JP2008262116A - Optical waveguide circuit and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easily manufactured and precise optical path transformation mirror. <P>SOLUTION: A flat optical waveguide circuit formed on a substrate 101 includes: an optical waveguide 104 composed of a core 102 and a clad layer 103; a mirror groove 108 which is formed at the end part 105 of the optical waveguide and has a depth larger than that of the core of the optical waveguide; and the optical path transformation mirror 121 in which a reflection body 122 is formed on one face of a structure body, wherein the optical path transformation mirror 121 is arranged in the mirror groove so that the reflection body and the end part of the optical waveguide face to each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical waveguide circuit and a manufacturing method thereof, and more particularly to an optical waveguide circuit having a function of converting an optical path by a micromirror structure and a manufacturing method thereof.

  In the fields of optical communication and optical information processing, optical functional components are configured and integrated using planar optical waveguide circuits. Between such a planar optical waveguide circuit and a light emitting / receiving element, a part or all of the light wave is taken out from one region of the planar optical waveguide circuit and received by a photodiode (hereinafter referred to as “PD”), or Coupling is required for inputting output light from a semiconductor laser diode (hereinafter referred to as “LD”) to the planar optical waveguide circuit. For example, in a node apparatus in the wavelength division multiplexing transmission system, it is necessary to integrate a large number of PDs for monitoring the light intensity for a plurality of optical waveguides in a planar optical waveguide circuit.

  As an optical coupling structure between such an optical element and a planar optical waveguide circuit, an optical path conversion mirror for converting the optical path is provided at a minute part at the end of the optical waveguide of the planar optical waveguide circuit, and light is transmitted in a direction perpendicular to the circuit surface. A vertical input / output structure for inputting and outputting is known. The optical path conversion mirror applied to the optical waveguide circuit of the node device described above is (1) a combination of an optical waveguide to be monitored and an optical waveguide that is not a target, (2) High positional accuracy and angular accuracy are required for optical coupling with an array-type PD (for example, (3) Position accuracy = ± 3 μm, Angular accuracy = ± 3 °), (3) High mirror surface roughness accuracy is required to prevent an increase in light receiving loss in PD and deterioration of crosstalk. (4) Miniaturization and integration Therefore, the PD can be mounted close to the optical path conversion mirror (for example, in the case of a PD having a light receiving diameter of 20 μm, 50 to 100 μm is desirable from the end of the optical waveguide to the light receiving surface of the PD), and (5) alignment when mounting the PD And use Requirements such as fixing with solder is preferable so as not to cause misalignment in boundary conditions, and (6) a mirror capable of adding a lens effect and a filter effect is preferable for enhancing the functionality of an optical waveguide circuit. It is necessary to satisfy.

  In the conventional vertical input / output structure, (a) a groove inclined at an angle with respect to the vertical direction of the substrate is formed in a planar optical waveguide circuit by machining such as a dicing saw, and a thin film reflection is formed in the groove. (B) A structure in which a micromirror is formed by laser ablation at one end of a polymer waveguide, (c) A groove is dug to the substrate surface by etching at the end of the waveguide, and a resin is inserted into the groove. A structure in which a slope using surface tension is formed and a mirror is installed on the slope has been proposed. Although the method of machining of (a) is simple, there is a possibility that optical waveguides other than the desired optical waveguide may be cut together at the end of the waveguide, and there is a problem that the application is limited. The method (b) can be applied only to polymer waveguides, and there is a problem that processing by laser ablation is extremely difficult for a silica-based optical waveguide that is most expected as a practical planar optical waveguide circuit.

  The method (c) is widely applicable to various waveguide materials including quartz-based optical waveguides, and a structure that can be easily manufactured has been proposed (for example, see Patent Document 1). The structure of Patent Document 1 is a structure in which a resin inclined surface is used as a mirror support, and is a high-performance and highly productive optical path conversion mirror with high mirror surface accuracy and alignment accuracy with an optical waveguide.

  FIG. 1 shows the structure and manufacturing method of a conventional optical path conversion mirror (see, for example, Patent Document 2). In the planar optical waveguide circuit, a waveguide 34 including a clad layer 33 surrounding a core 32 is formed on a flat substrate 31. As shown in FIG. 1A, a desired waveguide end 35 is dug until reaching the substrate 31 to form a groove 38 having a concave cross-sectional shape. As shown in FIG. 1C, resin supply grooves 37 a and 37 b are provided so as to be connected to the groove 38. When the liquid resin is supplied from the resin supply groove 37a, the liquid resin flows along the wall surface 36 of the groove 38, and an inclined surface 39 having an inclination angle of 40 to 50 degrees can be obtained. An optical path conversion mirror can be obtained by using a part of the inclined surface 39 to which light emitted from the waveguide 34 hits as a support for the mirror and forming a reflective material such as vapor deposition of gold.

  Here, as shown in FIG. 1 (c), on the bottom surface 40 of the groove 38, a region 41 having good wettability (small contact angle) with respect to the liquid resin and a poor wettability adjacent to this (contact angle). Region 42 having a large size) is formed in advance. In order to produce such a region, for example, a method described in Patent Document 3 is used. That is, Ti is deposited obliquely with a thickness of 0.1 μm from an angle of 35.3 degrees obliquely above the substrate 31. Then, the halftone dot portion of FIG. 1C becomes a shadow, and Ti does not adhere here. Next, while rotating the substrate 31, Cr is vapor-deposited on the entire surface with a thickness of 0.1 μm so that no shadow is formed. When Cr is lifted off with Ti after being immersed in dilute fluorinated liquid, Cr remains in the dot portion of FIG. Next, a surface treatment agent that gives a high contact angle to the liquid resin, such as diluted silicone oil, is spin-coated on the entire surface. When the surface treatment film is lifted off with a Cr etching solution, the halftone dot region in FIG. 1 (c) is smoother than the liquid resin, while the other region has a contact angle of 45 degrees or more and is a liquid curable resin. In contrast, the dullness gets worse. If the liquid resin is supplied, the liquid resin is automatically dammed at the boundary between the high contact angle region and the low contact angle region, so that the mirror slope can be easily formed.

Japanese Patent No. 3147327 Japanese Patent No. 3405005

  However, the conventional method of forming an optical path conversion mirror in a planar optical waveguide circuit is complicated in processes such as the formation of grooves by etching, supply and solidification of liquid resin, vapor deposition of metal materials, etc. There was a problem that all the required conditions could not be satisfied.

  Although the conventional method has a higher mirror surface accuracy than a manufacturing method by machining or laser processing, the accuracy of the inclined surface that becomes the mirror support formed by solidifying the liquid resin is accurately evaluated after the manufacturing. It is difficult. Since the resin is inferior in heat resistance, the mirror may be deformed depending on environmental conditions. It is also difficult to confirm whether or not the desired performance is exhibited after the optical path conversion mirror is formed and the planar optical waveguide circuit and the optical element are coupled.

  On the other hand, a structure has been proposed in which an optical path conversion mirror structure is prepared in advance separately from the planar optical waveguide circuit and mounted in a groove formed at the end of the optical waveguide. However, it is a conceptual proposal that the mirror structure is manufactured separately, and it is difficult to manufacture a small mirror with uniform accuracy and high yield so as to satisfy the above-described requirements. It is also difficult to appropriately mount the optical path conversion mirror structure on a planar optical waveguide circuit in which a large number of optical functional parts are integrated.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an optical waveguide circuit having an optical path conversion mirror that satisfies the above-described requirements, is easy to manufacture, and has high accuracy, and a manufacturing method thereof. Is to provide.

  In order to achieve the above object, according to the present invention, in an optical waveguide circuit formed on a substrate, an optical waveguide comprising a core, an upper clad and a lower clad, and the optical waveguide The mirror groove formed deeper than the core of the optical waveguide at the end of the optical waveguide and the reflector formed on one surface of the structure opposite the end of the optical waveguide The structure has a first metal film formed on a first surface in contact with the one surface on which the reflector is formed, and is formed on the bottom surface of the mirror groove. The structure is fixed to the second metal film by solder, and the structure has a distance between the second surface facing the first surface and the bottom surface of the mirror groove smaller than the depth of the mirror groove. The first metal film is formed of the reflector on which the reflector is formed. At least two grooves formed in parallel with the side in contact with the side, and the area of the second metal film is smaller than the area of the first metal film fixed by the solder, The area centroid of the metal film is formed so as to be shifted toward the end of the optical waveguide with respect to the area centroid of the first metal film fixed by the solder.

  The invention described in claim 2 is characterized in that the width of the groove according to claim 1 is 20 to 150 μm.

  According to a third aspect of the present invention, in an optical waveguide circuit formed on a substrate, an optical waveguide composed of a core, an upper cladding and a lower cladding, and an end of the optical waveguide are formed deeper than the core of the optical waveguide. A mirror groove, and a reflector disposed inside the mirror groove and formed on one surface of the structure, the optical path conversion mirror disposed so as to face the end of the optical waveguide, and the structure Has a recess formed in a first surface in contact with the one surface on which the reflector is formed, parallel to a side in contact with the one surface on which the reflector is formed, and the structure is formed on the inner surface of the recess. A second metal film formed on a bottom surface of the mirror groove and fixed by solder; and the structure includes a second surface facing the first surface; The distance from the bottom surface of the mirror groove is the depth of the mirror groove. Ri small, the area of the second metal film, characterized in that the smaller than the area of said first metal film is fixed by soldering.

  According to a fourth aspect of the present invention, in the optical waveguide circuit according to the third aspect, the area centroid of the second metal film is closer to the end of the optical waveguide than the area centroid of the first metal film. It is characterized by being formed in a shifted manner.

  The invention described in claim 5 is characterized in that the depth of the recess according to claim 3 or 4 is 3 to 10 μm.

  According to a sixth aspect of the present invention, the structure according to any one of the first to fifth aspects comprises a glass block, and the reflector is formed on a slope formed on one surface of a rectangular parallelepiped. Features.

  According to a seventh aspect of the present invention, the structure according to any one of the first to fifth aspects comprises a glass block, wherein a lens-shaped convex surface or concave surface is formed on a slope formed on one surface of a rectangular parallelepiped. It is characterized by being.

  The invention according to claim 8 is characterized in that the optical waveguide according to any one of claims 1 to 7 is a quartz-based planar optical waveguide or a silicon-based planar optical waveguide.

  According to a ninth aspect of the present invention, there is provided an optical waveguide circuit in which an optical path conversion mirror for converting an optical path is mounted on an optical waveguide circuit formed on a substrate and including an optical waveguide composed of a core, an upper cladding, and a lower cladding. In the method, a first step of forming a mirror groove formed deeper than the core of the optical waveguide at an end of the optical waveguide, and a reflector formed on one surface of the structure are provided at the end of the optical waveguide. A second step of disposing an optical path conversion mirror inside the mirror groove so as to face the first, and a first surface formed on a first surface in contact with the one surface on which the reflector of the structure is formed A second step of fixing the metal film and a second metal film formed on the bottom surface of the mirror groove by solder, wherein the first metal film is in contact with the one surface on which the reflector is formed At least by grooves formed parallel to The area of the second metal film is smaller than the area of the first metal film fixed by the solder, and the center of gravity of the area of the second metal film is fixed by the solder. The first metal film is formed so as to be shifted from the center of area of the first metal film toward the end of the optical waveguide.

  As described above, according to the present invention, the reflector is formed on one surface of the micromirror structure, and the end of the optical waveguide of the planar optical waveguide circuit is opposed to the reflector. Since it is disposed inside the mirror groove, it is possible to provide a highly accurate optical path conversion mirror that is easy to manufacture.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, a micromirror structure fabricated in advance is placed inside a groove formed at the end of the optical waveguide. By devising a method for manufacturing the micromirror structure, an optical path conversion mirror that is easy to manufacture and highly accurate can be realized. Further, by devising the mounting method of the micromirror structure, it can be appropriately mounted on the planar optical waveguide circuit.

  FIG. 2 shows the structure of an optical path conversion mirror according to an embodiment of the present invention. 2A is a cross-sectional view, and FIG. 2B is a perspective view. In the planar optical waveguide circuit, a waveguide 104 made of a clad layer 103 surrounding a core 102 is formed on a flat substrate 101. As shown in FIG. 2A, a desired waveguide end 105 is dug until reaching the substrate 101 to form a groove 108 having a concave cross-sectional shape. In the present embodiment, the length L of the groove 108 is 500 μm, the width W is 200 μm, and the depth d is 50 μm.

  On the other hand, the micromirror structure 121 has a shape in which an inclined surface 123 is formed on one surface of a rectangular parallelepiped, and is fixed to the bottom surface 110 of the groove 108. The micromirror structure 121 is made of a glass block, and a reflector 122 made of a metal thin film is formed on the inclined surface 123. The height of the micromirror structure 121 is lower than the depth of the groove 108. That is, the distance between the upper surface (second surface) and the bottom surface 110 of the micromirror structure 121 is made smaller than the depth of the groove 108. As described above, since only the grooves 108 need be formed in the planar optical waveguide circuit, the manufacturing process can be greatly simplified. Also, the optical path conversion mirror can be easily manufactured because the micromirror structure 121 prepared in advance is only fixed inside the groove 108.

  FIG. 3 shows a method for manufacturing a micromirror structure according to an embodiment of the present invention. First, a slope 133 is formed on one surface of a rectangular parallelepiped glass block 131, and mirror polishing is performed. A metal such as Au to be the reflector 132 is deposited on the polished surface (FIG. 3A). As the glass block 131, for example, a rectangular parallelepiped of 3 cm × 3 cm × 5 cm is used, and one surface thereof is cut with a dicing saw and polished to form a slope 133. Thus, since the slope 133 is formed over one surface of the large glass block 131, a highly accurate slope can be formed. Moreover, since the mirror surface formed on such a slope can be easily evaluated and inspected, a highly accurate reflector can be secured by sorting.

  Next, the glass block 131 is cut into a glass substrate 131 a having a thickness of 50 μm by a dicing saw 143. Here, the above-described reflector appears on the side surface of the plate-like glass substrate. The cut glass substrates 131a and 131b are fixed to the sample holder 141 and polished by the polishing plate 142 to adjust the plate thickness (FIG. 3B). The plate thickness is made thinner than the depth of the groove 108 formed in the above-described planar optical waveguide circuit. While being fixed to the sample holder 141, a metal film 135 such as Ti or Cr is formed on the bottom surfaces 134 of the glass substrates 131 a and 131 b, that is, the surface to be the bottom surface (first surface) of the micromirror structure by a method such as sputtering or vapor deposition. Is formed (FIG. 3C).

  FIG.3 (d) is the figure seen from the bottom face 134 of the glass substrate 131a. Here, before cutting out the micromirror structure 121, the metal film 135 formed on the bottom surface is patterned. In the patterning, one groove 136 is formed by mechanical cutting at a location that becomes the bottom surface of the micromirror structure 121. The groove 136 is formed in parallel with the side in contact with the inclined surface 133 on which the reflector 132 is formed. As described later, the width of the groove 136 is preferably 20 to 150 μm.

  Finally, the glass substrates 131a and 131b are cut into a width of 200 μm by a dicing saw, and further cut out so that the length of the structure including the inclined surface becomes 300 μm (FIG. 3D). In this way, the structure cut out so as to include the reflector on one surface of the rectangular parallelepiped becomes the micromirror structure 121.

  FIG. 4 shows a method for mounting a micromirror structure according to an embodiment of the present invention. 4A is a perspective view, and FIG. 4B is a cross-sectional view. The reflector 122 formed on the micromirror structure 121 is fixed to the groove 108 so as to face the core 102 of the waveguide. The fixing method includes a metal film 135b (first metal film) formed on the bottom surface of the micromirror structure 121 and a metal film 111 (second film) formed on the bottom surface 110 of the groove 108 provided to face each other. The metal film) is connected to the solder 144.

  Here, the area centroid of the metal film 111 on the bottom surface 110 connected by the solder 144 is provided so as to be shifted to the waveguide end 105 side from the area centroid of the metal film 135 of the micromirror structure 121. Specifically, each side parallel to the waveguide end portion 105 in the metal film 111 of the bottom surface 110 corresponds to each side parallel to the waveguide end portion 105 in the metal film 135b of the micromirror structure 121, that is, the inclined surface 133. Are formed so as to be shifted to the waveguide end portion 105 side from the respective sides parallel to the side in contact with. In FIG. 4B, the metal film 111 is shifted toward the waveguide end 105 by 10 μm on the side close to the waveguide end 105 and 20 μm on the far side. As a result, the micromirror structure 121 is attracted to the waveguide end portion 105 and exhibits a self-alignment effect.

  Further, the side parallel to the core 102 in the metal film 111 on the bottom surface 110 is shifted inward from the side parallel to the core 102 in the metal film 135b of the micromirror structure 121, and the area of the metal film 111 is set to be the same as that of the metal film 135b. It is formed smaller than the area.

  The self-alignment effect is generated by the solder tension so that the metal film 135 formed on the bottom surface of the micromirror structure 121 and the metal film 111 on the bottom surface 110 coincide with each other. Not limited to examples. For example, the side near the waveguide end 105 in the metal film 111 on the bottom surface 110 is set to the same position as the side parallel to the side in contact with the inclined surface 133 of the micromirror structure 121, and the waveguide end 105 in the metal film 111 Only the side that is parallel and that is far from the waveguide end 105 may be shifted to the waveguide end 105. Conversely, the far sides may be the same position and only the near sides may be shifted.

  The groove 136 on the bottom surface of the micromirror structure 121 has a role of preventing the solder 144 from adhering to the reflector 122 made of a metal thin film. Thereby, it is possible to prevent the deterioration of the performance of the reflector and the reduction of the self-alignment effect caused by the solder 144 spreading and adhering to the reflector 122. Note that AuSn or AuGe can be used for the solder 144, and AuGe having a high melting point is particularly preferable.

  According to this embodiment, since the slope 133 is formed over one surface of the large glass block 131, a highly accurate reflector can be ensured. Further, since the selectivity of the film as the reflector is expanded, the function can be added using, for example, a dielectric multilayer film. Furthermore, since the micromirror structure is cut out from the glass block having the reflector with uniform accuracy, the micromirror structure with uniform accuracy can be manufactured with high yield.

  Since such a micromirror structure is only fixed in the groove using the self-alignment effect, a plurality of highly accurate optical path conversion mirrors can be formed. In addition, the micromirror structure can be disposed close to the core of the waveguide by using both the self-alignment effect by the solder and mechanical alignment in which the edge of the micromirror structure is abutted against the waveguide end.

  FIG. 5 shows a mounting method of the micromirror structure according to the first embodiment. FIG. 5A is a view as seen from the bottom surface 134 of the glass substrate 131a. Although it is the same structure as the structure shown in FIG. 3D, here, before cutting out the micromirror structure 121, the metal film 135 formed on the bottom surface is patterned. In the patterning, a plurality of grooves 136a to 136c are formed by mechanical cutting at a location that becomes the bottom surface of the micromirror structure 121.

  FIG. 5B is a cross-sectional view showing the structure of the optical path conversion mirror. The reflector 122 formed on the micromirror structure 121 is fixed to the groove 108 so as to face the core 102 of the waveguide. As a fixing method, the two metal films formed on the bottom surface of the micromirror structure 121 and the two metal films 111a and 111b formed on the bottom surface 110 of the groove 108 are connected by solders 144a and 144b. Note that the solder may be supplied in the form of a preform agent or paste immediately before mounting. Further, it may be previously formed integrally with the metal film at the bottom of the groove or as a thin film pattern on the upper part of the metal film.

  Here, the metal films 111a and 111b formed on the bottom surface 110 of the groove 108 of the planar optical waveguide circuit are shaped like the metal film formed on the bottom surface of the opposing micromirror structure 121, as in the above-described embodiment. Also take a small shape. Further, the center of gravity of the metal films 111a and 111b connected by the solder 144a and 144b is formed so as to be shifted to the waveguide end portion 105 side with respect to the area of gravity of the metal film of each opposing micromirror structure 121. deep. In the first embodiment, the alignment effect can be improved by making the shape of the metal film for fixing the micromirror structure 121 square and increasing the number of edges. Thereby, even when a solder with low wettability such as AuGe is used, effective self-alignment can be realized.

  FIG. 6 shows a mounting method of the micromirror structure according to the second embodiment. FIG. 6A is a view seen from the bottom surface 134 of the glass substrate 131a. Although it is the same structure as the structure shown in FIG. 3D, here, before cutting out the micromirror structure 121, a groove having a width of 200 μm and a depth of 3 to 10 μm is formed on the bottom surface. The groove serves as a recess 136 formed on the bottom surface of the micromirror structure 121, and a metal film 135 is formed on the surface serving as the inner surface of the recess 136. For example, it is manufactured by the following method. After the polishing shown in FIG. 3B, a resist is applied to the entire surface that will be the bottom surface of the micromirror structure 121, and then a recess 136 is formed by a dicing saw. Next, a metal film is deposited on the bottom surface, and the resist is removed. In this way, a structure in which the metal film is provided only on the inner surface of the recess 236, that is, the inner bottom surface and the inner wall surface can be easily manufactured.

  FIG. 6B is a cross-sectional view showing the structure of the optical path conversion mirror. The reflector 122 formed on the micromirror structure 121 is fixed to the groove 108 so as to face the core 102 of the waveguide. As a fixing method, the metal film 135 formed on the inner surface of the recess 236 of the micromirror structure 121 and the metal film 111 formed on the bottom surface 110 of the groove 108 are connected by solder 144.

  Here, the metal film 111 formed on the bottom surface 110 of the groove 108 of the planar optical waveguide circuit has a smaller shape than the metal film formed on the bottom surface of the micromirror structure 121, as in the above-described embodiment. deep. In addition, it is preferable that the area centroid of the metal film 111 on the bottom surface 110 is shifted from the area centroid of the metal film 135 of the micromirror structure 121 toward the waveguide end 105.

  The depth of the recess 136 is preferably 3 to 10 μm. A solder film having a thickness of 2 to 3 μm is formed on the metal film 111 formed on the bottom surface 110. By adjusting the solder amount of the solder film, the alignment in the height direction can be performed. More simply, paste solder may be supplied to the metal film 111 by a dispenser or the like.

  According to the second embodiment, the alignment in the height direction is facilitated by mechanical alignment in which the convex portion on the bottom surface of the micromirror structure is brought into contact with the bottom surface of the groove by pulling the solder. In addition, by appropriately increasing the volume of the concave portion of the micromirror structure, it is possible to store surplus solder in the concave portion and not affect the bonding surface.

  FIG. 7 shows the structure of the optical path conversion mirror according to the third embodiment. The micromirror structure 121 has a shape in which a slope is formed on one surface of a rectangular parallelepiped, and is fixed to the bottom surface 110 of the groove 108. In the manufacturing method shown in FIG. 3, the micromirror structure 121 of Example 3 is polished on the upper surface of the cut glass substrate (see FIG. 3B), and the surface becomes the upper surface of the micromirror structure 121. Then, a metal film is formed (see FIG. 3C). Similar to the above-described embodiment, one groove is formed by mechanical cutting at a location on the upper surface (see FIG. 3D). The metal film 135 formed on the top surface of the micromirror structure 121 and the metal film 111 formed on the bottom surface 110 of the groove 108 are connected by solder 144. The shape of the metal film of the micromirror structure 121 and the groove 108 is the same as in the first and second embodiments.

  In FIG. 2A, the optical path of the light beam emitted from the core 102 of the waveguide 104 is converted vertically upward from the substrate plane direction. In the third embodiment, the conversion from the substrate plane direction to the vertically downward direction is performed. For example, the optical module 201 is bonded to the bottom surface of the substrate 101. The optical path conversion mirror optically couples the optical element 204 sealed by the housing 202 and the lid 203 and the core 102 of the waveguide 104.

  FIG. 8 shows the structure of the optical path conversion mirror according to the fourth embodiment. The micromirror structure 121 has a shape in which a slope is formed on one surface of a rectangular parallelepiped, and is fixed to the bottom surface 110 of the groove 108. The micromirror structure 121 of Example 4 is produced in the same manner as Example 3 using a transparent glass block. The reflector 122 of the micromirror structure 121 uses the inner surface of the glass block as a mirror surface, not the outer surface in contact with air.

  FIG. 9 shows the structure of an optical path conversion mirror according to the fifth embodiment. The micromirror structure 121 has a shape in which a slope is formed on one surface of a rectangular parallelepiped, and is fixed to the bottom surface 110 of the groove 108. In the micromirror structure 121 of the fifth embodiment, a reflector 122 made of a metal thin film is formed on the slope 123 in the same manner as in the fourth embodiment using a transparent glass block. In Example 5, a convex surface 124 having a lens shape is prepared in advance on the slope 123, and the reflector 122 is caused to function as a concave mirror.

  In FIG. 3A, the convex surface 124 is formed on one surface of a rectangular parallelepiped glass block 131 and then machined onto the inclined surface 133 by machining. The convex surface 124 may be transferred to the inclined surface 133 using a mold in which a concave lens is formed. Moreover, a convex shape can also be produced by processing a resist into a convex lens shape in advance and performing dry etching using the resist as a mask.

  The spot size of the waveguide 104 of a typical planar optical waveguide circuit is 5 μm. The light emitted from the core 102 can be condensed to a spot size of 1 to 2 μm by the concave mirror of the reflector 122.

  In FIG. 3A, after forming a slope 133 on one surface of the rectangular glass block 131, a concave surface having a lens shape is formed, and then a reflector 122 made of a metal thin film is manufactured. The reflector 122 may be mounted in the same manner as in the first and second embodiments to function as a concave mirror. That is, a lens-shaped convex surface or concave surface is prepared on the slope 123 in advance, and the lens effect can be imparted to the reflector 122.

It is a figure which shows the structure and production method of the conventional optical path conversion mirror. It is a figure which shows the structure of the optical path conversion mirror concerning one Embodiment of this invention. It is a figure which shows the preparation methods of the micromirror structure concerning one Embodiment of this invention. It is a figure which shows the mounting method of the micromirror structure concerning one Embodiment of this invention. It is a figure which shows the mounting method of the micromirror structure concerning Example 1. FIG. It is a figure which shows the mounting method of the micromirror structure concerning Example 2. FIG. FIG. 6 is a diagram illustrating a structure of an optical path conversion mirror according to a third example. FIG. 10 is a diagram illustrating a structure of an optical path conversion mirror according to a fourth example. FIG. 10 is a diagram illustrating a structure of an optical path conversion mirror according to a fifth example.

Explanation of symbols

31, 101 Substrate 32, 102 Core 33, 103 Clad layer 34, 104 Waveguide 35, 105 Waveguide edge 36 Wall surface 37 Resin supply groove 38, 108 Groove 39, 123, 133 Slope 40, 110, 134 Bottom surface 41 Nurability Region with good contact angle (small contact angle) 42 region with poor wetting property (large contact angle) 111,135 Metal film 121 Micromirror structure 122,132 Reflector 124 Convex surface 131 Glass block 136 Groove 141 Sample holder 142 Polishing plate 143 Dicing saw 144 Solder

Claims (9)

In an optical waveguide circuit formed on a substrate,
An optical waveguide consisting of a core, an upper cladding and a lower cladding;
A mirror groove formed deeper than the core of the optical waveguide at the end of the optical waveguide;
The reflector disposed inside the mirror groove and formed on one surface of the structure includes an optical path conversion mirror disposed so as to face the end of the optical waveguide,
The structure has a first metal film formed on a first surface in contact with one surface on which the reflector is formed, and is fixed by soldering with a second metal film formed on the bottom surface of the mirror groove. And
In the structure, a distance between a second surface facing the first surface and a bottom surface of the mirror groove is smaller than a depth of the mirror groove,
The first metal film is formed by at least two or more grooves formed in parallel with a side in contact with the one surface on which the reflector is formed,
The area of the second metal film is smaller than the area of the first metal film fixed by the solder, and the center of gravity of the area of the second metal film is fixed by the solder. An optical waveguide circuit, wherein the optical waveguide circuit is formed so as to be shifted toward the end side of the optical waveguide with respect to the area center of gravity.   The optical waveguide circuit according to claim 1, wherein the groove has a width of 20 to 150 μm. In an optical waveguide circuit formed on a substrate,
An optical waveguide consisting of a core, an upper cladding and a lower cladding;
A mirror groove formed deeper than the core of the optical waveguide at the end of the optical waveguide;
The reflector disposed inside the mirror groove and formed on one surface of the structure includes an optical path conversion mirror disposed so as to face the end of the optical waveguide,
The structure has a recess formed in a first surface in contact with the one surface on which the reflector is formed, in parallel with a side in contact with the one surface on which the reflector is formed;
The structure has a first metal film formed on the inner surface of the recess, and is fixed by solder to a second metal film formed on the bottom surface of the mirror groove,
In the structure, a distance between a second surface facing the first surface and a bottom surface of the mirror groove is smaller than a depth of the mirror groove,
An optical waveguide circuit, wherein an area of the second metal film is smaller than an area of the first metal film fixed by the solder.   4. The optical waveguide according to claim 3, wherein an area centroid of the second metal film is formed to be shifted toward an end of the optical waveguide with respect to an area centroid of the first metal film. circuit.   5. The optical waveguide circuit according to claim 3, wherein a depth of the recess is 3 to 10 μm.   6. The optical waveguide circuit according to claim 1, wherein the structural body is made of a glass block, and the reflector is formed on a slope formed on one surface of a rectangular parallelepiped.   6. The optical waveguide circuit according to claim 1, wherein the structural body is made of a glass block, and a lens-shaped convex surface or concave surface is formed on an inclined surface formed on one surface of a rectangular parallelepiped. .   8. The optical waveguide circuit according to claim 1, wherein the optical waveguide is a silica-based planar optical waveguide or a silicon-based planar optical waveguide. In a method of manufacturing an optical waveguide circuit in which an optical path conversion mirror for converting an optical path is mounted on an optical waveguide circuit formed on a substrate and including an optical waveguide composed of a core, an upper cladding, and a lower cladding.
A first step of forming a mirror groove formed deeper than the core of the optical waveguide at an end of the optical waveguide;
In the second step of disposing an optical path conversion mirror inside the mirror groove so that a reflector formed on one surface of the structure faces an end of the optical waveguide, the reflector of the structure A second step of fixing the first metal film formed on the first surface in contact with the one surface formed with the second metal film formed on the bottom surface of the mirror groove with solder,
The first metal film is formed by at least two or more grooves formed in parallel with a side in contact with the one surface on which the reflector is formed,
The area of the second metal film is smaller than the area of the first metal film fixed by the solder, and the center of gravity of the area of the second metal film is fixed by the solder. A method of manufacturing an optical waveguide circuit, wherein the optical waveguide circuit is formed so as to be shifted toward the end of the optical waveguide from the center of gravity.

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