JP2004212686A - Method for mounting optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for precisely storing an optical fiber in a V groove of a substrate to reduce coupling loss between an optical waveguide and the optical fiber by aligning the core of an optical waveguide with the center of the optical fiber. <P>SOLUTION: In the method for mounting the optical fiber, a plurality of optical fibers and adhesives are arranged in a plurality of parallel V grooves on the substrate, a presser is mounted on the optical fibers, and a pressure member is pressed against the top surface of the presser to bond and fix them. Here, the width when the area where the pressure member comes into contact with the presser is projected along the length of the optical fibers is smaller than the center distance of optical fibers at both ends. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for mounting a plurality of optical fibers in a plurality of V-grooves on a substrate.
[0002]
[Prior art]
In the production of an optical element using an optical fiber, it is necessary to accurately connect a plurality of optical fibers to a plurality of optical waveguides. That is, in order to reduce the coupling loss between the optical waveguide and the optical fiber by aligning the core of the optical waveguide with the center of the optical fiber, it is necessary to accurately store a plurality of optical fibers in the V-groove of the substrate. is there.
Conventionally, as a method of fixing a plurality of optical fibers in a V-groove on a substrate, as shown in FIG. 6, an optical fiber and an adhesive are arranged in the V-groove, and a glass block or the like is pressed on the optical fiber. This is performed by placing the tool and pressing the upper surface of the holding tool with a pressing member such as a glass rod larger than the area of the upper surface of the holding tool. However, in such a method, a gap is generated between the optical fiber and the substrate, causing an axis shift between the core of the optical waveguide and the center of the optical fiber.On the other hand, if the force is forced to close the gap, the holding member is damaged. There was a problem.
As a method of accurately storing the optical fiber in the V-groove, for example, a method in which a pressing plate is polished in advance to obtain a flat surface finish, and a protrusion is provided on the pressing plate (for example, see Patent Document 1), There has been reported a method of pressing the rubber through an elastic body or a wear-resistant smooth film layer (for example, see Patent Documents 2 and 3).
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 9-138311 [Patent Document 2]
JP 2001-33660 A [Patent Document 3]
JP-A-5-307116
[Problems to be solved by the invention]
The present invention provides a method for accurately accommodating an optical fiber in a V-groove of a substrate in order to reduce the coupling loss between the optical waveguide and the optical fiber by aligning the core of the optical waveguide with the center of the optical fiber. Aim.
Another object of the present invention is to provide a method for accurately accommodating an optical fiber in a V-groove of a substrate by a method simpler than a conventional method.
[0005]
[Means for Solving the Problems]
The object is to dispose a plurality of optical fibers and an adhesive in a plurality of parallel V-grooves on a substrate, place a holding member on the optical fiber, and press the upper surface of the holding member with a pressing member. In the optical fiber mounting method of bonding and fixing, the width of the pressing member when the region in contact with the holding member is projected in the longitudinal direction of the optical fiber is smaller than the distance between the centers of the optical fibers at both ends. Is solved by the following mounting method.
Further, in the above method, the region where the pressing member contacts the holding member is preferably located inside each center position of the optical fibers at both ends, and further, the region where the pressing member contacts the holding member. Is preferably equidistant from the respective center positions of the optical fibers at both ends.
Further, in the above method, a width of a region where the pressing member is in contact with the holding member when projected in a longitudinal direction of the optical fiber is 50% or less of a center-to-center distance of the optical fibers at both ends. Is preferred.
In the above method, it is preferable that the holding member is made of a light-transmitting material, and the light-transmitting material is preferably selected from the group consisting of glass and plastic.
Further, it is preferable that the pressure member is made of a material selected from the group consisting of metal, wood, glass, and plastic.
[0006]
In the optical fiber mounted product obtained by the above method, the optical fiber is accurately stored in the V groove without a gap between the V groove and the optical fiber. When this optical fiber is connected to the optical waveguide, the center of the core of the optical waveguide and the center of the optical fiber are accurately aligned, and the coupling loss can be reduced to about 0.4 dB. Further, the method of the present invention does not require the use of a complicated device or a specially processed instrument, and thus has an advantage that it can be performed at a low cost with a simple device as compared with the conventional method.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
In the method of the present invention, a plurality of optical fibers and an adhesive are arranged in a plurality of parallel V grooves on a substrate, a holding member is placed on the optical fiber, and an upper surface of the holding member is pressed with a pressing member. In the optical fiber mounting method of pressing and bonding, the width in which the region where the pressing member is in contact with the holding member is projected in the longitudinal direction of the optical fiber is smaller than the distance between the centers of the optical fibers at both ends. This is a mounting method characterized by the following.
[0008]
An embodiment of the method of the present invention will be described with reference to the drawings.
1 and 2 are schematic views showing a method for mounting the optical fiber of the present invention. FIG. 1 is a perspective view, and FIG. 2 is a sectional view taken along line II ′ of FIG. A large number of parallel V-grooves 2 are provided on a substrate 1 at predetermined intervals. In this embodiment, an optical waveguide 10 connected to each optical fiber 4 on the V-groove 2 is also provided on the substrate 1 in advance. The adhesive 3 and the optical fiber 4 are placed on the V-groove 2, the holding member 5 is placed on the optical fiber 4, and the pressing member 6 is pressed from above the holding member 5 by the pressing member 6 having a truncated cone-shaped tip.
[0009]
In the present invention, the size of the holding member on the optical fiber may be any as long as it has a width capable of holding at least all the optical fibers. That is, it is preferable to have a width of at least the distance between the centers of the optical fibers at both ends. The width may be longer than the distance between the centers of the two optical fibers at both ends. However, if the width is extremely long, the holding member may be inclined, which is not preferable.
In the present invention, a groove for fixing the optical fiber may be provided on the surface of the holding member that contacts the optical fiber. The shape of the groove may be a concave shape following the shape of the fiber (see FIG. 3) or a V-groove shape (see FIG. 4). The upper surface of the holding member may have any shape as long as it can be pressed by the pressing member, and is, for example, a flat surface.
[0010]
Here, the material constituting the holding member in the present invention may be any material having a certain degree of rigidity, and examples thereof include glass and metal. When a light-curing adhesive such as a UV-curable adhesive is used as the adhesive, it is preferable that the adhesive be made of a light-transmitting material such as glass or acrylic resin.
[0011]
The tip shape of the pressing member may be any shape as long as the width of the region where the pressing member contacts the holding member in the longitudinal direction of the optical fiber is smaller than the distance between the centers of the optical fibers at both ends. For example, various shapes such as a truncated conical shape, a conical shape, a spherical shape, and a cylindrical shape are exemplified, but the shape is not limited thereto. "The width of the region where the pressing member contacts the holding member when projected in the longitudinal direction of the optical fiber" is when the portion where the pressing member is in contact with the holding member is observed from the longitudinal direction of the optical fiber. , For example, the width indicated by “a” in FIG. The smaller the width of the area where the pressure member contacts the holding member when projected in the longitudinal direction of the optical fiber, the easier it is to maintain the balance of the moment to the holding member, so that the inclination of the holding member can be suppressed. As a result, the optical fiber can be stored in the V-groove without any gap, which is preferable. Specifically, it is preferable that the width of the region in which the pressing member contacts the pressing member when projected in the longitudinal direction of the optical fiber is 50% or less of the distance between the centers of the optical fibers at both ends, It is more preferably at most 20%.
[0012]
The width of the region where the pressing member is in contact with the holding member when projected in the lateral direction of the optical fiber is generally set to the width of the holding member (from the lateral direction of the optical fiber) in order to suppress the inclination of the holding member in the longitudinal direction of the optical fiber. It is preferably smaller than the width.
[0013]
The pressing member is preferably made of a material having a certain degree of rigidity. However, even if the pressing member is slightly deformed by pressing, the longitudinal direction of the optical fiber in the area where the pressing member and the pressing member finally come into contact with each other is preferable. It is only necessary that the width when projected onto is within the range described above. Specifically, a material selected from the group consisting of metal, wood, glass, and plastic can be used.
[0014]
It is preferable that the region where the pressing member contacts the holding member is located inside the center of each of the optical fibers at both ends. “Each center position of the optical fibers at both ends” means the position of the center line of each of the two outermost optical fibers. If the optical fibers are located outside the center positions of the optical fibers at both ends, the holding member is inclined to form a gap with the optical fiber, and as a result, a gap is easily generated between the optical fiber and the V-groove. Therefore, it is preferable that all the regions where the pressing member comes into contact with the holding member be inside the respective center positions of the optical fibers at both ends.
Further, it is preferable that the region where the pressing member contacts the holding member is a position closer to the center position between the optical fibers at both ends. More specifically, the position of the center of gravity of the region where the pressing member contacts the holding member is preferably closer to the center position between the optical fibers at both ends, and is equidistant from the center position of the optical fibers at both ends (between the optical fibers at both ends). Is most preferable. Here, “the center of gravity of the region where the pressing member comes into contact with the presser” means a centroid at which the first moment of area becomes zero in a shape determined by the region where the presser member comes into contact with the presser.
[0015]
The pressurizing method may be any method, but in one embodiment of the present invention, pressurization is performed by a weight. In addition, there is a method of applying pressure using a spring.
[0016]
[Example]
Example 1
Eight optical fibers having a diameter of 125 μm are mounted on a substrate (1.5 mm × 2.3 mm) having eight V grooves (140 μm in width × 100 μm in depth) similar to that shown in FIG. The agent was applied. At this time, the distance between the centers of the optical fibers at both ends was 1.75 mm. A glass having a size of 1 mm × 3 mm × 1.0 mm thick and provided with a round groove (200 μm wide × 50 μm deep) on the contact surface with the optical fiber so as to correspond to the eight V grooves of the substrate. A plate (holding tool) was placed. At a substantially central position (1.5 mm from each end) of the glass plate, a wooden cylindrical pressure member (50 mm in length × diameter) having a truncated cone shape (tip: a circle having a radius of 0.6 mm) is used. Irradiation with UV light was performed while applying a pressure of 163 g with a pressure of 1 mm). After bonding, the optical fiber and the substrate were cut vertically from the glass plate in the depth direction, and the state of fixing the optical fiber was observed (FIG. 3). As is clear from FIG. 3, the optical fiber was fixed in the V groove without any gap.
[0017]
Example 2
The optical fiber was mounted in the same manner as in Example 1 except that a cylindrical pressure member (length: 50 mm × diameter: 3 mm) having a conical metal tip was used. After bonding, the optical fiber and the substrate were cut from the glass plate in the depth direction, and the state of fixing of the optical fiber was observed. As in Example 1, the optical fiber was disposed in the V-groove without any gap, and was bonded and fixed. I was
[0018]
Examples 3 and 4
Adhesion and fixing were performed in the same manner as in Example 1 except that the glass plate (pressing tool) provided with a V-groove (160 μm width × 80 μm depth) in Example 1 was used (Example 3). Further, adhesive fixing was performed in the same manner as in Example 3 except that the weight was further changed to 214 g in Example 3 (Example 4). After bonding, the optical fiber and the substrate were cut from the glass plate in the depth direction, and the state of fixation of the optical fiber was observed. It was placed and adhesively fixed (FIGS. 4A and 4B). Further, the optical waveguide prepared in Example 4 was cut on the optical waveguide side (at a position corresponding to BB ′ in FIG. 1), and the direction of the optical fiber was observed from the optical waveguide side. Were observed to coincide well with each other (FIG. 5).
[0019]
Comparative Example 1
Adhesion and fixing were performed in the same manner as in Example 1 except that a cylindrical glass rod having a diameter of 3.5 mm and a length of 50 mm was used as a pressing member (Comparative Example 1). Was observed (FIG. 7).
[0020]
【The invention's effect】
In the conventional method, a gap is formed between the V-groove and the optical fiber, and the axis of the optical fiber is shifted. On the other hand, when the optical fiber is bonded and fixed by the method of the present invention, the optical fiber remains in the V-groove without a gap. The optical waveguide can be fixed with high accuracy, and the coupling loss between the optical waveguide and the optical fiber can be reduced.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a method for mounting an optical fiber of the present invention.
FIG. 2 is a sectional view taken along the line II ′ of FIG. 1;
FIG. 3 is a cross-sectional view of an optical fiber mounted in a V-groove according to the method of the present invention using a glass block having a round groove on the back surface (load: 163 g).
FIG. 4A is a cross-sectional view (cross-sectional view taken along the line AA ′ of FIG. 1) of an optical fiber mounted in a V-groove by a method of the present invention using a glass block having a V-groove on the back surface (weight 163 g). .
FIG. 4B is a cross-sectional view (cross-sectional view taken along the line AA ′ in FIG. 1) of the optical fiber mounted in the V-groove by the method of the present invention using the glass block having the V-groove on the back surface (weight: 214 g). .
FIG. 5 is a view showing a center of an optical fiber and an optical waveguide mounted in a V-groove by a method of the present invention using a glass block having a V-groove on the back surface (a cross-sectional view taken along the line BB ′ in FIG. 1). is there.
FIG. 6 is a schematic view showing a conventional method.
FIG. 7 is a cross-sectional view of an optical fiber mounted in a V-groove by a conventional method (with a weight of 163 g).
[Explanation of symbols]
1: silicon substrate, 2: V groove, 3: adhesive, 4: optical fiber, 5: holding member, 6: pressing member, 10: optical waveguide, 11: core, a: pressing member contacts the holding member. Width of optical fiber when projected in the longitudinal direction

Claims (7)

A plurality of optical fibers and an adhesive are arranged in a plurality of parallel V-grooves on a substrate, a holding member is placed on the optical fiber, and an upper surface of the holding member is pressed and bonded with a pressing member to be fixed. In the method for mounting an optical fiber, the width of the pressing member in contact with the holding member when projected in the longitudinal direction of the optical fiber is smaller than the center-to-center distance of the optical fibers at both ends, Implementation method. The method according to claim 1, wherein a region where the pressing member contacts the holding member is inside each center position of the optical fibers at both ends. 3. The width according to claim 1, wherein a width of a region where the pressing member contacts the holding member in a longitudinal direction of the optical fiber is 50% or less of a distance between centers of the optical fibers at both ends. 4. The described method. The method according to any one of claims 1 to 3, wherein a center of gravity of a region where the pressing member contacts the holding member is equidistant from respective center positions of the optical fibers at both ends. The method according to claim 1, wherein the retainer is made of a light transmissive material. The method according to any one of claims 1 to 5, wherein the light transmitting material is selected from the group consisting of glass and plastic. The method according to any one of claims 1 to 6, wherein the pressing member is made of a material selected from the group consisting of metal, wood, glass, and plastic.

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