JP2003215392A - Optical fiber array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber array which is robust against the tensile load of optical fibers and reduces increase of the transmission loss in the case of the temperature change. <P>SOLUTION: With respect to the optical fiber array wherein single or multiple optical fibers 1 are placed on an array substrate 5 provided with V grooves 7 in the front part and bare fibers 3 having the coatings removed are put in the V grooves 7 and are retained by a retaining member 6 and are fixed by adhesion, bare fiber parts 3a of the front parts are fixed in the V grooves 7 by a first adhesive which has ≥500 MPa Young's modulus of elasticity after being cured and has ≤10 Pa.s viscosity before being cured, and coating parts 2 of the optical fibers 1 are fixed in the rear end part of the array substrate by a second adhesive 12 which has a viscosity higher than that of the first adhesive before being cured, and bare fiber parts having coating removed, between the rear ends of the V grooves 7 and the coating parts 2 are covered with and fixed by a third adhesive 13 which has a Young's modulus of elasticity lower than that of the first adhesive after being cured. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber array in which a single-core or multi-core optical fiber is attached and fixed to a substrate used for connection with an optical component or a planar waveguide.

[0002]

2. Description of the Related Art In an optical fiber communication system, an optical fiber array is used to connect an optical fiber to an optical component, a planar waveguide or the like. The optical fiber array usually includes an array substrate provided with a V-groove for positioning a single-core or multi-core optical fiber end portion, and also includes a holding member for holding the optical fiber in the V-groove. In the optical fiber array, after the optical fibers are inserted and fixed, the optical fibers are attached and fixed using an adhesive or the like, and the front end portion where the end faces of the optical fibers are exposed is polished together with the optical fibers.

FIG. 4 shows, for example, Japanese Patent Laid-Open No. 11-84164.
It is a figure which shows an example of the conventional optical fiber array disclosed by the publication. In the figure, 1 is an optical fiber, 2 is a fiber coating, 3 is a bare fiber, 4 is an optical fiber array, 5 is an array substrate, 6 is a holding member, 7 is a V groove, and 8 and 9 are adhesives.

As the optical fiber 1, a single-core optical fiber or an optical fiber tape in which a plurality of single-core optical fiber strands are collectively coated is used. The optical fiber array 4 comprises an array substrate 5 and a pressing member 6, and the front portion of the array substrate 5 is V-shaped.
The fiber alignment portion 5a provided with the groove 7 and the rear portion are formed by the pedestal portion 5b. The adhesive 8 is poured into the V-groove 7 of the fiber alignment portion 5a, the front portion of the bare fiber 3 with the coating removed is inserted into the V-groove 7, and is pressed and fixed by the holding member 6 to be bonded and fixed. .

A part of the adhesive 8 in the V groove covers the rear end portion of the bare fiber 3 protruding from the rear end of the V groove so as to flow out onto the pedestal portion 5b. Further, a part of the adhesive 8 is partially covered with the fiber coating 2
And the pedestal portion 5b, and the rear portion of the bare fiber 3 and the front end portion of the fiber coating 2 are bonded and fixed onto the pedestal portion 5b. Further, in order to regulate the free movement of the optical fiber 1 at the rear end of the optical fiber array 4, the front end of the fiber coating 2 is adhesively fixed by using an adhesive 9 which is softer than the adhesive 8. There is.

[0006] With the above structure, it is known that if a resin having a relatively large Young's modulus (hard) is used as the adhesive 8 that covers the entire bare fiber 3, the loss of the optical fiber increases at low temperatures. . It is considered that the cause of this is that the optical fiber is pulled to the array substrate side due to thermal contraction of the adhesive resin at low temperature. The adhesive 9 applied to the fiber coating 2 is a resin softer than the adhesive 8. Since the adhesive 8 is not applied to the portion of the fiber coating 2 so much, the tensile load is applied to the portion of the bare fiber 3 from which the coating is removed, which is weak against the tensile load, and the optical fiber When a tensile load is applied in the longitudinal direction of 1, the bare fiber 3 is easily broken.

An adhesive 8 for covering the entire bare fiber 3 is also provided.
When a resin having a relatively small Young's modulus (soft) is used, even if it is combined with the adhesive 9,
It becomes weak overall. That is, as shown in FIG. 4, in the configuration in which the optical fiber 1 is adhesively fixed to the optical fiber array 4 with two or less kinds of adhesive resins, increase in transmission loss due to temperature change should be suppressed and satisfying a predetermined tensile load. It is difficult.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and is an optical fiber array that is strong against a tensile load of an optical fiber and can suppress an increase in transmission loss with respect to a temperature change. The challenge is to provide.

[0009]

The optical fiber array of the present invention is a bare fiber in which a single-core or multi-core optical fiber is placed on an array substrate having a V groove in the front portion and the coating is removed from the V groove. Is an optical fiber array in which a front bare fiber portion is cured in a V groove with a Young's modulus of 500 MPa or more and a viscosity of 10 P before curing.
It is fixed with a first adhesive of a · s or less, and the coating portion of the optical fiber is fixed at the rear end of the array substrate with a second adhesive having a viscosity before curing higher than that of the first adhesive. It is characterized in that the bare fiber portion from which the coating between the rear end and the coating portion is removed is covered and fixed by a third adhesive having a Young's modulus after curing smaller than that of the first adhesive.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. FIG. 1A shows a basic form of the present invention, FIG. 1B shows an example having a fusion splicing part in a bare optical fiber portion, and FIG. 1C shows a rear edge of an optical fiber array. The following is an example of forming a smooth surface. In the figure, 11 indicates a first adhesive, 12 indicates a second adhesive, 13 indicates a third adhesive, and other reference numerals are the same as those in FIG.

The shape itself of the optical fiber array 4 shown in FIG. 1A is almost the same as that described with reference to FIG. 4, and is composed of an array substrate 5 and a pressing member 6, and the front portion of the array substrate 5 is aligned with the fiber. Part 5a, pedestal part 5b having a flat upper surface
Is formed by. The fiber alignment portion 5a is provided with a V groove 7 for aligning and positioning the bare fiber 3 from which the fiber coating 2 is removed.

In the optical fiber 1, the bare fiber 3 is exposed by removing the fiber coating 2 at the end portion, and the bare fiber portion 3a at the front portion is put into the V groove 7 of the array substrate 5 and pressed by the holding member 6. Positioned. The tip portion of the fiber coating 2 is placed on the pedestal portion 5b of the array substrate 5, and the bare fiber portion 3b between the rear end of the V groove 7 and the fiber coating 2 is placed in a state of floating from the pedestal portion 5b. Placed.

In the present invention, the bare fiber portion 3a positioned by the V-groove 7 is bonded and fixed by the first adhesive 11, and the tip portion of the fiber coating 2 is bonded by the second adhesive 12 on the pedestal portion 5b. The bare fiber portion 3b, which is fixed and floats on the pedestal portion 5b, is bonded and fixed with the third adhesive 13. As the first adhesive 11, a relatively small adhesive resin having a Young's modulus after curing of 500 MPa or more and relatively hard and a viscosity before curing of 10 Pa · s or less is used. The second adhesive 12 has a Young's modulus after curing of 500 MPa or more and is relatively hard like the first adhesive 11, but is relatively harder than the first adhesive 11 whose viscosity before curing exceeds 10 Pa · s. A large adhesive resin is used. The third adhesive 13 has a Young's modulus of 500 MP.
An adhesive resin less than a and relatively softer than the first adhesive 11 is used. For these adhesives, for example, an acrylic UV-curable adhesive resin can be used.

Since the above first adhesive 11 has a relatively low viscosity, the bare fiber portion 3a is easily aligned with the V groove 7 and can be accurately positioned by the holding member 6. Since the Young's modulus after curing is large, the bare fiber portion 3a can be firmly adhered and fixed. When the second adhesive 12 is applied to the fiber coating 2 at the tip end, it flows if the viscosity is too low. Therefore, the second adhesive 12 having a viscosity higher than that of the first adhesive 11 is used. Can be surely applied by covering.
In addition, since the Young's modulus after curing is as large as that of the first adhesive agent 11, the tip end of the fiber coating 2 is fixed to the array substrate 5.
It can be firmly adhered and fixed to the rear end.

Therefore, by fixing the bare fiber portion 3a with the first adhesive 11, it is possible to prevent stress concentration on the bonded portion of the fiber coating 2 against a tensile load in the longitudinal direction of the optical fiber 1. it can. Further, by fixing the fiber coating 2 with the second adhesive 12, the movement of the optical fiber 1 is restricted, and stress concentration does not occur in the bonded portion of the bare fiber portion 3a, so that the first adhesive 11 and the second adhesive 12 Adhesive 1
Together with No. 2, it is possible to have sufficient proof stress against the tensile load in the longitudinal direction of the optical fiber 1.

The third adhesive 13 is applied so as to cover the bare fiber portion 3b and protects this portion and adheres and fixes it. However, one having a relatively small Young's modulus which is relatively softer than the first and second adhesives is used. It is used. Therefore, when the temperature becomes low, the heat shrinkage of the third adhesive 13 is reduced,
The degree of strain on the bare fiber portion 3b can be reduced, and the increase in transmission loss can be reduced.

As a concrete example of FIG. 1A, an example is shown in which an optical fiber having an exposed bare fiber length of 10 mm, a bare fiber outer diameter of 0.125 mm, and a coated outer diameter of 0.25 mm is used. The first adhesive 11 has a Young's modulus of 124 after curing.
An adhesive resin having a viscosity of 1.8 Pa · s before curing at 0 MPa is used, and the second adhesive 12 has a Young's modulus of 3950 MPa.
With an adhesive resin with a viscosity of 50 Pa · s before curing,
An optical fiber array was prepared by using an adhesive resin having a Young's modulus of 25 MPa and a viscosity of 0.44 Pa · s before curing as the adhesive 13.

This was left for 336 hours in a humid heat environment of temperature 85 ° C. and humidity 85% (wet heat test according to Telcoria 1209 standard), and 100 cycles or more at −40 ° C. to + 85 ° C. (heat cycle test according to Telcoria 1221 standard).
Was done. As a result, the tensile load strength of the optical fiber array was 14.7N or more, and the strength significantly exceeding the default value of 4.9N was obtained, and the transmission loss fluctuation due to temperature change was ±.
Good results of 0.1 dB or less were obtained.

FIG. 1 (B) shows an example in which a dissimilar optical fiber is connected to the tip side of the bare fiber 3 and has a fusion splicing portion 3c. As a heterogeneous optical fiber, for example,
A highly functional optical fiber having a mode field diameter smaller than that of a normal optical fiber can be used. The mode field diameter is expanded by additional heating in the vicinity of the fusion spliced portion so that the mode field diameter in the spliced portion between different kinds of fibers is matched (see, for example, Japanese Patent No. 2618500).

When the above-mentioned heterogeneous optical fibers are connected to the bare fiber 3 by fusion, the fusion spliced portion 3c often causes an increase in the outer diameter due to the fusion splicing. It is preferable to mount the portion 3c at the rear of the V groove 7 so that the portion 3c is located above the pedestal portion 5b. In this case, the third adhesive 13 has a function of reinforcing and protecting the fusion splicing portion 3c.

FIG. 1C shows an example in which the optical fiber 1 is prevented from rubbing or bending at the rear edge of the array substrate 5. The rear edge of the array substrate 5 is formed by a tapered or arcuate smooth surface 5c so that the optical fiber 1 is damaged by the rear edge of the array substrate 5 or is bent extremely below the optical fiber array 4. To reduce disconnection and increase in transmission loss.

FIG. 2 is a diagram showing a second embodiment. In the second embodiment, a tube-shaped protection member is attached to the tip portion of the fiber coating of the optical fiber.
In the figure, reference numeral 14 denotes a protection member, and other reference numerals are the same as those in FIG.

The tube-shaped protection member 14 is provided in a portion straddling the rear edge of the array substrate 5 and reduces the direct contact of the optical fiber 1 with the rear edge of the array substrate 5. The tubular protection member 14 is provided in advance by being mounted on the optical fiber 1 after being formed in advance, and is bonded and fixed to the optical fiber and mounted on the array substrate 5. However, the tube-shaped protection member 14 may be fixed in advance on the rear end of the array substrate 5 with an adhesive, and then the optical fiber 1 may be inserted into the tube of the protection member 14.

The shape itself of the optical fiber array 4 is almost the same as that described with reference to FIG. 1, and comprises an array substrate 5 and a pressing member 6, and the front portion of the array substrate 5 is a fiber alignment portion 5a,
The rear part is formed by the pedestal part 5b. Fiber alignment section 5
V-grooves 7 for aligning and positioning the bare fiber portions 3a from which the fiber coating 2 has been removed are provided in a. The bare fiber portion 3 a is positioned by being pressed by the pressing member 6 in the V groove 7.

The tubular protective member 14 is formed of a flexible and bendable material such as rubber, silicon, or nylon resin. The mounting position of the protective member 14 is a short distance (for example, 0.5 mm to 2.0 mm) so that an exposed portion that is not covered by the protective member 14 is formed at the tip of the fiber coating 2.
(about mm) is attached. In addition, the protection member 14
Is formed with a length having a certain amount of protrusion (for example, preferably about 3 mm to 5 mm) from the rear end of the array substrate 5. Further, the protection member 14 can be mounted and positioned by abutting its tip on the shoulder of the step 5d provided on the pedestal 5b of the array substrate 5.

The protective member 14 is filled with an adhesive different from the second adhesive 12 for adhering the fiber coating 2 to the array substrate 5 so as to fill a part or all of the gap between the protective member 14 and the fiber coating 2. And is bonded and integrated with the optical fiber 1. Further, the protection member 14 may be configured to be individually attached to each of the single-core optical fibers 1, and the plurality of optical fibers 1 may be attached to the flat protection member 1.
It is also possible to adopt a configuration in which the components are collectively attached in step 4.

In the configuration of FIG. 2 as well, as in the case of FIG. 1, the bare fiber portion 3a positioned by the V groove 7 is adhesively fixed with the first adhesive 11, and the tip portion of the fiber coating 2 is changed to the second portion. The adhesive 12 is adhered and fixed onto the pedestal portion 5b, and the bare fiber portion 3b floating on the pedestal portion 5b is fixed to the third adhesive 1
Adhesively fix with 3. As the first adhesive 11, a relatively small adhesive resin having a Young's modulus after curing of 500 MPa or more and relatively hard and a viscosity before curing of 10 Pa · s or less is used. The second adhesive 12 has a Young's modulus of 500 M after curing.
An adhesive resin having a hardness of Pa or more and being relatively hard like the first adhesive 11 but having a viscosity before curing of more than 10 Pa · s and being relatively larger than the first adhesive 11 is used. As the third adhesive 13, an adhesive resin having a Young's modulus of less than 500 MPa and relatively softer than that of the first adhesive 11 is used.

The second adhesive 12 for adhering and fixing the fiber coating 2 to the array substrate 5 is a part of the fiber coating 2 protruding from the tip of the protective member 14 and the protective member placed on the array substrate 5. It is applied so as to cover a part of 14. As a result, as in the case of FIG. 1, the tensile load in the longitudinal direction of the optical fiber 1 is relaxed from directly reaching the bare fiber portion 3a.

The protective member 14 is positioned so as to straddle the rear edge of the array substrate 5 and serves as a cushion for relaxing the direct contact of the optical fiber 1. Further, as shown in FIG. 1C, even if the rear edge of the array substrate 5 is not processed into a smooth surface, the optical fiber 1 may be damaged by the edge, or may be bent below the optical fiber array 4. It is possible to reduce the occurrence of disconnection and increase in transmission loss.

FIG. 3 is a diagram showing a third embodiment. In the third embodiment, a protective member is provided by molding at the tip of the fiber coating of the optical fiber. Figure 3
FIG. 3A shows an example of molding so that a part of the protection member covers the bare fiber, and FIG. 3B shows an example of molding the protection member with a tip of the fiber coating slightly left. In the figure,
Reference numeral 15 denotes a protection member, and the other reference numerals are the same as those in FIG.

The shape itself of the optical fiber array 4 is substantially the same as that described with reference to FIG. 1, and comprises an array substrate 5 and a pressing member 6, and the front portion of the array substrate 5 has a fiber alignment portion 5a,
The rear part is formed by the pedestal part 5b. Fiber alignment section 5
V-grooves 7 for aligning and positioning the bare fiber portions 3a from which the fiber coating 2 has been removed are provided in a. The bare fiber portion 3 a is positioned by being pressed by the pressing member 6 in the V groove 7.

In the example of FIG. 3A, the protective member 15 is provided by molding so as to cover the end portion of the fiber coating 2 of the optical fiber 1 and a part of the bare fiber 3. Protection member 15
Is provided in a portion straddling the rear edge of the array substrate 5,
It reduces the direct contact of the optical fiber 1 with the rear edge of the array substrate 5.

In the example of FIG. 3B, the protective member 15 is formed so that the coating tip is slightly exposed (for example, about 0.5 mm to 2 mm) on the outer periphery of the end portion of the fiber coating 2 of the optical fiber 1. Provided by. The protective member 15 is provided in a portion straddling the rear edge of the array substrate 5, and the optical fiber 1
To directly contact the rear edge of the array substrate 5.

The protective member 15 is formed of a flexible, bendable material such as rubber or silicon or nylon resin.
Further, it is desirable that the adhesiveness to the fiber coating 2 is good and the breaking elongation is large. The protection member 15 projects to some extent from the rear end of the array substrate 5 (for example, 3 mm to 5 mm).
Formed to have a desired degree). The protruding portion 15a is formed in a taper shape to relieve stress against bending. The protection member 15 can be mounted and positioned by abutting the tip of the protection member 15 on the shoulder of the step portion 5d provided on the pedestal portion 5b of the array substrate 5.

Also in the configuration of FIG. 3, as in the case of FIG. 1, the bare fiber portion 3a positioned by the V groove 7 is adhesively fixed with the first adhesive 11, and the tip portion of the fiber coating 2 is changed to the second portion. The adhesive 12 is adhered and fixed onto the pedestal portion 5b, and the bare fiber portion 3b floating on the pedestal portion 5b is fixed to the third adhesive 1
Adhesively fix with 3. As the first adhesive 11, a relatively small adhesive resin having a Young's modulus after curing of 500 MPa or more and relatively hard and a viscosity before curing of 10 Pa · s or less is used. The second adhesive 12 has a Young's modulus of 500 M after curing.
An adhesive resin having a hardness of Pa or more and being relatively hard like the first adhesive 11 but having a viscosity before curing of more than 10 Pa · s and being relatively larger than the first adhesive 11 is used. As the third adhesive 13, an adhesive resin having a Young's modulus of less than 500 MPa and relatively softer than that of the first adhesive 11 is used.

The second adhesive 12 for adhering and fixing the fiber coating 2 to the array substrate 5 is applied so as to cover the protective member 15 placed on the array substrate 5 in FIG. 3 (A). . Further, in FIG. 3B, the protection member 1
It is applied so as to cover a part of the fiber coating 2 that is exposed and protrudes from the tip of 5 and a part of the protection member 15 mounted on the array substrate 5. As a result, as in the case of FIG. 1, the tensile load in the longitudinal direction of the optical fiber 1 is relaxed from directly reaching the bare fiber portion 3a.

The protective member 15 is positioned so as to straddle the rear edge of the array substrate 5 and serves as a cushion for relaxing the direct contact of the optical fiber 1. Further, as shown in FIG. 1C, even if the rear edge of the array substrate 5 is not processed into a smooth surface, the optical fiber 1 may be damaged by the rear edge, or the optical fiber array 4 may be bent downward. It is possible to reduce the occurrence of disconnection and increase in disconnection and increase in transmission loss.

Note that, also in the configurations of FIG. 2 and FIG.
The bare fiber 3 portion shown in FIG. 1B may have a structure in which different kinds of optical fibers are connected to the tip side to have a fusion splicing portion 3c. Further, as in FIG. 1 (C),
The rear edge of the array substrate 5 may be formed by a smooth tapered or arcuate surface.

[0039]

As is apparent from the above description, according to the present invention, the tensile load in the longitudinal direction of the optical fiber is
Adhesive fixing at the V groove portion and adhesion at the covering portion can provide sufficient proof stress without concentration of stress on any portion. Further, even for the bare fiber portion floating on the intermediate array substrate, the increase in transmission loss due to temperature change can be suppressed by protection and fixing with a soft adhesive.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a third embodiment of the present invention.

FIG. 4 is a diagram illustrating a conventional optical fiber array.

[Explanation of symbols]

1 ... Optical fiber, 2 ... Fiber coating, 3 ... Bare fiber,
4 ... Optical fiber array, 5 ... Array substrate, 6 ... Holding member, 7 ... V groove, 11 ... 1st adhesive agent, 12 ... 2nd adhesive agent, 13 ... 3rd adhesive agent, 14 and 15 protection member .

Continued front page    (72) Inventor Mitsuaki Tamura             Sumitomoden 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa             Ki Industry Co., Ltd. Yokohama Works F-term (reference) 2H036 JA04 LA03 LA07 LA08

Claims (7)

[Claims] 1. A single-core or multi-core optical fiber is placed on an array substrate having a V groove in the front part, and a bare fiber whose coating has been removed is placed in the V groove and is pressed and fixed by a pressing member to be fixed. In the V-shaped groove, the front bare fiber portion is fixed with a first adhesive having a Young's modulus after curing of 500 MPa or more and a viscosity of 10 Pa · s or less before curing in the V groove,
At the rear end of the array substrate, the coating portion of the optical fiber is fixed by a second adhesive having a viscosity before curing higher than that of the first adhesive, and the optical fiber between the rear end of the V groove and the coating portion is fixed. An optical fiber array, characterized in that the bare fiber portion with the coating removed is covered and fixed with a third adhesive having a Young's modulus after curing smaller than that of the first adhesive. 2. The optical fiber array according to claim 1, wherein a protective member having flexibility is provided on a coating portion of the optical fiber which straddles a rear edge of the array substrate. 3. The optical fiber array according to claim 2, wherein the protection member is formed in advance and then mounted on an optical fiber. 4. The optical fiber array according to claim 2, wherein the protection member is provided on the fiber coating of the optical fiber by molding with a molding die. 5. The optical fiber array according to claim 4, wherein the rear side of the protective member is formed in a tapered shape. 6. The optical fiber array according to claim 2, wherein a fiber coating end portion of the optical fiber is slightly exposed from the protection member. 7. The optical fiber array according to claim 2, wherein a stepped portion on which the protection member is placed is formed on a rear portion of the array substrate.