JPH01154007A - Production of optical fiber coupler - Google Patents

Abstract

PURPOSE:To obtain an optical fiber coupler which decreases losses at the time of synthesizing the light powers of plural input light rays by bringing the ends of auxiliary optical fiber in tight and parallel contact with a main optical fiber and welding the tight contact part, then heating and stretching the welded part. CONSTITUTION:The ends of the auxiliary optical fibers 2 are first brought into tight and parallel contact with the main optical fiber 1 and the right contact part 3 is welded to form the welded part 4; finally, the welded part 4 is heated and stretched. The (m+n):m optical fiber couplers are obtd. if the number of the main optical fiber 1 is (m) and the number of the auxiliary optical fibers 2 is (n). Since the welded and stretched part 4 is formed in the tight contact part between the ends of the main optical fiber 1 and the auxiliary optical fibers 2 in such a manner, the coupling of the light powers takes place in this part. All the signal light rays inputted from the respective input parts except the excess loss components are thereby guided to the output part, by which the effective utilization of the light powers is enabled. The losses are decreased at the time of synthesizing the light powers of the plural input light rays.

Description

[Detailed Description of the Invention] Overview This invention relates to a method for manufacturing an optical fiber coupler made by fusing and stretching optical fibers, and aims to provide an optical fiber coupler that has a small loss when combining the optical power of multiple input lights. , the end of the auxiliary optical fiber is brought into close contact with the main optical fiber in parallel, the joined part is fused, and then the fused part is heated and stretched.

1. Field of Industrial Application The present invention relates to a method for manufacturing an optical fiber coupler by fusing and stretching optical fibers. “In the field of optical communication that uses optical fiber as a transmission path, multiple channels of multiplexed signal light are introduced into a single optical fiber in order to distribute the transmitted optical signal to multiple devices or for multiplex transmission. In order to Practical optical couplers are required to (a) have low optical power loss when inserted into an optical circuit, and (b) be easy to handle and have high reliability under operating environmental conditions. Things, etc.

Conventional technology Conventionally, optical couplers include micro-optical system types constructed using optical elements such as lenses and half mirrors, waveguide types, and optical couplers that fuse multiple (for example, two) optical fibers together.・Fiber fused types made by stretching are mainly used. Especially when the optical transmission line is a single-mode optical fiber, if it is a micro-optical type or a waveguide type, there will be a large loss when converting the light beam or when connecting with the optical transmission line. It is said that a fiber fusion type optical coupler (herein referred to as a Central American fiber coupler) that can be directly connected to an optical transmission line is advantageous.

FIG. 6 is an explanatory diagram of a conventional method of manufacturing an optical fiber coupler. Optical fibers 51 and 52 are closely attached in parallel, fused by heating means such as a burner 53, and stretched in the six directions of arrows to form a fused/stretched portion.

The optical fiber coupler manufactured by the above-mentioned manufacturing method is composed of input parts 61 and 62, output parts 63 and 64, and a fusing/stretching part 65, as shown in FIG. 7, for example. If the branching ratio of this optical fiber coupler is a and excess loss and isolation can be ignored, the input section 6
The optical power is P from 1 or 62. When the signal light of
Optical power aP, (1-a)P from output section 63.64
.

signal light is output. With this configuration, it is possible to connect directly to a single-mode optical fiber, so there is little optical power loss, and since the only component is the optical fiber, it is highly reliable against usage environmental conditions such as temperature and humidity. It can be said that.

Problem 1 to be Solved by the Invention: No problem occurs when the optical fiber coupler described above is used for splitting optical power as shown in FIG. 7, but when combining optical power as shown in FIG. When used for
The following problems arise.

That is, this optical fiber coupler is, for example, a 3 dB optical coupler (
When the branching ratio a=0.5), a signal light with optical power P1 is input from the input section 61, and a signal light with optical power P1 is input from the input section 62.
When two input lights are input, these signal lights are combined and output from the output parts 63 and 64 respectively with optical power (P + P2
)/2, it is necessary to handle combined light whose optical power is substantially reduced to 1/2, resulting in a problem of large losses.

The present invention was created in view of these problems.
The object of the present invention is to provide an optical fiber coupler that has low loss when combining the optical powers of multiple input lights.

. The problem with the above-mentioned conventional technology for solving the problem is f! of an optical fiber coupler whose principle is shown in FIG. A method of production is determined.

The manufacturing method for this optical fiber coupler is as follows: First, as shown in Figure (a), the end of the sub optical fiber 2 is closely attached to the main optical fiber 1 in parallel, and then as shown in Figure (b), the end of the sub optical fiber 2 is closely attached. The parts 3 are fused to form a fused part 4, and finally, the fused part 4 is heated and stretched as shown in FIG.

In the figure, the number of main optical fibers 1 and sub-lights 2 is 1, and in the end, the number of input sections is 2 and the number of output sections is 1.
Although a 2:1 optical fiber coupler is illustrated, the present invention is not limited to this, and it goes without saying that the number of main optical fibers or sub optical fibers may be two or more.

Effect According to the manufacturing method of the present invention described above, the number of main optical fibers is m.
When the number of sub-optical fibers is n, (m+n): m
You can get an optical fiber coupler.

Surface wave energy (Evanes
In optical fiber couplers that utilize field coupling (cent energy), optical power is transferred through an electric field that is perpendicular between the cores, and the surface wave energy is exponential with the distance from the core. Because it decreases to
Effective coupling requires the cores to be very close together. In the present invention, since the fused and stretched portion is formed in the close contact portion between the ends of the main optical fiber and the sub optical fiber, coupling of optical power occurs in this portion. Therefore, in the manufactured optical fiber coupler, all of the signal light input from each input section, except for excess loss, is guided to the output section, allowing effective use of optical power.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 2 is an explanatory diagram of the manufacturing process of an optical fiber coupler manufactured by applying the present invention. First, as shown in FIG. 2(a), the end of the sub-optical fiber 3 from which the sheathing material 14 has been removed is closely attached in parallel to the main optical fiber 1 from which the sheathing material 12 has been removed by an appropriate length (for example, several cttr). The joints are fused together using a conventional splicing technique such as arc discharge. 15.
Reference numeral 16 denotes an electrode when fusion bonding is performed by arc discharge.

In the same figure (b), 17 indicates the fused portion formed by the above method, and 18 indicates the optical fiber 11.
．． This is a fused portion formed by the same method as the fused portion 17 in the longitudinal direction of 13 at a different position. The reason why a plurality of fused parts are formed in this way is to prevent the optical fibers 11 and 13 from being separated from each other when forming a stretched part in the next step.

Next, as shown in FIG. 2C, while heating the fused portion 17 corresponding to the end of the sub optical fiber 3 with a heating means such as an H-02 burner 19, the main optical fiber 1 and the sub optical fiber The stretched portion 20 is formed by stretching 3 in the left-right direction in the figure. During this stretching operation, it is desirable to actually monitor the optical power output from the output section so that a desired branching ratio is achieved and excess loss is minimized.

In order to reduce the excess loss, the taper skewer in the stretching section 20, that is, the rate of change in cross-sectional area in the length direction of the stretching section can be made small.

Note that when the main optical fiber 11 and the sub-optical fiber 13 are single-mode optical fibers, the effect of reducing loss is remarkable, but the present invention can also be applied to step-index type or graded-index type multimode optical fibers. Applicable.

FIG. 3 is an explanatory diagram of another embodiment of the present invention, and FIG. 4 is a cross-sectional explanatory diagram taken along the rV-rV line in FIG. 3.

In this embodiment, the ends of three sub-optical fibers 32, 33, and 34 are tightly attached in parallel around the main optical fiber 31, and fused and stretched in the same manner as in the previous embodiment. According to this embodiment, since optical power coupling occurs between the main optical fiber 31 and the sub optical fibers 32, 33, 34 at the fusion/stretching section, a 4:1 optical fiber coupler is provided. Can be done.

FIG. 5 is a diagram for explaining still another embodiment of the present invention, and is a sectional view of a portion corresponding to FIG. 4. In this embodiment, three main optical fibers 41, 42, 43 are closely connected to each other, and three auxiliary optical fibers 44, 45 are placed around them.
．． The ends of 46 are tightly attached in parallel. According to this embodiment, it is possible to provide a 6:3 optical fiber coupler.

As described above, by providing various optical fiber couplers having different numbers of input sections and output sections according to the present invention, loss can be reduced and, as a result, optical power can be used effectively.

Effects of the Invention As detailed above, according to the manufacturing method of the present invention, since the fusion splicing and stretching are performed with the end of the sub-optical fiber closely attached parallel to the main optical fiber, the input section It is possible to provide an optical fiber coupler having a different number of output parts, and therefore it is possible to reduce the loss when combining the optical power of a plurality of input lights.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the principle of the present invention. Fig. 2 is an explanatory diagram of the manufacturing process of an optical fiber coupler showing an embodiment of the invention. Fig. 3 is a main optical fiber and a sub optical fiber showing another embodiment of the invention. FIG. 4 is a sectional view taken along the TV-TV line in FIG. 3, FIG. 5 is a sectional view showing still another embodiment of the present invention, and FIG. 6 is a conventional manufacturing method of an optical fiber coupler. FIG. 7 is an explanatory diagram of a conventional optical fiber coupler, and FIG. 8 is an explanatory diagram of problems with the conventional technique. 1.11.31.41°42.43...Main optical fiber, 2.13.32.33°34.44,45.46...Sub optical fiber, 3...
Adhesive part, 4.17.18... Fusion part, 20.
...Extension part. , thing 5 day moon 0. Principle Figure 1 Figure 31 ・Main Yufu Ding IJ\゛32.33,34° Subi F i'i IY''Y's Eastpube column Diagram Figure 330r:f, -keyr Explanation of Prime Number Wealth l Figure 4 Further 1 Niin 5 Ning [U 434 row 1 Figure 5 Sub 1 (A row S Figure 6 Ie [2] Domii 7 + J βq Open title branch, Hachi Ming concave Figure 8

Claims (2)

[Claims] (1) After the end of the sub-optical fiber (2) is brought into close contact with the main optical fiber (1) in parallel and the adhesion part (3) is fused, the fused part (4) is heated and stretched. A manufacturing method for a featured optical fiber coupler. (2) A plurality of the fused parts are formed in the longitudinal direction of the main optical fiber (1) and the auxiliary optical fiber (2), and one of these fused parts is formed at the extreme end of the auxiliary optical fiber (2). 2. The method of manufacturing an optical fiber coupler according to claim 1, wherein the fused portion is heated and stretched.