JP2008122474A - Optical waveguide, manufacturing method of optical waveguide, mold for manufacturing waveguide, and method for manufacturing mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide capable of reducing light guiding loss of the waveguide, and also to provide its manufacturing method, a mold for manufacturing the waveguide, and a method for manufacturing the mold. <P>SOLUTION: In an embodiment of the invention, an injection-moldable optical waveguide having a clad 21 and a core 22 is provided, wherein the cross section of the core 22 is semicircular. Thus, the semicircular cross section of the core 22 results in reduction in wall face reflection frequency in the boundary of the core 22 and the clad 21 compared to a conventional core of a rectangular cross section. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical waveguide, a method for producing an optical waveguide, a mold for producing a waveguide, and a method for producing a mold, and more particularly, an optical waveguide produced by transfer, a method for producing an optical waveguide, and transfer. The present invention relates to a mold for performing the above and a manufacturing method thereof.

  From the recent advancement of advanced information technology, a communication system capable of transmitting a large amount of information at high speed is desired, and an optical communication system is being developed as such a communication system. As such a system, various optical communication systems such as a wavelength division multiplexing (WDM) system have been developed. In an optical communication system, a waveguide is a very important component. Recently, a polymer waveguide has attracted attention as a waveguide because of its flexibility and toughness. In Non-Patent Document 1, an imprint process and a printing process are performed to produce a polymer waveguide.

1A to 1D are diagrams showing a conventional method for producing a polymer waveguide disclosed in Non-Patent Document 1. FIG.
In FIG. 1A, a lower cladding layer 2 is applied on a substrate 1. Next, the lower clad layer 2 applied on the substrate 1 is pressed on the mold 3 having the convex and concave portions 4 and the concave portions 5 that are formed into the concave and convex patterns, and the concave and convex patterns are transferred to the surface of the lower clad layer 2. (FIG. 1B). In this way, the imprint process is performed, and as shown in FIG. 1C, the convex portions 7 and the concave portions 8 formed by transferring the convex portions 4 and the concave portions 5 are formed in the lower cladding layer 2. . A printing process for printing the core 9 in the recess 8 formed in this way is performed (FIG. 1D). This printing process is performed by screen printing, offset printing, gravure printing, inkjet, dispenser application, or the like. In this way, the core 9 is formed on the lower cladding layer 2.

  Conventionally, the concave portion 5 of the mold used in the imprint process is formed by a lithography method, an electron beam drawing method, a laser beam drawing method or the like on a photosensitive resin layer formed on the glass of the die. It is manufactured by forming a latent image of a fine pattern, developing the photosensitive resin layer to form a fine pattern of the photosensitive resin, and then performing an electroforming process (see Non-Patent Document 2). That is, the concave / convex pattern of the mold is formed using physical etching. Conventionally, the concave / convex pattern may be formed by cutting the mold surface with an end mill or the like.

  That is, conventionally, a concavo-convex pattern has been formed on a mold (original) used in a waveguide manufacturing method by physical etching or cutting.

Yukihiro Sugihara and five others, “Preparation of large-diameter polymer optical waveguides using a molding process”, IEICE Technical Report, OME2003-83, p. 17-21, 2003 Akihiko Sano and two others, “Replicated Polymer Optical Waveguide“ SPICA ””, IEICE Technical Report, OME2003-82, p. 13-16, 2003

  The above-described method for producing a waveguide using transfer does not require development work for forming a core pattern when the core is formed on the clad, as compared with a production method using photolithography. It can be efficiently manufactured, and also eliminates the need for a resist material, leading to cost reductions. This is a powerful polymer waveguide fabrication method, but even this method using transfer was fabricated. In order to make a waveguide of high quality, there are still problems to be improved.

  In particular, in order to make the manufactured waveguide better, it is desirable to reduce the waveguide loss. The waveguide loss of the waveguide is caused by absorption and scattering of the material itself and scattering due to irregularities at the core / cladding interface. In general, at a wavelength where material loss is small, interface scattering between the clad and the core (hereinafter, also simply referred to as “interface scattering”) is a major factor of the loss. Therefore, when the interface between the cladding and the core has the same roughness, the smaller the number of times the guided light guided through the core is reflected by the interface, the smaller the waveguide loss, leading to a reduction in waveguide loss. Therefore, it is desirable to produce a waveguide with a reduced number of interface reflections.

  The present invention has been made in view of such problems, and the object thereof is an optical waveguide capable of reducing the waveguide loss of the waveguide, a method for manufacturing the optical waveguide, a mold for manufacturing the waveguide, It is another object of the present invention to provide a mold manufacturing method.

  In order to achieve the above object, according to the present invention, an invention according to claim 1 is an optical waveguide including a clad and a core, and the cross section of the core is semicircular.

  The invention according to claim 2 is a method of manufacturing an optical waveguide including a clad and a core, and a preparation step of preparing a mold in which a concave portion having a semicircular cross section is formed in a predetermined pattern on a first surface; A clad forming step for forming the clad, an applying step for imparting a material to be the core by being hardened and hardened on the clad, and a recess formed in the mold is transferred to the material. And a core forming step of curing the material to form a core having a cross-sectional shape that is inverted from the concave portion and having a semicircular cross section.

  The invention according to claim 3 is a method of manufacturing an optical waveguide including a clad and a core, wherein the first mold is formed with a first recess having a semicircular cross section formed in a predetermined pattern on a first surface. A first step of preparing a flexible second mold having a convex portion inverted from the first concave portion, and a fluidity on the substrate; An applying step for applying a material to be a clad, and a second concave portion having a cross-sectional shape that is inverted from the convex portion by transferring the convex portion formed on the second mold to the material and curing the material; And a clad forming step of forming the clad having the second concave portion having a semicircular cross section, and a core forming step of forming the core in the second concave portion. .

  The invention according to claim 4 is a method of manufacturing an optical waveguide including a clad and a core, wherein the first mold is formed with a first recess having a semicircular cross section formed in a predetermined pattern on a first surface. A step of preparing a flexible second mold having a second recess having a cross section of the same shape as the first recess, and a clad forming step of forming the cladding; A transfer step of applying a material to be the core by being fluidized and cured on the clad, and transferring a second recess formed in the second mold to the material, A core forming step of curing the material to form a core having a cross-sectional shape that is inverted with respect to the second recess and having a semicircular cross-section.

  The invention according to claim 5 is a mold for producing an optical waveguide including a clad and a core, and is a recess having a predetermined pattern formed on the substrate and the first surface of the substrate, And a recess having a semicircular cross section.

  The invention according to claim 6 is a method of manufacturing a mold for manufacturing an optical waveguide having a clad and a core, and is formed by polishing the substrate with a predetermined pattern on the first surface of the substrate. A recess having a semicircular cross section with the predetermined pattern is formed on the first surface.

  A seventh aspect of the invention is characterized in that, in the sixth aspect of the invention, the recess has a rounded tip, and is formed by means for grinding while rotating the tip.

  The invention according to claim 8 is the invention according to claim 7, wherein the tip is a grindstone.

  According to the present invention, since the cross-sectional shape of the core of the optical waveguide is semicircular, the number of wall surface reflections between the clad and the core can be reduced, and the waveguide loss can be reduced.

  One embodiment of the present invention is characterized by the cross-sectional shape of a core of an optical waveguide that can be molded, and the interface between the cladding and the core is made the same roughness with respect to waveguides of other cross-sectional shapes. In comparison, the number of wall surface reflections between the clad and the core (the number of interface reflections) is reduced.

In such an embodiment of the present invention, the cross-sectional shape of the core is a semicircular shape. FIG. 2 is a perspective view of a semi-circular optical waveguide according to an embodiment of the present invention.
In FIG. 2, a core 22 having a semicircular cross section is formed on a clad 21. Thus, by using the semicircular core 22, the interface scattering can be suppressed as compared with a conventional square cross section as will be described later, so that the waveguide loss can be reduced.

The following calculation was performed on the relationship between the waveguide shape and the loss. The cross-sectional area of the waveguide was square, circular, and semicircular so that the cross-sectional areas were the same (see Table 1 for parameters), and the average number of wall reflections was determined by ray tracing with a waveguide length of 10 cm. FIG. 3 is a diagram illustrating a state in which the relationship between the waveguide shape and the loss is obtained according to an embodiment of the present invention. In FIG. 3, a 10 cm-shaped waveguide 31 having a shape to be measured (a square waveguide, a circular waveguide, a right-angled triangle waveguide, or a semicircular waveguide) is placed at one end of a desired shape to be measured. One end of a waveguide 32 having the same shape as that of the waveguide 31 is connected, and the other end of the waveguide 32 is connected to one end of a circular waveguide 33 having a radius α and inscribed in the shape of the waveguide 32. Light enters from the other end of the circular waveguide 33. In each waveguide, the clad refractive index n _clad = 1.512 and the core refractive index n _core = 1.56.

  When the measured shape is a semicircle, the waveguide 31 and the waveguide 32 are waveguides having a semicircular cross section, and the junction 34 between the waveguide 32 and the circular waveguide 33 is denoted by reference numeral 35. In addition, the waveguide 32 and the circular waveguide 33 are connected so that a circle having a cross-sectional shape of the circular waveguide 33 is inscribed in a semicircle having a cross-sectional shape of the waveguide 32. When the shape to be measured is a triangle, the waveguide 31 and the waveguide 32 are triangular waveguides, and the junction 34 between the waveguide 32 and the circular waveguide 33 has a circular shape as indicated by reference numeral 36. The waveguide 32 and the circular waveguide 33 are connected so that a circle having a cross-sectional shape of the waveguide 33 is inscribed in a triangle having a cross-sectional shape of the waveguide 32.

  When the shape to be measured is circular, the waveguide 31 and the waveguide 32 are circular waveguides, and the junction point 34 between the waveguide 32 and the circular waveguide 33 has a radius α as indicated by reference numeral 37. The waveguide 32 and the circular waveguide 33 are connected. Further, when the shape to be measured is a square, the waveguide 31 and the waveguide 32 are square waveguides, and a circular guide is provided at the junction 34 between the waveguide 32 and the circular waveguide 33 as indicated by reference numeral 38. The waveguide 32 and the circular waveguide 33 are connected such that a circle having a cross-sectional shape of the waveguide 33 is inscribed in a square that is a cross-sectional shape of the waveguide 32.

  As can be seen from Table 1, the results show that the semicircular waveguide has fewer wall reflections than waveguides with other cross-sectional shapes.

  As described above, the waveguide loss of the waveguide is mainly caused by scattering due to unevenness at the core / cladding interface when the material loss is small. Therefore, if the cross-sectional shape is the same interface roughness for a square, a circle, a right triangle, and a semicircle, the waveguide loss decreases as the cross-sectional shape where the number of times the guided light is reflected by the interface is small.

  According to the ray tracing calculation described above, the waveguide having a semicircular cross section is only scattered at a rate of 31.0 / 47.68 = 0.65 (times) compared to the waveguide having a normal square cross section. I understand. Therefore, the cross-sectional shape of the core can suppress the loss in the semicircular shape as in the embodiment of the present invention rather than the normal square shape.

  In one embodiment of the present invention, since the core has a semicircular cross section, peeling during transfer described later can be easily performed.

  An example of the optical waveguide that can be molded is a polymer waveguide.

(First embodiment)
In this embodiment, a mold having flexibility (hereinafter also referred to as a soft stamper) is manufactured using a mold manufactured in a mold manufacturing process described later, and extrusion lamination is performed using the soft stamper. A polymer waveguide is produced.

  In the present specification, the “flexible mold (soft stamper)” refers to a resin that bends as the pushing means such as a roller comes into contact. As a material of the soft stamper, a material that has fluidity before curing, is cured by light or heat, and becomes a flexible (flexible) material after the curing is used. In the present embodiment, as a flexible mold (soft stamper), cycloolefin polymer; polyacrylate including polymethyl methacrylate, polycarbonate, polyether, polyimide, polyamide, epoxy resin, etc. Plastic resins; Thermosetting resins such as epoxy resins; Acrylics, resins obtained by making epoxy resins ultraviolet curable; Silicone resins; Fluorine resins and the like can be used.

FIG. 4 is a diagram illustrating a state in which the core is formed by extrusion lamination according to the present embodiment.
In FIG. 4, a core material 42 is formed on the entire surface of the clad film 41. The core material 42 is formed by being applied on the clad film 41. The application of the core material 42 may be dropping of the core material 42 or spraying with a spray. Moreover, application | coating with a roller etc. may be sufficient.

  In FIG. 4, the core material 42 is disposed on the entire surface of the clad film 41, but the present invention is not limited to this. In the present embodiment, as long as the core material 42 is disposed at the start point of the extrusion by the extrusion means such as a roller described later (movement start position of the extrusion means), the core material 42 may not be disposed on the entire surface.

  The core material may be a liquid material or a gel material. That is, any material can be used as the core material as long as the material has at least fluidity that can be extruded, is cured by light or heat, and functions as the core of the polymer waveguide after the curing. . For example, UV curable epoxy resin, thermoplastic resin, thermosetting resin, polyimide, silicone resin, acrylic resin / epoxy resin cured UV, polysilane, polyacrylate, polycarbonate, polyether, polyamide, etc. Can be used.

  In FIG. 4, the soft stamper 43 has a convex portion 44 and a concave portion 45 on one surface. The soft stamper 43 is arranged so that the convex portion 44 and the concave portion 45 are in contact with the core material 42. That is, the soft stamper 43 is bonded to the clad film 41 through the core material 42.

In the present specification, the “convex portion” includes a protrusion formed on a certain surface. Moreover, the area | region other than the recessed part formed in a certain surface is also included. That is, when a concave portion is formed on a certain surface, the other region can be seen as a projection when viewed from the concave portion.
Similarly, in the present specification, the “concave portion” includes a depression formed on a certain surface. Moreover, the area | region other than the convex part formed in a certain surface is also included. That is, when a convex portion is formed on a certain surface, it can be seen that the other region is depressed when viewed from the convex portion.

  Next, at one end of the soft stamper 43, the roller 46 is pressed against a surface of the soft stamper 43 that faces the surface on which the unevenness is formed. Next, from the one end toward the other end (in the direction of the arrow in the figure), a relative speed with respect to the soft stamper 43 is applied while applying a predetermined pressure so that pressure is applied to the soft stamper 43 with a line rather than a surface. The roller 46 is rolled so as to be 0, and extrusion lamination is performed.

  As the roller 46 moves, the convex portion 44 pushes the core material 42 in the moving direction of the roller 46 in order from the movement start position of the roller 46 and comes into contact with the clad film 41. On the other hand, the concave portion 45 is maintained when the core material 42 is filled in the concave portion 45 when the soft stamper 43 is bonded to the clad film 41. The core material 42 is filled in each concave portion 45 by the extrusion by the portion. In this way, the core material 47 filled in the recesses is formed.

  In this way, the roller 46 is rolled to the other end, and the soft stamper 43 and the clad film 41 are bonded together in a state where the core material 47 is left in the region between the concave portion 45 and the clad film 41. Is transferred to the core material 42. When the roller 46 is rolled to the other end, the excess core material pushed out by each convex portion 44 is pushed out from the other end, and in the space between each concave portion 45 and the clad film 41, the core The material 47 will remain.

  In the present embodiment, since extrusion lamination is performed using the soft stamper 43 having flexibility as described above, the core material to be extruded is the roller 46 even if the surface of the convex portion 44 or the surface of the clad film 41 is rough. Therefore, the amount of the core material remaining as a residue can be reduced because the roller 46 moves by the pushing force along the surface of the convex portion 44 and the clad film 41. That is, even if a residue remains, the amount can be reduced to a scale that is the same as or lower than the wavelength of the light used. Therefore, it is possible to reduce the required surface accuracy of the soft stamper and the clad, and the manufacturing cost and the manufacturing time can be reduced.

  In this specification, the term “extrusion laminate” means that a first material having flexibility such as a soft stamper or a resin film serving as a base of the soft stamper is bonded to an arbitrary second material while the first material is bonded. This is a step of transferring a concave portion and / or a convex portion of either one of the material and the second material to the other material while applying pressure with a line. Note that the shape of the unevenness between the transfer source and the transfer destination is inverted. That is, by moving the first material from one side to the other while applying pressure by an extruding means such as a roller, the first material is bonded to the second material, and excess material is removed. This is the intended process.

  The extruded laminate described above can be used when producing a core as described above, or can be used when producing a soft stamper as described later. When the core is manufactured, the first material is a soft stamper and the second material is a clad, and when the soft stamper is manufactured, the first material is a resin film and the second material is an original plate. It is a certain mold.

  As described above, in the case of producing the core, in the extrusion lamination, the core material is filled in the concave portion of the soft stamper and the other core material is extruded, and the core material is extruded from one end of the soft stamper in a predetermined direction. The extra core material is pushed out while the soft stamper is stuck to the clad by moving the pushing means such as a roller toward. That is, the extrusion laminating in this case is not a purpose of attaching the soft stamper to the clad but a process aiming at removing excess core material in order to form the core of the polymer waveguide. Therefore, after extrusion lamination, the soft stamper may stick to the clad or may not stick, and it is not essential whether the soft stamper sticks to the clad.

  Further, after the extrusion lamination, the core material may not be completely extruded at the interface between the clad and the convex portion, and the core material may remain as a residue.In this embodiment, the extrusion means such as a roller as described above. Since the excess core material is pushed out by the movement, the amount of the remaining core material can be suppressed to the scale of the wavelength of light used or less.

  Further, as in this embodiment, when a soft stamper is used as a mold for a soft stamper for producing a polymer waveguide, cutting and pasting can be easily performed, so that an increase in area can be easily performed at low cost. it can.

Mold Manufacturing Process FIGS. 5A and 5B are schematic diagrams for explaining a mold manufacturing process according to this embodiment.
In FIG. 5A, a silicon substrate 51 serving as a mold base is prepared. Next, the tip of the router 52 having a tip made of a grindstone is pressed against one surface of the silicon substrate 51, and the tip of the router 52 is moved in the direction of the arrow while rotating. By this movement of the router 52, the silicon substrate 51 along the moving direction of the router 52 is scraped while being polished. A recess having a semicircular cross section is formed in the ground silicon substrate 51. When the movement of the router 52 is stopped and the grinding is finished, a recess 53 having a semicircular cross section is formed on the silicon substrate 51. In this way, the mold 54 is produced.

  The router 52 may be moved along the pattern to be formed. In the present embodiment, the shape of the recess 53 is later transferred to the core and the clad, and the core is formed according to the transferred shape. A recess 53 may be formed on the surface.

  In the present embodiment, the router 52 is used to form the concave portion 53 having a semicircular cross-sectional shape, but the present invention is not limited to this. In the present embodiment, any means can be used as long as it can form a recess having a semicircular cross-sectional shape on one surface of a mold by grinding (shaving while polishing) with a linear pattern or a predetermined pattern. good. For example, a grinder that is thin (thickness about the width of the core to be formed) may be used. That is, in this embodiment, a transfer pattern having a semicircular cross section is formed by polishing, instead of forming a transfer pattern on a mold by cutting with an end mill or the like as in the prior art.

  In the present embodiment, since the mold 54 is formed by the reuter 52 or the like, the surface of the concave portion 53 is rough as much as a concave portion having a rectangular cross-sectional shape formed by an end mill or the like as in the conventional method ( (Surface roughness) may remain. This surface roughness is reflected on the surface of the core to be formed by the transfer described later. However, as described above, if the core has a semicircular cross section as in the present embodiment, the number of wall surface reflections can be greatly increased even if the surface roughness is the same as that of a concave portion with a rectangular cross section formed by an end mill or the like. Can be reduced. Therefore, the waveguide loss can be reduced compared to the conventional case.

  In the present embodiment, the concave portion 53 patterned in the mold 54 is transferred to the soft stamper to define the core shape (in the second embodiment, the core shape is transferred to define the core shape). In this case, the smoother the surface of the recess 53, the more the waveguide loss can be reduced. However, it is not the essence of the present embodiment to reduce the waveguide loss by smoothing the surface. What is important in this embodiment is that the waveguide loss is reduced even if the surface roughness of the recess formed in the mold is comparable to the surface roughness of the recess of the mold formed by the conventional method. It is to let you. For this purpose, in this embodiment, a recess having a semicircular cross-sectional shape is formed in a mold, the mold is transferred to a soft stamper, and the soft stamper is transferred to a core material or a clad material (second In this embodiment, the core is formed by transferring to the core material). In this embodiment, since the number of wall surface reflections can be reduced by making the core cross-section semicircular, if the concave portion of the mold serving as the transfer source can be made semicircular, the surface roughness of the concave portion can be made higher than before. There is no need to be smooth. That is, the waveguide loss can be sufficiently reduced even with the same surface roughness as that of the conventional method.

Soft Stamper Manufacturing Process FIGS. 6A to 6D are views for explaining a soft stamper manufacturing process according to this embodiment.
First, a mold 54 is prepared, and recesses 61a and 61b are formed so as to sandwich the recess 53 (FIG. 6A). The recesses 61a and 61b may be formed by physical etching or cutting, or may be formed by wet etching. Further, the depths of the recesses 61 a and 61 b are set to be deeper than at least the depth of the recess 53.

  6B, cycloolefin resin 62 (80% mesitylene solution) is dropped on the surface of the mold 54 where the recesses 53 and recesses 61a and 61b are formed, and the cycloolefin resin 62 is made of gold by spin coating. Spread over the entire processed surface of the mold 54. In this way, the cycloolefin resin is applied to at least a part of the mold 54.

  In FIG. 6C, a laminator is used to bring the cycloolefin film 63 (base film serving as the base of the soft stamper) into close contact with the cycloolefin resin 62 application surface of the mold 54. One end of the cycloolefin film 63 is in contact with the outer side of the recess 53 on the surface of the mold 54 where the cycloolefin resin 62 is applied, and the other side of the film is warped. The laminator roller 64 is pressed from the portion where the mold 54 and the cycloolefin film 63 are in contact, and the roller is pressed with a strong force (10 kg / cm) while rolling, so that the inside of the recess 53 and the recesses 61a and 61b of the mold 54 are pressed. The cycloolefin resin 62 is pushed in, and the excess cycloolefin resin and the air in the recesses 53 and the air in the recesses 61a and 61b are brought into close contact with each other to perform extrusion lamination.

  That is, the cylindrical roller 64 is pressed against the surface of the cycloolefin film 63 that contacts the cycloolefin resin 62. At this time, it goes without saying that the cycloolefin resin 62 is disposed on the surface (the movement start position of the roller) opposite to the surface against which the roller 64 is pressed. Next, the roller 64 is pressed at a pressure of 10 kg / cm while rolling the roller 64 so that the relative speed of the cycloolefin film 63 with respect to the cycloolefin film 63 on the roller contact line becomes zero from one end to the other end. By performing extrusion lamination in this manner, excess cycloolefin resin 62 is extruded along with the movement of the roller. In this way, the semicircular shape that is the shape of the concave portion 53 of the mold 54 is transferred to the cycloolefin resin 62.

  In this embodiment, the cycloolefin resin 62 is disposed on the entire surface (processed surface) of the mold 54 on which the recess 53 is formed. However, the cycloolefin resin 62 is disposed at least at the movement start position of the roller. It should be. At this time, needless to say, after the roller 64 has moved to the other end, an amount of cycloolefin resin that can sufficiently fill the recess 53 with the cycloolefin resin 62 is applied to the movement start position.

  In FIG. 6D, the die 54 subjected to extrusion lamination is placed on a hot plate, and the cycloolefin resin 62 is cured by heating. Next, the cycloolefin film 63 is peeled from the mold 54. In this way, the cured cycloolefin resin (semicircular convex portion (semicircular convex portion) 65, convex portions 67a and 67b) having a shape in which the concave portion 53 and the concave portions 61a and 61b of the mold 54 are inverted is attached. A cycloolefin sheet is produced. This is the soft stamper 66.

Polymer Waveguide Fabrication Process FIGS. 7A to 7F are diagrams for explaining a polymer waveguide fabrication method according to this embodiment.
In FIG. 7A, an ultraviolet curable epoxy resin 72 as a clad material is dropped on a glass substrate 71. Next, the glass substrate 71 is tilted so that the ultraviolet curable epoxy resin 72 is spread over the entire surface of the glass substrate 71. By this inclination of the glass substrate 71, an ultraviolet curable epoxy resin 72 is disposed on the entire surface of the glass substrate 71.

  The clad material may be a liquid material or a gel material. What is important in the present invention is that the clad material existing on the glass substrate is extruded during the extrusion lamination described later. Therefore, any material can be used as the cladding material as long as it is a material that has at least fluidity that can be extruded, is cured by light or heat, and functions as the cladding of the polymer waveguide after the curing. it can.

  In this embodiment, a thermoplastic resin, a thermosetting resin, a polyimide, a silicone resin, an acrylic resin / epoxy resin made of UV curable resin, polysilane, polyacrylate, polycarbonate, polyether, polyamide, or the like is used as a clad material. be able to. Needless to say, the cladding material is set to have a refractive index smaller than that of the core material.

  In FIG. 7B, the soft stamper 66 is brought into close contact with the surface of the glass substrate 71 to which the ultraviolet curable epoxy resin 72 (cladding material) is applied using a laminator. One end of the outer portion of the soft stamper 66 with the projections and depressions is in contact with the application surface of the ultraviolet curable epoxy resin 72 of the glass substrate 71, and the other end is warped. By pressing the roller 73 of the laminator from the soft stamper 66 side where the glass substrate 71 and the soft stamper 66 are in contact, and pressing the roller 73 with a strong force while rolling, the convex portion 67a of the soft stamper 66 and the semicircular convex portion 65, and the ultraviolet curable epoxy resin 72 is pushed into the area between the semicircular convex portion 65 and the convex portion 67b, and the excess ultraviolet curable epoxy resin 72 and air in the region are pushed out. Adhesive laminating and extrusion lamination.

  Next, after irradiating ultraviolet light from the soft stamper 66 side, heat treatment is performed to completely cure the ultraviolet curable epoxy resin. Next, the soft stamper 66 is peeled from the glass substrate 71. A cured epoxy resin having a shape in which the unevenness of the soft stamper 66 (semicircular convex portion 66, convex portions 67a and 67b) is inverted is formed. This cured epoxy resin becomes the clad 74. The clad 74 is transferred with a recess 53 formed in a mold 54 as a master. That is, the clad 74 is formed with a semicircular recess 75 having the same shape as the recess 53 (FIG. 7C).

  In FIG. 7D, an ultraviolet curable epoxy resin 76 as a core material is dropped on the clad 74. Next, the glass substrate 71 is tilted so that the ultraviolet curable epoxy resin 76 is spread over the entire surface of the clad 74. With the inclination of the glass substrate 71, an ultraviolet curable epoxy resin 76 is disposed on the entire surface of the clad 74. The ultraviolet curable epoxy resin 76 is adjusted to have a higher refractive index than the ultraviolet curable epoxy resin 72 in order to function as a core.

  Excessive ultraviolet curable epoxy resin 72 is extruded by pressing the plate material 77 from the ultraviolet curable epoxy resin 72 side toward the glass substrate 71 side so that the ultraviolet curable epoxy resin 76 remains in the recess 75 ( FIG. 7 (e)). Next, ultraviolet rays are irradiated and heat treatment is performed to completely cure the ultraviolet curable epoxy resin. This cured ultraviolet curable epoxy resin becomes the core. Next, the plate material 77 is peeled from the glass substrate 71. In this way, a polymer waveguide in which a semicircular core 78 is formed can be produced (FIG. 7 (f)).

  In this embodiment, the core shape is formed (transferred) using the soft stamper 66. However, the present invention is not limited to this, and a second soft stamper (hereinafter referred to as a secondary soft stamper) is used based on the soft stamper 66. The transfer may be performed using a secondary soft stamper.

FIGS. 8A and 8B are views for explaining a method of manufacturing a secondary soft stamper according to the present embodiment.
In FIG. 8A, a cycloolefin resin 82 (80% mesitylene solution) is dropped on a cycloolefin film 81 as a base film of a secondary soft stamper, and the cycloolefin resin 82 is formed by spin coating. Spread over the entire surface.

  In FIG. 8A, a laminator is used to bring the soft stamper 66 into close contact with the cycloolefin resin 82 application surface of the cycloolefin film 81. The one end of the cycloolefin resin 82 applied surface of the cycloolefin film 81 is made to contact one end of the soft stamper 66 and the other soft stamper 66 is kept warped. By pressing the laminator roller 83 from the portion where the cycloolefin film 81 and the soft stamper 66 are in contact with each other, and pressing the roller with a strong force (10 kg / cm) while rolling, the convex portion 67a and the semicircular convex portion of the soft stamper 66 The cycloolefin resin 82 is pushed into the region between 65 and the region between the semicircular convex portion 65 and the convex portion 67b, and the excess cycloolefin resin and the air in the region are pushed out and closely adhered, Perform extrusion lamination.

  In FIG.8 (b), the cycloolefin film 81 which performed extrusion lamination is arrange | positioned on a hotplate, and the cycloolefin resin 82 is heat-hardened. Next, the soft stamper 66 is peeled from the cycloolefin film 81. In this manner, a cycloolefin sheet with a cured cycloolefin resin (convex portion 84) having a shape in which the unevenness of the soft stamper 66 is inverted is produced. This is the secondary soft stamper 86. The shape of the semicircular convex portion 65 is transferred to the secondary soft stamper 86, and the semicircular concave portion 85, which is a shape obtained by inverting the shape of the semicircular convex portion 65, is formed on the convex portion 84. .

  The polymer waveguide is manufactured by performing the above-described polymer waveguide manufacturing process using the secondary soft stamper 86 manufactured as described above. When a secondary soft stamper is used, the core material is transferred with the soft stamper.

  In this embodiment, when a polymer waveguide is manufactured by a primary soft stamper, a concave / convex pattern inverted from the mold is formed on the primary soft stamper. Will be done on the material. On the other hand, when a polymer waveguide is manufactured by a secondary soft stamper, an uneven pattern having the same shape as the mold is formed on the secondary soft stamper. Will do.

  In this embodiment, the soft stamper 66 (primary soft stamper) and the secondary soft stamper 86 are manufactured based on the mold 54, and the tertiary soft stamper can be manufactured based on the secondary soft stamper. Therefore, it is possible to produce the Nth order soft stamper based on the (N-1) th order soft stamper (N: an integer of 2 or more). What is important in this embodiment is that when the concave and convex shape formed on the soft stamper that performs the transfer for producing the waveguide is the same shape as the mold, the transfer is performed on the core material and the shape reversed with the mold In this case, the transfer is performed on the clad material.

(Second Embodiment)
In the present embodiment, a polymer waveguide is manufactured using the mold 54 manufactured in the first embodiment.
Polymer waveguide fabrication process
FIGS. 9A to 9D are views for explaining a method for producing a polymer waveguide according to the present embodiment.
In FIG. 9A, an Arton film 92 as a clad film is bonded onto a glass substrate 91, and an ultraviolet curable epoxy resin 93 as a core material is dropped onto the Arton film 92. Next, the glass substrate 91 is tilted so that the ultraviolet curable epoxy resin 93 is spread over the entire surface of the ARTON film 92. By tilting the glass substrate 91, an ultraviolet curable epoxy resin 93 is disposed on the entire surface of the arton film 92.

  Next, the mold 54 is arranged so that the concave portion 53 and the ultraviolet curable epoxy resin 93 face each other (FIG. 9B), and pressure is applied from the entire surface of the mold 54 facing the concave portion 53. Due to the pressure from the entire surface of the mold 54, the ultraviolet curable epoxy resin 93 enters the recess 53, and the other ultraviolet curable epoxy resin 93 is pushed out of the arton film 92 (FIG. 9C). . Next, by irradiating with ultraviolet rays, the ultraviolet curable epoxy resin 94 present in the recess 53 is cured, and the mold 54 is removed from the arton film 92. Then, a polymer waveguide in which a core 95 having a semicircular cross section is formed on the Arton film 92 is produced (FIG. 9D).

  In this embodiment, the concave portion 53 of the mold 54 is transferred to the core material. However, the present invention is not limited to this, and it may be transferred to the clad. In this case, a clad material may be applied to a substrate such as a glass substrate as in the first embodiment, and the recess 53 may be transferred to the clad material. What is important in the present embodiment is not to determine what is to be transferred, but to make the cross section of the core to be formed into a semicircular shape.

  In each of the above-described embodiments, the ridge type waveguide has been described, but a buried type waveguide may be used. In the case of an embedded waveguide, after forming a core, a clad may be formed so as to embed the core.

(A)-(d) is a figure which shows the preparation methods of the conventional conventional polymer waveguide. 1 is a perspective view of a semicircular optical waveguide according to an embodiment of the present invention. It is a figure which shows a mode that the relationship between waveguide shape and loss based on one Embodiment of this invention is calculated | required. It is a figure which shows a mode that a core is formed by extrusion lamination based on one Embodiment of this invention. It is a schematic diagram for demonstrating the manufacturing process of the metal mold | die based on one Embodiment of this invention. (A)-(d) is a figure explaining the preparation process of the soft stamper based on one Embodiment of this invention. (A)-(f) is a figure for demonstrating the manufacturing method of the polymer waveguide based on one Embodiment of this invention. (A) And (b) is a figure for demonstrating the manufacturing method of the secondary soft stamper based on one Embodiment of this invention. (A)-(d) is a figure for demonstrating the manufacturing method of the polymer waveguide based on one Embodiment of this invention.

Explanation of symbols

21 Cladding 22 Core 31, 32 Waveguide to be measured 33 Circular waveguide 34 Junction point 35, 36, 37, 38 Cross section at junction 41 Cladding film 42, 47 Core material 43 Soft stamper 44 Convex part 45 Concave part 46 Roller 51 Silicon substrate 52 Reuter 53 Recessed portion 54 Mold 61a, 61b Recessed portion 62 Cycloolefin resin 63 Cycloolefin film 64 Roller 65 Semicircular convex portion 66 Soft stamper 67a, 67b Convex portion 71 Glass substrate 72, 76 UV curable epoxy resin 73 Roller 74 Cladding 75 Concave portion 77 Plate material 78 Core 81 Cycloolefin film 82 Cycloolefin resin 83 Roller 84 Convex portion 85 Semicircular concave portion 86 Secondary soft stamper 91 Glass substrate 92 Arton film 93, 94 External curable epoxy resin 95 core

Claims (8)

An optical waveguide comprising a cladding and a core,
An optical waveguide characterized in that the core has a semicircular cross section. A method for producing an optical waveguide comprising a clad and a core,
A preparation step of preparing a mold in which concave portions having a semicircular cross section are formed in a predetermined pattern on the first surface;
A cladding forming step of forming the cladding;
On the clad, there is a fluidizing step, and an imparting step for imparting the core material by curing,
A core forming step of transferring a recess formed in the mold to the material, curing the material, and forming a core having a cross-sectional shape reversed from the recess, the core having a semicircular cross section. An optical waveguide manufacturing method characterized by the above. A method for producing an optical waveguide comprising a clad and a core,
The first surface is made of a first mold having a semicircular cross section formed in a predetermined pattern on the first surface, and has a convex portion that is inverted with respect to the first recess. A preparation step of preparing a second mold having;
On the substrate, the application step of providing the material to be the cladding by having fluidity and curing,
A convex portion formed on the second mold is transferred to the material, the material is cured, and is a second concave portion having a cross-sectional shape reversed from the convex portion, and having a semicircular cross section. A clad forming step of forming the clad having a second recess;
And a core formation step of forming the core in the second recess. A method for producing an optical waveguide comprising a clad and a core,
A second recess having a cross section of the same shape as the first recess, the first recess having a semicircular cross section formed on the first surface and having a predetermined pattern. A preparing step of preparing a flexible second mold having
A cladding forming step of forming the cladding;
On the clad, there is a fluidizing step, and an imparting step for imparting the core material by curing,
A core having a semicircular cross section, in which the second concave portion formed in the second mold is transferred to the material, the material is cured, and the core has a cross-sectional shape reversed from the second concave portion. And a core forming step of forming an optical waveguide. A mold for producing an optical waveguide comprising a clad and a core,
A substrate,
A mold comprising: a recess having a predetermined pattern formed on the first surface of the substrate and having a semicircular cross section. A method for producing a mold for producing an optical waveguide having a clad and a core,
A mold having a semicircular cross section with the predetermined pattern formed on the first surface by grinding the substrate while polishing the substrate with a predetermined pattern on the first surface of the substrate. Manufacturing method.   The mold manufacturing method according to claim 6, wherein the recess has a rounded tip, and is formed by means for grinding while rotating the tip.   The method for producing a mold according to claim 7, wherein the tip is a grindstone.

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