JPH0429044B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method of manufacturing an optical splitter for an optical fiber cable used in an optical communication system, and in particular, it relates to a method for manufacturing an optical splitter for an optical fiber cable used in an optical communication system. It is also possible to branch signals, combine multiple optical signals into one optical signal, arbitrarily branch multiple optical signals to multiple terminals, or combine signals. The present invention also relates to a method for manufacturing an optical distributor.

[Prior Art] Conventionally, there are known types of optical splitters for optical fiber cables used in optical communication systems, such as multi-mode fiber couplers, single-mode fiber couplers, and polarization-maintaining fiber couplers.

Various manufacturing methods are known for manufacturing such optical distributors, such as a twist-stretch type, a side fused tapered type, and an eccentric core fiber fused type.

In the case of side-fused tapered type and eccentric core fiber type, the cladding layer of the optical fiber, which consists of a core layer in the center through which light propagates and a cladding layer with a lower refractive index than the core layer, is removed by etching or polishing. By doing this, the diameter is approximately 65 μm.
The first layer with almost the core layer exposed
The exposed core layer portion of the fiber and the exposed core layer portion of a second fiber processed in the same manner as the first fiber are brought close together and fused together, and light is incident on the fiber,
This is a method of manufacturing a light distributor by stretching the fused portion to achieve an arbitrary coupling ratio while monitoring the output light.

However, making two fibers thinner and then bringing only the extremely thin core layer exposed portions closer together involves bending the fibers at room temperature so that the core layer exposed portions are brought closest to each other. It is difficult to handle the fiber because it easily breaks due to stress caused by bending, and it is extremely difficult to fuse an area of about 2 mm in such an unstable state.

In the case of the twist-stretch type, for example, the cladding layer has been removed within a range of several millimeters to expose the core layer, and both ends of the two fibers are held in a cage on the headstock, and the cage is rotated to separate the fibers. Add a twist to the bundle. The exposed portion of the core is then heated using an oxyhydrogen burner. In this method, light is input into an optical fiber, and while the output light is monitored, the optical fiber is further twisted, fused, stretched, and connected to produce an optical distributor with arbitrary distribution.

However, when polarization-maintaining fibers are used, the direction of the stress-applying part of the polarization-maintaining fibers varies between the two fibers at the fused portion because the fiber bundle is twisted until an arbitrary distribution is achieved. Furthermore, by twisting the fiber, stress is applied to the core layer of the fiber from sources other than the stress-applying portion, making it impossible to output the incident light while maintaining its polarization plane.

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned problems, and there is no fear of the fiber breaking, and moreover, when a polarization maintaining fiber is used, the polarization plane of the incident light can be changed. The purpose of the present invention is to manufacture an optical distributor that can distribute light while maintaining the same.

[Means for Solving the Problems] The present invention makes a connection without fear of breakage by bending the fiber while softening it by heating. After bending the fiber while heating, the cladding layer at the tip of the bent portion is removed to expose the core layer, and the core layer of another optical fiber is fused and connected to the exposed core layer. This is a method of manufacturing a characteristic optical distributor.

[Detailed Description of the Invention] When bending an optical fiber, the optical fiber is heated and bent using a burner or the like at a temperature that softens the optical fiber and does not generate bubbles in the fiber.

Inside the bent portion, the core layer portion is enclosed within the cladding layer portion and connected into one. Therefore, if the cladding layer at the tip of this bent part is removed by polishing, etching, or cutting,
A portion of the core layer inside is exposed. An optical fiber with an exposed core layer portion to be connected to this exposed core layer portion is prepared, and after the core layer portion of this optical fiber is aligned with the exposed core layer portion, the optical axis is aligned with the exposed core layer portion. , and connect them by fusing them together. At this time, connections are made by fusing and stretching while monitoring to achieve an arbitrary bonding ratio, thereby producing a light distributor.

For connection, a 2:1 optical splitter can be created by connecting one optical fiber with its core layer exposed to the bent and exposed optical fiber, and a 2:1 optical splitter can be created by connecting the bent and exposed optical fibers together. A 2:2 light splitter or even more light splitters are manufactured.

The optical fiber optical splitter that is bent and connected in this manner is further covered with a cover to prevent damage.

Such an optical splitter is one of the fiber optic cables.
Branching one optical signal into multiple signals, merging multiple optical signals into one optical signal, or arbitrarily branching multiple optical signals to multiple terminals. or a combined signal.

[Example] 1 to 5 in FIG. 1 are schematic diagrams illustrating the steps of an example of the method for manufacturing an optical distributor of the present invention.

In 1 of FIG. 1, 1 is a multimode optical fiber in which the outer diameter of the cladding layer 2 is 125 μm and the diameter of the core layer 3 is 50 μm.

First, the optical fiber 1 is heated by the burner 4, and as the optical fiber begins to soften, both ends thereof are bent in directions A and A'.

2 in FIG. 1 is a perspective view of the optical fiber 1 of FIG. 1 shown in FIG. 1 bent at an angle of 180° and overlapped with each other. It is included in part 2 and connected to one piece.

The cladding layer portion 2 beyond the tip of the core layer portion 3 of the bent portion 5 is removed by polishing along lines C and C', and a portion of the core layer 3 is exposed.

3 in FIG. 1 shows the core layer portion 3 at the tip of the bent portion 5 of the optical fiber 1 manufactured according to 2 in FIG. 1 exposed.

Reference numeral 4 in FIG. 1 indicates two sets of optical fibers for connecting the core layer portion 3 of the optical fiber 1 shown in 3 in FIG. 1, 1' to connect both optical fibers 1,
1' shows a state in which optical axis alignment is being performed.

5 in FIG. 1 heats and fuses the two sets of optical fibers 1 and 1' shown in 4 in FIG.
It shows a state where it is slightly stretched and connected in the D′ direction.

[Effects of the Invention] Since the optical distributor manufactured by the optical distributor manufacturing method of the present invention is made by bending a single optical fiber while softening the fiber by heating, the connecting core layer portion Since the fibers are completely connected and the fibers are not made thinner, they are easier to handle.

Furthermore, since the end faces of the folded portions of the fiber bundle are fused together, the fused area is smaller than that in the fiber side fusion method, which facilitates positioning during fusion and enables uniform fusion.

In polarization-preserving couplers, when bending the polarization-maintaining fiber, the direction of the stress-applying part can be determined arbitrarily, and since it does not twist as in the twist-stretching method, there is no stress on the core layer other than the stress-applying part. Stress can be reduced.

As a result, the optical splitter obtained by the method of the present invention can branch one optical signal of an optical fiber cable into multiple signals while efficiently maintaining the plane of polarization, or can split multiple optical signals into one. You can combine multiple optical signals into one optical signal, or arbitrarily branch multiple optical signals to multiple terminals.
Alternatively, it is useful as an optical splitter that can produce combined signals.

[Brief explanation of drawings]

1 to 5 in FIG. 1 are schematic diagrams illustrating the steps of an embodiment of the method for manufacturing an optical distributor of the present invention. 1,1'...optical fiber, 2...cladding layer,
3, 3'...core layer, 4...burner, 5...bending portion.

Claims (1)

[Claims] 1. A first optical fiber having a core layer in the center and a cladding layer formed on the outside thereof is heated and bent at an acute angle, and then the cladding layer at the tip of the bent portion is removed and the core layer is removed. Another second optical fiber is placed on the bending center line of the first optical fiber with this layer exposed, and the exposed portions of the core layers of the first and second optical fibers are brought close to each other on the bending line. 1. A method for manufacturing an optical distributor, characterized in that the optical distributor is connected by 2. The method of manufacturing an optical distributor according to claim 1, wherein the bending portion is formed while heating the optical fiber while stretching the tip of the bending portion. 3. The method for manufacturing a light distributor according to claim 1 or 2, wherein after fusion bonding, fusion stretching is carried out while monitoring to obtain an arbitrary bonding ratio.