Method of manufacturing waveguide type optical device

Abstract

To provide a waveguide type optical device that is improved in waveguiding efficiency.SOLUTION: There is provided a method of manufacturing a waveguide type optical device 100 which has a refractive index periodic structure. On a base material 200 which has a first refractive index n1, a waveguide layer is formed (S102) which includes a holographic material 210 having a second refractive index n2 higher than the first refractive index n1. A region of the waveguide layer where a refractive index periodic structure 122 is to be formed is exposed (122) to two-beam interference light. Consequently, the refractive index periodic structure 122 is obtained by causing refractive index variation corresponding to an interference pattern.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing an optical waveguide device. [Background technology]

[0002] A waveguide-type optical device has a laminated structure in which a waveguide layer (core) formed of a medium with a high refractive index is sandwiched between a medium (clad) with a lower refractive index.

[0003] In general optical waveguide processes, plasma CVD (Chemical Vapor Deposition) and flame deposition are used to fabricate such waveguide structures (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. WO2022 / 157958 [Patent Document 2] Patent Publication No. 2021-124646 Summary of the Invention [Problem to be solved by the invention]

[0005] The present inventors have investigated the fabrication of optical devices such as wavelength-selective filters and diffraction gratings, and have come to recognize the following problems.

[0006] These optical devices have a microstructure in the waveguide layer, in which materials with different refractive indices are periodically arranged in the direction of light guiding. When such optical devices are fabricated using conventional processes, the surface of the waveguide layer is provided with concave and convex portions corresponding to the microstructure, and a material with a low refractive index is filled into the concave portions.

[0007] However, with plasma CVD (Chemical Vapor Deposition) and flame deposition, it is difficult to fill recesses with a low refractive index waveguide material in recesses with an aspect ratio of 3 or more, resulting in the formation of voids. The presence of voids in the waveguide reduces the waveguiding efficiency due to scattering loss.

[0008] The present disclosure has been made in view of the above-mentioned problems, and one exemplary purpose of an embodiment thereof is to provide a waveguide-type optical device with improved waveguide efficiency. [Means for solving the problem]

[0009] One aspect of the present disclosure relates to a method for manufacturing a waveguide optical device having a periodic refractive index structure, which includes a first step of forming a waveguide layer on a substrate having a first refractive index, the waveguide layer including a holographic material having a second refractive index higher than the first refractive index, and a second step of exposing a region of the waveguide layer where the periodic refractive index structure is to be formed to two-beam interference light.

[0010] Any combination of the above elements, or mutual substitution of elements or expressions between methods, devices, systems, etc., are also valid aspects of the present invention or the present disclosure. Furthermore, the description in this section (Means for Solving the Problems) does not explain all essential features of the present invention, and therefore, subcombinations of the described features may also constitute the present invention. [Effects of the Invention]

[0011] According to certain aspects of the present disclosure, waveguiding efficiency can be improved. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating a waveguide-type optical device. [Figure 2] 1A to 1C are diagrams illustrating a method for manufacturing a waveguide-type optical device according to an embodiment. [Figure 3] FIG. 1 is a diagram showing a two-beam interference exposure apparatus. [Figure 4] 1 is a diagram illustrating two laser beams irradiated onto a workpiece W. FIG. [Figure 5] 2 is a plan view showing an effective irradiation area on a workpiece W. FIG. [Figure 6] FIG. 10 is a cross-sectional view of a calculation model of a waveguide used in a simulation. [Figure 7] FIG. 10 is a diagram showing the relationship between the diameter of the cavity and the waveguide efficiency. [Figure 8] 1A to 1C are plan views illustrating an example of a method for manufacturing a waveguide-type optical device. [Figure 9] 10A to 10C are plan views illustrating another example of a method for manufacturing a waveguide-type optical device. DETAILED DESCRIPTION OF THE INVENTION

[0013] (Outline of the embodiment) A summary of some exemplary embodiments of the present disclosure is provided below. This summary is intended as a prelude to the more detailed description that follows, or to provide a basic understanding of the embodiments. This summary is intended to briefly explain some concepts of one or more embodiments and is not intended to limit the scope of the invention or disclosure. Furthermore, this summary is not an exhaustive overview of all possible embodiments, nor does it limit essential elements of the embodiments. For convenience, the term "one embodiment" may refer to one embodiment (example or variant) or multiple embodiments (examples or variants) disclosed herein.

[0014] A method for manufacturing a waveguide-type optical device having a periodic refractive index structure according to one embodiment includes a first step of forming a waveguide layer on a substrate having a first refractive index, the waveguide layer including a holographic material having a second refractive index higher than the first refractive index, and a second step of exposing a region of the waveguide layer where the periodic refractive index structure is to be formed to two-beam interference light.

[0015] This method does not require filling the recesses with a waveguide material with a low refractive index, which prevents the formation of voids in the waveguide, thereby improving the waveguide efficiency.

[0016] "Holographic material" refers to a photosensitive material whose refractive index changes when irradiated with light, and is also called a photorefractive polymer.

[0017] In one embodiment, the second step may form an interference pattern in a limited area having a predetermined shape and a predetermined size. By limiting the two-beam interference light to only the area where the refractive index periodic structure is to be formed and irradiating it after shaping it into a predetermined shape, it is possible to prevent the guided light from spreading and dissipating in the periodic structure area, thereby achieving the effect of increasing the waveguide efficiency.

[0018] In one embodiment, the manufacturing method may further include a third step of forming an input waveguide from the input end of the waveguide-type optical device to the periodic refractive index structure and an output waveguide from the periodic refractive index structure to the output end of the waveguide-type optical device.

[0019] In one embodiment, the holographic material has a refractive index that decreases in response to the intensity of light irradiated thereon, and the third step may include exposing the holographic material with a second mask placed over the holographic material, the second mask covering the input and output waveguides.

[0020] In one embodiment, the holographic material has a refractive index that increases in response to the intensity of the light irradiated thereto, and the third step may include exposing the holographic material while placing a third mask, which has openings for the input and output waveguides, over the holographic material.

[0021] In one embodiment, the aspect ratio of the periodic refractive index pattern may be equal to or greater than 3. When the aspect ratio is equal to or greater than 3, cavities tend to occur easily in plasma CVD and flame deposition methods, and therefore the advantages of the manufacturing method according to the present disclosure become more pronounced.

[0022] In one embodiment, the waveguide optical device may be a wavelength selective filter.

[0023] (Embodiment) Preferred embodiments will be described below with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing will be designated by the same reference numerals, and redundant descriptions will be omitted where appropriate. Furthermore, the embodiments are merely examples and do not limit the disclosure or invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the disclosure or invention.

[0024] In addition, the dimensions (thickness, length, width, etc.) of each component shown in the drawings may be enlarged or reduced as appropriate for ease of understanding. Furthermore, the dimensions of multiple components do not necessarily represent their relative sizes, and even if a component A is depicted as being thicker than another component B in the drawings, it is possible that component A is thinner than component B.

[0025] First, a waveguide-type optical device manufactured by a manufacturing method according to an embodiment will be described.

[0026] 1 is a diagram showing a waveguide-type optical device 100. The waveguide-type optical device 100 receives incident light L1 at one end (incident end) thereof. The incident light L1 is guided in the z-axis direction (to the right on the page) and is emitted as output light L2 from the other end (output end).

[0027] The waveguide-type optical device 100 has a waveguide structure including a cladding layer 110 and a waveguide layer 120 stacked in the y-axis direction (upward in the plane of the paper). The refractive index n1 of the cladding layer 110 is relatively lower than the refractive index n2 of the waveguide layer 120. The function of the waveguide-type optical device 100 is not particularly limited, but may be, for example, a wavelength selection filter.

[0028] A periodic refractive index structure 122 is formed in a part of the waveguide layer 120. In the periodic refractive index structure 122, materials 124 and 126 having different refractive indices are arranged regularly and periodically in the light guiding direction.

[0029] The specific structure of the refractive index periodic structure 122, i.e., the number of periods, height, dimensions and refractive index of material 124, dimensions and refractive index of material 126, etc., is not particularly limited and is designed depending on the functions to be possessed by the waveguide-type optical device 100. The layer above the waveguide layer 120 may be air, or a cladding layer having a refractive index lower than that of the waveguide layer 120 may be formed.

[0030] An incident-side waveguide 130 is formed on the path from the incident end of the waveguide-type optical device 100 to the periodic-refractive-index structure 122. An exit-side waveguide 132 is formed on the path from the periodic-refractive-index structure 122 to the exit end of the waveguide-type optical device 100.

[0031] 2A and 2B are diagrams showing a method for manufacturing the waveguide-type optical device 100 according to the embodiment. First, a substrate 200 that will later become the cladding layer 110 is prepared (S100).

[0032] After cleaning the surface of the substrate 200, a holographic material 210 is applied onto the substrate 200 to obtain a laminate 212 (S102). Specific examples of the holographic material 210 include dichromated gelatin and photopolymerizable polymers such as Bayfol (registered trademark) from Covestro GmbH of Germany.

[0033] Next, by two-beam interference exposure, a beam having a periodic intensity distribution is irradiated onto an area of ​​the holographic material 210 where the refractive index periodic structure 122 shown in Figure 1 is to be formed (S104). The holographic material 210 is a layer that will later become the waveguide layer 120.

[0034] The refractive index of the holographic material 210 changes in response to the amount of light received, and the refractive index at high light intensity changes to n3. The changed refractive index n3 may be higher or lower than the original refractive index n2.

[0035] Thus, a refractive index periodic structure 122 containing regions with different refractive indexes periodically is formed in the holographic material 210 (S106).

[0036] Next, the two-beam interference exposure device used in step S104 will be described.

[0037] 3 is a diagram showing a two-beam interference exposure apparatus 1. The two-beam interference exposure apparatus (hereinafter simply referred to as exposure apparatus) 1 generates interference light (interference fringes) having brightness (light intensity distribution) at a pitch equal to or smaller than the wavelength of the laser beams by intersecting two laser beams at a predetermined angle θ, and irradiates the workpiece W with this.

[0038] In this two-beam interference exposure method, highly coherent light from a light source such as a laser is split into two beams, which are then made to interfere with each other, thereby obtaining a fine and periodic exposure illuminance distribution without the need for a fine mask.

[0039] The exposure apparatus 1 includes a light source 2, a beam expander 3, a down-stroke mirror 4, a shutter 5, a beam splitter 6, folding mirrors 7a and 7b, condenser lenses 8a and 8b, pinholes 9a and 9b, and collimator lenses 10a and 10b. The exposure apparatus 1 also includes a stage 11, a suction cup 12, a mask 13, a gap sensor 14, a controller 20, and a stage drive circuit 21.

[0040] Light source 2 is a coherent light source that emits coherent light, for example, a semiconductor-pumped solid-state laser that emits laser light with a wavelength λ of 266 nm. The beam diameter of laser beam B0 emitted by light source 2 is expanded by beam expander 3, and its optical path is deflected by down-stroke mirror 4.

[0041] The shutter 5 is used to switch the laser light emission ON / OFF, and is disposed between the mirror 4 and the beam splitter element 6. The opening and closing of the shutter 5 is controlled by a controller 20.

[0042] The beam splitting element 6 splits one laser beam into two laser beams. The beam splitting element 6 is, for example, a concave-convex diffraction element that realizes its function by utilizing the shape effect of a fine concave-convex shape formed on the surface of quartz or the like.

[0043] The two laser beams B1 and B2 generated by the beam splitter element 6 are reflected by reflecting mirrors 7a and 7b, respectively, and enter condenser lenses 8a and 8b.

[0044] The laser light focused by the focusing lens 8a enters a pinhole 9a, where its beam diameter is expanded, and then collimated by a collimating lens 10a. In this way, a collimated laser beam B3 is obtained. Similarly, the laser light focused by the focusing lens 8b enters a pinhole 9b, where its beam diameter is expanded, and then collimated by a collimating lens 10b. In this way, a collimated laser beam B4 is obtained.

[0045] Here, pinholes 9a and 9b function as spatial filters to remove disturbances in the beam wavefront that occur on the optical path up to condenser lenses 8a and 8b, and collimator lenses 10a and 10b are used to convert the wavefront of the laser light into an ideal plane wave.

[0046] The two laser beams B3 and B4 intersect at a predetermined interference angle 2θ. This generates interference fringes due to the interference of the two laser beams B3 and B4 above the workpiece W, which are then irradiated onto the workpiece W as an exposure beam. In other words, a striped line-and-space pattern is transferred onto the workpiece W. The workpiece W corresponds to the substrate 200, the holographic material 210, and the laminate 212.

[0047] In this way, the optical system elements consisting of the beam expander 3, down mirror 4, shutter 5, beam splitting element 6, folding mirrors 7a, 7b, condenser lenses 8a, 8b, pinholes 9a, 9b, and collimating lenses 10a, 10b cause the two beams of light split from the output light of the light source 2 to intersect at an interference angle 2θ, generating interference light. Of these optical system elements, the set of elements between the beam splitting element 6 and the workpiece W are arranged in pairs, and the two laser beams split by the beam splitting element 6 are guided to the workpiece W, shaped, and caused to interfere on the workpiece W.

[0048] Returning to FIG. 3, the workpiece W is fixed on a suction cup 12 provided on the stage 11. The stage 11 has the freedom to move in the X and Y directions relative to the surface of the workpiece W, and the controller 20 is able to move the stage 11 in the X and Y directions by driving and controlling the stage drive circuit 21. In other words, the workpiece W moves in the X and Y directions by moving the stage 11 in the X and Y directions.

[0049] In this embodiment, taking into consideration lens aberration, only light extracted from near the centers of the collimating lenses 10a and 10b is used to expose the workpiece W. Specifically, a mask 13 having a rectangular opening (light-transmitting portion) is placed on the top surface of the workpiece W, and interference light formed only by light near the centers that has passed through the collimating lenses 10a and 10b via the mask 13 is irradiated onto the workpiece W as an exposure beam.

[0050] The mask 13 is made of a light-shielding member having a rectangular light-transmitting portion. Here, the mask 13 is made of a metal substrate with a rectangular opening formed in the approximate center. Alternatively, the mask 13 may be made of a transparent substrate such as glass, on which a light-shielding film is formed with a rectangular light-transmitting portion that exposes the transparent substrate. Here, the light-shielding film is made of, for example, chromium. The light-transmitting portion may have a shape close to a rectangle (approximately rectangular).

[0051] By placing such a mask 13 above the workpiece W, when two light beams are incident on the mask 13 at an interference angle 2θ, the area on the workpiece W that is irradiated with the interference light in one shot can be shaped into a rectangle. The area on the workpiece W that is separated by the rectangular openings of this mask 13 and that is irradiated with light is hereinafter referred to as the effective irradiation area.

[0052] The rectangular opening of the mask 13 is formed smaller than the irradiation area on the workpiece W of the light that has passed through the collimator lenses 10a and 10b. The size of this rectangular opening is approximately the same as the effective irradiation area, and is, for example, 20.5 mm × 13.8 mm.

[0053] The optimal size of the mask's rectangular opening varies depending on the exposure conditions. For example, assume a wavelength of λ = 266 nm, an interference angle of θ = 47.6° (interference pattern L&S pitch of 180 nm), an irradiation area (beam 1 / e² diameter) of φ82 mm, an interference pattern contrast of 70%, a laser output of 100 mW, a resist exposure threshold of 5 mJ / cm², an 8-inch wafer as the workpiece, and an exposure area of ​​90%. For a target line width of L = 60 ± 10 nm, the mask's rectangular opening size is preferably in the range of 8 mm × 5 mm to 36 mm × 24 mm. For a target line width of L = 60 ± 5 nm and a takt time of 10 min / sheet or less, a range of 18 mm × 12 mm to 24 mm × 16 mm is even more preferable.

[0054] If the long side of the rectangular opening of the mask is A and the short side is B, the area of ​​the effective irradiation region for one shot can be maximized when the relationship A=B / cos θ holds.

[0055] Beam diameter (1 / e 2 ) can be determined arbitrarily depending on the magnification of the beam expander 3, the condenser lenses 8a and 8b, and the collimator lenses 10a and 10b. Therefore, the size of the mask 13 is changed appropriately depending on the application, including the size of the beam diameter.

[0056] 4 is a diagram illustrating two laser beams B3 and B4 that are irradiated onto the workpiece W. The mask 13 is positioned with a gap D provided between it and the workpiece W. As shown in FIG. 3, a gap sensor 14 is embedded in the stage 11 and the suction cup 12, and this gap sensor 14 makes it possible to measure the distance between the suction cup 12 and the mask 13.

[0057] In addition, the mask 13 is held in a holder whose distance from the suction cup 12 is adjustable, and prior to exposure to the workpiece W, the distance between the suction cup 12 and the mask 13 is adjusted so as to provide an arbitrary gap D depending on the thickness of the workpiece W to be fixed to the suction cup 12.

[0058] By placing the mask 13 above the workpiece W with a gap D, as shown in Figure 4, there are regions on the workpiece W that are irradiated with the interference light of laser beams B3 and B4, and regions that are irradiated with only one of laser beams B3 and B4. That is, the effective irradiation region consists of an interference light irradiation region E1 (hereinafter simply referred to as the "interference region") that is irradiated with the interference light, and a non-interference light irradiation region E2 (hereinafter simply referred to as the "non-interference region") that is formed on both sides of the interference region E1 in the X direction due to the geometrical wraparound of the light beam. The width of the non-interference region E2 depends on the gap D and the interference angle θ and is 2D tan θ.

[0059] FIG. 5 is a plan view showing an effective irradiation area E0 on a workpiece W. Here, the left-right direction in FIG. 5 is the X direction, and the up-down direction in FIG. 5 is the Y direction. An interference area E1 is formed in the center of the effective irradiation area E0 in the X direction, and non-interference areas E2 are formed on both sides of it. Interference fringes are formed in the interference area E1, and no interference fringes are formed in the non-interference areas.

[0060] For example, when the wavelength λ of the light source 2 is 266 nm and the interference angle is 15°≦θ≦60°, stripe-shaped interference fringes are formed in the interference region E1, with the pitch between adjacent lines being 154 nm to 514 nm. The pitch of the interference fringes depends on the interference angle θ, the wavelength λ of the light source 2, and the refractive index n of the exposure environment, and is λ / (2n sinθ). In other words, when n=1 (exposure in air), the pitch of the interference fringes can be shortened to nearly half the wavelength λ of the laser light from the light source 2.

[0061] The above is the configuration of exposure apparatus 1. With this exposure apparatus 1, in step S104, it is possible to limit the area where the interference pattern is formed to an area having a predetermined shape and size determined by the opening in mask 13 and gap D.

[0062] The method for limiting the region where the interference pattern is formed is not limited to using the mask 13, and other methods may be used for limiting the region.

[0063] The method for manufacturing the waveguide-type optical device 100 has been described above.

[0064] This manufacturing method does not require filling the recesses with a waveguide material having a low refractive index when forming the refractive index periodic structure 122. This prevents the formation of cavities in the waveguide, thereby improving the waveguide efficiency.

[0065] Simulations were performed to investigate the effects of cavities in the waveguide. Figure 6 is a cross-sectional view of a calculation model of waveguide 300 used in the simulation. Waveguide 300 has a structure in which waveguide layer 302 is sandwiched between cladding layers 304 and 306. SiO2 was selected as the material for waveguide layer 302 and cladding layers 304 and 306, and the refractive index n5 of waveguide layer 302 was set to 1.52, and the refractive index n4 of cladding layers 304 and 306 was set to 1.47.

[0066] The height h of the waveguide layer (waveguide) was set to 3 μm, and the width w of the waveguide was set to 3 μm. The waveguide layer 302 is provided with a fine periodic structure 310 in which different refractive indices n4 and n5 appear alternately. The periodic interval is set to 1 μm, and the number of periodic layers is set to 100. A spherical cavity 312 with a refractive index of 1 exists in the center of the low refractive index portion of the fine periodic structure 310. In the simulation, the diameter φ of the cavity 312 was used as a parameter to calculate the waveguiding efficiency.

[0067] 7 is a diagram showing the relationship between the diameter of cavity 312 and the waveguide efficiency. With conventional manufacturing methods, it is difficult to fill a recess with a low refractive index material in a large aspect ratio (for example, an aspect ratio of 3 or more), and empirically, it is believed that cavities 312 with a diameter φ of about 0.5 μm are formed. Therefore, with conventional technology, the waveguide efficiency was limited to about 20%.

[0068] In contrast, the waveguide-type optical device 100 obtained by the manufacturing method according to the embodiment does not, in principle, generate voids, and therefore the waveguide efficiency is improved to 95%, which corresponds to the simulation result when the diameter φ of the cavity 312 is set to 0 μm. Thus, according to the manufacturing method according to the embodiment, the waveguide efficiency can be improved by suppressing the generation of voids.

[0069] As described above, the holographic material 210 may be a material whose refractive index increases or decreases upon exposure to light. Depending on the polarity of the change in refractive index of the holographic material 210, several variations in the method for manufacturing the waveguide-type optical device 100 are possible.

[0070] 8 is a plan view illustrating an example of a method for manufacturing the waveguide-type optical device 100. In this example, the refractive index of the holographic material 210 is lowered by exposure to light.

[0071] First, holographic material 210 is applied onto substrate 200 (wafer) with a refractive index n1, to create laminate 212 of substrate 200 and holographic material 210 (S300). Before light irradiation, the refractive index of holographic material 210 is uniformly n2. The subsequent exposure process is shown by enlarging the area of ​​one chip.

[0072] Next, a mask 400 is placed on the laminate 212 coated with the holographic material 210 (S302). The mask 400 has a pattern that blocks light from reaching the waveguide region including the incident-side waveguide 130, the output-side waveguide 132, and the periodic refractive index structure 122.

[0073] Next, laminate 212 is irradiated with ultraviolet light through mask 400 (S304). As a result, holographic material 210 is exposed to ultraviolet light patterned according to the openings of mask 400. The refractive index of the portion of holographic material 210 that is irradiated with the light is reduced to n3. This process forms waveguide 214, which includes incident-side waveguide 130 and output-side waveguide 132.

[0074] Next, two-beam interference exposure is performed on a region 216 of the waveguide 214 where the periodic refractive index structure 122 is to be formed (S306). With respect to the width direction of the waveguide, the two-beam interference exposure may be limited to the width of the waveguide 214, or may be performed without limitation across the entire width of the chip or across multiple chips.

[0075] The two-beam interference exposure reduces the refractive index in the areas with high light intensity to n3, thereby forming a refractive index periodic structure 122 in the region 216, where the refractive indexes n2 and n3 alternate at a predetermined pitch.

[0076] In this example, the incident-side waveguide 130 and the output-side waveguide 132 are formed before the refractive index periodic structure 122, but this is not a limitation and they may be formed afterwards.

[0077] 9 is a plan view illustrating another example of a method for manufacturing the waveguide-type optical device 100. In this example, the refractive index of the holographic material 210 is increased by exposure to light.

[0078] First, holographic material 210 is applied onto substrate 200 (wafer) with a refractive index n1, to create laminate 212 of substrate 200 and holographic material 210 (S400). Before light irradiation, the refractive index of holographic material 210 is uniformly n2. The subsequent exposure process is shown by enlarging the area of ​​one chip.

[0079] Next, two-beam interference exposure is performed on the laminate 212 coated with the holographic material 210 (S402). In the width direction of the waveguide, the two-beam interference exposure may be limited to the width of the waveguide 214, or may be performed across the entire width of the chip without being limited thereto, or across multiple chips.

[0080] The two-beam interference exposure increases the refractive index of the area with high light intensity to n3, thereby forming a refractive index periodic structure 122 in the area 216, where the refractive indexes n2 and n3 alternate at a predetermined pitch.

[0081] Next, a mask 402 is placed (S404). The mask 402 has a pattern that blocks light from entering areas other than the areas where the incident-side waveguide 130 and the output-side waveguide 132 are to be formed.

[0082] Next, laminate 212 is irradiated with ultraviolet light through mask 400 (S406). As a result, holographic material 210 is exposed to ultraviolet light patterned according to the openings of mask 400. The refractive index of the portions of holographic material 210 exposed to the light, i.e., the portions of incident-side waveguide 130 and output-side waveguide 132, increases to n3. Through this process, incident-side waveguide 130 and output-side waveguide 132 are formed.

[0083] In this example, the incident-side waveguide 130 and the output-side waveguide 132 are formed after the refractive index periodic structure 122, but this is not a limitation and they may be formed beforehand.

[0084] In the embodiment, a wavelength-selective filter has been described as an example of the waveguide-type optical device 100, but the application of the present disclosure is not limited thereto. In addition to the wavelength-selective filter, examples of the functions of the waveguide-type optical device 100 include input / output using a grating coupler, phase modulation, multiplexing / demultiplexing, and the like.

[0085] The embodiments merely illustrate the principles and applications of the present invention, and many modifications and changes in arrangement are permitted to the embodiments as long as they do not deviate from the spirit of the present invention as defined in the claims. [Explanation of symbols]

[0086] 100 Waveguide optical devices 110 Cladding layer 120 Waveguide layer 122 Microstructure 130 Input side waveguide 132 Output side waveguide 200 Base material 210 Holographic Materials 212 Laminate 400,402 Mask

Claims

1. A method for manufacturing a waveguide-type optical device having a periodic refractive index structure, comprising: a first step of forming a waveguide layer on a substrate having a first refractive index, the waveguide layer including a holographic material having a second refractive index higher than the first refractive index; a second step of exposing a region of the waveguide layer where the periodic refractive index structure is to be formed to two-beam interference light; A manufacturing method comprising:

2. 2. The manufacturing method according to claim 1, wherein the second step forms an interference pattern in a limited area having a predetermined shape and a predetermined size.

3. 3. The manufacturing method according to claim 1, further comprising a third step of forming an input waveguide from an input end of the waveguide-type optical device to the periodic-refractive-index structure and an output waveguide from the periodic-refractive-index structure to an output end of the waveguide-type optical device.

4. the holographic material has a refractive index that decreases in response to the intensity of light irradiated thereon; 4. The method of claim 3, wherein the third step includes exposing the holographic material with a second mask positioned over the holographic material, the second mask covering the input and output waveguides.

5. The holographic material has a refractive index that increases in response to the intensity of light irradiated thereon; 4. The method of claim 3, wherein the third step includes exposing the holographic material with a third mask, the third mask having openings for the input waveguide and the output waveguide, positioned above the holographic material.

6. 3. The manufacturing method according to claim 1, wherein the periodic pattern of refractive index has an aspect ratio of 3 or more.

7. 3. The method according to claim 1, wherein the waveguide-type optical device is a wavelength-selective filter.

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