JPH0580225A - Optical fiber array - Google Patents

Abstract

PURPOSE:To inhibit the scratch of ends of the optical fibers of an optical fiber array at the time of polishing an end of the array and to prevent optical transmission in the optical fibers from being adversely affected. CONSTITUTION:Optical fibers 20 are held and fixed between a fiber array substrate 15 and a holding member 29 with an adhesive 33 having >=60 Shore D hardness after curing. The max. gap between the coated optical fibers 21 and the insides of grooves 14 for fixing the fibers is regulated to <=50mum.

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 used for connecting an optical fiber to a waveguide type optical switch or the like.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional optical fiber array. In the figure, 70 is an optical fiber array substrate,
Reference numeral 73 is a waveguide type optical switch connected to an optical fiber array, and 74 is its waveguide. Each optical fiber 72
Exposes the fiber core wires 75 at their respective ends, inserts them into the fiber core wire fixing grooves 76 of the optical fiber array substrate 70, and connects them to the corresponding waveguides 74. Reference numeral 77 is a sandwich substrate that sandwiches the optical fiber core wire 75 with the optical fiber array substrate 70, and the optical fiber array substrate 70 and the sandwich substrate 77 constitute an optical fiber array 78.

[0003]

An optical fiber array 7 having a high alignment accuracy, which is connected to an optical waveguide 74 or the like.
For manufacturing 0, silicon that can align the optical fiber 72 with high accuracy is used. In manufacturing the optical fiber array 78 using the optical fiber array substrate 70 made of silicon, the end face is mirror-polished for connection to the optical waveguide 74 and the like. However, in the case of the optical fiber array 78 formed by adhering high hardness silicon (fiber array substrate 70) and quartz (fiber 75 of the optical fiber) with an adhesive that is an organic material, the mechanical strengths of the optical fiber array 78 are different from each other. It is extremely difficult to polish the optical fiber core wire 75 to a mirror surface without damaging it, thus adversely affecting the propagation of light.

Therefore, an object of the present invention is to provide an optical fiber array capable of reducing scratches on the end surface of the optical fiber when polishing the end surface of the optical fiber array.

[0005]

This invention (first invention)
In the optical fiber array of No. 2, the optical fiber is sandwiched and fixed between the optical fiber array substrate and the sandwiching member via an adhesive having a hardness of Shore D60 or more at the time of curing.

According to another optical fiber array of the present invention (the second invention), the optical fiber is sandwiched and fixed with an adhesive in an optical fiber fixing groove provided in the optical fiber array substrate and the sandwiching member. In the optical fiber array, the optical fiber fixing groove is formed so that the maximum gap between the outer surface of the optical fiber and the inner surface of the fiber fixing groove is 50 μm or less. To do.

Therefore, a preferred embodiment of the present invention is the second invention, wherein the Shore D6 when cured as an adhesive is used.
An adhesive having a hardness of 0 or more is used. The hardness of the adhesive having a hardness of Shore D60 or more used in the present invention is measured by ASTM D2240 Shore hardness, preferably Shore D8.
It is 0 or more, more preferably Shore D 85 or more. When the end surface of the fiber array is less than Shore D60,
The end surface of the optical fiber is likely to be scratched and the adhesive surface is likely to be peeled off.

Examples of such an adhesive include the following. That is, a UV curable adhesive (eg, acrylic UV curable resin, urethane UV curable resin,
Examples thereof include modified acrylic ultraviolet curable resin) and thermosetting adhesives (thermosetting epoxy resin). In the present invention, even if the adhesive is concealed between the sandwiching member and the fiber array substrate, the inside of the adhesive is completely cured by heat, so that the thermosetting adhesive (in particular, the thermosetting adhesive) is used. Epoxy adhesives) are preferred.

The maximum gap between the fiber fixing groove and the outer surface of the optical fiber inserted into the fiber fixing groove of the fiber array substrate is preferably 50 μm or less, more preferably 15 μm or less, and further preferably 10 μm or less. ..

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention is shown in FIGS. In FIG. 1, reference numeral 15 denotes an optical fiber array substrate 15 having an optical fiber fixing groove 14, and an optical fiber 20
The exposed fiber core wire 21 is inserted into the optical fiber fixing groove 14 and is clamped and fixed by the holding member 29 having the optical fiber fixing groove. An adhesive 33 such as a UV-curable or thermosetting epoxy adhesive having a hardness (at the time of curing) of Shore D60 or more is applied between the holding member 29 and the optical fiber array substrate 15 to fix the fiber core wire 21. There is.

FIG. 2 shows an end face of the optical fiber array 10, in which the optical fiber core wire 21 includes the optical fiber fixing groove 14 of the optical fiber array substrate 15 and the optical fiber fixing groove 28 formed in the holding member 29. Has been inserted into. By polishing the end face of the optical fiber array 10 with a phase difference precision automatic polishing machine or the like, the tip of the optical fiber core wire 21 is finished into a mirror surface.

[0012]

[Experimental Example] An experiment was conducted to measure the size of polishing scratches generated on the end face of the fiber core wire 21 during mirror polishing by changing the conditions of hardness and thickness of the adhesive.

Experimental Example 1 An optical fiber core wire 21 is sandwiched between a silicon optical fiber array substrate 15 and a sandwiching member 29 each having a sectional structure shown in FIG. 2, and various kinds of adhesives having different hardness during curing are exposed to light. The gap between the fiber core wire 21 and the optical fiber fixing grooves 14 and 28 was filled and sufficiently cured to fix the optical fiber.

After curing and fixing, the end surface of the optical fiber core wire 21 was mirror-polished with a phase-contrast precision automatic grinder, and the size of the polishing scratch generated on the end surface of the optical fiber core wire 21 was measured. The experimental results are shown in Table 1.
Shown in.

[0015]

[Table 1]

In Table 1, the number in parentheses in the model number column of the adhesive 45CL indicates the mixing ratio of the main agent and the curing agent. Further, the gap (μm) represents the maximum value of the gap between the fiber core wire 21 and the inner surface of the fiber fixing groove 14 shown by T in FIG. FIG. 3 is a graph showing the relationship between the adhesive hardness (shore) and polishing scratches (μm) in Table 1.
Is.

As is clear from the results of this experiment, as the hardness of the adhesive increases, the length of polishing scratches generated on the end face of the fiber core wire 21 decreases.

Considering the size of the polishing scratches allowed from the spread of the field of the light propagating through the core of the optical fiber 20, in the case of a 1.3 μm single mode fiber, 1 / th of the electric field field of the propagating light is considered. The size of e is about 8 to 9 μm, which is equivalent to the size of the core, and most of the energy is confined and propagated in this.
Therefore, theoretically, if there are no polishing scratches that reach this portion, the effect is considered to be small, but in reality, reducing the length of polishing scratches as much as possible is not only for structural reliability and product Leads to improved reliability. That is, as shown in FIG. 3, when an adhesive having Shore D80 or higher is used, good results with small polishing scratches are obtained, and when Shore D85 or higher, extremely good results can be obtained. But Shore D
If the adhesive is 60 or more, the length of the flaw is relatively short even if it extends to the light propagation field of the optical fiber, so that the light propagation is not affected. Therefore, Shore D6
If the adhesive is 0 or more, it can withstand practical use.

Experimental Example 2 An adhesive having a hardness of Shore D85 when cured (Ecobond 2
4) is used to change the maximum gap T (see FIG. 2) between the outer surface of the fiber core wire 21 and the fiber fixing grooves 14 and 28 (basically, depending on the depth of the fiber fixing grooves 14 and 28). Change), mirror-polish with phase-difference precision automatic polisher,
This is the same as in Experimental Example 1 where the scratches on the fiber core wire 21 were measured.

The experimental results are shown in FIG. As is clear from FIG. 4, the smaller the maximum gap T (that is, the adhesive thickness), the shorter the length of the polishing scratch. That is, when the maximum gap T is 15 μm or less, good results with small polishing scratches are obtained, and when the maximum gap T is 10 μm or less, extremely good results are obtained. However, if the maximum gap T is 50 μm or less, the length of the flaw is relatively short even if it extends to the light propagation field of the optical fiber, and therefore the light propagation is not affected. Therefore, if the maximum gap T is 50 μm or less, it can sufficiently withstand practical use. A similar tendency was observed with any of the adhesives.

[0021]

According to the optical fiber array of the present invention, it is possible to reduce the occurrence of scratches on the end surface of the optical fiber when polishing the end surface of the fiber array, and to prevent the propagation of light in the optical fiber from being adversely affected. The effect is obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of an optical fiber array of the present invention.

FIG. 2 is an end view of the optical fiber array of the present invention.

FIG. 3 is a graph showing the relationship between the hardness of the adhesive and the length of scratches.

FIG. 4 is a graph showing the relationship between the thickness of an adhesive and the length of a scratch.

FIG. 5 is a perspective view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Optical fiber array 14 Fiber fixing groove 15 Fiber array substrate 20 Optical fiber 21 Fiber core wire 28 Fiber fixing groove 29 Clamping member 33 Adhesive

Claims (2)

[Claims] 1. An optical fiber array in which an optical fiber is sandwiched and fixed between an optical fiber array substrate and a sandwiching member via an adhesive having a hardness of Shore D60 or more at the time of curing. 2. An optical fiber array in which an optical fiber is sandwiched and fixed via an adhesive in an optical fiber fixing groove provided in an optical fiber array substrate and a sandwiching member, wherein An optical fiber array, wherein the optical fiber fixing groove is formed such that the maximum gap between the outer surface and the inner surface of the fiber fixing groove is 50 μm or less.