossible to exhibit the function of reflecting and demultiplexing near-infrared wavelength light like the wavelength demultiplexing optical element of the present invention.

The demultiplexing element (H-2) illustrated in FIG. 14A is a case where the intermediate layer (L1) is not provided unlike the demultiplexing element (D-1) of the present invention.
This is a demultiplexing element (H-2) according to comparative embodiment-2 in which the intermediate layer (L1) 12 is removed from the demultiplexing element (D-1) of the present invention shown in FIG. 5A.

In this wavelength demultiplexing optical element, there is no reflection target light W _vmax in formula (I), and therefore formula (I) does not hold.
As a result, as apparent from the reflection spectrum waveform diagram shown in FIG. 14B, the reflection spectrum waveform is displayed as a broad uniform mountain-shaped reflection spectrum with weak reflection over the near infrared region. As is apparent from this waveform diagram, the incident near-infrared wavelength light is not reflected at all and almost all the incident wavelength light is transmitted. Such an optical element (H-2) cannot exhibit the function of reflecting and demultiplexing near-infrared wavelength light like the wavelength demultiplexing optical element of the present invention.

  Therefore, the transparent resin intermediate layer (L1) 12 having a refractive index (n1) and a film thickness (m1) in the branching element (D-1) of the present invention is a transparent resin having a refractive index (n2) and a film thickness (m2). It can be said that it functions as a waveguide layer for incident wavelength light that is refracted and transmitted through the top layer 11.

n2-n1 = 0.06-0.25 (1)
n0−n1 = −0.1 to 0.3 (2)
The demultiplexing element (H-3) illustrated in FIG. 15A is a PMMA having a refractive index (n1) = 1.485 in the demultiplexing element (D-1) of the present invention illustrated in FIG. The film thickness (m1) = 3 μm of the resin-based resin intermediate layer (L1) 12 was replaced with the PMMA-based resin intermediate layer 12d having a film thickness (m1) = 0.5 μm of the ultrathin film. At the same time, the transparent substrate 13 having a refractive index (n0) = 1.65 is changed to a transparent substrate 13c having a refractive index (n0) = 1.65 and a film thickness (m0) = 100 μm. -3).

In this wavelength demultiplexing optical element, there is no reflection target light W _vmax in formula (I), and therefore formula (I) does not hold.
As a result, as apparent from the reflection spectrum waveform diagram shown in FIG. 15B, the reflection is weak and turbulent mountain-shaped reflection spectrum waveform diagram is displayed over the entire near infrared region. As is apparent from this waveform diagram, the incident near-infrared wavelength light is not reflected at all and almost all the incident wavelength light is transmitted. Such an optical element (H-3) cannot exhibit the function of reflecting and demultiplexing near-infrared wavelength light as in the wavelength demultiplexing optical element of the present invention.

  The main factor is that, in the demultiplexing element (H-3), the film thickness (m1) of the transparent resin intermediate layer (L1) 12d = 0.5 μm, so that the wavelength demultiplexing optical element (D -1) The thickness (m1) of the transparent resin intermediate layer 12 is 3 μm, which is an extremely thin film, which is clearly a preferable requirement in the wavelength demultiplexing optical element of the present invention as described above. (M1) An extremely thin film that deviates greatly from ≧ 2 μm.

  The demultiplexing element (H-4) shown in FIG. 16 (a) is different from the demultiplexing element (D-1) of the present invention shown in FIG. = 0.25 to 0.95, but the formation period (P) of protrusions provided on the transparent resin top layer (L2) = 1.23 μm.

In this wavelength demultiplexing optical element, there is no reflection target light W _vmax in formula (I), and therefore formula (I) does not hold.
As a result, as is apparent from the reflection spectrum waveform diagram shown in FIG. 16B, the reflection is weak over the near-infrared region and a broad mountain-shaped reflection spectrum waveform is displayed, which is apparent from this waveform diagram. Further, the incident near-infrared wavelength light is not reflected and demultiplexed at all, and almost all incident wavelength light is transmitted, and the near-infrared wavelength light is reflected and demultiplexed like the wavelength demultiplexing optical element of the present invention. I can't.

  The demultiplexing element (H-5) illustrated in FIG. 17A is different from the demultiplexing element (D-1) of the present invention illustrated in FIG. (P) = 1.03 μm and the protrusion width (A) = 1.00 μm. Further, since the width (A) of the protrusion is 1.00 μm, the fill factor (FF) of the lattice is 0.97.

In this wavelength demultiplexing optical element, there is no reflection target light W _vmax in formula (I), and therefore formula (I) does not hold.
As a result, as is apparent from the reflection spectrum waveform diagram shown in FIG. 17B, a broad mountain-shaped reflection spectrum waveform is displayed with weak reflection over the near infrared region, and the incident near infrared wavelength light is incident. Is not reflected and demultiplexed at all. Therefore, almost all incident wavelength light is transmitted, and near infrared wavelength light cannot be reflected and demultiplexed as in the present invention.

  In the branching element (H-6) illustrated in FIG. 18A, the transparent resin intermediate layer 12 is obtained by setting the refractive index (n2) of the resin forming the transparent resin top layer (L2) 11b to 1.835. This is the optical element (H-6) of Comparative Embodiment-6 in which the refractive index difference n2−n1 = 0.35 and the refractive index (n1) = 1.485. That is, it is an optical element (H-6) that greatly deviates from the requirement of n2-n1 = 0.06 to 0.25, which is a preferable configuration requirement in the wavelength demultiplexing optical element of the present invention.

In this wavelength demultiplexing optical element, the light W _{vmax to be} reflected in the formula (I) is ₁₅₂₅ nm, the pitch width P is 1.03 μm, n is 1, and K is 0.675.
As a result, as is apparent from the reflection spectrum waveform diagram shown in FIG. 18B, reflected light having a considerable reflection intensity over the near-infrared region can be obtained, but at the same time, the reflection of the sideband is large and incident. Most of the light is not reflected and demultiplexed with respect to near-infrared wavelength light. Therefore, the function of transmitting almost all incident wavelength light and reflecting and branching near infrared wavelength light as in the present invention cannot be exhibited.

  In the branching element shown in FIG. 19A, the refractive index (n2) of the resin forming the transparent resin top layer (L2) 11b is 1.565, and the refractive index (n1) of the transparent resin intermediate layer 12 is 1. .452 is an optical element having a refractive index difference n2−n1 = 0.113.

In this wavelength demultiplexing optical element, the reflection target light W _vmax in the formula (I) is ₁₅₂₅ nm, the pitch width P is 0.47 μm, n is 1, and K is 0.308 . Formula (I) is not satisfied.

  As a result, as is apparent from the reflection spectrum waveform diagram shown in FIG. 19B, reflected light having a considerable reflection intensity over the near-infrared region can be obtained. Most of the light is not reflected and demultiplexed with respect to near-infrared wavelength light. Therefore, the function of transmitting almost all incident wavelength light and reflecting and branching near infrared wavelength light as in the present invention cannot be exhibited.

  20A, the refractive index (n2) of the resin forming the transparent resin top layer (L2) 11b is set to 1.565, and the refractive index (n1) of the transparent resin intermediate layer 12 is set to 1. .452 is an optical element having a refractive index difference n2−n1 = 0.113.

In this wavelength demultiplexing optical element, the reflection target light W _vmax in the formula (I) is ₁₅₂₅ nm, the pitch width P is 3.1 μm, n is 1, and K is 2.033 , Formula (I) is not satisfied.

  As a result, as is apparent from the reflection spectrum waveform diagram shown in FIG. 20B, reflected light having a considerable reflection intensity over the near-infrared region can be obtained, but at the same time, the reflection of the sideband is large and incident. Most of the light is not reflected and demultiplexed with respect to near-infrared wavelength light. Therefore, the function of transmitting almost all incident wavelength light and reflecting and branching near infrared wavelength light as in the present invention cannot be exhibited.

  The wave demultiplexing optical element of the present invention can be used in an ultraviolet region, a visible region, a near infrared region, an optical communication region, and a wavelength region of 200 nm to 2000 nm exceeding the optical communication region. For example, a resin having a refractive index of 1.565 can be used as the transparent resin top layer, a refractive index of 1.432 can be used for the transparent resin intermediate layer, and a resin having a refractive index of 1.67 can be used for the transparent substrate layer.

In the ultraviolet region (wavelength: 0.235 μm), the width of the ridges is 0.1 μm, the formation period of the ridges (P: pitch width) is 0.155 μm or 0.46 μm, and K in the formula (I) is 0 .650,
In the visible region (wavelength: 0.534 μm), the width of the ridge is 0.3 μm, the period of formation of the ridge (P: pitch width) is 0.572 μm or 0.621 μm, and K in the formula (I) is 0 .659,
In the near-infrared region (wavelength: 0.868 μm), the width of the ridge is 0.3 μm, and the formation cycle of the ridge (P: pitch width) is 0.572 μm or 0.621 μm. Is 0.659,
In the optical communication region (wavelength: 1.302 μm), the width of the ridge is 0.3 μm, the formation cycle of the ridge (P: pitch width) is 1.302 μm, and K in the formula (I) is 0.668. Yes, over the optical communication region (wavelength: 1.844 μm), the width of the ridge is 0.972 μm, the formation period (P) of the ridge is 1.272 μm, and K in the formula (I) is 0.689 is there.

  FIG. 21A shows a reflection peak of ultraviolet light having a wavelength of 0.235 μm in the ultraviolet region reflected and demultiplexed by the wavelength demultiplexing optical element, and FIG. 21B shows a visible region of 0.534 μm visible. FIG. 21 (c) shows the reflection peak of the light beam, and the reflection peak in the near infrared region (wavelength: 0.868 μm. FIG. 21 (b) and FIG. 21 (c) show a side band slightly. However, it can be seen that light of the target wavelength can be separated and reflected from other light by the wavelength demultiplexing optical element of the present invention.

<Method for Manufacturing Wavelength Demultiplexing Optical Element According to the Present Invention>
The wavelength demultiplexing optical element according to the present invention comprising a three-layer transparent structure having a different refractive index that effectively reflects and demultiplexes the specific wavelength light desired for the near-infrared wavelength range light described in detail above. The manufacturing method will be described below with reference to FIGS.

  In the present invention, as the “first step”, the resin film thickness (m1) is measured with the refractive index (n1) on the transparent substrate or the transparent glass substrate (L0) with the refractive index (n0) and the resin film thickness (m0). After layering the transparent resin intermediate layer (L1) using a resin, the refractive index (n2) for forming a convex or concave lattice microstructure as the transparent resin top layer as the “second step” A transparent resin top layer (L2) having a resin film thickness (m2) is laminated and formed.

  Next, as a “third step”, the transparent resin top layer (L2) is transferred and arranged in a one-dimensional cycle with convex or concave long lattice microstructures in a one-dimensional direction by thermal nanoimprinting (= long lattice). Are transferred in the form of vertical stripes) to prepare the wavelength demultiplexing optical element of the present invention.

In the production method comprising “first step” to “third step” of the present invention, particularly important process evaluations are the viewpoints (a) to (c) described below.
(A) The SEM photographic image displayed in FIG. 22A is obtained by spin-coating a PMMA resin solution for an intermediate layer on a transparent substrate by the “first step” and the “second step”, It is a SEM photograph image showing the cut surface of the laminated body formed by spin-coating the top layer styrene-type resin liquid after hardening a coating film, hardening a coating film, and carrying out lamination | stacking film formation.

For example, from a photographic image of one embodiment of the present invention, a polystyrene top layer (L2) with a film thickness (m2) = 1.34 μm on an intermediate layer (L1) with a film thickness (m1) = 3.21 μm. However, it can be clearly seen that both layers are extremely smooth and have excellent flatness, and the laminated boundary surface is laminated.
(B) Next, the SEM photographic image displayed in FIG. 22 (b) is obtained by projecting the protrusion depth (D2) = 0.26 μm on the polystyrene top layer by the thermal nanoimprint method by the “third step”. It is a SEM photograph image showing the cut surface of the wavelength demultiplexing optical element (D-1) of this invention after transferring the grating | lattice which consists of a strip | belt and a recessed part with a one-dimensional period.

Similarly, from the photographic image of one embodiment of the present invention, even after the lattice-like microstructure is transferred by the manufacturing method of the present invention, the film thickness of both layers is a predetermined film thickness (m1) = 3. It can be seen that 21 μm and film thickness (m2) = 1.34 μm maintain good smoothness and good flatness.
(C) Also, in FIGS. 23 (a), (b) and (c), the conceptual plan view shown in FIG. 23 (a) shows a lattice-like microstructure to be transferred by a thermal nanoimprint method [projection line formation period. (P)), [groove width] mold is displayed, and the conceptual plan view shown in FIG. 23B shows a reverse image [projection formation period in which the lattice-like microstructure of the mold is transferred to the transparent resin top layer. (P), (lattice width (A)], a conceptual diagram arranged in a one-dimensional period of the convex lattice of the present invention is displayed.

Therefore, referring to the table of FIG. 23 (c), in the wavelength demultiplexing optical element (D-1) according to the present invention, which has already been described in detail, the transparent resin top in the “third step” of manufacture. The ridge lattice having a predetermined formation period (P) and lattice width (A) formed on the surface of the layer is transferred in accordance with each dimension (size) of the favorable one-dimensional period and lattice width (A). Is well understood.
<Various transparent resins for the transparent resin intermediate layer and the transparent resin top layer (L1, L2)>
In the present invention, the thermoplastic and thermosetting resin members used for the lattice-shaped resin layer (L2) and the transparent resin layer (L1) include, for example, acrylic resins, polystyrene resins, (thio) phenol derivative resins, inorganic Lattice-like resin layer (L2) and transparent resin selected from the group consisting of nanoparticle-added resin, organic nanoparticle-added resin, and organic-inorganic hybrid-based resin, alone or in combination of any two or more. It can be used for the layer (L1).

In the present invention, the resin used in combination of two or more types is preferably any one selected from the group of acrylic resins, polystyrene resins, (thio) phenol derivative resins, and organic-inorganic hybrid resins. Resin can be used in combination with an inorganic nanoparticle-added resin as appropriate.
<Various transparent members for transparent substrate layer (L0)>
In the present invention, as a transparent member used for the transparent substrate layer (L0), for example, as thermoplastic and thermosetting resins, polyolefin resins, polystyrene resins, polycarbonate resins, polybutylene terephthalate (PBT) resins, Polylactic acid (PLA) resin, cyclic polyolefin resin, polyamide (PA) resin, liquid crystal polymer (LCP) resin, polyarylate (PAR) resin, polytetrafluoroethylene (PTFE) resin, polysulfone (PSF) Any resin selected from the group of resin and polyethersulfone (PES) resin is suitably used for the transparent substrate layer (L0), and in the present invention, transparent glass is also used for the transparent substrate layer ( L0) can be suitably used as appropriate.

<Application of wavelength demultiplexing optical element according to the present invention>
Useful applications of such surface microstructure members include diffraction grating optical filters, wavelength light conversion elements, waveguide mode wavelength filters, transmissive blazed diffraction gratings, diffraction gratings for optical pickups, wavelengths, and the like that have been known and used in the past. Examples thereof include optical components (or optical elements) such as a polarization conversion element for a demultiplexed communication system. It is also used for color discrimination of color copies, bar coat scanners, optical noise removal filters for optical sensors, and the like.

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.
(Example)
In this example,
(1) A PET film, a PSF film and a PES film having a refractive index (n0) and a film thickness (m0) = 100 μm were used for the transparent substrate (L0).
(2) A transparent PMMA-based transparent resin layer (L1) or PMMA / PSt-based copolymer resin layer (L1) having a refractive index (n1) and a film thickness (m1) = 3 to 4.6 μm is transparently formed on the substrate. A film was formed as the resin intermediate layer (L1).
(3) Next, on the transparent resin intermediate layer, a polystyrene based transparent resin intermediate layer (L2) having a refractive index (n2) and a film thickness (m2) = 0.85 to 1.44 μm, zirconia oxide nanoparticle dispersion The PSt resin layer (L2) or the organic-inorganic hybrid resin layer (L2) was formed as a transparent resin top layer (L2).
(4) Next, on the transparent resin top layer (L2), by a thermal nanoimprint method, for example, a lattice structure such as an SEM photographic image shown in FIG. 22 (b) [lattice depth (D2) = 0.26 μm, A wavelength demultiplexing optical element according to the present invention was prepared by transferring a predetermined grating period (P) and a predetermined fill factor.
<Measurement method of refractive index of transparent resin intermediate layer and transparent resin top layer>
In the present invention, the refractive indexes of the transparent resin intermediate layer and the resin for the transparent resin top layer were measured by a prism coupling method (Model 2010 prism coupler manufactured by Metri-con, 25 ° C., wavelength: 1556 nm). For the measurement, glass was used for the substrate.
<Preparation of resin for transparent resin intermediate layer (L1) having refractive index (n1) and film thickness (m1)>
(Reference Example 1)
A PMMA transparent resin (L1-1) for the transparent resin intermediate layer (L1) was prepared.

  In a 1 liter four-necked flask equipped with a thermometer and a nitrogen inlet tube, 100 parts by mass of MMA, 0.5 parts by mass of butyl peroxide, 1 part by mass of polyvinyl alcohol (PVA), and 200 parts by mass of tap water Was added and emulsified with stirring at 3300 rpm, and then sufficiently purged with nitrogen, heated to 72 ° C and held, and then held at 90 ° C for 1 hour.

The thus prepared emulsion having an approximate polymerization rate of 100% was IPA washed / dried / pulverized. The weight average molecular weight (Mw) measured by GPC method for this resin was 1.6 million, and the molecular weight distribution coefficient was 2.7. Further, the refractive index (n1) of the PMMA resin for intermediate layer (L1-1) thus prepared was 1.485.
(Reference Example 2)
Similarly, a PMMA-based transparent resin (L1-2) for the transparent resin layer (L1) was prepared. As in Reference Example 1, in a four-necked flask with a volume of 1 liter, 97.4 parts by mass of MMA, 1.6 parts by mass of glycidyl methacrylate (GMA), 1 part by mass of methacrylic acid (MAA), and 200 parts by mass of methyl cellosolve And after sufficiently purging with nitrogen, the temperature was raised to 65 ° C., 0.5 parts by mass of azo initiator (azobisdimethylvaleronitrile) was added, and the mixture was held at 65 ° C. for 6 hours. The polymerization reaction was terminated. Further, the refractive index (n1) of the PMMA resin for intermediate layer (L1-2), which was measured in the same manner as in Reference Example 1, was 1.482.
(Reference Example 3)
<Preparation of PMMA / PSt copolymer resin for transparent resin intermediate layer (L1)>
Similarly, a PMMA / PSt copolymer transparent resin (L1-3) used to form the transparent resin intermediate layer (L1) was prepared.

  Similarly, in a 1 liter four-necked flask equipped with a thermometer and a nitrogen inlet tube, 90 parts by mass of methyl methacrylate, 10 parts by mass of styrene, 0.5 parts by mass of lauryl peroxide, 1 part by mass of polyvinyl alcohol, 200 tap water After mass part was added and emulsified and purged with nitrogen, the temperature was raised to 72 ° C and held, and then held at 90 ° C for 2 hours.

The thus prepared emulsion having an approximate polymerization rate of 100% was IPA washed / dried / pulverized. The weight average molecular weight (Mw) measured by the GPC method was 600,000, and the molecular weight distribution coefficient was 3.0. Further, the refractive index (n1) of the PMMA / PSt copolymer resin for intermediate layer (L1-3), which was measured in the same manner as in Reference Example 1, was 1.493.
(Reference Example 4)
<Preparation of transparent resin layer resin for top layer (L2) with refractive index (n2) and film thickness (m2)>
<PSt resin>
A PSt transparent resin (L2-4) used for forming a transparent resin top layer (L2) of a polystyrene transparent resin was prepared.

  In a 1-liter four-necked flask equipped with a thermometer and a nitrogen inlet tube, 100 parts by mass of styrene (St), 0.45 parts by mass of butyl peroxide, 130 parts by mass of tap water, and dodecylbenzenesulfone 0.004 part by mass of ammonium phosphate and 10 parts by mass of tricalcium phosphate (TCP) were added. Next, after emulsification with stirring at a rotational speed of 10,000 rpm, the mixture was sufficiently purged with nitrogen and polymerized at 87-90 ° C. and held for about 3.5 hours, and further held at 89-91 ° C. × 1.5 hours, Subsequently, it hold | maintained at 96-97 degreeC x 1 hour.

The polymerized emulsion was washed with 35% hydrochloric acid and water, dried and powdered. The polymerization rate of the emulsion thus prepared was about 100%, and as a result of GPC measurement, the weight average molecular weight was 200,000 and the dispersion index was 2.3. The refractive index (n2) of the PSt transparent resin for top layer (L2-4), which was measured in the same manner as in Reference Example 1, was 1.565.
(Reference Example 5)
<PSt resin>
Similarly, a PSt transparent resin (L2-5) for a top transparent resin layer (L2) of a polystyrene transparent resin was prepared.

100 parts by mass of styrene (St) and 0.366 parts by mass of butyl peroxide were added to a 1-liter four-necked flask equipped with a thermometer and a nitrogen introduction tube, and a nitrogen purge was performed at room temperature. Subsequently, after heating up to 80 degreeC and making it superpose | polymerize, after heating up to 90 degreeC and hold | maintaining for 2 hours, 0.433 mass parts of butyl peroxides were added further, and it hold | maintained at 100 degreeC x 3 hours. The polymerized varnish had an approximate polymerization rate of 100%. Similarly, as a result of GPC measurement, the weight average molecular weight was 100,000, and the molecular weight distribution was 2.14. Further, the refractive index (n2) of the PSt-based transparent resin for top layer (L2-5), which was measured in the same manner as in Reference Example 1, was 1.566.
(Reference Example 6)
<Zirconia oxide nanoparticles dispersed PSt resin>
Similarly, the zirconia nanoparticle dispersion | distribution PSt type transparent resin (L2-6) for top layer transparent resin layers (L2) was prepared. A zirconia nanoparticle with a particle size of 10 nm dispersed in MEK under stirring at a rotational speed of 5000 rpm to (Mw) = 100,000 polystyrene resin prepared in Reference Example 5 was expressed in a weight ratio of 95: 5. And mixed well. In addition, the refractive index (n2) of the zirconia nanoparticle-dispersed PSt transparent (L2-6) for the top layer, measured in the same manner as in Reference Example 1, was 1.607.
(Reference Example 7)
<Organic-inorganic hybrid resin>
Similarly, an organic-inorganic hybrid resin (L2-4) for the top layer transparent resin layer (L2) was prepared.

In a 300 ml flask equipped with a thermometer and a stirrer, 46 parts by mass of γ-methacryloxypropyltrimethoxysilane [B1], 15 parts by mass of methyl methacrylate (MMA), and tetra-n-propoxytitanium 0.3 Mass part [A1] was added and mixed with stirring ([B1]: [A1] = 1: 3.52 × 10 ⁻³ ).

  Next, after adjusting the pH to 2 with an aqueous hydrochloric acid solution, 30 parts by mass of MMA and 60 parts by mass of tetra-n-propoxytitanium [A2] are added, and then an aqueous hydrochloric acid solution [C2] of pH = 2 is added, followed by removal. A water-containing MMA mixed solution containing a titanium / silane condensate having an alcohol-type reactive radical was prepared (([B1] + [A1] + [A2]): [C2] = 1: 0.58).

Next, the obtained mixed solution was allowed to stand / the upper layer was separated by a decantation method, and the lower layer was dehydrated with anhydrous magnesium sulfate. The obtained resin solution had a solid content of 74%, (Mw) = 50,000 by the GPC method of the resin content, and the dispersion index was 3.4. Further, the refractive index (n2) of the resin thus prepared was 1.610.
<Production of wavelength demultiplexing optical element according to the present invention>
Using the intermediate layer and top layer resins prepared in (Reference Example 1) to (Reference Example 7) described above, wavelength demultiplexing optical elements according to the present invention were prepared according to the methods described in Examples 1 to 6.
(Examples 1 and 2)
<Formation of transparent resin intermediate layer (PMMA layer)>
Example 1; A liquid resin having a viscosity of 1.6 P of the PMMA resin (L1-1) prepared in Reference Example-1 was coated on a PET film which is a transparent substrate (L0) having a film thickness (m0) = 100 μm. (Coating conditions: spin coating at 1000 rpm for 5 seconds, spin coating at 2000 rpm for 10 seconds), followed by drying at 40 ° C. × 10 minutes, further at 90 ° C. × 30 minutes, and having a film thickness of about 4.5 to 4.6 μm A cured PMMA layer was deposited.

  Example 2; Similarly, a liquid resin obtained by adding and mixing 0.5% (vs. resin) of 4-dimethylaminopyridine to the viscosity of 0.59 P of the PMMA resin (L1-2) prepared in Reference Example-2, Coating on a PSF film which is a transparent substrate (L0) having a film thickness (m0) = 100 μm (coating conditions: spin coating at a rotation speed of 1000 rpm × 5 seconds, and further rotation speeds of 1500 rpm, 2000 rpm, and 3000 rpm) The cured PMMA layer having a film thickness of about 3 to 4.6 μm was dried at 40 ° C. for 10 minutes, further at 90 ° C. for 30 minutes, and further at 105 ° C. for 60 minutes. Was deposited.

In the present invention, spin coating was performed using a spin coater 1H-DX2 manufactured by Mikasa Industries.
<Evaluation of film formability of transparent resin intermediate layer>
The film thicknesses (m1) at arbitrary 10 points in the 10 cm × 10 cm square size test pieces obtained in Example 1 and Example 2 were measured, and the results are shown in Table 1. As is clear from the standard deviation (σ) value of the film thickness described in Table 1, it can be seen that an intermediate layer (m1) that is smooth and excellent in flatness is formed. In addition, the film thickness measurement in this invention was performed using the thin film measuring apparatus F20 made from FILMETRICS.

(Examples 3 and 4)
<Transparent resin top layer (PSt layer) film formation>
Example 3: On the intermediate PMMA layer formed in Example 1, a 0.4 P viscosity resin liquid of the polystyrene-based transparent resin (L2-2) [(Mw) = 200,000] prepared in Reference Example 4 was used. After spin coating at a rotational speed of 5000 rpm × 20 seconds, drying was performed at 40 ° C. × 10 minutes, and then drying was performed at 90 ° C. × 10 minutes to form a top layer transparent resin layer (L2).

Example 4: On the intermediate PMMA layer formed in Example 2, a 0.4 P resin liquid having a viscosity of polystyrene-based transparent resin (L2-2) [(Mw) = 100,000] prepared in Reference Example 5 was used. After spin-coating at a rotation speed of 7000 rpm × 20 seconds, drying was performed at 40 ° C. × 10 minutes, and then drying was performed at 90 ° C. × 30 minutes to form a top layer transparent resin layer (L2).
<Evaluation of film formability of transparent resin top layer>
The film thickness (m2) at any 10 points of the 10 cm × 10 cm square size test pieces obtained in Example 3 and Example 4 was measured, and the results are shown in [Table 2]. As is clear from the standard deviation (σ) of the film thickness described in Table 2 being around ± 10 nm, the film formation surface is highly smooth and the top layer (m2) is extremely flat. It can be seen that a film is formed.

<Mold production>
In the production of the mold, a predetermined convex long lattice is formed on a transparent silicon top layer (L2) on a commercially available silicon substrate through normal procedures such as resist coating, EB irradiation, development, etching, and removal of residual resist. A mold that can be transferred in a one-dimensional cycle was prepared. The produced mold was subjected to surface treatment using Novec surface treatment agent EGC1720 manufactured by Sumitomo 3M. The side length of the produced mold was measured by SEM and AFM.

Condition; Resist: ZEP-520 made by Sumitomo Chemical
Mold base: Silicone EB: Use ELIONIX ELS3700 (1 × 10 ^-6 A, 30kV)
Etching: SF ₆ gas (20 SCCM, 0.28 Pas, 2 kV, 20 mA, 12 min)
Etching (removal of residual resist): O ₂ gas (5Pas, 100W)
Mold peeling treatment: Sumitomo 3M Novec surface treatment agent EGC1720
<Lattice structure transfer method>
Equipment used: ST50 manufactured by Toshiba Machine Co., Ltd. was used. Transfer method: Performed by thermal nanoimprint. Depending on the performance (temperature accuracy, surface accuracy, shot accuracy, etc.) of the molding machine used, it was appropriately dealt with. Among them, in the present invention, the transfer was carried out by setting temperature: 130 ° C., pressing force: 1.53 MPa, pressing speed: 0.01 mm / sec, pressing time: 300 seconds, mold release temperature: 60 ° C.
(Examples 5 and 6)
Example 5: A PMMA resin (L1-1) for the transparent resin intermediate layer (L1) prepared in Reference Example 1 was formed on a COP substrate (m0) of a polyolefin transparent resin in the same manner as in Example 1. A transparent resin intermediate layer (L1) having a thickness (m1) = 14.5 μm was deposited, and the zirconia nanoparticle-dispersed PSt resin (L2-) for the transparent resin top layer (L2) prepared in Reference Example 6 was prepared. 3) A liquid resin solution having a viscosity of 0.6 P was spin-coated at 5000 rpm and 7000 rpm × 20 seconds, dried at 40 ° C. × 10 minutes, and further dried at 90 ° C. × 30 minutes to obtain a film thickness (m 2 ) = 1.16 μm transparent resin top layer (L2) was deposited.

  Example 6: The PMMA / PSt copolymer resin (L1-3) for the transparent resin intermediate layer (L1) prepared in Reference Example 3 was formed on the PES substrate (m0) in the same manner as in Example 2. (M1) = 4.5 μm intermediate layer (L1) was deposited, and the viscosity of the organic-inorganic hybrid resin (L2-4) for the transparent resin top layer (L2) prepared in Reference Example 7 was 0. A 6P liquid resin solution is spin-coated at a rotational speed of 5000 rpm at 7000 rpm × 20 seconds, then dried at 40 ° C. × 10 minutes, further dried at 90 ° C. × 30 minutes, and a film thickness (m2) = 1.15 μm top Layer (L2) was deposited.

  Next, the grating width (A) = 0.68 μm and the grating depth (D2) = 0 are respectively formed on the top layers of the wavelength separators (Da) and (Db) manufactured in Examples 4 and 5, respectively. A convex long lattice with a .26 μm and fill factor (FF) = 0.66 is provided.

Further, in FIGS. 22A and 22B below, the three-layer structure of “transparent resin top layer (L2) / transparent resin intermediate layer (L1) / transparent substrate (L0)” produced in Example 4 and its The SEM photograph image of the cut surface of the three-layer structure which provided the convex long lattice in "top layer (L2)" is displayed on Fig.22 (a) and FIG.22 (b). From this photographic image, no foreign substances, bubbles or the like are observed inside the wavelength demultiplexing optical element as the refractive index three-layer structure according to the present invention, each laminated interface is smooth, and the planes between the laminated surfaces are flat. It is well understood that the property (or parallelism) is also good.
<Light transmittance evaluation of transparent substrate layer, transparent resin intermediate layer, and transparent resin top layer>
Using the Haze meter HM-150 type manufactured by Murakami Color Research Laboratory Co., Ltd. and the UV-Vis near-infrared spectrophotometer V-670 manufactured by JASCO Corporation, the total light transmittance and the spectrum in the near infrared region are used. The transmittance was measured. As a result of measuring the three-layer structure film test piece produced in the present invention, the total light transmittance was 80% or more with respect to the wavelength range of 360 nm to 1.6 μm.
<Optical element evaluation results>
Next, near infrared light having a wavelength of 1.0 to 1.6 μm was incident on the transparent resin top layer surfaces of the wavelength demultiplexing optical elements (Da) and (Db) as vertical light.

As a blank, manufactured by Gold Mirror Sigma Koki Co., Ltd. with a reflectance of 96%. A wavelength tunable laser Anritsu 8146A was used as the light source, and an Anritsu power meter 81632A was used as the detector.
As a result, in the wavelength demultiplexing optical element (Da), the 1.554 μm wavelength light is demultiplexed with a reflectance = 95%, and in the wavelength demultiplexing optical element (Db), the 1.563 μm wavelength light is demultiplexed. Was demultiplexed at a reflectance of 90%.

  As described above, according to the wavelength demultiplexing optical element of the present invention, the transparent laminate that reduces the sideband reflectivity and reflects and demultiplexes only a specific wavelength with high reflectivity with respect to the incident light in the near infrared region wavelength. The wavelength demultiplexing optical element composed of the structure can be provided at a low production cost.

  Further, the wavelength demultiplexing optical element excellent in the reflection demultiplexing property of the specific near-infrared wavelength light thus provided includes, for example, a wavelength separation (demultiplexing) element, a polarization separation element, a wavelength light conversion element, and a diffraction grating light filter. In particular, it is usefully used as a narrow band wavelength filter for wavelength division multiplexing optical communication in the field of wavelength separation optical elements such as a wavelength selection filter, a waveguide mode resonance grating filter, and a diffraction grating of an optical pickup unit. It is also used for color discrimination of color copies, barcode scanners, optical noise removal filters for optical sensors, and the like.

Claims (9)

It has a three-layer structure of transparent resin layers with different refractive indexes . As the transparent resin layer, a transparent substrate layer (L0), a transparent resin intermediate layer (L1), and a transparent resin top layer (L2) are arranged in this order. are stacked, the surface of the transparent resin top layer (L2) in the top surface layer, a number of projections to form a predetermined spacing transparent resin top layer (L2) a transparent resin top layer resin forming the (L2 ) And inseparably formed,
The refractive index of the transparent resin top layer (L2) is 1.5 to 1.8, the refractive index of the transparent resin intermediate layer (L1) is 1.35 to 1.6, and the transparent substrate layer (L0 ) Has a refractive index of 1.4 to 1.8,
The difference (n2-n1) between the refractive index (n2) of the transparent resin top layer (L2) and the refractive index (n1) of the transparent resin intermediate layer (L1) is in the range of 0.06 to 0.25. And the difference (n0−n1) between the refractive index (n0) of the transparent substrate layer (L0) and the refractive index (n1) of the transparent resin intermediate layer (L1) is −0.1 to 0.3. Within range (but not 0),
The height of the protrusion from the upper surface of the transparent resin top layer (L2) is in the range of 0.05 to 1.0 μm, and the thickness (m2) of the transparent resin top layer (L2) is 0.30 to 0.30. In the range of 3.00 μm, the layer thickness (m1) of the transparent resin intermediate layer (L1) is 2.0-30 μm, the layer thickness of the transparent substrate layer (L0) is 20-1000 μm,
On the surface of the transparent resin top layer (L2), the occupied volume (fill factor; FF) of the protrusions with respect to the total volume of the protrusions and the gap is in the range of 0.07 to 0.95,
A wavelength demultiplexing optical element characterized in that the formation period width (P) of the adjacent protrusions has a relationship represented by the following expression with respect to the wavelength (W _vmax ) of light to be reflected;

(However, in the above formula (I), W _vmax is the wavelength of light to be reflected, W _vmax is in the range of ₂₀₀ to 2000 nm, n is 1 , and K is 0.5 to 0.00. 75.) 2. The wavelength demultiplexing optical element according to claim 1, wherein a reflectance of light having a wavelength (W _vmax ) to be reflected is 70% or more.   The standing direction of many protrusions formed on the surface of the transparent resin top layer is substantially parallel (0 °) to 60 ° with respect to multi-wavelength light or single-wavelength light including incident light having a wavelength to be reflected. 2. The wavelength demultiplexing optical element according to claim 1, wherein the wavelength demultiplexing optical element is formed with an azimuth angle within a range.   2. The wavelength demultiplexing optical element according to claim 1, wherein the protrusions formed to have the predetermined interval have a shape of a ridge having a substantially rectangular longitudinal section.   2. The wavelength demultiplexing optical element according to claim 1, wherein the protrusions formed to have the predetermined interval have a polygonal column shape having a substantially rectangular longitudinal section.   2. The wavelength demultiplexing optical element according to claim 1, wherein the protrusions formed to have the predetermined interval have a cylindrical shape having a substantially rectangular longitudinal section.   2. The wavelength demultiplexing optical element according to claim 1, wherein the protrusions formed so as to have the predetermined interval have an elliptic cylinder shape having a substantially rectangular longitudinal section.   The protrusions formed so as to have the predetermined interval have a joint point between adjacent protrusions, a protrusion is formed by the bonded protrusion group, and a recess is formed in a portion where the protrusion does not exist. 2. The wavelength demultiplexing optical element according to claim 1, wherein:   The resin forming the wavelength demultiplexing optical element is made of an acrylic resin, a polystyrene resin, a (thio) phenol derivative resin, a fluorine-modified acrylic resin, an inorganic nanoparticle-added resin, and an organic-inorganic hybrid resin. 2. The wavelength demultiplexing optical element according to claim 1, comprising at least one resin selected from the group consisting of:

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