JPS61290410A - Optical fiber type distribution circuit and its production - Google Patents

Abstract

PURPOSE:To increase mechanical strength, to permit easy handling and to stabilize optical characteristics by covering the outside circumferential part of the tapered region of an optical fiber bundle where the bundle is stretched by heating, with a dielectric material. CONSTITUTION:A gas for glass raw material from an arrow 12 is fed from the central nozzle of a burner 8 of concentrical quadruple pipes, gaseous Ar from an arrow 10, gaseous H2 from arrow 11 and gaseous O2 from an arrow 9 on the outermost circumference, respectively. The optical fiber bundle 5 is twisted several times in an arrow 14 direction and the central part thereof is heated by the burner 8; further the bundle is stretched toward an arrow 13 direction while the bundle is twisted. The light from a light source 3 is detected by a photodetector 7 and the operation is stopped when the light intensity of all the fibers is approximately equal. Since the outside circumferential surface of the stretched part 15 is covered with the glass, the stretched part is protected by the large outside diameter and the high mechanical strength is obtd. The optical characteristics are thus stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an optical distribution circuit that distributes an optical signal transmitted through an optical fiber to a plurality of optical fibers, and a method for manufacturing the same.

[Background of the invention]

With the rapid development of optical fiber transmission technology, research and development of optical data links that use optical fibers for data transmission between computers or between one computer terminal and another are being actively conducted. In configuring this optical data link,
An optical star coupler is an essential device that can mix optical signals from a plurality of input optical fibers and distribute them evenly and with low loss to a plurality of output optical fibers.

Conventionally, a typical example of an optical star coupler is the piconical taper type shown in Figure 1 (see pages 324-325 of the 1st printing of ``Optical Communication Handbook'' edited by Hisayoshi Yanai, published by Chokoku Shoten, September 1, 1982). .

29, by twisting and stretching a large number of optical fibers 1 while heating, fusing them together, and forming a tapered region 2 in the center, an input optical fiber (with a tapered region 2 The optical signal from the left side) is distributed to a plurality of output optical fibers (the right side of the tapered region 2).

Note that in the figure, arrows indicate the traveling direction of the optical signal. As a heating source for this optical fiber bundle, an oxyhydrogen burner, an oxypropane burner, an electric furnace, an arc discharge device, etc. are usually used. In the optical star coupler with this structure, the outer diameter of the tapered region 2 is very small (for example, when there are several optical fibers, it is several tens of μm to several hundred μm, and even when the number of optical fibers is about 100, it is several hundred μm). ), it is easy to break during work.

Also, if it is heated too much, it may melt. Furthermore, the optical characteristics vary depending on the surface condition of the tapered region 2. In addition, OH ions, transition metal ions, alkali metals, earth metal ions, etc. contained in the air or flame are likely to mix in, increasing insertion loss. Furthermore, slight fluctuations in the flame tend to disturb the shape of the spacing region, that is, the light distribution ratio tends to be disturbed. It was found that the yield was very low and there were problems with reproducibility and mass production. [Object of the Invention] The object of the present invention is to provide an optical fiber type distribution circuit and a method for manufacturing the same that solves the above-mentioned gap problem. There is a particular thing. That is, the present invention provides an optical fiber type distribution circuit that has high mechanical strength, is easy to handle, and has good optical properties, and a method for manufacturing the same.

[Summary of the invention]

The optical fiber type distribution circuit and its manufacturing method of the present invention include:
Twist the fiber optic bundle while heating it.

When fusing and stretching, a gas containing a dielectric material (e.g., glass) raw material is sprayed onto the heated portion of the optical fiber bundle, or
Or use oxygen in an oxyhydrogen burner for heating.

This is a method in which a gas containing hydrogen and a dielectric material (e.g., glass) raw material is fed, a flame containing dielectric material (e.g., glass) fine particles is generated by flame hydrolysis, and this flame is sprayed onto the optical fiber bundle. As a result, the above optical fiber bundle is twisted and fused.

While stretching, the outer peripheral surface of the optical fiber bundle is coated with a dielectric material (
For example, it is covered with glass). Therefore, compared to the conventional method, the outer diameter of the tapered region is increased and is reinforced and protected by a dielectric material, so that increased mechanical strength and good optical properties can be obtained.

[Embodiments of the invention]

FIG. 2 shows an embodiment of the optical fiber type distribution circuit of the present invention. In this example, a case will be described in which glass is used as the dielectric material. This figure shows an example of a method of manufacturing a 4-to-4 port type optical distribution circuit when both λ and the number of output ports are 4. 6 is the base and 4a.

4b grabs the optical fiber bundle 5 and arrow 14a.

This headstock has a mechanism that rotates in the direction 14b and a mechanism that extends in the directions of arrows 13a and 13b. Reference numeral 3 denotes a light source for inputting light from the end of one of the optical fibers in the optical fiber bundle 5. 7 is a photodiode detector for detecting the light intensity at the output end of the optical fiber. 8 is a burner, which in this case has a concentric quadruple tube nozzle structure, in which frit gas is fed into the center nozzle as shown by arrow 12, and Ar gas is fed into the first nozzle provided outside the nozzle. H2 gas was fed into the second nozzle outside the first nozzle as shown by arrow 11, and 02 gas was fed into the outermost nozzle as shown by arrow 9. Here, as the glass raw material gas,
5ICQ4 was fed with Ar gas as a carrier gas. First, as a manufacturing method, the arrow 14a is attached to the optical fiber bundle 5.
, 14b, rotate and twist several times.

Next, an oxyhydrogen flame containing glass raw material gas is generated,
The center of the optical fiber bundle is heated. The optical fiber bundle softened by heating is further stretched in the directions of arrows 13a and 13b while being twisted in the manner described above. When the light intensities at the output ends of the optical fibers become approximately equal, twisting and stretching are stopped and the burner flame is extinguished. Since the outer circumferential surface of the twisted, fused, and stretched portion 15 is covered with glass, the outer diameter does not become as thin as in the conventional case. The glass coating acts as reinforcement, protection, and stabilization of optical properties. This coating is effective even if it is thin like a membrane. Here, as the glass raw material gas, a silicon compound including a halide, an alkylate, a hydride, a silicon compound containing a refractive index controlling compound, etc. can be used. For example, 51CQ
In addition to 4, S i (QCz H5)4. S i (
GeCQ 4y POCQ as a dopant added to control the refractive index such as OCH3)4゜5i84 etc.
3°B(○C2H3)3, etc.

FIG. 3 shows another embodiment of the optical fiber type distribution circuit of the present invention. This connects the optical fiber bundle 5 to the glass tube 1
8 and heating the glass tube 18 with the oxyhydrogen burner 16, the optical fiber bundle 5 in the glass tube 18 is heated.
In this method, an optical fiber distribution circuit is formed by thermally softening the optical fiber bundle 5, and twisting, fusing, and stretching the optical fiber bundle 5 according to the softening. Here, 17a and 17b are holding devices that hold the glass tube 18. 19a and 19b are holes provided in the glass tube 18, and the inside of the nozzle 2Oa is indicated by the arrow 12.
The glass raw material gas sent in the direction a is passed through the hole 19a.
It is introduced through the hole 19b and exhausted through the hole 19b. 20
b is a nozzle for discharging exhaust gas in the direction of arrow 12b. Note that instead of the glass tube 18, a U-shaped, V-shaped
Character shape.

Alternatively, by using half-split glass tubes and blowing the frit gas from the open portions of these tubes, it becomes easier to form a glass film on the tapered region.

The glass film preferably has a refractive index equal to or lower than the refractive index of the cladding portion of the optical fiber.

FIG. 4 shows an embodiment of the optical fiber type distribution circuit of the present invention. This is an example of a 2-to-2 port optical fiber coupler. la, lb are input port fibers, lc,
ld is an output boat fiber, and 2I is a glass coated on the outer periphery of the tapered region 2. 22 is a sealing adhesive for fixing the optical fiber bundle within the glass tube 18.

The invention is not limited to the above embodiments. For example, Figure 2,
In FIG. 3, more than one burner (including a ring burner) may be used. The optical fiber may be a quartz fiber, a multicomponent fiber, or a plastic fiber. The glass tube may be a Vycor glass tube or a multi-component glass tube in addition to a quartz glass tube. Further, a glass tube containing a refractive index controlling dopant, for example, a glass tube in which a glass layer containing the above-mentioned dopant is formed on the inner surface of the glass tube may be used.

Further, the outer periphery of the glass tube may be coated with a water-resistant glass film. The number of optical fibers may be any number as long as it is two or more. In FIG. 3, the glass raw material gas may be introduced by providing a hole 19a in the lower part of the glass tube. Alternatively, it may be introduced from one end of the glass tube. Furthermore, in FIG. 4, by introducing a polymer gas or liquid through the hole 19a and heating the glass tube 18, the outer peripheral surface of the glass coating 21 is further coated with the polymer. Mechanical strength may be reinforced. For example, an ultraviolet curing resin may be introduced and the outer peripheral surface of the glass coating 21 may be coated with the resin by ultraviolet irradiation.

Note that a certain degree of reinforcing effect can be obtained by coating with the resin described above instead of coating with glass.

The method for introducing the ultraviolet curable resin is to introduce it in a liquid (or gas) state through the hole 19a, and after wetting the tapered area with the liquid (or in the case of gas, after wiping it on the tapered area), it is introduced through the hole 19b. It is discharged and then cured by ultraviolet irradiation to form a polymer film on the outer peripheral surface of the tapered region. If you want to make the film thicker, you can increase the viscosity of the liquid or repeat the above process many times.

The headstocks 4a and 4b may be moved not only in both directions 13a and 13b, but also in only one direction, 13a or 13b. Further, the optical fiber bundle 5 may be twisted only in either 14a or 14b, instead of in both directions 14a and 14b. Also, the burners 8.16 are 13 of the headstocks 4a and 4b.
By similarly moving in either the direction of 13a or the direction of 13b as a and 13b move, light can be equally distributed without the outer diameter of the central portion of the tapered region becoming thinner.

In FIG. 4, the glass tube 18 may be filled with resin to alleviate mechanical vibrations and shocks.

〔Effect of the invention〕

According to the present invention, there are the following effects.

(1) Since the outer periphery of the tapered region is coated with a dielectric material, it has high mechanical strength and is easy to handle.

(2) Since the outer diameter of the above-mentioned tapered region is particularly large, it is stable against mechanical vibrations and impacts.

(3) Since the tapered region is covered with a dielectric material, there is almost no deterioration in optical characteristics even if impurities adhere to the surface. Furthermore, radiation loss is also reduced, resulting in low loss characteristics.

(4) Since a tapered region is formed and covered with a dielectric material, the outer diameter as a whole does not become thinner than in the past, so unnecessary deformation of the tapered region due to flame fluctuations can be suppressed, and as a result, the distribution It is possible to obtain an optical fiber type star coupler with small variations. In addition, for the above reason, it can be performed with good reproducibility, so it is possible to reduce costs through mass production.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional optical fiber type distribution circuit, FIGS. 2 and 3 are explanatory diagrams of an embodiment of the method for manufacturing an optical fiber type distribution circuit of the present invention, and FIG. 4 is an optical fiber type distribution circuit of the present invention. This is an example of a distribution circuit. 1.1a-1d...Optical fiber, 2...
・Tapered region, 3...Light source, 4a, 4b...
... Headstock, 5 ... Optical fiber bundle, 6 ...
...Base, 7...Photodiode array detector, 8, 16...Burner, 9-12...
...Arrows indicating the direction of gas introduction, 13a, 13b...
...Arrows indicating the direction of movement of the headstock, 14a, 14b.
...Arrow indicating the twisting direction of the optical fiber bundle, 15
...... Tapered region covered with glass, 17a
, 17b... Holding device, 18... Glass tube, 19a, 19b... Hole, 20a, 20b
······nozzle. 12a, 12b...Arrow indicating the flow direction of gas, 21...Glass, 22...Adhesive. Representative Patent Attorney Masao Ogawa Figure 1

Claims (1)

[Claims] 1. In an optical fiber type distribution circuit in which a tapered region is formed by twisting, fusing, and stretching the central portion of an optical fiber bundle consisting of a plurality of optical fibers while heating the tapered region. An optical fiber distribution circuit characterized in that the outer periphery of the circuit is covered with a dielectric material. 2. The optical fiber type distribution circuit according to claim 1, wherein the dielectric material is made of glass, a high molecular weight polymer, or a composite material thereof. 3. The optical fiber type distribution circuit according to claim 1, wherein the refractive index of the dielectric material is equal to or lower than the refractive index of the cladding portion of the optical fiber. 4. The optical fiber according to claim 1, wherein the processed portion of the optical fiber bundle is inserted into a glass tube or into a U-shaped, V-shaped, or half-split glass container. shape distribution circuit. 5. A method for manufacturing an optical fiber type distribution circuit in which a tapered region is formed by twisting, fusing, and stretching the central part of an optical fiber bundle consisting of a plurality of optical fibers while heating,
Manufacture of an optical fiber type distribution circuit characterized in that during heating processing of the optical fiber bundle, a gas containing a dielectric material raw material is blown onto the heating section to cover the tapered region with the dielectric material. Method. 6. The method of manufacturing an optical fiber type distribution circuit according to claim 5, wherein the dielectric material is glass. 7. The light according to claim 6, characterized in that a silicon compound consisting of a halide, an alkylate, a hydride, or a silicon compound containing a refractive index controlling dopant is used as the glass raw material gas. A method of manufacturing a fiber type distribution circuit. 8. A method for manufacturing an optical fiber type distribution circuit in which a tapered region is formed by twisting, fusing, and stretching the central part of an optical fiber bundle consisting of a plurality of optical fibers while heating,
When heating the optical fiber bundle, a gas containing oxygen, hydrogen, and a dielectric material raw material is sent to a heating oxyhydrogen burner, and a flame containing dielectric material particles is generated by flame hydrolysis. A method of manufacturing an optical fiber type distribution circuit, which comprises spraying the optical fiber bundle to form a dielectric material. 9. A method of manufacturing an optical fiber type distribution circuit according to claim 8, wherein the dielectric material is glass. 10. The light according to claim 9, characterized in that a silicon compound consisting of a halide, an alkylate, a hydride, or a silicon compound containing a refractive index controlling dopant is used as the glass raw material gas. A method of manufacturing a fiber type distribution circuit.