JP4763497B2 - Optical module coupling structure and assembly method thereof - Google Patents

Description

  The present invention relates to a coupling structure between an optical module in which an optical waveguide is formed and an optical fiber, and a method for assembling the coupling structure.

As a coupling structure between an optical waveguide and an optical fiber of a conventional optical module, for example, those disclosed in Patent Document 1 and Patent Document 2 are known. FIG. 4 shows an example of a 1 × 4 splitter module disclosed in Patent Document 1. A waveguide block 49 is formed by adhering a quartz dummy plate 42 onto the waveguide element 41 with a highly elastic and heat resistant UV adhesive. One end and the other end of the waveguide block 49 are sandwiched between the incident side optical fiber array 50 and the output side optical fiber array 51. The incident-side single-core optical fiber 43 is disposed on the V-groove of the single-core-type V-groove block 44, and the pressing plate 45 is bonded from above to form the incident-side optical fiber array 50. The exit-side four-core tape fiber 46 is disposed on the four-core type V-groove block 47, and the exit-side holding plate 48 is bonded from above to form the exit-side optical fiber array 51. The optical axis alignment between the both end faces of the waveguide block 49 and the both end faces of the incident side and outgoing side optical fiber arrays 50 and 51 in contact with the surfaces is performed by a centering device that performs fine movement after mirror finishing by mirror polishing or the like ( Alignment) is performed. The optical axis alignment is performed while the light is incident from the single-core optical fiber 43 and the power of the emitted light from the four-core tape fiber 46 on the emission side is monitored. After the alignment of the optical axis, the waveguide block 49 and the end surfaces of the optical fiber arrays 50 and 51 on the incident side and the outgoing side are bonded and fixed by, for example, an epoxy-based UV adhesive substantially equal to the refractive index of the core of the optical fiber to 1 × A 4-splitter module is configured.
Japanese Patent Laid-Open No. 8-86933 (FIG. 1) JP 2005-17648 A

  However, in the coupling structure of the waveguide and the optical fiber as described above, since the end faces of the waveguide and the optical fiber array on the incident side and the output side are aligned and fixed, only when the working distance of the optical fiber is zero This enables high-efficiency optical coupling, and could not be used with an optical fiber having a working distance equipped with a lens mechanism such as a front-end fiber. Further, both end surfaces of the waveguide block 49 and the incident side and outgoing side optical fiber arrays 50 and 51 in contact with the surface need to be mirror-finished, so that there are cleavage planes. A semiconductor optical waveguide could not be used.

The coupling structure of the optical module according to the present invention is bonded and fixed on the optical waveguide support substrate, is opposed to both ends of the optical waveguide substrate on which the optical waveguide is formed, and protrudes outward from the optical waveguide support substrate. A fiber alignment support bonded and fixed on the optical waveguide support substrate, and an incident side fiber support and an output side fiber support whose outer edges are bonded and fixed to the outer surfaces of the fiber alignment support, respectively. Body.
The optical module coupling structure assembly method includes the steps of bonding and fixing the optical waveguide substrate on which the optical waveguide is formed on the optical waveguide support substrate, and outside the both end faces of the optical waveguide support substrate in the optical waveguide direction of the optical waveguide. Positioning the input-side fiber support and the output-side fiber support, respectively, and aligning the optical fiber and the optical waveguide fixedly supported by the input-side fiber support and the output-side fiber support, respectively, the end face of the core input side fiber support and the output side fiber support, input fiber alignment support of the input side and the output side of fiber alignment support for each other outside surfaces against each and adhering secure the fiber alignment for support and output side fiber alignment support of the side in the optical waveguide support substrate, the fiber alignment of the adhesive fixed input side The outer surface of each other of the support and the output side of the fiber alignment for support, and a step of bonding and fixing the outer edge of the respective end face of the input side fiber support and the output side fiber support member.

  As described above, according to the optical module coupling structure of the present invention, the fiber alignment support for aligning the optical fiber and the optical waveguide substrate is optically guided on the optical waveguide support substrate to which the optical waveguide substrate is bonded and fixed. Since the outer edges of the input and output side fiber supports are bonded and fixed to the outer surfaces of the fiber alignment supports, they are fixed to the optical waveguide board. The entire end face of the side and output side fiber supports is not in contact. Therefore, it is possible to provide an optical module coupling structure that can use an optical fiber having a working distance and can use a semiconductor optical waveguide having a cleavage plane as an optical waveguide substrate.

  Embodiments of the present invention will be described below with reference to the drawings. Corresponding portions between the drawings are denoted by the same reference numerals, and redundant description will not be given.

  FIG. 1 shows an embodiment of an optical module coupling structure according to the present invention. Fig.1 (a) is a perspective view of an Example, FIG.1 (b) is a front view, FIG.1 (c) is a top view. This embodiment shows an example of a 1 × 2 optical switch. For example, an optical waveguide substrate 2 is bonded and fixed on an optical waveguide support substrate 1 made of quartz glass or Pyrex (registered trademark) glass with both ends protruding from the optical waveguide support substrate 1. The optical waveguide substrate 2 is made of a compound semiconductor such as InGaAsP. Opposite end portions of the optical waveguide substrate 2, fiber alignment supports 3 a and 3 b are protruded outward from the optical waveguide substrate 2 and bonded and fixed onto the optical waveguide support substrate 1. In this example, the fiber alignment supports 3 a and 3 b have a concave cross-sectional shape perpendicular to the optical waveguide direction of the optical waveguide substrate 2, and the fiber alignment supports 3 a and 3 b have both ends of the optical waveguide substrate 2. It is fixed to the optical waveguide support substrate 1 so as to straddle each part. An end portion of the input side optical fiber 4 is sandwiched between fixing blocks 5a and 5b in which V grooves for positioning the optical fiber are formed to form an input side fiber support 5. For example, in the case of the input side optical fiber 4 having a working distance in which a lens is provided at the fiber tip 4a, the fiber tip 4a protrudes from the end face of the fixed block 5b and is fixed. The fixed block 5b protrudes closer to the fiber tip 4a than the fixed block 5a. The thickness and width of the fixed block 5b are set such that sufficient strength can be obtained when bonded to the outer end face of the fiber alignment support 3a. The concave cross section of the fiber alignment support 3a and the fiber tip protruding side outer edge portion of the fixing block 5b are bonded and fixed.

  The optical waveguide substrate 2 includes an optical waveguide 6 into which an optical signal is incident from the input side optical fiber 4 side, and two optical signals that are branched into two and transmitted to the other end of the optical waveguide substrate 2. Optical waveguides 6a and 6b are formed. Thin film heater electrodes 7a and 7b are provided on the surfaces of the bifurcated optical waveguides 6a and 6b, respectively. The optical waveguides 6a and 6b are heated by passing a current through the thin film heater electrodes 7a and 7b, and the phase of the optical signal can be changed by changing the refractive index of the optical waveguide. That is, when the thin film heater electrode 7a is heated, the light of the optical waveguide 6a can be phase-modulated. Optical signals output from the optical waveguides 6 a and 6 b are transmitted to two output side optical fibers 9 a and 9 b supported by an output side fiber support 8 configured similarly to the input side fiber support 5. That is, the end portions of the output side optical fibers 9a and 9b are sandwiched and fixed between the fixing blocks 8a and 8b in which V grooves for positioning the optical fibers are formed, thereby constituting the output side fiber support 8. . The fixed block 8b protrudes closer to the optical waveguide support substrate 1 than the fixed block 8a, and the thickness and width thereof are such that sufficient strength is obtained when the fiber alignment support 3b is contacted and bonded. Yes. The end tips of the output side optical fibers 9a and 9b protrude beyond the end face of the fixed block 8b. The concave cross section of the fiber alignment support 3b and the outer edge portion of the fixed block 8b are bonded and fixed.

  As described above, the fiber alignment supports 3a and 3b protrude outward from the optical waveguide substrate 2 and are bonded and fixed on the optical waveguide support substrate 1. The fiber alignment supports 3a and 3b Since the opposing edge portions of the input and output side fiber supports 5 and 8 are bonded and fixed, the end face of the optical waveguide substrate 2 and the end faces of the input and output side fiber supports 5 and 8 do not directly contact each other. Structure. Accordingly, it is possible to provide a distance between the fiber tip 4a and the optical waveguide 6 so as to have a so-called working distance, and it is also possible to use a semiconductor optical waveguide having a cleavage plane as the optical waveguide substrate.

  FIG. 2 shows a cross section taken along the line II-II shown in FIG. The optical waveguide support substrate 1 and the optical waveguide substrate 2 are formed by, for example, depositing a metal film on a surface where the optical waveguide support substrate 1 and the optical waveguide substrate 2 are in contact with each other, and bonding the surfaces by soldering, or an adhesive layer 20 using a silicone-based thermosetting adhesive Is fixed by bonding. The fiber alignment support 3a that is bonded and fixed to the optical waveguide support substrate 1 adjusts the optical axes of the optical waveguide 6 of the optical waveguide substrate 2 and the input-side optical fiber 4 supported by the input-side fiber support 5. Since it is a core component, it is bonded with, for example, an epoxy UV adhesive 21 that cures in a short time during alignment.

  In addition, although the example where both ends of the optical waveguide substrate 2 are protruded from the optical waveguide support substrate 1 and bonded and fixed has been described, this is because the optical waveguide substrate 2 is more preferably fixed in the reverse relationship. . That is, if both end portions of the optical waveguide substrate 2 are located inside the end portions of the optical waveguide support substrate 1, connection when the working distance is zero is not possible. As described above, in the case of an optical fiber having a working distance, the fiber tip 4a protrudes from the end face of the fixed block 5b and is fixed by adhesion, so that both end portions of the optical waveguide substrate 2 are end portions of the optical waveguide support substrate 1. Theoretically, connection is possible even if it is located inside. However, when the working distance is zero, the surfaces of the input side and output side fiber supports 5 and 8 that are in contact with the optical waveguide substrate 2 are both mirror-finished and are closely connected with an error of 1 μm or less. That is, unlike the case where there is a working distance, both end surfaces of the input side and output side fiber supports 5 and 8 and the optical waveguide substrate 2 need to be closely fixed. Therefore, if both end portions of the optical waveguide substrate 2 are located inside the end portions of the optical waveguide support substrate 1, connection is impossible.

  Although it has been explained that the connection is theoretically possible when there is a working distance, the protruding amount of the fiber tip 4a prevents the adhesive when the fixing blocks 5a and 5b are bonded from flowing around the fiber tip 4a. This is the main purpose, and the amount of protrusion cannot be made too large. The protruding amount is preferably about twice the diameter of the input side optical fiber 4. For example, when the diameter of the optical fiber cable is 125 μm, the protruding amount is set to about 250 μm. Although it is possible in terms of structure to set the protruding amount of the fiber tip 4a to be larger than this, if it is made too long, there arises a problem that the reliability of the connecting portion deteriorates due to the eccentricity of the optical fiber. Also, there is an increased risk of contacting the fiber tip with other components during assembly and damaging the fiber tip. As described above, since the amount of protrusion of the optical fiber is limited, even when there is a working distance, both ends of the optical waveguide substrate 2 are located on the inner side from the end of the optical waveguide support substrate 1 to be larger than the working distance. It is not preferable to have it. However, it is not necessary to stick both ends of the optical waveguide substrate 2 so as to protrude from the optical waveguide support substrate 1, and the positions of both ends of the optical waveguide substrate 2 are flush with the end surface of the optical waveguide support substrate 1. You may make it a position to do. Of course, for example, when the optical waveguide substrate 2 is bonded to the optical waveguide support substrate 1, the adhesive layer 20 does not wrap around the end surface of the optical waveguide substrate 2, and the positions of both ends of the optical waveguide substrate 2 are determined as follows. You may make it protrude from the end surface of 1. Note that the mutual relationship between the output side fiber alignment support 3b and the output side fiber support 8 and the output side optical fibers 9a and 9b of the optical waveguides 6a and 6b of the optical waveguide substrate 2 is also a corresponding relationship on the input side. It is the same.

  In addition, the fixed blocks 5b and 8b constituting the input side and output side fiber supports 5 and 8 have a length in the fiber extension direction larger than that of the one fixed block 5a and 8a, and the thickness is also shown in the example. The coupling structure of the optical module of the present invention is not limited to this embodiment. What is necessary is just the structure by which the end surface of one component is adhere | attached with respect to each support body 3a, 3b for fiber alignment. For example, if the extension lines of the contact surfaces of the fixed blocks 5b and 8b and the fixed blocks 5a and 8a do not pass through the fiber alignment supports 3a and 3b, the fixed blocks 5b and 8b are fixed to the fixed blocks 5a and 5b. It is not necessary to project from 8a. This is because the end faces of the fixed blocks 5a, 8a on the fiber alignment support 3a, 3b side do not affect the surface adhesion between the fiber support and the fiber alignment support.

Further, the cross-sectional shape of the fiber alignment supports 3a, 3b in the direction orthogonal to the optical waveguide direction is a concave shape, and is bonded and fixed on the optical waveguide support substrate 1 with a space from the optical waveguide substrate 2. An example is shown. In this example, since the fiber alignment supports 3a and 3b are not in direct contact with the optical waveguide substrate 2, the heat capacity of the optical waveguide substrate 2 is not increased. As described above, when light waveguide control is performed by heating with the thin film heater electrodes 7a and 7b, it is preferable to reduce the heat capacity of the optical waveguide substrate 2 in order to increase the control speed. However, although not shown, in the case of a system in which the optical waveguide control is performed by an electric field, the heat capacity is not a problem, so whether or not the fiber alignment supports 3a and 3b are in direct contact with the optical waveguide substrate 2 is also a problem. It will not be made.
[Assembly process example of optical module coupling structure]
Next, an assembly process of the optical module coupling structure shown in FIG. 1 will be described. FIG. 3 illustrates an example of the assembly process of the embodiment. FIG. 3A is a front view of a state in which both ends of the optical waveguide substrate 2 are bonded to the optical waveguide support substrate 1 with adhesives 20a and 20b. The assembly process after FIG.3 (b) is performed using the alignment apparatus which is not shown in figure. Epoxy UV adhesives 21a and 21b are applied to both end surfaces of the optical waveguide support substrate 1 to which the optical waveguide substrate 2 is fixed, and fiber alignment supports 3a and 3b are temporarily fixed thereon. In this state, the surface of the optical waveguide support substrate 1 opposite to the surface to which the optical waveguide substrate 2 is fixed is fixed on a center support base of an alignment device (not shown). In the step of FIG. 3C, alignment between the input side and output side fiber supports 5 and 8 and the optical waveguide substrate 2 is performed. Each of the input side and output side fiber supports 5 and 8 is fixedly supported by an alignment unit base (not shown), and an optical signal is input from the input side optical fiber 4 and output to the output side optical fibers 9a and 9b. Alignment is performed so that the output power is maximized by finely moving the input side and output side fiber supports 5 and 8 on the alignment unit by computer control while observing the power of. The alignment unit base has a total of six degrees of freedom of three axes of X, Y, and Z axes and the respective rotation directions θX, θY, and θZ, and finely moves with submicron resolution. In the process of FIG. 3C, triaxial alignment is performed, and when this process is completed, the position in the fiber extension direction in accordance with the working distance of the optical fiber is determined.

  In the step of FIG. 3D, the positions of the fiber alignment supports 3 a and 3 b with respect to the input side and output side fiber supports 5 and 8 whose positions in the fiber extension direction are fixed are fixed to the optical waveguide support substrate 1. Each of the fiber alignment supports 3a and 3b is fixed to the end faces of the fixed blocks 5b and 8b of the input side and output side fiber supports 5 and 8 that are fixed on the alignment unit and whose positions in the Z-axis direction are determined. Each outer surface of 3b is abutted. Ultraviolet rays 30 are irradiated from a UV irradiation unit (not shown) onto the UV adhesives 21a and 21b that temporarily fix the fiber alignment supports 3a and 3b that have been fixed to the end faces of the fixed blocks 5b and 8b. Then, it is cured and fixed on the optical waveguide support substrate 1. The method of abutting the fiber alignment supports 3a and 3b with the input and output side fiber supports 5 and 8 is originally performed with a human finger. Alternatively, the positions of the fiber alignment supports 3a and 3b may be abutted against the input side and output side fiber supports 5 and 8 by a computer controlled manipulator, respectively. In this step, alignment in the Z-axis direction is completed. Examples of the optical fiber with a lens include a front-end fiber, a lensed fiber having a distributed refractive index type lens welded to the tip of the optical fiber, and a lensed fiber having a GI (graded index) type multimode fiber welded. The working distance is set here. That is, in this step, the distance between the fiber tip 4a and the optical waveguide 6 of the optical waveguide substrate 2 is set to a working distance interval of about 5 μm to 20 μm. When the working distance is zero, the end face of the optical waveguide substrate 2 and the end faces of the input side and output side fiber supports 5 and 8 are fixed tightly.

In the step of FIG. 3E, UV adhesives 31a and 31b are applied to the outer surfaces of the fiber alignment supports 3a and 3b that have been aligned in the fiber extension direction.
In the step of FIG. 3 (f), the input side and output side fiber supports 5 and 8 are brought into contact with the UV adhesives 31a and 31b applied to the outer surfaces of the fiber alignment supports 3a and 3b. In the state, alignment is performed in the same manner as in FIG. In this step, since the alignment in the fiber extension direction is the same as that shown in FIG. 3C, the positions of the two axes of the X axis and the Y axis are adjusted. At the stage where the in-plane adjustment is finished, as shown in FIG. 3G, the adhesives 31a and 31b are irradiated with ultraviolet rays 30 from the UV irradiation unit to complete the optical module coupling structure.

The input side and output side fiber supports 5 and 8 used in FIG. 3C and the input side and output side fiber supports that complete the optical module coupling structure in the process of FIG. The same thing is preferable when performing optical axis alignment. However, for example, a pair of standard input side and output side fiber supports is prepared, and components up to the state where the fiber alignment supports 3a and 3b are fixed to the optical waveguide support substrate 1 shown in FIG. The optical module coupling structure may be completed by integrating and storing arbitrary input and output side fiber supports for the parts.
The completed coupling structure of the optical module is entirely sealed with a can, for example, to become a product of the optical module component. Although the embodiments have been described with reference to an example of a 1 × 2 optical switch, the optical module coupling structure of the present invention is applied to, for example, an n × n optical switch, an optical modulator, an optical transceiver, or the like. Needless to say, it is possible.

FIG. 1A is a perspective view, FIG. 1B is a front view, and FIG. 1C is a plan view showing an embodiment of an optical module coupling structure according to the present invention. Sectional drawing cut | disconnected by the II-II cutting line of FIG.1 (c). FIG. 3A is a front view showing a state in which the optical waveguide substrate 2 is bonded onto the optical waveguide support substrate 1, and FIG. Front view of a state in which epoxy UV adhesives 21a and 21b are applied to both end surfaces of the waveguide support substrate 1 and the fiber alignment supports 3a and 3b are temporarily fixed. FIG. The figure which shows the alignment process between the fiber support bodies 5 and 8 and the optical waveguide board | substrate 2, FIG.3 (d) is the figure which shows the process of fixing the support bodies 3a and 3b for fiber alignment to the optical waveguide support board | substrate 1. FIG. FIG. 3 (e) shows a state in which UV adhesive is applied to the outer surfaces of the fiber alignment supports 3a and 3b, and FIG. 3 (f) shows the input side and output side fiber supports 5. , 8 shows the alignment process, FIG. 3 (g) shows the input side and output side fiber supports 5 and 8 being bonded and fixed. Re is a diagram showing a completed state as coupling structure of optical fibers. The figure which shows the coupling structure of the optical waveguide and optical fiber of the conventional optical module disclosed by patent document 1. FIG.

Claims (6)

An optical waveguide support substrate;
An optical waveguide substrate that is bonded and fixed on the optical waveguide support substrate, and an optical waveguide is formed;
A fiber alignment support that is opposed to both ends of the optical waveguide substrate and protrudes outward from the optical waveguide support substrate and is adhesively fixed on the optical waveguide support substrate;
An input-side fiber support and an output-side fiber support, each of which supports and fixes the end of the optical fiber, and whose outer edge portions are bonded and fixed to the outer surfaces of the respective fiber-alignment supports.
An optical module coupling structure comprising: In the coupling structure of the optical module according to claim 1,
The cross-sectional shape of the fiber alignment support in a direction perpendicular to the optical waveguide direction of the optical waveguide is concave, and the fiber alignment support is separated from the optical waveguide substrate and placed on the optical waveguide support substrate. An optical module coupling structure characterized by being bonded and fixed. In the coupling structure of the optical module according to claim 1 or 2,
An optical module coupling structure, wherein the optical waveguide substrate and the fiber alignment support are protruded in the optical waveguide direction and bonded and fixed to the optical waveguide support substrate. In the coupling structure of the optical module according to claim 2 or 3,
An optical module coupling structure, wherein an end of the optical fiber protrudes from an end surface of the input side and output side fiber support bonded to the fiber alignment support. The optical module coupling structure according to any one of claims 1 to 4,
The input side and output side fiber supports have a structure in which an end portion of an optical fiber is sandwiched between two fixed blocks, and one end face of the two fixed blocks is on an outer surface of the fiber alignment support. An optical module coupling structure characterized by being bonded and fixed. Adhering and fixing the optical waveguide substrate on which the optical waveguide is formed on the optical waveguide support substrate;
The optical waveguide than both end faces of the supporting substrate and the input side fiber support outside the output side fiber support in the light guiding direction of the optical waveguide is position, respectively it, the input-side fiber support and the output side fiber support Aligning the optical fiber fixedly supported by the optical waveguide and the optical waveguide ,
The end face of the centering input side fiber support and the output side fiber support, butt fibers alignment support of the input side and the output side of fiber alignment support for one another the outer surface, respectively a step of bonding fixed to the optical waveguide support substrate on the output side fiber alignment support of the support fiber alignment of the input side Te,
On the outer surfaces of the input side fiber alignment support and the output side fiber alignment support fixed to each other, the end faces of the input side fiber support and the output side fiber support are respectively Adhering and fixing the outer edge,
For assembling a coupling structure of an optical module.

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