JP2001066467A - Multiple optical fiber fixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the exertion of an excessive stress on optical fibers in the curing of an adhesive by forming the diameter of the coating parts at the rear of the optical fibers to an inter-pitch distance or below and holding the coating parts with a protective member. SOLUTION: A cylindrical capillary 3 consisting of ceramics and having two through-holes 3a is joined to the front end of the through-holes of a cylindrical support 2 consisting of metal, etc. Next, the coating removed parts 1a at the front end of the two optical fibers are inserted into the through-holes 3a of the capillary 3 and the coating parts 1b on the rear end side of the respective optical fibers 1 are fixed by packing the adhesive 5 into the through-holes of the support 2. Further, the roots of the coating parts 1b of the optical fibers 1 emerging from behind the support 2 have a protective resin 6 as the protective member. The multiple optical fiber fixture 4 is thus constituted. The diameter D of the coating parts 1b of the coating removed parts 1a is specified to the inter-pitch distance d or below with the fixture 4. As a result, the coating removed parts 1a of the optical fibers 1 may be inserted into the through-holes 3a without bending the coating removed parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-core optical fiber fixture.

[0002]

2. Description of the Related Art Conventionally, a multi-core optical fiber fixture holding a plurality of optical fiber tips has been used. This is used when a plurality of signals are transmitted and received, bidirectional signal transmission is performed, or a spare optical fiber is provided for improving security.

As shown in FIG. 4, a conventional multi-core optical fiber fixing device 4 is composed of two optical fibers whose coatings are stripped on a support 2 on which a capillary 3 having one long hole type through hole 3a is mounted. The fiber 1 is inserted, the respective coating removal portions 1a are arranged side by side, inserted into the through holes 3a, and the epoxy-based adhesive 5 is filled and fixed between the coating portion 1b of the optical fiber 1 and the support member 2. Was. In this case, since the coating removal portions 1a are arranged, the pitch distance d of this portion is 0.125.
mm.

[0004] In the multi-core optical fiber fixing device 4, there is also a through hole 3a formed of two independent holes having a pitch distance d of about 0.25 mm.

[0005]

However, in the multi-core fiber fixing device 4 shown in FIG. 4, the diameter D of the covering portion 1b of the optical fiber 1 is as large as 0.9 mm and the distance d between the pitches is 0.125 mm. Therefore, the coating removal portion 1a of the optical fiber 1 has to be bent and inserted into the through hole 3a, stress is applied to the coating removal portion 1a, and an environmental test such as after curing of the adhesive 5 and at high temperature and high humidity. There is a problem that the characteristics of the optical fiber 1 are deteriorated or broken below.

Even when the through hole 3a is formed as two independent holes as described above, the distance d between the pitches is 0.2.
Since the distance between the pitches is about 5 mm, which is also smaller than the diameter D of the covering portion 1b, the above problem could not be solved.

In this case, it is possible to increase the distance d between the pitches by increasing the distance between the two independent through holes, but in this case, the plurality of optical fibers 1 fixed in the capillary 3 are moved from the center of the capillary 3 There is a problem in that the optical module is separated and the overall characteristics of the module are deteriorated in the optical system, or the diameter of a lens connected to the module must be increased. For this reason, it is desirable that the optical fiber 1 is located at the center of the capillary 3 and the pitch distance d
Should be shorter.

Further, as described above, in the conventional multi-core optical fiber fixture 4, the diameter D of the coating portion 1b is determined by the distance d between the pitches.
Therefore, it is necessary to form the coating removing portion 1a of the optical fiber 1 long, and the epoxy adhesive 5 is also in contact with the coating removing portion 1a. Since the epoxy-based adhesive 5 and the coating removal portion 1a of the optical fiber 1 have different thermal expansion coefficients and hygroscopicity, the epoxy bonding agent 5 adheres to the coating removal portion 1a under environmental tests such as curing of the adhesive 5 and high temperature and high humidity. The stress from the agent 5 acts, and the coating removal portion 1a bends, thereby causing the optical fiber 1 to deteriorate in characteristics. Further, there is a problem that the coating removal portion 1a of the optical fiber 1 is cracked by coming into contact with the cone portion 3b of the capillary 3 at the time of assembling or the like, and in the worst case, the crack progresses and may be broken.

In order to solve the above problem by reducing the diameter D of the covering portion 1b of the optical fiber 1, for example, in the case of the optical fiber 1 in which the covering portion 1b has a diameter D of 0.25 mm, a multi-core optical fiber The optical fiber 1 could be broken at the open end of the fixture.

[0010]

In view of the above, the present invention provides
In the multi-core optical fiber fixture for holding the ends of a plurality of optical fibers, the coating removal portions at the ends of the plurality of optical fibers are inserted into the through holes and held at a predetermined pitch distance d, and the coating portion behind the optical fibers is formed. The diameter D is set to be equal to or less than the pitch distance d, and the covering portion is held by a protective member.

[0011] Further, a cone portion is provided behind the through hole into which the coating removal portion of the optical fiber is inserted, and a distance between the cone portion and the optical fiber coating portion is set to 500 µm or less.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a first embodiment of the present invention.

As shown in FIG. 1, this multi-core optical fiber fixing device 4 has a through hole 2a of a cylindrical support 2 made of metal or the like.
A cylindrical capillary 3 made of ceramic or the like and having two through holes 3a is joined to the tip of
The coating removal part 1a at the tip of the through hole 3 of the capillary 3
a, the coating 1b on the rear end side of each optical fiber 1 is filled and fixed with an epoxy-based adhesive 5 in the through hole 2a of the support 2, and the light exiting from the back of the support 2 A protection resin 6 is provided as a protection member at the root of the fiber coating portion 1b.

An important point of the multi-core optical fiber fixture 4 is that the diameter D of the covering portion 1b is set to be equal to or less than the pitch distance d. For this reason, as shown in FIG.
a, and no excessive stress is applied to the coating removing portion 1a.

From the viewpoint of the optical characteristics, the distance d between the pitches needs to be within the range of the effective diameter of the lens to be connected thereto. In order to make the diameter D of the covering portion 1b equal to or less than the pitch distance d as described above, it is necessary to reduce the diameter D of the covering portion 1b. However, since the protective resin 6 is provided as a protective member, the covering portion 1b Optical fiber 1 even if diameter D is small
Disconnection can be prevented.

In the present invention, the distance between the tip of the coating 1b of the optical fiber 1 and the cone 3b of the capillary 3 is set to 5
By setting the thickness to 00 μm or less, the exposed portion of the coating removal portion 1a of the optical fiber 1 is shortened, and the adverse effect of the stress on the coating removal portion 1a from the epoxy-based adhesive 5 caused by the difference in thermal expansion coefficient and hygroscopicity is prevented. are doing.

That is, in the optical fiber 1, a primary coating or a secondary coating made of plastic, polyamide resin, UV curable resin or the like is applied on a bare optical fiber consisting of a core and a clad. Since the secondary coating and the secondary coating have elasticity, the primary coating removes the stress from the epoxy-based adhesive 5 or the like on the coating removal portion 1a of the optical fiber 1 due to the difference in thermal expansion coefficient and hygroscopicity. Since the portion of the secondary coating plays the role of a cushioning material and cancels out, the optical fiber 1 does not lose its characteristics. Further, neither cracking nor breakage of the coating removal portion 1a of the optical fiber 1 in the cone portion 3a of the capillary 3 occurs. Therefore, reliability is improved even in an environmental test.

According to the method of assembling the multi-core fiber fixing device 4 of the present invention, first, the coating of the optical fiber 1 is stripped in a dimension longer than the entire length of the capillary 3, and the coating inserted into the coating removing portion 1 a and the support 2. The part 1b is ultrasonically cleaned or wiped and cleaned with an organic solvent or the like. The epoxy-based adhesive 5 used for fixing the optical fiber 1 is one obtained by sufficiently stirring a two-part adhesive and subjecting it to a centrifugal defoaming machine or vacuum defoaming to perform a defoaming treatment. The defoamed epoxy-based adhesive 5 or the like is filled in the through-hole 2a of the support 2 to which the capillary 3 is joined so that air does not enter, and the coating removal portion 1a and the coating of the washed optical fiber 1 are further filled. Insert the part 1b. After that, the adhesive 5 is cured. The curing conditions are such that the glass transition temperature of the adhesive 5 is set higher than the storage temperature of the product in which the multi-core optical fiber fixture 4 is used, and the curing time is adjusted under the temperature at which the coating of the optical fiber 1 can withstand. .

In the above embodiment, as the material of the capillary 3, ceramic materials such as zirconia and alumina are often used, but glass, metal, plastic and the like can also be used. The material of the support 2 is stainless steel,
A metal material such as copper and Kovar is used, but ceramic, glass, plastic, and the like can also be used.
In addition, a material obtained by integrally molding the support 2 and the capillary 3 can be used. In this case, the material may be a ceramic material such as zirconia or alumina, but glass, metal, plastic, or the like may also be used. Note that the support 2 and the capillary 3 are not limited to a cylindrical shape, and may be a rectangular tube.

As the protective resin 6 provided at the root of the covering portion 1b of the optical fiber 1 coming out from the back of the support 2, a highly flexible resin such as silicon rubber is used.
As shown in (1), a protective cap 7 made of rubber or resin can be provided as a protective member.

[0021]

EXAMPLE Here, an experiment was conducted by the following method. Pressure cooker test (acceleration life test) usually performed in the field of electronic components for Examples and Comparative Examples of the present invention
A durability test was performed using This test is also used as an acceleration test in a high-temperature and high-humidity test. The conditions are as follows.

Temperature: 120 ° C. Humidity: 100% RH Atmospheric pressure: 2 atm Time: 168 hours Under these conditions, a comparative example shown in FIG. 4 (material of capillary 3: zirconia, material of support 2: stainless steel, coating The diameter D of the portion 1b: 0.25 μm, the distance d between the pitches: 0.125 μm) and the embodiment of the present invention shown in FIG. 1 (material of the capillary 3: zirconia, material of the support 2: stainless steel, diameter of the coating portion 1b) D: 0.25 μm, pitch-to-pitch distance: 0.25 μm). Table 1 shows the results after the acceleration test. The return loss was measured for the purpose of detecting the disconnection of the optical fiber. FIG. 3 shows the respective return loss distributions after the acceleration test.

From the results shown in Table 1, the comparative example (the diameter D of the covering portion 1b> the distance d between the pitches) had a breaking rate of 40%, while the embodiment of the present invention (the diameter D of the covering portion 1b ≦ the pitch). With respect to the distance d), an excellent result was obtained with a breaking rate of 0%. Also,
From the results of FIG. 3, the distribution of the return loss is scattered in the comparative example (the diameter D of the covering portion 1b> the distance d between the pitches), and the standard (70 dB) is obtained.
On the other hand, in some embodiments of the present invention (the diameter D of the covering portion 1b ≦ the distance d between the pitches), the distribution of the return loss is concentrated, and all of the standards (70 dB or more) are satisfied. Especially good results were obtained.

[0024]

[Table 1]

[0025]

As described above, according to the present invention, in the multi-core fiber fixing device, it is necessary to make the coating removal portion of the optical fiber curved by setting the diameter D of the coating portion of the optical fiber to the pitch distance d or less. And the exposed portion of the coating removal portion is shortened. For this reason, it is possible to prevent an excessive stress from being applied to the optical fiber when the adhesive is cured.

Further, by holding the covering portion of the optical fiber with a protective member, the occurrence of disconnection can be prevented even if the diameter of the covering portion is reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a multi-core optical fiber fixture of the present invention.

FIG. 2 is a sectional view of a multi-core optical fiber fixture according to another embodiment of the present invention.

FIG. 3 is a graph showing return loss after a durability test in Examples of the present invention and Comparative Examples.

FIG. 4 is a sectional view of a conventional multi-core optical fiber fixture.

[Explanation of symbols]

 1: optical fiber 1a: coating removal portion 1b: coating portion 2: support 2a: through hole 3: capillary 3a: through hole 3b: cone portion 4: multi-core optical fiber fixing device 5: adhesive 6: protective resin 7: Protective cap

Claims (2)

[Claims] 1. A multi-core optical fiber fixture for holding the tips of a plurality of optical fibers, wherein the coating removal portions of the tips of the plurality of optical fibers are inserted into through holes and held at a predetermined pitch distance d. A multi-core optical fiber fixture, wherein the diameter D of the covering portion behind the fiber is set to be equal to or less than the pitch distance d and the covering portion of each optical fiber is held by a protective member. 2. The optical fiber according to claim 1, wherein a cone portion is provided behind the through hole into which the coating removal portion of the optical fiber is inserted, and a distance between the cone portion and the optical fiber coating portion is 500 μm or less. Multi-core optical fiber fixture.