JPH11223742A - Optical fiber connector and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] To provide a method of manufacturing an optical fiber connector having good temperature characteristics at a low temperature. SOLUTION: The coating of the optical fiber tip is removed, the bare optical fiber 3a is exposed, aligned in a V-groove of a substrate 1, pressed by a first pressing member 2, and rearwardly pressed by a second pressing member. The member 8 is arranged (A). The adhesive 4 is poured from the adhesive inlet 8a (B). An optimal adhesive layer is formed by the pressing member 8. In the step (C) of curing the adhesive, the pressing member 8 can be easily peeled off and removed by the shrinkage generated at the time of curing. Therefore, the adhesive 4
At the time of shrinkage, the occurrence of peeling and cracks can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber connector to which an optical fiber is fixed, which is used for connecting an optical fiber to an optical device such as an optical waveguide, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Japanese Patent No. 2557164 discloses a method of coating a coated optical fiber using a substrate having a V-groove at the front and a coating mounting portion formed with a step from the V-groove at the rear. The bare optical fiber that has been removed and exposed is aligned with the V-groove, the coated portion is placed on the coating mounting portion, the bare optical fiber is pressed against the V-groove by a pressing member, and the optical fiber is fixed with an adhesive. A fiber connector is described. The step of the coating mounting portion is about の of the diameter of the coating portion of the optical fiber, and the optical fiber is positioned at the center of the V-groove when the optical fiber is mounted on the coating mounting portion. ing.

FIG. 5 is a view for explaining such an optical fiber connector. FIG. 5 (A) is a perspective view before an optical fiber is arranged, and FIG. 5 (B) is a state in which the optical fiber is gripped. FIG. 5 (C) is a longitudinal sectional view through the center of the optical fiber. In the figure, 1 is a substrate, 1a is a V-groove, 1b is a coating mounting portion, 2 is a pressing member, 3 is a coated optical fiber, 3a is a bare optical fiber, 3b is a coating portion, and 4 is an adhesive. In FIG. 5B, illustration of the adhesive is omitted.

As shown in FIG. 5A, a V-groove 1a is formed on the upper surface in front of the substrate 1, and a coating mounting portion 1b is formed with a step behind it. The bare optical fiber 3a exposed by removing the coating of the coated optical fiber 3 is arranged in the V-groove 1a, and as shown in FIG. 5B, the V-groove 1a is pressed by the pressing member 2 from above. And pressing member 2
The adhesive 4 is applied to the periphery of the bare optical fiber 3a and the periphery of the optical fiber placed on the coating placing part 1b, thereby fixing the optical fiber 3. For example, the outer diameter of the bare optical fiber 3a is 125 μm, and the outer diameter of the coating 3b is 250 μm.
μm. Bare optical fiber 3 placed in V-groove 1a
The step between the center of a and the upper surface of the coating placing portion 1b is 125 μm.
From the bare optical fiber 3a placed in the V-groove 1a to the covering portion 3b, in the optical fiber connector,
As shown in FIG. 5C, the center of the optical fiber is positioned so as to be substantially straight. Note that the end face of the front end is polished for connection with a waveguide or the like. Normally, it is polished at an angle of 8 ° to reduce reflected return light.

An example of connection between an optical fiber connector and a waveguide will be described. FIG. 6 is a view for explaining an example of a use state of the optical fiber connector.
6A is a side view, and FIG. 6B is a plan view. In addition, in order to make it easy to see the inside, it is illustrated by thin lines. In the figure, 11,
11 'is an optical fiber connector, 12 and 12' are eight core optical fiber ribbons, 13 is a waveguide chip, and 14 is a waveguide. Both end surfaces of the waveguide chip 13 are polished at an inclination angle of 8 °, are aligned from both sides, and the optical fiber connectors 11 and 11 ′ are bonded. The waveguide chip 13 includes:
Four sets of couplers are formed by the waveguide 14, and 8 couplers on both sides are formed.
Optical ports 11 on each side
11 'is coupled to the tape-shaped optical fiber core wires 12 and 12', and performs multiplexing and demultiplexing.

Referring back to FIG. As shown in FIG. 5C, in the state where each member of the optical fiber connector and the optical fiber are fixed with an adhesive, it has been described that the center of the optical fiber is substantially linear. The adhesive shrinks when cured. In addition, when the ambient temperature changes, the adhesive expands and contracts. Such a change in the volume of the adhesive causes deformation of each component of the optical fiber connector, applies stress to the optical fiber, and deteriorates the temperature characteristics of a device such as an optical waveguide to which the optical fiber connector is connected. As shown in FIGS. 5 (B) and 5 (C), the step portion of the coating placing portion and the rear end surface of the pressing member 2 substantially match, so that the adhesive 4 is applied along the rear end surface of the pressing member 2. And the amount of adhesive at the rear of the V-groove increases.

FIG. 7 is a schematic diagram showing how the optical fiber connector is deformed at low and high temperatures. At a low temperature, the adhesive 4 contracts, and as shown in FIG.
A local stress is applied to the bare optical fiber 3a at a portion A which is a rear corner of the bare optical fiber 3a. Also, at high temperatures, FIG.
As shown in (B), at the B portion which is the corner of the V groove,
Local stress is applied to the bare optical fiber 3a. Such stress increases as the amount of adhesive behind the V-groove increases. According to the model calculation, when there is a temperature change from room temperature to 60 ° C., a stress of about 2 kg / mm ² is applied to the bare optical fiber 3a in the part A or the part B. Actually, due to the general properties of the adhesive, the Young's modulus increases as the temperature decreases, so the stress generated between the low temperature and the high temperature is smaller than that of the bare optical fiber when the Young's modulus is large. The applied stress increases. Further, since shrinkage due to curing of the adhesive is always involved, it is important to reduce the stress applied to the portion A.

To solve this problem, an attempt was made to fix the second pressing member as shown in FIG. 8 in order to make the amount of adhesive behind the pressing member appropriate. FIG.
FIG. 8A is a perspective view showing a state where an optical fiber is gripped, and FIG.
FIG. 8B is a perspective view of the second pressing member, FIG. 8C is a longitudinal sectional view centering on the optical fiber, and FIG. 8D is an explanatory view in which main parts are enlarged. In the figure, the same parts as those in FIG. 4a is peeling, 4b is a crack, and 8 is a pressing member. The second pressing member 8 is arranged behind the pressing member 2. As shown in FIG. 8C, the pressing member 8 can suppress the adhesive from crawling up on the rear surface of the pressing member 2 and limit the amount of the adhesive behind the pressing member 2. it can.

[0009] However, this method has also been found to have problems. The adhesive 4 shrinks during curing, and the shrinkage stress exceeds the adhesive strength at the interface of the adhesive.
As shown in (D), it was found that there was peeling 4a at the interface of the adhesive and cracks 4b occurred inside the adhesive. Peeling 4a at the adhesive interface and crack 4 inside the adhesive
The occurrence of b may cause a local stress on the optical fiber to cause an increase in loss or break the optical fiber. Therefore, there is a problem in the method of using the second pressing member to limit the amount of the adhesive.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an optical fiber connector having good temperature characteristics, particularly at low temperatures, and a method of manufacturing the same. Is what you do.

[0011]

According to the first aspect of the present invention, an optical fiber is arranged on a substrate having a V-groove at the front and a coating mounting portion at the rear, and the optical fibers arranged in the V-groove. Is pressed by a first pressing member, and the optical fiber, the substrate, and the first pressing member are fixed by an adhesive. A member is provided, the adhesive is applied and cured, and the second pressing member is removed in a curing process.

According to a second aspect of the present invention, in the method of manufacturing an optical fiber connector according to the first aspect, at least a surface of the second pressing member that contacts the adhesive is made of Teflon. Is what you do.

According to a third aspect of the present invention, in the optical fiber connector, the optical fiber connector is manufactured by the method for manufacturing an optical fiber connector according to the first aspect.

[0014]

FIG. 1 is a perspective view of a main part of an optical fiber connector used in a method of manufacturing an optical fiber connector according to the present invention before assembling. 5 and 8 in the figures.
The same parts as those described above are denoted by the same reference numerals and description thereof will be omitted. 8
a is an adhesive injection port. In this embodiment, an adhesive injection port 8 a is provided in a part of the pressing member 8. Although the adhesive injection port 8a is not always necessary, it is effective to provide the adhesive injection port 8a when applying the adhesive with the pressing member 8 arranged at a predetermined position. . Note that the position and number of the adhesive injection port 8a may be arbitrary. Substrate 1
Has one or a plurality of V-grooves 1a formed in the front, and is provided with a coating mounting portion 1b with a step. The length of the pressing member 2 is made substantially equal to the length of the V-groove 1a.
Although the rear end surface of the pressing member 2 is substantially flush with the rear end surface of the pressing member 2, the rear end surface of the pressing member 2 may be slightly back and forth with respect to the rear end surface of the V-groove 1 a. The pitch of the V-grooves 1a is formed so as to be substantially equal to the pitch of the aligned bare optical fibers 3a. The shape of the V-groove is selected such that when the bare optical fiber 3a is arranged in contact with both side surfaces of the V-groove 1a, the top of the bare optical fiber protrudes from the V-groove forming surface. In a specific example, the protrusion amount is about 20 μm.

Although the manufacturing process will be described with reference to specific examples, the present invention is not limited to the numerical values of the specific examples. The case where an optical fiber having an outer diameter of 125 μm and a coating outer diameter of 250 μm of a bare optical fiber is used will be described as an example.

FIG. 2 is a longitudinal sectional view through the center of the optical fiber for explaining the manufacturing process. In the drawings, the same parts as those in FIGS. 1, 5, and 8 are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 2A shows a state in which the substrate 1 holds an optical fiber. The substrate 1 is formed by forming one or a plurality of V grooves on a silicon substrate. The V-groove can be easily and accurately produced by processing with a dicer. The coating of one or a plurality of single-core coated optical fibers is removed to expose the bare optical fiber 3a, align it in the V-groove, and press the bare optical fiber 3a with the pressing member 2 made of quartz glass.
, And the second pressing member 8 behind the first pressing member 2.
Place.

FIG. 2B shows an adhesive injection step.
The adhesive 4 is poured from the adhesive injection port 8a and applied to the gap between the substrate 1, the pressing member 2, and the bare optical fiber 3a.
Cover mounting portion 1b formed as a step portion behind substrate 1
, The second pressing member 8 and the covering portion 3 following the bare optical fiber 3a
b. The height of the inner surface of the pressing member 8 is preferably set so that an optimum adhesive layer is formed so that the stress at the rear end of the V-groove does not increase.

FIG. 2C shows a curing step. The applied adhesive 4 is cured. When an ultraviolet-curable adhesive is used as the adhesive 4, ultraviolet rays are irradiated in the curing step.

FIG. 2D shows a step of removing the second pressing member. It is desirable that the surface of the pressing member 8 to which the adhesive 4 is applied is made of a material that is not easily bonded. Due to the shrinkage generated when the adhesive 4 is cured, the pressing member 8 can be easily peeled off and removed. Therefore, when the adhesive 4 contracts, the pressing member 8 is not adhered to the adhesive 4 with a large adhesive force, and the adhesive 4 does not have peeling or cracks as described with reference to FIG. . Even if the curing proceeds further, no problem occurs because the pressing member 8 has already been removed. The pressing member 8 may be removed from the adhesive if the applied adhesive does not sag even if the pressing member 8 is removed in the process of hardening the adhesive 4. You may remove it so that it may peel off.

As described above, the material of the pressing member 8 may be provided with a layer of a material that is hardly adhered to at least the surface in contact with the adhesive, or the entire pressing member may be made of a material that is hardly adhered. Further, a coating layer, such as grease, which is not easily adhered to the adhesive may be provided. Teflon is suitable as a material that is difficult to adhere.

The optical fiber gripped by the optical fiber connector is not limited to a single-core optical fiber as described above, but may be a tape-like optical fiber in which a plurality of optical fibers are arranged in parallel to form a common coating. Optical fibers can also be used.

The front end of the substrate 1 to which each member and the optical fiber are fixed by the adhesive 4 is polished together with the front surface of the pressing member 2 to connect to a waveguide or the like. Normally, it is polished at an angle of 8 ° to reduce reflected return light.

FIG. 3 shows an example of the mode of use of the optical fiber connector thus manufactured. In the figure, 5, 5 '
Is an optical fiber connector, 6, 6 'are tape-shaped optical fibers, and 7 is a waveguide chip. Optical fiber tape 6,
6 'uses an eight-core tape-shaped optical fiber in this example. The waveguide chip 7 was a 1 × 8 branch waveguide. Light is input from one optical fiber of the tape-shaped optical fiber 6, light passing through the branch waveguide of the waveguide chip 7 is received by the eight-core optical fiber connector 5 ', and the optical axes of the waveguide and the optical fiber are aligned. Adjust and align for maximum power. After the alignment, an adhesive having a matched refractive index is poured into the connection between the waveguide chip 7 and the optical fiber connectors 5 and 5 ', and the mixture is cured and fixed, whereby a waveguide module can be manufactured.

FIG. 4 shows the temperature characteristics of the waveguide module manufactured as described above. The figure also shows, as a comparative example, the results of a waveguide module manufactured with an optical fiber connector having a conventional structure. The optical fiber connector having the conventional structure is made of silicon as the second pressing member, and is fixed after the adhesive is cured. This is the average value of the eight cores of the loss fluctuation when the temperature is changed. In a waveguide module using an optical fiber connector having a conventional structure, stress is generated due to shrinkage of an adhesive, particularly at a low temperature, and a loss variation of 0.3 to 0.4 dB is observed. Then
Loss variation has been reduced to about 0.1 dB. At a high temperature, a large increase in loss does not occur because the amount of the adhesive is small and the Young's modulus of the adhesive is low.

As the material of the substrate, in addition to the above-mentioned silicon, any suitable material such as glass, molded resin, ceramic, etc. can be used as long as it can process the V-groove. When silicon is used, the substrate may be manufactured by wet etching with KOH or the like. However, the material of the substrate is desirably a material having an expansion coefficient close to that of glass, which is a material of the optical fiber. The same applies to the material of the pressing member. However, when an ultraviolet-curable adhesive is used, it is desirable that the pressing member be transparent to ultraviolet light. As the waveguide, a polymer waveguide, a semiconductor waveguide, or the like may be applied in addition to the quartz-based waveguide.

As the adhesive for fixing the optical fiber, the pressing member, and the like to the substrate, an ultraviolet-curing adhesive that can be quickly cured, a thermosetting adhesive, a hot melt, or the like can be used. Given the stress on the optical fiber,
It is preferable that the Young's modulus, expansion coefficient, and cure shrinkage ratio are as small as possible. The adhesive used for connection with the waveguide is preferably an ultraviolet curable adhesive in which the refractive index of the waveguide and the optical fiber are matched, but a thermosetting adhesive can also be used.

[0028]

As apparent from the above description, according to the present invention, the amount of the adhesive applied can be reduced by disposing the second pressing member behind the pressing member for pressing the bare optical fiber on the V-groove. Thus, the stress on the optical fiber caused by the expansion and contraction of the adhesive can be reduced, and an optical fiber connector having good temperature characteristics can be provided. Further, since the second pressing member is removed in the curing process of the adhesive, the peeling of the adhesive and the occurrence of cracks can be prevented, and the loss of the optical fiber can be prevented from being broken.

[Brief description of the drawings]

FIG. 1 is a perspective view of main components of an optical fiber connector used in a method of manufacturing an optical fiber connector according to the present invention before assembly.

FIG. 2 is a longitudinal sectional view centered on an optical fiber for explaining a manufacturing process.

FIG. 3 is an explanatory diagram of an example of a mode of use of the optical fiber connector of the present invention.

FIG. 4 is a diagram showing temperature characteristics of the waveguide module of FIG. 3;

5A and 5B are views for explaining a conventional optical fiber connector, and FIG. 5A is a perspective view before an optical fiber is arranged;
(B) is a perspective view of a state in which the optical fiber is gripped, and (C) is a longitudinal sectional view centered on the optical fiber.

FIGS. 6A and 6B are diagrams for explaining an example of a use state of the optical fiber connector, where FIG. 6A is a side view and FIG. 6B is a plan view.

FIG. 7 is a schematic diagram showing a state of deformation of the optical fiber connector at low and high temperatures.

8A and 8B are views for explaining an example of an optical fiber connector using a second pressing member. FIG. 8A is a perspective view of a state where an optical fiber is gripped, and FIG. FIG. 8 (C) is a perspective view of the pressing member, FIG. 8 (C) is a longitudinal sectional view through the center of the optical fiber, and FIG. 8 (D) is an enlarged explanatory view of a main part.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 1a ... V groove, 1b ... Coating mounting part, 2 ... Pressing member, 3 ... Coated optical fiber, 3a ... Bare fiber, 3b ... Coated part, 4 ... Adhesive, 4a ... Peeling, 4b ... Crack, 5,
5 ': optical fiber connector, 6, 6': tape-shaped optical fiber, 7: waveguide chip, 8: pressing member, 8a: adhesive inlet.

Claims (3)

[Claims] An optical fiber is arranged on a substrate having a V-groove in the front and a coating mounting portion in the rear, and the optical fibers arranged in the V-groove are pressed by a first pressing member, and In the method for manufacturing an optical fiber connector in which the substrate and the first pressing member are fixed by an adhesive, a second pressing member is disposed behind the first pressing member, and the adhesive is applied. Curing, and in the curing process, the second
A method for manufacturing an optical fiber connector, comprising: removing the pressing member. 2. The method for manufacturing an optical fiber connector according to claim 1, wherein at least a surface of said second pressing member which is in contact with the adhesive is made of Teflon. 3. An optical fiber connector manufactured by the method for manufacturing an optical fiber connector according to claim 1.