JPH0266503A - Fixing method for optical fiber of optical module - Google Patents

Abstract

PURPOSE:To improve coupling efficiency by moving a 2nd end part of a ferrule for optical axis adjustment while positioning the ferrule by support means nearby a 1st end part close to an end part of an optical fiber, then fixing the ferrule to a fiber saddle with an adhesive nearby a 2nd end part. CONSTITUTION:The front end of the ferrule 4 is positioned by the support means 5a and 5b nearby the end part (front end) of the ferrule 4 close to a semiconductor laser 2. Here, the support means 5a and 5b support the ferrule 4 so that the ferrule 4 can rotate at right angles to its center axis as shown by arrows A. Then, the rear end of the ferrule 4 is moved at an optional position at the end part (rear end) of the ferrule 4 at a distance from the semiconductor laser 2 to align the optical axes of the optical fiber 3 and semiconductor laser 2 with each other. When this optical axis alignment is completed, the ferrule 4 is fixed to the fiber saddle 6 by soldering 7 nearby the rear end. Consequently, the coupling efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for fixing optical fibers. More specifically, the present invention provides precision control of the end of an optical fiber when optically coupling the end of the optical fiber to another device such as a light emitting element or a light receiving element inside an optical module or the like. This invention relates to a novel method for fixing while positioning.

2. Description of the Related Art In various optical communication systems such as optical LAN and optical CATV, devices that perform optical/electrical conversion or electrical/optical conversion are collectively referred to as optical modules.

When optically coupling the end of an optical fiber to another device such as a light emitting element or a light receiving element inside an optical module, a metal ferrule is actually attached to the end of the optical fiber to be fixed. A common method is to fix this ferrule to a member called a fiber saddle using an adhesive such as solder.

Problems to be Solved by the Invention By the way, in optical coupling between an optical fiber and another device, it is necessary to perform extremely precise optical axis alignment.

FIG. 3 is a graph showing the relationship between optical axis misalignment of an optical fiber and coupling efficiency. As shown in this graph, even when the amount of axis misalignment is about 1 μm, the coupling efficiency decreases by 1 to 3 dB.

However, in the conventional optical fiber fixing method described above, since the ferrule moves during the process of melting/solidifying the solder, axis misalignment of about 0.1 to 0.13 μm is unavoidable at best, and furthermore, in reality Other factors combined to cause a larger axis misalignment, resulting in a significant drop in coupling efficiency. For this reason, in the past, fixing optical fibers was extremely precise work, but it was difficult to achieve high coupling efficiency and the work efficiency was poor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel optical fiber fixing method that solves the problems of the prior art described above and can easily achieve higher coupling efficiency.

Means for Solving the Problems According to the present invention, there is a method of fixing an optical fiber by mounting a ferrule near the end of the optical fiber and fixing the ferrule to a fiber saddle with an adhesive, the method comprising: Using a support means that supports the ferrule from the side so that the ferrule can swing about the support position and that can position the ferrule at the support position, first, the end of the optical fiber is After adjusting the optical axis by moving the other second end of the ferrule while positioning the ferrule by the supporting means at a position sufficiently close to the first end of the ferrule on the side close to the part, A method for fixing an optical fiber in an optical module is provided, the method comprising fixing the ferrule to the fiber saddle near the second end using an adhesive.

In conventional methods of fixing optical fibers in optical modules, the fiber saddle for fixing the ferrule was only located near the end of the optical fiber.

However, the optical fiber fixing method according to the present invention is characterized in that the ferrule is mainly fixed on the side far from the end of the optical fiber.

In the method of the present invention, first, a support means is used to position the ferrule so that the ferrule can swing in a direction perpendicular to the propagation optical axis of the optical fiber to be fixed. This support means rotatably positions the ferrule sufficiently close to the end of the optical fiber, as will be specifically described below.

That is, in the method according to the present invention, prior to fixing with adhesive, the vicinity of the end of the ferrule is first positioned using the support means, and then the axis of the optical fiber is aligned at the other end of the ferrule, that is, on the rear end side. Further, while maintaining the positioning by this support means, the ferrule is fixed with an adhesive near the rear end.

As mentioned above, when fixing with solder, some deviation occurs during the solidification process of the solder itself, but in the method according to the present invention, the vicinity of the front end of the optical fiber is fixed by the support means, so that Even if the rear end of the ferrule moves, the amount of movement at the tip of the optical fiber is small.

According to one embodiment of the present invention, it is practically preferable to further fix the ferrule on the side closer to the end of the optical fiber following the fixing operation described above. That is, by fixing the ferrule even near the end of the optical fiber, the reliability and durability of the optical module after installation can be improved.

The present invention will be described in more detail below with reference to the drawings, but the following disclosure is only one example of the present invention and does not limit the technical scope of the present invention in any way.

Embodiment FIG. 1 is a diagram schematically explaining a method for fixing an optical fiber according to the present invention.

The work described here is to fix the optical fiber 3 so that the end of the optical fiber 3 is located just in front of the semiconductor laser 2 fixed on the chip carrier 1. That is, a ferrule 4 is attached near the end of the optical fiber 3, and in reality, this ferrule 4 is attached to a fiber saddle 6.
(and 8) by soldering. It is assumed that the fiber saddles 6 (and 8) are arranged at both ends of the ferrule 4 at positions sufficiently close to the ends, as will be described later.

In the method according to the present invention, first, the supporting means 5a, 5b are placed at an arbitrary position close to the end of the ferrule 4 on the side closer to the semiconductor laser 2 (hereinafter referred to as the front end of the ferrule).
The front end of the ferrule 4 is positioned by the following steps. here,
The support means 5a, 5b support the ferrule 4 so that the ferrule 4 can rotate in a direction perpendicular to its central axis, as shown by arrow A in the figure.

Next, by moving the rear end of the ferrule 4 to an arbitrary position close to the end of the ferrule 4 on the side far from the semiconductor laser 2 (hereinafter referred to as the rear end of the ferrule),
The optical axes of the optical fiber 3 and the semiconductor laser 2 are aligned.

When this optical axis alignment is completed, the ferrule 4 is fixed to the fiber saddle 6 near its rear end with solder 7.

Here, as shown in FIG. 1, since the support position by the support means 5a and 5b is close to the front end of the ferrule 4, the distance l from the front end of the optical fiber 3 to the support position is from the support position to the top of the fiber saddle 6. It is shorter than the distance 12 to the fixed position.

Therefore, even if the ferrule 4 is displaced at the fixed position due to deformation during solidification of the solder 7 when fixing the ferrule 4 as described above, the displacement of the front end of the optical fiber is very small.

That is, when the displacement of the ferrule 4 at the fixed position is X, the displacement X' of the tip of the optical fiber 3 is x'=L/β
It becomes 2.

As described above, according to the method of the present invention, the optical axis deviation of the optical fiber due to deformation when the solder solidifies is greatly reduced.

In addition, in the fixing method as described above, since the ferrule 4 is fixed near the rear end, the ferrule 4 is supported in a so-called cantilevered manner. Therefore, in practice, it is preferable that the vicinity of the front end of the ferrule 4, for example, the position where it is supported by the supporting means 5a and 5b, is separately fixed to the fiber saddle. In this case, since the ferrule 4 is already fixed, adjustments such as axis alignment are not necessary.

FIGS. 2(a) and 2(b) illustrate fiber saddle and ferrule shapes that may be used advantageously in practicing the present invention.

FIG. 2(a) shows a proposal for a shape near the front end of the ferrule, in which a pair of recesses 11 and 12 are formed on the side surfaces of the ferrule symmetrically with respect to the central axis of the ferrule. That is, this concave portion 11.12 is removed using a support device with a sharp tip.
The ferrule is configured so that it can be rotated in a certain direction by gripping the ferrule, and the supporting position does not shift when the ferrule is rotated.

Further, FIG. 2 0)) is a proposal regarding the shape of a fiber saddle, and is configured so that the fiber saddle can also be used as the above-mentioned support means.

That is, this fiber saddle is composed of a pedestal 13 for stably fixing the fiber saddle itself to the upper surface of a substrate, etc., and a ferrule support part 14 formed on this pedestal 13. A hole 15 for inserting a ferrule is formed as shown by the dotted line in the figure.

A feature of this fiber saddle is that the diameter of the hole 15 is formed to gradually increase as it approaches the opening at the end of the hole surface, which makes it easy to insert the ferrule into the fiber saddle and This allows for slight rotation. In other words, when actually aligning the optical axis of an optical fiber, the rough adjustment can be made by moving the position of the fiber saddle itself, so even if the ferrule inserted into the fiber saddle moves only slightly, the necessary adjustment can be made. Optical axis alignment is possible.

Effects of the Invention As detailed above, according to the method for fixing an optical fiber according to the present invention, in the work of fixing an optical fiber in an optical module, deformation of the adhesive such as solder itself during fixation of the optical fiber can be avoided. The effects of axis misalignment are minimized.

Therefore, the coupling efficiency of optical fibers in the optical module can be easily improved, and the performance of various optical systems can be improved.

Further, the work efficiency in fixing the optical fiber can also be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating a method of fixing an optical fiber according to the present invention, and FIGS. 2(a) and 2) illustrate a ferrule and a FIG. 3 is a diagram showing an example of a fiber saddle, and FIG. 3 is a graph showing the relationship between optical fiber axis misalignment and coupling efficiency in an optical module. [Main reference numbers] 1... Chip carrier, 2... Semiconductor laser, 3... Optical fiber, 4... Ferrule, 5a, 5b... Supporting means (supporting position), 6.8...・・・
Fiber saddle, 7...Solder, 1112...Recessed portion, Patent applicant Sumitomo Electric Industries, Ltd.

Claims (1)

[Claims] A method of fixing an optical fiber by attaching a ferrule near the end of the optical fiber and fixing the ferrule to a fiber saddle with an adhesive, the method comprising: supporting the ferrule from the side; , using support means that allows the ferrule to swing about the support position and to position the ferrule at the support position; first, the ferrule on the side closer to the end of the optical fiber; After adjusting the optical axis by moving the other second end of the ferrule while positioning the ferrule with the support means at a position sufficiently close to the first end, the ferrule is moved to the second end. A method for fixing an optical fiber in an optical module, the method comprising fixing an optical fiber to a fiber saddle using an adhesive in the vicinity thereof. (2) The method according to claim 1, wherein following the fixing operation of the ferrule near the second end, the first
A method for fixing an optical fiber in an optical module, characterized in that the ferrule is fixed to the fiber saddle with an adhesive also near the end.