JP3886249B2 - Fiber array - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fiber array, and more particularly to a fiber array having functions such as the ability to relieve stress against bending from the outside.
[0002]
[Background Art and Problems to be Solved by the Invention]
Conventionally, a fiber array having a structure as shown in FIG. 5 has been proposed.
[0003]
This fiber array is configured by combining a substrate 21 (FIG. 5B) and a cover glass 22 (FIG. 5A) (FIG. 5C). The substrate 21 has a substrate thick portion 26 in which a single core V groove 25 for holding the core wire 24 of the optical fiber 23 is formed, and a substrate thin portion 27 following the substrate thick portion 26. Has a cover thick part 30 and a cover thin part 31 following the cover thick part 30.
[0004]
In the fiber array configured as described above, as shown in FIG. 5 (c), a fiber core wire 24 in which the outer sheath 28 of the optical fiber 23 is peeled off is inserted into the V groove 25 of the substrate 21. After the jacket 28 is placed on the thin substrate portion 27 of the substrate 21, an ultraviolet curable adhesive 32 is applied onto the optical fiber 23, and the thick substrate portion 26 of the substrate 21 and the thick cover portion of the cover glass 22. 30 is pasted together. Therefore, the jacket 28 of the optical fiber 23 is installed between the substrate thin portion 27 of the substrate 21 and the cover thin portion 31 of the cover glass 22.
[0005]
FIG. 6 shows a cross-sectional view of polishing of the fiber array prepared in the above-described process. In this fiber array, the tip 25V of the V-groove 25 of the substrate 21 is pointed, and the core wire 24 of the optical fiber 23 installed in the substrate 21, the cover glass 22 and the V-groove 25 of the substrate 21 is point-contacted at three points. The adhesive layer t11 between the substrate 21 and the cover glass 22 is configured to be thick (about 10 to 20 μm), and the cutting depth t12 of the V-groove 25 of the substrate 21 is configured to be shallow. Yes.
[0006]
FIG. 7A is a side view showing the structure of the conventional fiber array shown in FIGS. 5C and 6, and FIG. 7B is a detailed view of the terrace portion shown in FIG. 7A.
[0007]
In this fiber array, as shown in FIG. 7A, both the substrate 21 and the cover glass 22 have a terrace portion which is a boundary portion between the optical fiber 23 and the bonding portion t13 between the optical fiber 24 and the longitudinal direction of the optical fiber. It is comprised so that it may become a right angle to.
[0008]
Further, as shown in FIG. 7B, the distance between the core wire 24 from which the UV protective sheath of the optical fiber 23 is peeled off and the adhesive layer t14 is infinitely close to 0 (zero).
[0009]
[Problems to be solved by the invention]
However, the conventional fiber array is weak against fiber bending stress from the outside and causes a failure due to fiber breakage, which deteriorates due to expansion and contraction of the adhesive due to changes in operating temperature, causing peeling and cracking of the adhesive layer, and expensive adhesive However, there are problems in that the amount of injection of the resin increases, the cost increases, and the mechanical strength characteristics deteriorate.
[0010]
The present invention was made in order to solve the above-mentioned difficulties, and can relieve stress against bending from the outside, save the injection amount of the adhesive, reduce the adhesive, peeling due to the adhesive, cracks, etc. Defects are reduced, temperature characteristics are good, fiber movement due to adhesive expansion and contraction due to changes in operating temperature can be mitigated, and disconnection can be prevented, and it is excellent in mechanical strength and kept stable for a long time It is an object to provide a fiber array.
[0011]
[Means for Solving the Invention]
In order to achieve such an object, the fiber array of the present invention includes a substrate on which a V-groove for holding the core wire from which the outer sheath of the optical fiber is removed, and a gate for holding the outer sheath of the optical fiber. A fiber in which a mold-shaped groove is formed and a cover glass bonded to a substrate is inserted, a core wire from which the outer sheath of the optical fiber is removed is inserted into the V-groove, and the outer sheath of the optical fiber is held in the portal-shaped groove The substrate has a substrate thick portion formed with a V-groove for holding a core wire from which the outer sheath of the optical fiber is removed, and a substrate thin portion following the substrate thick portion. It has a cover thick part formed with a gate-shaped groove for holding the outer jacket of the fiber, and a cover thin part following the cover thick part, and the substrate thick part, the cover thin part, the substrate thin part, and the cover thickness meat portions are bonded to each other, respectively, the substrate In order to prevent peeling and cracking due to expansion of the adhesive that holds the core wire between the cover glasses, both the substrate and the cover glass reach from the end surface facing the outer cover of the V groove to the end surface facing the outer cover V groove. The holding portion of the core wire from which the outer sheath of the optical fiber is removed is provided with a gentle taper, and the distance t7 from the end surface facing the outer sheath of the V-groove to the end surface facing the outer sheath of the V-groove is 1.5 mm or more. And has a tensile strength of 1 kgf or more.
[0012]
According to such a fiber array, the stress due to bending from the outside can be dispersed, and the amount of adhesive used can be reduced by saving the amount of adhesive injected. Defects such as peeling and cracking are reduced, the temperature characteristics are good, the movement of the fiber due to expansion and contraction of the adhesive due to changes in the operating temperature can be reduced, and disconnection can be prevented, and it is excellent in mechanical strength and stable for a long time The state can be maintained, and the amount of expensive adhesive injected can be saved.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments to which the fiber array of the present invention is applied will be described with reference to the drawings.
[0014]
The fiber array of the present invention basically comprises a substrate 1 and a cover glass 2 (FIG. 1 (c)).
[0015]
The substrate 1 has a substrate thick portion 6 in which a V-groove 5 for holding the core 4 of the optical fiber 3 is formed, and a substrate thin portion 7 following the substrate thick portion 6 (FIG. 1B). . Further, the V-groove 5 is formed by cutting on the substrate thick portion 6 of the substrate 1. The thickness of the substrate 1 on which the above-described V groove 5 is formed is set to 1.6 mm, for example.
[0016]
The cover glass 2 includes a cover thick portion 10 in which a gate-shaped groove 9 for holding the outer cover 8 that is a UV protection layer of the optical fiber 3 is formed, and a cover thin portion 11 following the cover thick portion 10. (FIG. 1A). In addition, the thickness of the above-mentioned cover glass 2 was 1.1 mm, for example.
[0017]
In the fiber array configured as described above, the fiber core wire 4 from which the jacket 8 of the optical fiber 3 is peeled is inserted into the V groove 5 of the substrate 1. Further, the jacket 8 of the optical fiber 3 is installed on the thin substrate portion 7 of the substrate 1.
[0018]
Next, an ultraviolet curable adhesive 12 is applied onto the optical fiber 3 and the substrate thick portion 6 and the cover thin portion 11, and the substrate thin portion 7 and the cover thick portion 10 are wound together, thereby covering the cover glass. Two gate-shaped grooves 9 are inserted on the jacket 8 of the optical fiber 3.
[0019]
In the fiber array manufacturing process described above, if bubbles are entrained in the ultraviolet curable adhesive 12, the fibers 3 are bent (bent), resulting in an increase in manufacturing accuracy loss. Therefore, the bubbles are completely removed. For this purpose, the above-described fiber array was inserted into a vacuum desiccator (not shown), evacuated to about 1.0 mm torr, and then cured by irradiation with UV light.
[0020]
This UV light was irradiated at 50 mW / cm ² and 180 S, and further heat treated (annealed) in a thermostatic bath at 60 ° C. for 60 minutes in order to further increase the adhesive strength.
[0021]
The fiber array having the structure of the present invention shown in FIG. 1 exhibits excellent characteristics against bending from the outside as compared with the fiber array having the conventional structure shown in FIG.
[0022]
In addition, an environmental test was conducted over a long period (5,000 hours). When comparing the conventional fiber array and the fiber array of the present invention, there were 25 defects such as optical fiber disconnection and resin peeling in the conventional structure. None of the five were found in the structure of the present invention.
[0023]
Therefore, by performing the above-mentioned process and forming the gate-shaped groove 9 in the cover glass 2 as shown in FIG. 1A, the substrate 1 and the cover glass 2 having a shape as shown in FIG. Can be manufactured, and the core wire 4 of the optical fiber 3 is cut and polished at the edge of the V-groove 5 of the substrate 1 and aligned with another optical fiber, for example, an optical waveguide. Connected / held by the agent.
[0024]
According to such a fiber array, stress against bending from the outside can be relieved, the amount of adhesive injected can be saved, and the adhesive is reduced, so that defects such as peeling and cracking due to the adhesive are reduced, and the temperature is reduced. It has good characteristics, can relax the movement of the fiber due to expansion and contraction of the resin due to changes in the use temperature, can prevent disconnection, is excellent in mechanical strength, is reliable in use temperature, is in good condition and stable for a long time The manufacturing cost is reduced, and optical passive devices such as optical couplers, optical couplers and splitters (optical waveguides) used in optical communication systems, devices such as optical fibers and optical waveguides, etc. It can be applied in various ways.
[0025]
Next, another embodiment of the fiber array of the present invention will be described with reference to FIG.
[0026]
The fiber array shown in FIG. 2 has a single (FIG. 2 (a)) or multiple (FIG. 2 (b)) V-groove 5 for holding the core 4 of the optical fiber 3 as a single core or multiple cores. 1 and the cover glass 2 having the shape shown in FIG. 1 (a) in which the groove 5 for holding the jacket 4 of the optical fiber 3 is formed.
[0027]
In the thus configured fiber array, as shown in FIGS. 2 (a) and 2 (b), an ultraviolet curable adhesive 12a is applied to the single-core and multi-core optical fibers 3, respectively, and the V-groove of the substrate 1 is applied. 5 and the cover glass 2 are bonded to each other so that the core 4 of the single-core and multi-core optical fiber 3 is not separated from the V-groove 5 cut into the substrate 1 at an interval (t0) of 1.0 μm. The contact (clearance) is held between the cover glasses 2 by the ultraviolet curable adhesive 12a. The V-groove 5 of the substrate 1 has a curved surface (R) with the tip of the V-groove being 0.025 mm or more, and is cut and configured in advance.
[0028]
Moreover, the adhesive material layer 12a which is the separation distance (t1) between the board | substrate 1 and the cover glass 2 shall be 0-20 micrometers. Furthermore, when the fiber array is multi-core as shown in FIG. 2B, the accuracy of the pitch t5 between the cores of the core 4 is within ± 0.5 μm and is held in the adhesive 12a layer with high accuracy. Is done.
[0029]
Further, the grinding depth t4 of the V groove 5 of the substrate 1 is 170 to 210 μm, preferably 180 to 200 μm, more preferably 185 to 195 μm, and the separation distance t1 for the adhesive layer between the substrate 1 and the cover glass 2. 0 <t1 ≦ 20 μm, preferably 0 <t1 ≦ 10 μm, more preferably 0 <t1 ≦ 5 μm.
[0030]
When the fiber array having the structure of the present invention is compared with the fiber array having the conventional structure shown in FIG. 6, a tensile test was performed on the core portion 4 of the optical fiber 3 with respect to the adhesion distance with the number of samples n = 30. Compared to 412 gf, the structure of the present invention is 1723 gf, which clearly indicates that the tensile strength is increased and the mechanical strength characteristics are improved compared to the conventional structure.
[0031]
In addition, a fiber array having the structure of the present invention was connected to both ends of the optical waveguide, and an environmental test was conducted for a long period (5000 hours). The optical loss fluctuation was within 0.1 db, and good characteristics were exhibited.
[0032]
According to such a fiber array, as in the conventional case, the optical fiber core wire is bonded and held by three-point contact of two points of the V groove cut into the substrate and one point of the cover glass. Since the fiber core is not contacted between the curved (R) -shaped V-groove and the cover glass cut by the substrate, stress against tension, impact, vibration, etc. can be relieved, and the stress does not remain. In addition, the mechanical properties are improved. Therefore, it is possible to prevent the deterioration due to the damage of the core of the optical fiber. Further, by providing a curved surface (R) at the tip of the V groove, it is possible to prevent the occurrence of cracks at the bottom of the V groove. Furthermore, the adhesive layer between the substrate and the cover glass can be made thin, and the adhesive can be saved. Therefore, it is possible to prevent the occurrence of defects such as cracks due to the above-mentioned peeling due to the adhesive and the moisture resistance due to the temperature characteristics of the adhesive, and the movement of the fiber due to the expansion and contraction of the resin due to changes in the operating temperature can be reduced By preventing disconnection, it is excellent in mechanical strength, reliable in operating temperature, good and stable for a long time, and can reduce manufacturing costs, making it an optical communication system. The present invention can be applied to optical passive devices (optical waveguides) such as optical couplers and optical couplers / splitters used, devices such as optical fibers and optical waveguides, and the like.
[0033]
Further, another embodiment of the fiber array of the present invention will be described with reference to FIGS. 3 (a) and 3 (b).
[0034]
The fiber array shown in FIG. 3A has a substrate 1 having a V-groove 5 (FIG. 1) for holding the core wire 4 of the optical fiber 3, and an optical fiber 3 shown in FIG. And the cover glass 2 in which the groove 9 for holding the surface is cut.
[0035]
The substrate 1 and the cover glass 2 are respectively provided with gently tapered portions 7 a and 7 b at the holding portion of the core 4 of the optical fiber 3. Further, a groove 9 (FIG. 1) for protecting the jacket 8 of the optical fiber 3 is formed in the cover glass 2. Further, the distance t7 between the taper 7a, 7b, the core 4 of the optical fiber 3 and the adhesive 12a, that is, the end face of the V groove 5 facing the outer cover 8 reaches the end face of the outer cover 8 facing the V groove 5. The distance (hereinafter referred to as “distance of the core wire bonding portion”) t7 is set to be 1.5 mm or more.
[0036]
It was confirmed that the distance t7 has a significant effect on the tensile test strength.
[0037]
In the prior art, the distance between the core wire bonding portions is almost 0 (zero). However, the fiber array of the present invention is obtained by changing this distance. Compared with. The results will be described with reference to the graph shown in FIG. In both the structure of the present invention and the conventional structure, the substrate, the optical fiber, and the cover glass are in contact with each other.
[0038]
In this tensile strength, as shown in the graph of FIG. 4, the average fiber structure of the conventional fiber array is about 400 gf, but it was confirmed that the mechanical strength increases by increasing the distance of the core wire bonding portion. From this result, it is possible to ensure a mechanical strength of 1 kgf or more when the distance between the core wire bonding portions is about 1.5 mm.
[0039]
Moreover, the heat cycle test (-40- + 75 degreeC, 1000 cycles, 4.5Hr / cycle) was done, and the comparison was performed after completion | finish of a test. As a result, conventionally, with respect to the input number 11, cracks occurred in the substrate 1 or the cover glass 2 at the boundary between the thick part and the thin part (A in FIG. 7B). Defects such as disconnection were confirmed. In addition to this, when one of the optical fibers having an abnormality was disassembled and examined, the core 4 of the optical fiber 3 was disconnected in the fiber array.
[0040]
On the other hand, in the present structure provided with a taper, such a phenomenon was not confirmed at all. Therefore, with respect to the reliability due to the optical characteristics, the fluctuation amount is good at a maximum of 0.1 db, and good results are obtained that do not affect the optical loss.
[0041]
According to such a fiber array, since the disconnection of the core wire 4 of the optical fiber 3 in the fiber array was not confirmed, damage (adverse effect) to the core wire 4 of the optical fiber 3 was also alleviated and externally applied. Stress for bending can be relieved, adhesive injection amount can be saved, and the amount of adhesive can be reduced, reducing defects such as peeling and cracking due to adhesive, good temperature characteristics, and resin due to changes in operating temperature The fiber movement due to the expansion and contraction of the fiber can be mitigated and disconnection can be prevented, and the mechanical strength is excellent. And can be applied to devices such as optical couplers, optical couplers and splitters used in optical communication systems, optical passive devices (optical waveguides) such as optical couplers and splitters, and optical fibers and optical waveguides.
[0042]
【The invention's effect】
As is clear from the above description, according to the fiber array of the present invention, it is possible to disperse and relieve the stress due to bending from the outside, and it is possible to save the injection amount of the adhesive and to reduce the adhesive. Defects such as peeling and cracking due to adhesive are reduced, temperature characteristics are good, fiber movement due to expansion and contraction of adhesive due to change in operating temperature can be mitigated, and disconnection can be prevented, excellent in mechanical strength It becomes possible to maintain a stable state for a long time.
[Brief description of the drawings]
FIG. 1 (a), FIG. 1 (b), and FIG. 1 (c) are perspective views of a cover glass in an embodiment of a fiber array of the present invention, respectively, and a fiber is incorporated (single-core V-groove). The perspective view of a board | substrate, the figure of the fiber array which incorporated the cover glass, the fiber, and the board | substrate.
FIGS. 2 (a) and 2 (b) are cross-sectional views of single-core and multi-core fiber arrays in another embodiment of the fiber array according to the present invention, respectively.
3 (a) and 3 (b) are explanatory diagrams viewed from the side in another embodiment of the fiber array according to the present invention, respectively, and are detailed views showing the terrace portion of FIG. 3 (a).
FIG. 4 is a graph showing the distance between the core wire bonding portions in each fiber array of the present invention (the distance from the end surface facing the outer cover of the V groove to the end surface facing the V groove of the outer cover) and the mechanical strength characteristics.
5 (a), 5 (b), and 5 (c) are a perspective view of a cover glass in a conventional fiber array, a perspective view of a substrate incorporating the fiber, a cover glass, a fiber, and a substrate, respectively. The figure of the fiber array which incorporated.
6 is a polished cross-sectional view of the conventional fiber array shown in FIG.
7A and FIG. 7B are structural cross-sectional views of the conventional fiber array shown in FIG. 5 and detailed views showing the terrace portion of FIG. 7A, respectively.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2 ... Cover glass 3 ... Optical fiber 4 ... Core wire 5 ... V groove 6 ... Thick part 7 of a board | substrate 7・ ・ ・ ・ ・ Substrate thin section 8 ・ ・ ・ ・ ・ Coat 9 …… Port-shaped groove (groove)
10 ··· Cover thick portion 11 ··· Cover thin portion t1 ··· Separation distance t4 for adhesive layer between substrate and cover glass ··· Grinding depth t7 · .... Distance from the end face of the V groove facing the outer cover to the end face of the outer cover facing the V groove (distance of the core bonding portion)
R: Curved surface

Claims (1)

A substrate formed with a V-groove for holding the core wire from which the outer sheath of the optical fiber is removed, and a cover formed with a portal-shaped groove for holding the outer sheath of the optical fiber and bonded to the substrate Made of glass,
A fiber array in which a core wire from which the outer sheath of the optical fiber is removed is inserted into the V-groove, and the outer sheath of the optical fiber is held in the portal-shaped groove,
The substrate includes a substrate thick portion in which a V-groove for holding a core wire from which the outer sheath of the optical fiber has been removed is formed, and a substrate thin portion following the substrate thick portion, A cover thick part formed with a gate-shaped groove for holding the outer jacket of the fiber and a cover thin part following the cover thick part;
The substrate thick part and the cover thin part and the substrate thin part and the cover thick part are bonded together,
In order to prevent peeling and cracking due to the expansion of the adhesive that holds the core wire between the substrate and the cover glass, both the substrate and the cover glass are exposed from the end surface of the V groove facing the outer cover. A gentle taper is provided in the holding portion of the core wire from which the outer sheath of the optical fiber that reaches the end surface facing the V groove is removed,
The distance (t7) from the end face of the V groove facing the outer cover to the end face of the outer cover facing the V groove is 1.5 mm or more and has a tensile strength of 1 kgf or more. Fiber array.

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