JP2004302401A - Optical path converting element and its manufacturing method, optical integrated circuit and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical path converting element in which the conversion of optical paths when coupling optical elements to an optical waveguide optically is facilitated. <P>SOLUTION: This optical path converting element 1A is equipped with a silicon substrate 2 and an optical waveguide 3A which is formed on the silicon substrate 2 and has inclined end faces 4 at its both ends as end faces. The optical waveguide 3A is formed as a polymeric organic compound optical waveguide and is constituted as a planar optical waveguide which consists of three layers of a lower clad 5, a core 6 on the clad 5 and an upper clad 5 on the core 6 each of which is made of polymeric organic compound resin. End of faces 2a of the silicon substrate 2 is formed as a face perpendicular to the longitudinal direction of the substrate 2 and the inclined end face 4 is formed at an external angle θ of, for example, 135 degrees with respect to the end face 2a of the substrate 2, that is, the face 4 is inclined outward at 45 degrees with respect to the face 2a of the substrate 2. As a result, optical elements can be provided directly under the inclined faces 4 without being interfered by the substrate 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical path conversion element for converting an optical path of an optical signal when an optical element such as a surface emitting semiconductor laser element or a photodiode is optically coupled to an optical waveguide, a method for manufacturing the same, and light using the optical path conversion element. The present invention relates to an integrated circuit and a manufacturing method thereof. More specifically, the configuration is such that an inclined end face can be formed on the end face of the optical waveguide so that the optical path can be changed when the optical element and the optical waveguide are optically coupled.

  In the current interconnection, electrical wiring is mainly used as a wiring connecting elements constituting a system, elements and components, or components, for example, transistors. On the other hand, next-generation interconnections require large-capacity and high-speed communication, so that electric wiring has a limit in high-frequency response, and there is a limit to speeding up the system. For this reason, in next-generation interconnections, optical circuits using optical wiring, which enables large-capacity and high-speed communication, as transmission means have been receiving attention instead of electric wiring.

  By the way, in an optical circuit for transmitting and receiving an optical signal, a semiconductor laser element provided as a light source of a transmitting device and emitting laser light as signal light, a photodiode for receiving laser light as signal light, a semiconductor laser element and a photodiode are provided. An optical waveguide for optically connecting is required.

  In order to miniaturize and integrate an optical circuit, an optical integrated circuit in which an optical element such as a semiconductor laser element and a photodiode and an optical waveguide connecting the optical element are integrated is required.

  In an optical integrated circuit, use of a vertical cavity surface emitting laser (VCSEL) has been considered as a semiconductor laser device. The surface-emitting semiconductor laser device emits light in a direction perpendicular to the surface of the substrate. Light is also incident on the photodiode from a direction perpendicular to the surface of the mounted substrate. On the other hand, the optical waveguide is mounted horizontally with respect to the surface of the substrate. Therefore, when optical connection between an optical element and an optical waveguide is performed in an optical integrated circuit, it is necessary to convert the optical path of an optical signal. Therefore, in order to realize an optical integrated circuit, it is important to develop an optical path conversion element that can convert the optical path of an optical signal.

  Therefore, in order to compactly couple an optical device such as a surface emitting semiconductor laser device or a photodiode with a planar optical waveguide, a light having a structure in which the optical device and the planar optical waveguide are coupled using a 45-degree micromirror. Transceivers are being actively researched and developed.

Techniques for manufacturing a 45-degree micromirror on the end face of a planar optical waveguide include, for example, (1) a method in which the end face of the optical waveguide is cut obliquely mechanically by a microtome, and (2) a tilt in the optical waveguide by reactive ion etching. A method of forming an end face, (3) a method of forming an inclined end face in an optical waveguide by laser ablation,
(4) A method has been reported in which a 45 ° cut is made in an optical waveguide by a rotating blade to form an inclined end face (see Patent Document 1).

  FIG. 11 is a cross-sectional view of a conventional optical path conversion element disclosed in this conventional document. Patent Document 1 discloses a method in which a V-shaped blade is attached to a dicing saw and an optical waveguide is cut to form a 45-degree mirror on an end face of the optical waveguide.

  According to the above-mentioned publication, as shown in FIG. 11, when a cutting process is performed using a diamond blade 40 whose cutting edge is formed to about 90 degrees, the planar optical waveguide has inclined end faces (micro mirrors) 42, 42. The V groove 44 can be formed. The depth of the cutting process may be made deeper than the boundary between the core 48 and the lower clad 50 through the upper clad 46 and the core 48, and may be stopped in the lower clad 50 or the substrate 52 may be cut. I have.

JP-A-10-30961 (FIG. 7)

  By the way, starting with the above-mentioned publication, all conventional methods for forming an inclined end face are methods of cutting from the upper surface of an optical waveguide formed on the substrate toward the substrate, and forming the inclined end face by a conventional method. As far as possible, the inclination angle of the inclined end surface with respect to the substrate is acute at the substrate end surface with respect to the substrate surface as shown in FIG.

  Therefore, in a planar optical waveguide having an inclined end surface (a 45-degree mirror) formed by this method, light propagating inside the planar optical waveguide and reflected by the 45-degree mirror is emitted toward the substrate. become. As a result, if an optical element such as a surface emitting semiconductor laser element is provided directly below the 45-degree mirror, the substrate becomes an obstacle.

  Therefore, after the optical waveguide is formed on the substrate, it is necessary to take a troublesome measure such as peeling off the substrate obstructing the optical path from the optical waveguide or using a transparent glass substrate as the substrate.

  However, if the optical device is to be mounted on the optical waveguide with high precision after the substrate is separated from the optical waveguide, it is difficult to position the optical waveguide and the optical device with each other, and the mounting operation takes a long time, resulting in an increase in manufacturing cost. Further, when a glass substrate is used, there is a problem that the optical coupling efficiency is reduced because the glass substrate is interposed between the optical waveguide and the optical element.

  For this reason, in an optical integrated circuit, a technology for directly forming an optical waveguide on a substrate on which an optical element is mounted by using a semiconductor manufacturing process has been considered. However, directly manufacturing an optical waveguide on a substrate on which an optical element is mounted has a problem that a complicated process is required and the manufacturing cost is increased.

  The present invention has been made to solve such a problem, and an optical path conversion element that can easily convert an optical path when optically coupling an optical element and an optical waveguide, a method for manufacturing the same, and a method using the optical path conversion element. It is an object of the present invention to provide an optical integrated circuit and a manufacturing method thereof.

  In order to achieve the above object, an optical path conversion element according to the present invention includes a substrate and at least one inclined end surface formed on the substrate and forming an angle of 90 ° or more and 180 ° or less with respect to an end surface of the substrate. And an optical waveguide provided on an end face.

  The optical path conversion element according to the present invention is formed so that the inclined end face of the optical waveguide forms an angle of 90 ° or more and 180 ° or less with respect to the end face of the substrate, that is, formed outside the end face of the substrate. Therefore, when the optical element is provided immediately below the inclined end surface, the substrate does not become an obstacle as in the related art.

  Therefore, the optical element and the optical waveguide can be optically coupled without peeling the substrate from the optical waveguide. Further, it is not necessary to use a glass substrate as the substrate. The angle of inclination of the inclined end surface is arbitrary as long as the inclined end surface of the optical waveguide forms an angle of 90 ° or more and 180 ° or less with respect to the end surface of the substrate, in other words, as long as it forms an acute angle with the extended surface of the substrate surface. Angle is fine.

  With the above configuration, in the optical path conversion element according to the present invention, the light path of the laser light emitted from the surface emitting semiconductor laser element is totally reflected inside the core of the optical waveguide by utilizing the light reflection at the inclined end face. The optical path can be converted to an optical path that travels through the optical waveguide, or the optical path of light incident from outside the optical waveguide can be freely converted and coupled to the optical waveguide. Further, the light propagating through the optical waveguide can be converted into an optical path at an arbitrary angle with respect to the optical waveguide and incident on the photodiode.

  Although there are no restrictions on the material for forming the substrate and the optical waveguide of the optical path conversion element according to the present invention, from the viewpoint of economy and ease of manufacture, the optical waveguide is preferably a polymer optical waveguide, and a polymer resin. Form. That is, the clad and the core of the optical waveguide are each formed of a polymer organic compound. In addition, in order to obtain an optical waveguide having a high cost but an advanced communication function, each of the core and the clad of the optical waveguide may be formed of a glass material. In the present invention, the substrate may be a silicon substrate.

  Further, preferably, the inclined end surface is covered with an optical reflection film. Thereby, the light reflection efficiency at the inclined end surface can be increased.

  The optical waveguide of the optical path conversion element according to the present invention is not necessarily a planar optical waveguide, but may be a two-dimensional optical waveguide in which a plurality of band-shaped or column-shaped cores extend in parallel.

  The number of optical waveguides need not be limited to one, but may be a planar optical waveguide or a three-dimensional optical waveguide comprising a multi-stage optical waveguide in which two-dimensional optical waveguides are stacked.

  In the optical path conversion element according to the present invention, an optical path conversion mirror is attached to the optical waveguide formed on the substrate, and the optical element can be mounted without peeling the substrate. It is not necessary to peel off the optical waveguide from the substrate and to adhere the optical waveguide to the substrate again, and the fabrication is simple. Therefore, a small-sized optical wiring can be realized at low cost.

  In addition, the light path conversion element according to the present invention allows light to enter and exit from the side opposite to the substrate, so that an optical device such as a surface emitting semiconductor laser element or a photodiode can be efficiently placed on a mounting substrate. can do. Therefore, the optical path conversion element according to the present invention can realize an optical wiring with high optical coupling efficiency at low cost.

  In the method for manufacturing an optical path conversion element according to the present invention, the step of forming an optical waveguide on a substrate and the step of cutting the substrate using a V-shaped blade to form a cutting groove reaching the optical waveguide, and then temporarily stopping the cutting A step of removing the cutting groove from the cutting groove and the V-shaped blade, and a step of aligning the V-shaped blade with the cutting groove and then restarting the cutting to cut the optical waveguide. And

  In the embodiment of the present invention, a dicing saw is used for the cutting with the V-shaped blade. Preferably, a diamond blade having diamond particles having an average particle diameter of 1 to 10 μm is used as a blade used for cutting the substrate and the optical waveguide. Thereby, a smooth inclined end surface can be formed.

  The V-shaped blade does not need to be limited to one having a slope on both sides, and may have a structure having a slope only on one side.

  According to the method of the present invention, the substrate is cut to form a cutting groove reaching the optical waveguide, and then the cutting is temporarily stopped, the cutting groove is removed from the cutting groove and the V-shaped blade, and cutting is restarted to resume the optical waveguide. By cutting, an optical path conversion element having a smooth inclined end face can be manufactured.

  Note that, unlike the method of the present invention, when the optical waveguide is cut without removing the cutting chips following the cutting of the substrate, the cutting surface of the optical waveguide is roughened by the substrate cutting chips when cutting the optical waveguide, and the cutting surface is smooth. The inclined end face cannot be formed in the optical waveguide.

  An optical integrated circuit according to the present invention uses the above-described optical path conversion element. That is, an optical path conversion element in which an optical waveguide is formed on a substrate, and a mounting substrate on which the optical element is mounted are provided, and the optical path conversion element has an angle of 90 degrees or more and 180 degrees or less in an outer circumference with respect to an end surface of the substrate. The optical waveguide has a clad and a core, and the end face of the core is exposed on the same plane as the inclined end face to form a reflection surface, and the reflection surface is formed. An optical path-changing element is attached to one surface of the mounting board at a position facing the optical element.

  In the optical integrated circuit according to the present invention, the light emitted in the direction perpendicular to the surface of the mounting substrate is reflected by the reflection surface, and the light path is changed to light horizontal to the surface of the mounting substrate. Therefore, light can be propagated by the core extending in the horizontal direction with respect to the surface of the mounting substrate by using the surface emitting element as the optical element. Further, the light propagating through the core is reflected by the reflection surface, and the optical path is changed to light perpendicular to the surface of the mounting substrate. Therefore, light can be received by the light receiving element mounted on the mounting substrate.

  In the method for manufacturing an optical integrated circuit according to the present invention, an optical waveguide is formed on a substrate, and at least one end face of the optical waveguide has an inclination of 90 degrees or more and 180 degrees or less with respect to an end face of the substrate. The method is characterized in that the method includes a step of aligning and attaching the optical path conversion element having the end surface formed thereon to the mounting substrate on which the optical element is mounted.

  In the method for manufacturing an optical integrated circuit according to the present invention, the optical path conversion element is attached to the mounting substrate after the mounting of the optical element. In the optical path conversion element, the optical waveguide is supported by a substrate, and so-called passive alignment mounting can be realized. Further, since the optical path conversion element is attached after the soldering work involved in mounting the optical element on the mounting board, the optical path conversion element is not affected by heat.

  According to the present invention, by forming an optical waveguide having at least one end face having an inclined end face forming an outer rotation angle of 90 ° or more and 180 ° or less with respect to the end face of the substrate, a surface emitting semiconductor laser device, a photodiode, or the like can be obtained. An optical path conversion element that can easily and optically couple an optical element and an optical waveguide with high optical coupling efficiency can be realized.

  In the conventional optical path conversion element, light is incident on the substrate side because the direction of the mirror is at an acute angle inward with respect to the substrate surface of the substrate, that is, at an angle of 180 degrees or more with respect to the end surface of the substrate. In addition, the configuration has to be such that light is emitted from the substrate side. Therefore, when the optical element and the optical path conversion element are optically coupled, the obstructive substrate is temporarily separated from the optical waveguide, and then, when the optical path conversion element is mounted on the mounting substrate, the optical waveguide is again attached to the substrate. It required a complicated process of pasting on to. On the other hand, in the present invention, since the direction of the inclined end face of the optical path conversion element is directed outward from the end face of the substrate, the optical element can be mounted without peeling the substrate and the optical waveguide.

  Further, according to the method of the present invention, the substrate is cut to form a cutting groove reaching the optical waveguide, then the cutting is temporarily stopped, cutting chips are removed from the cutting groove and the V-shaped blade, and then the cutting is restarted. Then, by cutting the optical waveguide, an optical path conversion element having a smooth inclined end face can be manufactured.

  Further, according to the optical integrated circuit of the present invention, an optical path conversion element is provided between an optical element that emits light in a direction perpendicular to the mounting substrate and an optical element that emits light in a direction perpendicular to the mounting substrate. And optical transmission / reception can be performed.

  Since the optical path conversion element supports the optical waveguide with the substrate, a member for reinforcing the optical waveguide is not required. Therefore, an optical integrated circuit can be realized with a simple configuration.

  Further, according to the method for manufacturing an optical integrated circuit according to the present invention, the optical path conversion element is attached to the mounting substrate after the optical element has been mounted. In the optical path conversion element, the optical waveguide is supported by a substrate, and so-called passive alignment mounting can be realized. Therefore, an optical integrated circuit can be provided at low cost. Further, since the optical path conversion element is attached after the soldering work involved in mounting the optical element on the mounting board, the optical path conversion element is not affected by heat. Therefore, the optical waveguide can be formed using a polymer resin-based material.

  Hereinafter, embodiments of the present invention will be described specifically and in detail with reference to the accompanying drawings.

First Embodiment of Optical Path Conversion Element This embodiment is a first embodiment of an optical path conversion element according to the present invention, and FIG. 1 shows a configuration example of the optical path conversion element according to the first embodiment. FIG.

  As shown in FIG. 1, the optical path conversion element 1A of this embodiment includes a silicon substrate 2 and an optical waveguide 3A. The silicon substrate 2 is an example of a substrate, and may be a glass substrate. The optical waveguide 3A is formed on the silicon substrate 2 and has inclined end faces 4 at both ends.

  The optical waveguide 3A is formed, for example, as a polymer organic compound optical waveguide, and is formed of a polymer organic compound resin, and includes a lower clad 5, a core 6 on the lower clad 5, and an upper clad 5 on the core 6, respectively. Are formed as a planar optical waveguide. The core 6 is formed of a high molecular weight organic compound having a refractive index about 0.1 to 3.0% larger than that of the lower clad 5 and the upper clad 5.

  Examples of the polymer organic compound for an optical waveguide include, for example, oxetane resin (manufactured by Sony Chemical), fluorinated polyimide (manufactured by NTT Advanced Technology, manufactured by Hitachi Chemical), and gracia (polysilane) (manufactured by Nippon Paint).

  In the present embodiment, the core 6 is formed of an oxetane resin, and the lower clad 5 and the upper clad 5 are formed of an oxetane resin having a refractive index smaller than that of the core 6 by about 0.1 to 3.0%.

  A method of forming an optical waveguide using an oxetane resin is described in detail in JP-A-2000-356720. With reference to the above-mentioned publication, the oxetane resin will be briefly described. And a resin component that is cured by irradiation with an energy beam such as ultraviolet rays, and is sold, for example, by Sony Chemical Corporation.

  Examples of oxetane compounds include di [1-ethyl (3-oxetanyl)] methyl ether (liquid at room temperature), 1,4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} benzene and di [4- (1-ethyl-3-oxetanylmethoxymethyl)] benzyl ether (hereinafter also referred to as xylene dioxetane) (liquid at room temperature), phenol novolak oxetane (solid at room temperature), oxetanyl silsesquioxetane (liquid at room temperature) And the like.

  As the oxirane compound, for example, limonenedoxide, a polyfunctional aliphatic cyclic epoxy resin, a mixture of a bisphenol A type epoxy resin and a bisphenol F type epoxy resin (mixing ratio: about 1: 1), a bisphenol A type epoxy resin, a bifunctional aliphatic A cyclic epoxy resin, a polyfunctional aliphatic cyclic epoxy resin and the like can be mentioned.

  The cationic polymerization initiator is, for example, 4-4'bis [di (β-hydroxyethoxy) phenylsulfonio] phenylsulfide-bis-hexafluoroantimonate (manufactured by Asahi Denka Co., Ltd.).

  The refractive index (25 ° C., sodium D line) of the oxetane compound varies depending on the type of the oxetane compound. For example, di [1-ethyl (3-oxetanyl)] methyl ether is about 1.4544, and phenol novolak oxetane is about 1.57. It is.

  Further, the refractive index of the oxirane compound (25 ° C., D line) is, for example, 1.4656 for limonenedoxide and 1.5683 for bisphenol A type epoxy resin.

  The refractive index of the oxetane resin can be adjusted by adjusting the types and the mixing ratio of the oxetane compound and the oxirane compound.

  For example, in order to form a core portion of an optical waveguide, a material having a refractive index of less than 1.5 is included in an amount of 10 to 30% by weight so that a difference in refractive index from the cladding portion can be stably obtained. Is an oxetane resin containing 40 to 60% by weight of which is 1.5 or more, and the balance being an oxirane compound. Further, in order to form the clad portion, an oxetane compound having a refractive index of less than 1.5 is contained in an amount of more than 40% by weight, and the rest is an oxirane compound and an oxetane compound having a refractive index of 1.5 or more is contained. Use no oxetane resin.

  Specifically, for example, 10 parts by weight of xylene dioxetane, 20 parts by weight of phenol novolak oxetane, 30 parts by weight of a bifunctional aliphatic cyclic epoxy resin, 20 parts by weight of a mixture of a bisphenol A type epoxy resin and a bisphenol F type epoxy resin, and After mixing 20 parts by weight of a bisphenol A type epoxy resin and dissolving by heating at 90 ° C. for 2 hours, 2 parts by weight of a cationic polymerization initiator is blended, and further filtering is performed to remove dust and the like, thereby obtaining a photoconductive resin. An oxetane resin for forming a waveguide core can be obtained.

  Also, 22 parts by weight of di [1-ethyl (3-oxetanyl)] methyl ether, 13 parts by weight of oxetanyl silsesquioxetane, 35 parts by weight of a polyfunctional aliphatic cyclic epoxy resin, and 30 parts by weight of a bifunctional aliphatic cyclic epoxy resin After mixing and dissolving by heating at 90 ° C. for 2 hours, 2 parts by weight of a cationic polymerization initiator is blended, and further, dust and the like are removed by filtering to obtain an oxetane resin for forming an optical waveguide clad. be able to.

  The end surface 2a of the silicon substrate 2 is formed as a surface orthogonal to the longitudinal direction of the substrate 2, as shown in FIG.

  The inclined end surface 4 is formed at an angle θ of 90 degrees or more and 180 degrees or less, for example, 135 degrees in an outer circumference with respect to the end surface 2 a of the silicon substrate 2, in other words, an extension surface of the substrate surface 2 b of the substrate 2. To the outside at an angle of 45 degrees. Although not shown, for example, aluminum may be vapor-deposited on the inclined end surface 4 and the surface of the inclined end surface 4 may be covered with an optical reflection film. Thereby, the light reflection efficiency at the inclined end surface 4 can be increased.

  By using the optical path conversion element 1A of this embodiment, an optical element, for example, a surface emitting semiconductor laser element or a photodiode can be mounted directly below the inclined end face 4 without peeling the silicon substrate 2. Therefore, it is not necessary to peel the substrate from the optical waveguide or to re-adhere the substrate to the optical waveguide for positioning the optical waveguide when mounting the optical waveguide, so that the fabrication is simple. Therefore, a small-sized optical wiring can be realized at low cost.

  Then, by using the optical path conversion element 1A of the present embodiment, by arranging the surface emitting semiconductor laser element and the photodiode directly below the inclined end faces 4 at both ends of the optical waveguide 3A, light transmission and reception can be performed. That is, the light emitted from the surface emitting semiconductor laser device is changed in optical path on one inclined end face 4 and propagates through the core 6, and the light propagated through the core 6 is changed in optical path on the other inclined end face 4 and is converted into a photodiode. Incident.

Second Embodiment of Optical Path Conversion Element This embodiment is a second embodiment of the optical path conversion element according to the present invention, and FIGS. 2 and 3 show the optical path conversion element of the second embodiment. 2A is a side view, FIG. 2B is a top view, and FIG. 3 is a perspective view.

  The optical path conversion element 1B according to the second embodiment includes a silicon substrate 2 and an optical waveguide 3B. The silicon substrate 2 is an example of a substrate, and may be a glass substrate or an organic substrate. The optical waveguide 3B is formed on, for example, one surface of the silicon substrate 2 and has inclined end surfaces 4 at both ends.

  Both the silicon substrate 2 and the optical waveguide 3B have a flat plate shape, and the end surface 2a of the silicon substrate 2 is formed as a vertical surface orthogonal to the longitudinal direction of the substrate 2. On the other hand, the inclined end face 4 of the optical waveguide 3 is formed at an angle of 90 ° or more and 180 ° or less, for example, 135 ° around the outer circumference with respect to the end face 2a of the substrate 2. In other words, the inclined end surface 4 is inclined outward at an angle of 45 degrees with respect to the extension surface of the substrate surface 2b of the substrate 2.

  The optical waveguide 3 </ b> B is a two-dimensional optical waveguide in which a plurality of cores 8 extend in parallel inside the clad 7. The core 8 has a refractive index larger than that of the clad 7 by 0.1 to 3.0%, preferably by about 0.2 to 3.0%. The clad 7 and the core 8 are formed of a glass-based material, a high-molecular organic compound resin, or the like. For example, it is desirable that the clad 7 and the core 8 be made of the oxetane resin described above in order to increase the light propagation efficiency.

  The cores 8 are parallel to each other and extend from one inclined end surface 4 of the optical waveguide 3B to the other inclined end surface 4. One end surface and the other end surface of each core 8 are flush with the inclined end surface 4, respectively. The exposed surface 8a is formed. Although not shown, for example, aluminum may be vapor-deposited on the inclined end surface 4 on which the reflection surface 8a is formed, and the surface of the inclined end surface 4 may be covered with an optical reflection film. Thereby, the light reflection efficiency at the inclined end surface 4 can be increased.

  By using the optical path conversion element 1B of the second embodiment, for example, a plurality of surface emitting semiconductor laser elements as light emitting elements are provided just below one inclined end face 4 opposite one reflecting surface 8a of each core 8. Can be arranged. Further, for example, a plurality of photodiodes can be arranged as light receiving elements directly under the other inclined end face 4 in opposition to the other reflective surface 8a of each core 8. Thus, light transmission and reception can be performed using a plurality of light emitting elements and a plurality of light receiving elements.

Embodiment of Optical Integrated Circuit This embodiment is an example of an embodiment of an optical integrated circuit according to the present invention, and FIG. 4 shows a configuration example of the optical integrated circuit of the present embodiment. ) Is a side view, and FIG. 4B is a top view.

  The optical integrated circuit 11 of the present embodiment includes a mounting substrate 12 and the optical path conversion element 1B described with reference to FIGS. The optical path conversion element 1B includes the silicon substrate 2 and the optical waveguide 3B as described with reference to FIGS. The optical waveguide 3B is formed on the silicon substrate 2 and has inclined end faces 4 at both ends. The inclined end face 4 is inclined at an angle of, for example, 45 degrees with respect to the extending direction of the optical waveguide 3B.

  The optical waveguide 3 </ b> B is a two-dimensional optical waveguide in which a plurality of cores 8 extend in parallel inside the clad 7. The core 8 has a refractive index larger than the cladding 7 by about 0.2 to 3.0%. The clad 7 and the core 8 are formed of a glass-based material, a high-molecular organic compound resin, or the like. For example, it is desirable that the clad 7 and the core 8 be made of the oxetane resin described above in order to increase the light propagation efficiency.

  The cores 8 are parallel to each other and extend from one inclined end surface 4 of the optical waveguide 3B to the other inclined end surface 4. One end surface and the other end surface of each core 8 are flush with the inclined end surface 4, respectively. The exposed surface 8a is formed. Although not shown, for example, aluminum may be vapor-deposited on the inclined end surface 4 on which the reflection surface 8a is formed, and the surface of the inclined end surface 4 may be covered with an optical reflection film. Thereby, the light reflection efficiency at the inclined end surface 4 can be increased.

  The mounting substrate 12 includes a plurality of surface emitting semiconductor laser elements 13 and a plurality of photodiodes 14. In the present embodiment, for example, four surface emitting semiconductor laser elements 13 and four photodiodes 14 are provided.

  Each surface emitting semiconductor laser element 13 is mounted such that the light emitting surface is on one side of the mounting substrate 12. The surface emitting semiconductor laser elements 13 are arranged at a predetermined pitch, for example, at a pitch of 250 μm. Each photodiode 14 is mounted such that the light receiving surface is on one side of the substrate 12. Each photodiode 14 is arranged at the same pitch as the surface emitting semiconductor laser element 13, here, at a pitch of 250 μm. The arrangement of the surface emitting semiconductor laser elements 13 and the arrangement of the photodiodes 14 are parallel.

  The optical path conversion element 1B is attached to one surface of the mounting board 12. In the optical path conversion element 1B, each surface emitting semiconductor laser element 13 is located directly below one inclined end face 4 of the optical waveguide 3B, and each photodiode 14 is located immediately below the other inclined end face 4 of the optical waveguide 3B. It consists of.

  Then, each surface emitting semiconductor laser element 13 faces one reflection surface 8a of each core 8 exposed on one inclined end surface 4, and a photo is provided on the other reflection surface 8a of each core 8 exposed on the other inclined end surface 4. The diode 14 faces.

  As an example of the size of the optical path conversion element 1B, the core 8 has a rectangular cross-sectional shape of 40 μm in length and 60 μm in width. Each core 8 is arranged at a pitch of 250 μm in accordance with the pitch of the surface emitting semiconductor laser element 13 and the photodiode 14. The length of the optical waveguide 3B is 3 cm. Further, the thickness of the clad 7 on the silicon substrate 2 side is 30 μm with the core 8 interposed therebetween, and the thickness of the clad 7 on the substrate 12 side is 30 μm.

  The operation of the optical integrated circuit 11 will be described. Each surface-emitting semiconductor laser element 13 emits a laser beam in a direction perpendicular to the surface of the mounting substrate 12 as shown by a solid arrow in FIG. The light emitted from the surface emitting semiconductor laser element 13 enters the optical waveguide 3B, and is reflected by one of the reflection surfaces 8a of the core 8, whereby the optical path is converted to a direction parallel to the surface of the mounting substrate 12, and The light propagates while being totally reflected inside. The light propagating through the core 8 is reflected by the other reflection surface 8 a, whereby the light path is changed in a direction perpendicular to the surface of the mounting substrate 12 and enters the photodiode 14.

  As described above, in the optical integrated circuit 11 of the present embodiment, light transmission and reception can be performed between the surface emitting semiconductor laser element 13 mounted on the mounting substrate 12 and the photodiode 14. By providing a plurality of cores 8 in the optical path conversion element 1B, light transmission and reception can be performed between the plurality of surface-emitting semiconductor laser elements 13 mounted on the mounting substrate 12 and the plurality of photodiodes 14, so that large-capacity communication can be performed. Becomes possible.

  Further, since the optical path conversion element 1B supports the optical waveguide 3B with the silicon substrate 2, a member for reinforcing the optical waveguide 3B is not required. Therefore, the configuration of the optical integrated circuit 11 can be simplified.

  In the present embodiment, the configuration in which the surface emitting semiconductor laser element 13 and the photodiode 14 are directly mounted on the mounting substrate 12 has been described. However, the surface emitting semiconductor laser element 13 and the photodiode 14 are mounted on an independent substrate. Alternatively, the configuration may be such that each substrate is mounted on one substrate.

  Next, an example will be described in which the above-described optical integrated circuit is modeled and experiments are conducted on the loss of propagated light and the presence or absence of crosstalk between adjacent cores. FIG. 5 is a perspective view showing an experimental example of the optical integrated circuit. Explaining the experimental conditions, an optical waveguide 3B made of oxetane resin was formed on a silicon substrate 2 as an optical path conversion element 1B. In this optical waveguide 3B, an inclined end face 4 inclined at 45 degrees and having a reflecting surface 8a was formed on one end face, and aluminum having a thickness of 100 nm was deposited on the surface of the inclined end face 4 to form an optical reflection film. The other end face of the optical waveguide 3B was a vertical end face.

  The oxetane resin core 8 was formed with a composition having a refractive index 1.6% larger than that of the oxetane resin clad 7. The size of the core 8 was 90 μm in width and 40 μm in length, and the length was 1 cm. The thickness of the clad 7 was 30 μm on the silicon substrate 2 side and 30 μm on the optical element side.

  The above-described optical path conversion element 1B was mounted on a substrate (not shown) on which the surface emitting semiconductor laser element 13 was mounted. The mounting position of the optical path conversion element 1B is a position where the reflecting surface 8a of an arbitrary core 8 faces the surface emitting semiconductor laser element 13.

  When light is emitted from the surface emitting semiconductor laser element 13 under the above conditions, the light from the surface emitting semiconductor laser element 13 propagates through only one core 8 and seeps into the surrounding cladding 7 or is parallelized. There was no crosstalk to the existing core 8. When the vertical end face of the other end of the optical waveguide 3B was observed with a measuring instrument using a CCD (charge coupled device), it was confirmed that light was confined in the core 8 and propagated.

  Next, the loss of the above-described optical path conversion element 1B having a length of 1 cm was measured. When the ratio of the optical power emitted from the surface emitting semiconductor laser device 13 to the optical power at the other vertical end face of the optical waveguide 3B was measured, the total loss was 3.6 dB. The propagation loss of the oxetane resin optical waveguide determined by the cutback method in a preliminary experiment was 0.5 dB / cm. Therefore, a value of 3.1 dB, which is obtained by subtracting the loss of the optical waveguide 3B having a length of 1 cm of 0.5 dB from the total loss, is 3.1 dB, which is the loss when the light from the surface emitting semiconductor laser element 13 enters the reflecting surface 8a.

Modification of Optical Path Conversion Element of First Embodiment This embodiment is a modification of the optical path conversion element of the first embodiment , and FIG. 6 is a cross-sectional view showing the configuration of a modification of the optical path conversion element. It is.

  As shown in FIG. 6, the optical path conversion element 1C of this modification is formed by peeling the silicon substrate 2 described in FIG. 1 from the optical waveguide 3A.

  The optical waveguide 3A can be peeled off from the silicon substrate 2 by forming the optical waveguide 3A of oxetane resin on a composite substrate formed of polyimide on the silicon substrate 2 at the time of forming the optical path conversion element. Since 3A is not chemically or physically bonded to the silicon substrate 2, it can be easily peeled off.

Third Embodiment of Optical Path Conversion Element This embodiment is a third embodiment of the optical path conversion element according to the present invention, and FIG. 7 shows a configuration example of the optical path conversion element of the third embodiment. FIG.

  In the optical path conversion element 1D of the third embodiment, as shown in FIG. 7, one end face of the optical waveguide 3C is formed as a vertical end face 15 which is an extension plane of the end face 2a of the silicon substrate 2. Except that the optical waveguide 3C is provided on the silicon substrate 2, it has the same configuration as the optical path conversion element 1A of the first embodiment.

  In the optical path conversion device 1D according to the third embodiment, a surface-emitting type semiconductor laser device or a photodiode is arranged immediately below the inclined end surface 4 of the optical waveguide 3C, and an optical fiber (not shown) is connected to the vertical end surface 15 side. By coupling, it can be used for optical transmission and reception.

Modified Example of Third Embodiment of Optical Path Converting Element This embodiment is a modified example of the optical path changing element of the third embodiment , and FIG. 8 is a cross-sectional view showing a configuration of an optical path changing element of a modified example. It is.

  As shown in FIG. 8, the optical path conversion element 1E of this modification is formed by peeling the silicon substrate 2 shown in FIG. 7 from the optical waveguide 3C.

Embodiment of the method of manufacturing the optical path conversion element This embodiment is directed to the method of manufacturing the optical path conversion element according to the present invention by using the optical path conversion element 1A of the first embodiment or the optical path conversion element of the second embodiment. 1B is an example of an embodiment applied to the fabrication of 1B. FIGS. 9A to 9C are cross-sectional views of respective steps when fabricating an optical path conversion element according to the method of the present embodiment. In the following description, an example in which the present invention is applied to the optical path conversion element 1A will be described.

  First, as shown in FIG. 9A, an oxetane resin layer is formed on a silicon substrate 2 and then cured by irradiating ultraviolet rays to form a lower clad 5. Next, an oxetane resin layer having a refractive index larger than that of the clad by about 0.1 to 3.0% is formed on the lower clad 5, and is then cured by irradiating ultraviolet rays to form the core 6. Further, the same oxetane resin layer as that of the lower clad 5 is formed on the core 6, and then cured by irradiating ultraviolet rays to form the upper clad 5.

  Thus, a laminated structure in which the optical waveguide 3A is laminated on the silicon substrate 2 can be formed. The clad 5 and the core 6 may be made of a glass material.

Next, as shown in FIG. 9B, the silicon substrate 2 is cut to the boundary with the lower clad 5 using a dicing saw equipped with a V-shaped blade at an angle of 90 degrees, and the tip of the silicon substrate 2 is 90 degrees. Forming V-shaped cutting groove 16 Next, once cutting is stopped, the V-shaped blade is separated from the cutting groove 16, and the cutting chips are washed and removed from the cutting groove 16 and adhered to the V-shaped blade. Remove cutting debris.

  As the dicing apparatus, for example, a dicing apparatus manufactured by Disco Corporation equipped with a V-shaped blade using diamond having a particle diameter of 3 μm as abrasive grains is used. The dimension of the V-shaped blade is, for example, a blade having a thickness of 300 μm and a slope inclined at 45 degrees with a width of 150 μm from the center. As such a blade, for example, Disco Model MBT-1204, SD5000L25MT38, and blade dimensions of 52 × 0.3 × 40 × 45 ° can be used.

  At the time of dicing, an ultraviolet-peelable adhesive tape is stuck on the optical waveguide 3A, and the back surface of the tape is stuck to a vacuum-type chuck table of a dicing device to fix the laminated structure to a dicing saw.

  In the present embodiment, after forming the optical waveguide 3A having a thickness of 120 μm on the silicon substrate 2 having a substrate thickness of 620 μm, cutting was performed at a rotation speed of 30,000 rpm and a cutting speed of 0.3 mm / sec. When the cutting speed is 0.3 mm / sec, a smooth inclined end face 4 can be formed. If a smooth inclined end face 4 can be formed, the light reflection efficiency can be increased.

  Next, as shown in FIG. 9C, the V-shaped blade obtained by cutting the silicon substrate 2 is aligned with the cutting groove 16, and the optical waveguide 3A is cut under the same conditions as those for cutting the silicon substrate 2. Thereby, the inclined end face 4 for changing the traveling direction of the optical signal can be formed on the end face of the optical waveguide 3A.

  In addition, when the cutting is stopped once at the stage of cutting the silicon substrate 2 and the optical waveguide 3A is cut following the cutting of the silicon substrate 2 without removing the cutting chips of the silicon substrate 2, the optical waveguide 3A is cut. At this time, the cutting surface of the optical waveguide 3A is roughened by silicon cuttings, and a smooth inclined end face cannot be formed on the optical waveguide 3A. In the present embodiment, the cutting is temporarily stopped, the V-shaped blade is separated from the cutting groove 16, the cutting chips are washed and removed from the cutting groove 16, and the cutting chips attached to the V-shaped blade are removed. Then, by performing the two-stage cutting in which the optical waveguide 3A is cut, a smooth inclined end face 4 can be formed in the optical waveguide 3A.

Embodiment of the method for manufacturing an optical integrated circuit This embodiment is an example of an embodiment of a method for manufacturing an optical integrated circuit according to the present invention, and FIG. 10 shows an example of a method for manufacturing an optical integrated circuit according to the present embodiment. 10A is a side view, and FIG. 10B is a top view.

  First, the optical path conversion element 1B described with reference to FIGS. 2 and 3 is manufactured through the steps described with reference to FIG. That is, the optical waveguide 3B having the clad 7 and the core 8 is formed on the silicon substrate 2 with oxetane resin or the like. Then, an inclined end face 4 having reflection surfaces 8a at both ends of the optical waveguide 3B is formed using a V-shaped blade.

  Further, the mounting substrate 12 on which the surface emitting semiconductor laser element 13 and the photodiode 14 are mounted is manufactured by a process not shown. In the step of manufacturing the mounting substrate 12, a soldering operation for electrically connecting the surface emitting semiconductor laser element 13 and the photodiode 14 to the mounting substrate 12 is performed. Further, as shown in FIG. 10B, the mounting substrate 12 is provided with a marker 17 as a position target for positioning the optical path conversion element 1B. The marker 17 is, for example, one in which marks indicating mounting positions of four corners of the optical path conversion element 1B are previously attached to one surface of the mounting substrate 12. In FIG. 10B, the outer shape of the optical path conversion element 1B is shown by a dashed line.

  As described above, the optical path conversion element 1B is held and attached to the mounting substrate 12 on which the surface emitting semiconductor laser element 13 and the photodiode 14 are mounted by a handling device (not shown). When attaching the optical path conversion element 1B, the position of the optical path conversion element 1B is aligned with the marker 17 while checking the positions of the marker 17 and the optical path conversion element 1B with a measuring device (not shown) equipped with a CCD. Such a mounting method is called passive alignment. The optical path conversion element 1B is fixed using, for example, an adhesive.

  Through the above steps, the optical integrated circuit 11 shown in FIG. 4 is manufactured. Now, since the optical path conversion element 1 of the present embodiment supports the optical waveguide 3 with the silicon substrate 2, the mounting operation can be performed using a handling device used in a semiconductor manufacturing process. Therefore, passive alignment mounting becomes possible.

  Further, since the optical path conversion element 1 is mounted on the mounting substrate 12 on which the soldering operation has been completed, a step of applying heat to the mounting substrate 2 after mounting the optical path conversion element 1 can be eliminated. Therefore, since no heat is applied to the optical path conversion element 1, the optical waveguide 3 can be formed using a polymer resin such as oxetane resin.

  Furthermore, in a manufacturing method of forming an optical waveguide directly on a mounting substrate, a flattening step of the mounting substrate is generally required, but it is difficult to flatten the mounting substrate on which the optical element is formed. The formed optical waveguide is in a wavy state. On the other hand, in the present embodiment, the optical waveguide 3 is supported by the silicon substrate 2, and other elements are not mounted on the silicon substrate 2. The optical waveguide 3 having a thickness can be formed. Since the optical waveguide 3 is supported by the silicon substrate 2, the flattening of the mounting substrate is unnecessary.

  In each of the above embodiments, the planar optical waveguide is described as an example. However, the number of optical waveguides in the optical path conversion element according to the present invention is not limited to one, and the plate-shaped core 6 Or a three-dimensional optical waveguide composed of a multistage optical waveguide in which an optical waveguide 3B in which a plurality of cores 8 are arranged in parallel is stacked.

  INDUSTRIAL APPLICABILITY The present invention can be applied to an optical interconnection in which an optical element is mounted on a substrate and light is transmitted.

FIG. 2 is a cross-sectional view illustrating a configuration example of the optical path conversion element according to the first embodiment. FIG. 2A is a side view and FIG. 2B is a top view showing a configuration example of an optical path conversion element according to a second embodiment. It is a perspective view showing the example of composition of the optical path conversion element of a 2nd embodiment. 4A and 4B show a configuration example of an optical integrated circuit according to the present embodiment. FIG. 4A is a side view, and FIG. 4B is a top view. It is a perspective view showing an example of an experiment of an optical integrated circuit. It is sectional drawing which shows the modification of the optical path conversion element of 1st Embodiment. It is an explanatory view showing the example of composition of the optical path conversion element of a 3rd embodiment. It is sectional drawing which shows the modification of the optical path conversion element of 3rd Embodiment. It is sectional drawing of each process at the time of manufacturing an optical path conversion element according to the method of the embodiment. FIGS. 10A and 10B are a side view and a top view, respectively, illustrating an example of a method for manufacturing an optical integrated circuit of this embodiment. FIG. 1 is a cross-sectional view of a conventional optical path conversion element disclosed in Japanese Patent Application Laid-Open No. 10-30961.

Explanation of reference numerals

Reference numerals 1A to 1E: optical path conversion element, 2: silicon substrate, 3A to 3C: optical waveguide, 4: inclined end face, 5: clad, 6: core, 7: clad , 8: core, 8a: reflective surface, 11: optical integrated circuit, 12: mounting substrate, 13: surface emitting semiconductor laser element, 14: photodiode, 15 ... Vertical end face, 16: Cutting groove, 17: Marker

Claims (22)

Board and
An optical waveguide formed on the substrate and having an inclined end surface at an angle of 90 degrees or more and 180 degrees or less with respect to an end surface of the substrate on at least one end surface thereof. .   The optical path conversion element according to claim 1, wherein the optical waveguide has a clad and a core, and an end surface of the core is exposed to the same surface as the inclined end surface to form a reflection surface.   The optical path conversion element according to claim 1, wherein the optical waveguide has a plurality of cores formed in parallel inside the cladding.   The optical path conversion element according to claim 1, wherein the cladding and the core of the optical waveguide are each formed of a high-molecular organic compound.   The optical path conversion device according to claim 1, wherein the cladding and the core of the optical waveguide are each formed of a glass-based material.   The optical path conversion device according to claim 1, wherein the substrate is a silicon substrate.   The optical path conversion element according to claim 1, wherein the inclined end surface is covered with an optical reflection film.   The optical path conversion device according to claim 1, wherein the optical waveguide is a planar optical waveguide. The optical waveguide includes:
An oxetane compound having an oxetane ring,
An oxirane compound having an oxirane ring,
A cationic polymerization initiator that initiates polymerization of the oxetane compound by a chain reaction,
The optical path conversion device according to claim 1, wherein the oxetane resin is a oxetane resin made of a resin component that is cured by irradiation with an energy beam. Forming an optical waveguide on the substrate;
Cutting the substrate using a V-shaped blade to form a cutting groove reaching the optical waveguide, and then temporarily stopping the cutting;
Removing cutting chips from the cutting groove and the V-shaped blade;
Then, aligning the V-shaped blade with the cutting groove, restarting the cutting, and cutting the optical waveguide, to cut the optical waveguide.   The method according to claim 10, wherein a silicon substrate is used as the substrate, and the cladding and the core of the optical waveguide are each formed of a high-molecular organic compound.   The method according to claim 10, wherein a silicon substrate is used as the substrate, and the cladding and the core of the optical waveguide are each formed of a glass-based material.   The method according to claim 10, wherein a dicing saw is used in the cutting with the V-shaped blade.   14. The method according to claim 13, wherein a diamond blade having diamond particles having an average particle diameter of 1 to 10 [mu] m is used as the V-shaped blade. An optical path conversion element having an optical waveguide formed on a substrate,
A mounting board on which the optical element is mounted,
The optical path conversion element has, on at least one end surface of the optical waveguide, an inclined end surface that forms an angle of 90 degrees or more and 180 degrees or less with respect to an end surface of the substrate, and the optical waveguide has a clad and a core. The end surface of the core is exposed to the same surface as the inclined end surface to form a reflection surface,
The optical integrated circuit, wherein the optical path conversion element is mounted on one surface of the mounting substrate at a position where the reflection surface faces the optical element. As the optical element, a surface light emitting element that emits light in a direction perpendicular to the surface of the mounting substrate, and a light receiving element that receives light from the direction perpendicular to the surface of the mounting substrate,
The optical path conversion element includes, at both ends of the optical waveguide, the inclined end surface on which the reflection surface is formed,
16. The light-emitting device according to claim 15, wherein the surface light-emitting element is disposed to face the reflection surface of one of the inclined end surfaces, and the light-receiving element is disposed to face the reflection surface of the other inclined end surface. An optical integrated circuit as described in the above.   16. The optical integrated circuit according to claim 15, wherein the optical waveguide has a plurality of cores formed in parallel inside the clad.   The optical integrated circuit according to claim 15, wherein the inclined end surface on which the reflection surface is formed is covered with an optical reflection film.   The optical integrated circuit according to claim 15, wherein the clad and the core are each formed of a high molecular organic compound. The cladding and the core,
An oxetane compound having an oxetane ring,
An oxirane compound having an oxirane ring,
A cationic polymerization initiator that initiates polymerization of the oxetane compound by a chain reaction,
The optical integrated circuit according to claim 15, wherein the optical integrated circuit is an oxetane resin made of a resin component that is cured by irradiation with an energy beam.   An optical path conversion element in which an optical waveguide is formed on a substrate, and at least one end surface of the optical waveguide has an inclined end surface that forms an angle of 90 ° or more and 180 ° or less with respect to the end surface of the substrate, A method for manufacturing an optical integrated circuit, comprising a step of aligning and mounting a device on a mounting board on which an element is mounted. 22. The method of manufacturing an optical integrated circuit according to claim 21, wherein the optical path conversion element is aligned with reference to a position target attached to the mounting substrate.

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