Optical waveguide device manufacturing method and optical waveguide device

Abstract

There is a problem that, in order to ensure a light input / output function of a silicon photonics optical waveguide substrate, enormous time and cost are required for an optical polishing step, an active alignment step, and the like of each member. In the present invention, a V-groove (103) is formed on an Si substrate (101) of a silicon photonics optical waveguide according to the position of the optical waveguide by a photolithography technology and an etching step. The depth of the V-groove (103) is adjusted such that the center of a core of an optical fiber (102a) matches the height of the optical waveguide. An end surface of the optical fiber (102a) is a diced surface. Low-loss optical connection is established by disposing the optical fiber (102a) in the V-groove (103).

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an optical waveguide device and an optical waveguide device, and more particularly to a technique for connecting an optical fiber to an optical waveguide substrate. [Background technology]

[0002] The technology for connecting optical fibers to such optical waveguides involves first dicing the optical waveguide substrate vertically and horizontally to divide it into chips of several millimeters square, and then optically polishing the input and output sections of the optical waveguide using an abrasive such as selenium oxide. Then, multiple optical fibers for inputting and outputting optical signals are connected to the optical waveguide substrate.

[0003] When connecting multiple optical fibers, a substrate is prepared that has multiple V-grooves whose spacing is adjusted to match the spacing of the optical waveguides to be connected. Then, the optical fibers are aligned and placed in the corresponding V-grooves (Non-Patent Document 1). After that, a glass plate is used to press the optical fibers toward the substrate so that the optical fibers are in close contact with the slope of the V-groove. In the above process, the optical fibers The connection end face of the bundle of bars (optical fiber array) is optically polished in the same manner as the substrate side of the optical waveguide. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] NTT Advanced Technology, "Adhesive for Fiber Array Assembly," [online], April 27, 2021, 1 / 4-4 / 4, [Retrieved June 29, 2021] Internet (URL: https: / / keytech.ntt-at.co.jp / adhesive / prd_10012.html) Summary of the Invention

[0005] In the above-mentioned technology for connecting an optical fiber to a waveguide substrate, the optical polishing process for the substrate and optical fiber member is carried out through a rough polishing process using an abrasive containing coarse abrasive grains, a medium polishing process, and a finish polishing process using fine silica particles, which takes a relatively long time. Furthermore, the polishing process requires special jigs and tools to control the polishing angle of the end face. Furthermore, for highly integrated substrates with electrode patterns formed on their surfaces, such as silicon photonics chips, special processing steps such as providing a cover to protect the surface from contamination that occurs during the polishing process are required.

[0006] In the process of connecting the optical waveguide substrate and the optical fiber array, the optical waveguide substrate or the optical fiber array is fixed to a fine adjustment stage with a resolution of 0.1 μm or less, and a separately prepared light source and optical power monitor are connected to the optical fiber and aligned by active alignment to maximize the optical power. After that, an ultraviolet (UV) curing adhesive is dropped onto the connecting end face and cured to fix the connection.

[0007] As described above, there is a problem in that connecting an optical fiber array to an optical waveguide substrate and ensuring a certain level of optical input / output function requires a great deal of time and cost for processes such as optical polishing and alignment of each component.

[0008] An object of the present invention is to provide a method for manufacturing a fiber array that can omit the polishing step and alignment step when connecting an optical waveguide substrate and an optical fiber.

[0009] To achieve this object, one aspect of the method for manufacturing an optical waveguide device of the present invention includes: passing a plurality of optical fibers through a plurality of through holes formed in a fixing block and having a diameter larger than the diameter of the optical fibers; arranging tip portions of the plurality of optical fibers exposed from the fixing block in a plurality of recesses of a temporary fixing substrate, respectively, and fixing the plurality of optical fibers to the temporary fixing substrate and the fixing block while pressing the plurality of optical fibers against the recesses with a temporary holding plate; dicing the temporary fixing substrate and the temporary holding plate together with the plurality of optical fibers to set the tip portions of the plurality of optical fibers to a predetermined length; removing the temporary fixing substrate and the temporary holding plate from the tip portions of the plurality of optical fibers; An optical waveguide was formed In multiple recesses on the waveguide substrate While aligning and fixing the recesses of the temporary fixing substrate to the waveguide substrate, the intervals between the recesses of the temporary fixing substrate being equal to the intervals between the recesses of the waveguide substrate. the plurality of recesses of the waveguide substrate are formed in accordance with the positions of the optical waveguides; It is characterized by, characterized by.

[0010] This makes it possible to omit the polishing process and active alignment for both the optical waveguide substrate (chip) and the fiber array, and also reduces the size of the fiber array, resulting in reduced manufacturing time and costs. [Brief explanation of the drawings]

[0011] [Figure 1] 1 shows a diagram of an implementation of a fiber array according to an embodiment of the present invention. [Figure 2] 1A to 1C are diagrams showing a process for producing a fiber array according to an embodiment of the present invention. [Figure 3] 1A to 1C are diagrams showing a process for producing a fiber array according to an embodiment of the present invention. [Figure 4] 1 shows a diagram of an implementation of a fiber array according to an embodiment of the present invention. [Figure 5] FIG. 10 is a diagram showing a fiber array of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] In this embodiment, a recess (in this specification, a recess having a roughly V-shaped cross section is referred to as a V-groove) is formed on a Si substrate on which a silicon photonics optical waveguide has been formed, by photolithography and etching processes, in accordance with the position of the optical waveguide. The cross section of the recess may be roughly U-shaped, or it may be sufficient if there is a recess. The depth of the V-groove is determined in accordance with the height of the waveguide. In other words, when an optical fiber is placed and fixed in the V-groove, the center of the core of the optical fiber The depth of the V-groove is determined so that it matches the height of the optical waveguide.

[0014] Figure 1 shows a substrate on which a silicon photonics optical waveguide is formed, with a fiber array mounted in multiple V-grooves formed in accordance with the position (height) of the optical waveguide, as described above. FIG.

[0015] As shown in FIG. 1, a plurality of V-grooves 103 are formed on a substrate 101 on which a silicon photonics waveguide is formed (hereinafter, also simply referred to as an optical waveguide substrate). The number of V-grooves 103 corresponds to the number of optical fibers that make up the optical fiber array 102. Meanwhile, the optical fiber array 102 is fixed to a glass block 104. The block 104, which holds a portion of the optical fiber array 102 in this manner, is connected to the substrate 101 while aligning each optical fiber 102a of the optical fiber array 102 with the corresponding V-groove 103.

[0016] Then, an ultraviolet (UV) curing adhesive is filled into the interface between the optical waveguide substrate 101 and the block 104, thereby fixing the optical fiber array 102 to the optical waveguide substrate 101.

[0017] In the connection between the optical waveguide substrate 101 and the optical fiber array 102, The corresponding optical fiber 102a is placed and pressed against the optical waveguide so as to be in close contact with it, and then glued and fixed. This ensures reliable optical coupling between the optical fiber and the waveguide, and also ensures adhesive strength. Note that if adhesive leaks into the V-groove 103 of the optical waveguide substrate 101, Even if they are transmitted, they contribute to fixing the optical fiber array 102, so there is no problem.

[0018] 2(a) to 2(c) and 3(a) and 3(b) are diagrams for explaining the method of fabricating a fiber array in order.

[0019] First, as shown in Fig. 2(a), the optical fiber array 102 is passed through a fixing glass block 104. More specifically, the block 104 has through-holes formed therein that are several tens of micrometers larger than the diameter of each optical fiber 102a. The through-holes are then subjected to coating removal and cleavage. The slotted optical fiber 102a is passed through the slotted optical fiber 102a.

[0020] Next, as shown in FIG. 2(b), a substrate having V-grooves 105a formed thereon in the same number as the optical fibers is formed. The optical fiber array 102 and the block 104 are moved relative to the substrate 105, and the optical fibers 102a are aligned with the V-grooves 105a. At this time, the optical fiber array 102 and the block 104 are not fixed to each other. In manufacturing the optical fiber array 102, as described above, a V-groove substrate 105 is prepared separately from the V-grooves 103 of the optical waveguide substrate 101 to be finally connected. The V-grooves of this substrate 105 are determined by the arrangement pitch (spacing) of the multiple V-grooves 103 of the optical waveguide substrate 101 and The block 104 used in this embodiment may be an upper and lower split type. In this case, the block 104 is split into two parts, and after the optical fibers 102a are aligned, the block 104 is placed on the V-groove substrate 105.

[0021] Next, as shown in FIG. 2(c), with the optical fiber 102a and the V-groove aligned, The optical fiber array 102 is temporarily held to the V-groove substrate 105 by a temporary fixing plate 106 made of glass. Then, in this state, the individual optical fibers 102a are adhesively fixed in the corresponding V-grooves. After temporary holding with a temporary holding plate 106, the through holes in the block 104 are filled with a UV-curable adhesive and UV is irradiated to fix the optical fiber array 102 to the block 104. In addition, a reinforcing resin 107 is piled up around the base of the coated side of the optical fiber array 102 for protection.

[0022] Next, as shown in FIG. 3(a), the V-groove substrate 105 is cut by a dicing device 108. More specifically, the temporary fixing presser plate 106 is diced together to obtain an optical fiber array 102 having oblique end faces at a predetermined angle, as will be described in detail later with reference to FIG.

[0023] As described above, the optical fiber array 102 is fixed in the V-groove of the V-groove substrate 105, and By performing dicing while the wafer is temporarily fixed with the presser plate 106, the accuracy of the cut surface can be increased, and a cut surface similar to the polished surface can be obtained. As a result, it is possible to omit the optical polishing process, which requires a relatively large number of steps.

[0024] Next, the optical fiber array 102 is pulled out together with the block 104 from the V-grooved substrate 105 for temporary fixing. After punching, an optical fiber array is completed as shown in Figure 3(b).

[0025] FIG. 4 is a diagram illustrating the connection relationship between the optical waveguide substrate and the optical fiber array according to this embodiment. As shown in the figure, in this embodiment, the optical fiber is connected to the optical waveguide in a state inclined by θ from the perpendicular direction of the connection surface. In this embodiment, θ is a few degrees (approximately 8 to 10°). ) This makes it possible to prevent reflection at the connection surface when optically coupled. In this embodiment, this inclination is achieved by the above-mentioned dicing cut. The position at which the optical fiber array 102 is cut is determined to match the length of the V-groove formed in the optical waveguide substrate 101. Make a decision.

[0026] The optical fiber array 102 fixed to the completed block 104 is connected to the optical waveguide substrate 101 to manufacture an optical waveguide device. More specifically, the optical fiber array 102 fixed to the block 104 is spaced at equal intervals with the V-grooves 103 of the optical waveguide substrate 101 via the V-grooves of the V-groove substrate 105, and in this state is placed in the V-groove 103 of the optical waveguide substrate 101, as shown in FIG. 1. This allows the completed optical fiber array 102 to be connected to the optical waveguide substrate 101 with their centers aligned. As a result, it is possible to omit the alignment of the V-grooves 103 of the optical waveguide substrate 101 with the corresponding optical fibers.

[0027] It is possible to omit the polishing process and active alignment for both the optical waveguide substrate (chip) 101 and the fiber array, and the fiber array can be made smaller, resulting in the effect of reducing the manufacturing time and manufacturing costs.

[0028] Although the optical waveguide device employs a plurality of optical fibers, the present invention is not limited to this configuration. In the case of a single-function device using an optical waveguide, for example, in the case of only an optical modulator, a single core may be used. This is also possible.

[0029] (Comparative Example) 5(a) and 5(b) are diagrams illustrating connections in an optical fiber array according to a comparative example. As shown in these figures, each optical fiber 202a of the optical fiber array is connected to a V-groove base. The fiber is placed in the V-groove of the plate 205 and fixed with adhesive 209 for fixing the fiber in the V-groove. The root portion of the fiber is fixed with adhesive 210.

[0030] The optical fiber 202a fixed to the V-groove substrate 205 in this manner is then attached to the substrate (not shown). ) is connected to a waveguide (not shown) formed in the V-groove substrate 205. In this connection, the optical fiber 202a is simply fixed in the V-groove of the V-groove substrate 205, and the V-groove of the V-groove substrate 205 is not aligned with the waveguide, so alignment is required. In addition, since the above-mentioned dicing is not performed, an optical polishing process is required for the optical fiber.

Claims

1. Passing a plurality of the optical fibers through a plurality of through holes formed in a fixing block and having a diameter larger than the diameter of the optical fibers; the tip portions of the optical fibers exposed from the fixing block are respectively placed in the recesses of a temporary fixing substrate, and the optical fibers are fixed to the temporary fixing substrate and the fixing block while pressing the optical fibers against the recesses with a temporary holding plate; the temporary fixing substrate and the temporary holding plate are diced together with the plurality of optical fibers to cut the tip portions of the plurality of optical fibers to a predetermined length; removing the temporary fixing substrate and the temporary holding plate from the tip portions of the plurality of optical fibers; the tip portions of the optical fibers fixed to the fixing block are aligned with and fixed to a plurality of recesses of a waveguide substrate on which optical waveguides are formed; The method comprises the steps of: a plurality of recesses of the temporary fixing substrate and a plurality of recesses of the waveguide substrate are spaced apart by the same distance, and the plurality of recesses of the waveguide substrate are formed to match the positions of the optical waveguides.

2. a distance between the recesses in the temporary fixing substrate being equal to a distance between the optical waveguides connected to the optical fibers; The method for manufacturing the optical waveguide device according to claim 1 .

3. a depth of the recess of the temporary fixing substrate being adjusted so that the center of the core of the optical fiber is aligned with the height of the optical waveguide; 3. The method for manufacturing the optical waveguide device according to claim 1.

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