JPH06289245A - Optical fiber coupler - Google Patents

Abstract

PURPOSE:To provide the optical fiber coupler variable in branching ratio or dividing characteristic by constituting an optical fiber of an expandable material consisting of a high-polymer material. CONSTITUTION:The spacing between arms 7a and 7b of the optical fiber coupler formed by using the optical fibers which are formed by using the high-polymer material, such a transparent plastic, and have expanding and contracting properties varied mechanism 5 for adjusting movable fixtures is properly adjusted. Movable fixing parts 4a, 4b connected with these arms 7a and 7b and stationary parts 6a, 6b vary as well and, therefore, tensile compressive force is applied on a fusing part 3 existing between the stationary parts 6a and 6b to fluctuate the stretching state of the fusing part 3, by which the branching ratio characteristic and dividing characteristic as the optical fiber coupler are changed. Since the optical fibers are made of the transparent plastic, the optical fiber coupler have the expanding and contracting properties and the failure of the coupler does not arise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a branching device for branching the power of light used in the field of optical communication or the like, or a branching device for splitting incident light of a plurality of wavelengths to a plurality of exit ports The present invention relates to an optical fiber coupler that functions as a demultiplexer that emits all monochromatic light.

[0002]

2. Description of the Related Art An optical fiber coupler is constructed by splicing a plurality of optical fibers in parallel at their substantially central portions (including the case of twisting), and heating and fusing these portions at the same time. , Is a basic component used for branching and coupling lines between optical transmission lines in optical communication systems. This optical fiber coupler is conventionally manufactured using a silica glass fiber.

[0003]

In the conventional optical fiber coupler, the branching ratio has wavelength dependence. For example, in an optical fiber coupler having two output side optical fibers,
Even if it is manufactured so that the output side optical fiber has an output ratio of 1: 1 at a wavelength of 1.3 microns, it should have a branching ratio of 4: 1 or more for light having a wavelength of 1.55 microns. There is. The wavelength dependence of the branching ratio value of the output side optical fiber is determined by the stretched state of the fusion splicing part during the manufacture of the optical fiber coupler, and the branching ratio characteristic of each optical fiber coupler is determined by the degree of stretching. In other words, the characteristics of the branching ratio are determined by the processing state at the time of manufacture, and it was not possible to change this while being used as a coupler. Further, in an optical fiber coupler having two output side optical fibers, composite light composed of light of a plurality of wavelengths from the input side optical fiber, for example, wavelengths λ1, λ
When light having a wavelength of 2 is incident, only the light having the wavelength λ1 can be output to one of the two output fibers and only the light having the wavelength λ2 can be output to the other by adjusting the stretched state of the fusion-bonded portion. It is also possible to function as a duplexer. However, the demultiplexing characteristics for the wavelengths λ1 and λ2 are also determined by the stretched state at the time of manufacture, like the above-mentioned branching ratio characteristic, so that any desired value can be obtained while using the optical fiber coupler.
It could not function as a demultiplexer for one wavelength.

An object of the present invention is to provide an optical fiber coupler having a variable branching ratio or a variable demultiplexing characteristic which has not been heretofore available as described above.

[0005]

The optical fiber coupler of the present invention, which has been made to solve the above problems, is an optical fiber coupler formed by splicing and fusing a plurality of optical fibers in parallel at substantially the center thereof. A mechanism for expanding or contracting the axial length of the optical fiber on both sides of the fused portion of the optical fiber, if necessary, by constructing an elastic member made of a polymer material in a part or all of the optical fiber. It is characterized by having attached.

The operation of the optical fiber coupler of the present invention will be described below.

[0007]

According to the present invention, a stretchable optical fiber made of a polymer material such as transparent plastic is used.
Unlike the quartz glass fiber, this has elasticity in the axial direction of the optical fiber, so that it will not be damaged even if a certain amount of tensile compression force is applied. In the optical fiber coupler made of these elastic materials, the stretched state can be adjusted by expanding and contracting the fused portion using the variable fixing tool during use. As a result, the stretched state can be adjusted at any time during use, so that the desired branching ratio and demultiplexing characteristics can be obtained.

[0008]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a sectional view of an embodiment of an optical fiber coupler according to the present invention. In this embodiment, an optical fiber coupler is formed by coupling two optical fibers made of transparent plastic. In the figure, 1a and 1b are input side optical fibers and 2a.
a and 2b are output side optical fibers, 3 is a fusion splicing part, 4a and 4b
Is a movable fixture, and 5 is a movable fixture adjusting mechanism. The input side optical fibers 1a, 2a and the movable fixture 4a are fixed parts 6a.
Then, the output side optical fibers 2a and 2b and the movable fixture 4b are fixed by an adhesive agent at the fixing portion 6b. The movable fixtures 4a and 4b have a cylindrical shape, and the outer diameter of 4a and the inner diameter of 4b are designed to be equal so that one end of 4a is inscribed in 4b. Is configured to be. The movable fixture 4a, 4b has an arm 7
a and 7b are attached and connected to the movable fixture adjustment mechanism 5. For the movable fixture adjusting mechanism 5, for example, a micrometer using a piezo element is used. This is an adjustment mechanism that utilizes the fact that the strain amount of the piezo element fluctuates according to an electric signal from the outside, and is suitable for controlling minute fluctuations. By interposing this piezo element between the arm 7a and the arm 7b and adjusting the amount of strain, the arm portion 7a,
The distance between 7b is adjusted.

The fusion-bonded portion 3 is formed by melting two optical fibers by a conventional method and simultaneously stretching them. That is, for example, one optical fiber is twisted to cross the other optical fiber, and the optical fiber is melted and stretched in the optical fiber axial direction while being heated by an oxyhydrogen flame. It is bonded to each other. At this time, the monitor light is incident from the incident side optical fiber, and the branching ratio as an optical fiber coupler in the state where no tensile compression force is applied by melting and stretching while measuring the output light at the output side optical fiber And other characteristics are determined.

In the optical fiber coupler configured as described above, when the movable fixture adjusting mechanism 5 is properly adjusted, the distance between the arms 7a and 7b varies. Then, the movable fixed portions 4a and 4b to which the arms 7a and 7b are connected and the fixed portions 6a and 6b also change, so that the fixed portions 6a and 6b.
A tensile compression force is applied to the fusion-bonded portion 3 located between b, and the fusion-bonded portion 3
The drawing state of the optical fiber changes, and the branching ratio characteristic, the demultiplexing characteristic and the like of the optical fiber coupler can be changed. At this time, since the optical fiber is made of transparent plastic, it has elasticity and is not damaged.

When it is desired to adjust the branching ratio to a desired value, monitor light is input from the input side optical fiber and the output side optical fiber is movably fixed while measuring the output light as in the manufacture of the optical fiber coupler. This can be facilitated by adjusting the tool adjusting mechanism.

In the above embodiment, the micrometer using the piezo element was used for the variable fixture adjusting mechanism.
Not limited to this, a manual micrometer may be used. An automatic adjustment mechanism that uses a stepping motor or the like as a positioning mechanism can be used when the adjustment is frequently changed or when it is desired to perform adjustment according to a change in an external signal.

[0014]

As described above, according to the present invention,
A fiber coupler is formed by using a stretchable optical fiber such as a transparent plastic, and the stretched state of the fused portion is made variable so that the branching ratio is variable, and for any wavelength. A demultiplexer having a demultiplexing ability is obtained. As a result, when changing the branching ratio and the demultiplexing characteristic, a plurality of branching devices and demultiplexing devices which were conventionally required are sufficient for the branching device and the demultiplexing device according to the present invention, and they need to be replaced one by one. It becomes easy because there is no problem.

Further, since the branching ratio and the like fluctuate depending on the expansion / contraction state (displacement) of the fusion-bonded portion, it is possible to make a displacement sensor or the like using this, and it can be applied to various applications.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an optical fiber coupler manufacturing apparatus of the present invention.

[Explanation of symbols]

 1a, 1b: Input side optical fiber 2a, 2b: Output side optical fiber 3: Fusion part 4a, 4b: Movable fixture 5: Movable fixture adjustment mechanism

Claims (1)

[Claims] 1. An optical fiber coupler formed by splicing and fusing a plurality of optical fibers in parallel at approximately the center thereof.
All or part of this optical fiber is constituted by a stretchable member made of a polymer material, and a mechanism for adjusting the length in the axial direction is provided on both sides of the fused portion of the optical fiber as needed. Attached optical fiber coupler.