JPH02127604A - Manufacture of fiber type coupler - Google Patents

Abstract

PURPOSE:To improve the breaking strength of the fiber type coupler by incorporating carbon in combustion gas and burning the gas, and forming a carbon film on the surface of the drawn part of a glass member. CONSTITUTION:When a coupler member is formed by fusing and drawing >=2 optical fibers 1 and 2 from which films are removed by a burner 4 which is supplied with the combustion gas to heat the fibers, at least carbon is incorporated in the combustion gas to form the carbon film on the surface of the drawn part of the coupler member. In this case, when the burner 4 is arranged above the drawn part A and a heat-resisting flat plate 5 is arranged opposite the burner 4 by pinching the drawn part A, the temperature of the flame is lowered to suppress wind pressure, thereby adjusting the combustion state. The burner 4 is supplied with the carbon-containing combustion gas and oxidizing gas individually through flow rate valves, etc., so the flow rate can be adjusted individually. Consequently, the breaking strength of the fiber type coupler which deteriorates owing to the presence of a flaw, etc., is increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a burner that heats at least two or more tip fibers from which the coating has been removed by receiving a supply of combustion gas.
The present invention relates to a method of manufacturing a fiber coupler, which forms a coupler member by fusing and stretching.

[Conventional technology]

Fiber-type couplers have the function of branching/combining light of a single wavelength or splitting/combining light of multiple wavelengths, and the manufacturing methods include the fusion drawing method in which fibers are fused together and stretched. There is a polishing method in which two fibers with polished side surfaces are placed facing each other.

FIG. 4 shows a method for manufacturing a fiber coupler according to the prior art (
5 is a flowchart showing the fusion drawing method ("5TA
BLE LM-LO8S 5INGLE-140DE
C0IJl'LER8゜ELECTRONIC9LET
TER315th March 1984 Vol, 2
0No., 8 p., 230-232). A fiber coupler using, for example, a single mode fiber will be described below.

First, the coatings of two optical fibers are partially removed and the first fibers are brought into close contact with each other (step 101). Next, by heating with a burner or the like, this part is fused in parallel, and then stretched in the optical axis direction (step 102
). In this case 1, the optical branching ratio is detected by measuring the light incident from one end of the optical fiber at the other end (step 103). When a predetermined branching ratio is obtained, the stretching of the optical fiber is stopped and a coupler member is formed (step 104). Next, this coupler member is fixed and adhered to the protective part (O) to form a fiber type coupler (step 105).

In addition, as another conventional technique, there is a method in which two optical fibers are heated and stretched in a twisted state without being fused or stretched. A study of a method for manufacturing a piconical taper type optical splitter).

[Problem to be solved by the invention]

All fiber-type couplers according to the prior art are fixed to a protective member with an adhesive or the like, but after stretching, the diameter of the stretched portion is reduced to less than 20 μm, which is approximately 1 µm of the outer diameter before stretching.
It will be close to 1/0.

However, when fixing to this protective member, it is necessary to hold the extended portion in a straight line to prevent branching or changes in the branching state, so it is necessary to apply a certain tension to the extended portion.

However, when fixed to a protective member with a certain tension applied, if there is a slight flaw in the stretched part, the stress applied to the stretched part becomes large due to the small outer diameter, and the fiber coupler breaks. There was a problem.

The breakage phenomenon of fiber couplers is due to the growth of scratches on the surface of the optical fiber due to the addition of stress. The growth of this wound is
In an atmosphere such as water vapor, it is promoted by contaminants present in the atmosphere.

Therefore, an object of the present invention is to improve the breaking strength of a fiber coupler by coating the extended portion of the fiber coupler with a carbon film.

[Failure to solve the problem]

In order to achieve the above object, the present invention provides a fiber type coupler in which at least two optical fibers from which the coating has been removed are fused and stretched to form a coupler member using a burner that is supplied with combustion gas and heated. The manufacturing method is characterized in that combustion gas contains at least carbon and is combusted to form a carbon film on the surface of the extended portion of the coupler member.

In this case, it is effective to arrange a heat-resistant flat plate at a position facing the burner, sandwiching the extended portion, and adjust the combustion state of the flame of the burner.

Further, the carbon film can be formed before the optical fiber is fused, before it is stretched, during or after it is stretched.

[Effect]

Since the present invention is configured as described above, gaseous carbon covers the extended portion of the fiber coupler by combustion of the carbon-containing combustion gas, thereby coating the extended portion. Therefore, the breaking strength of the fiber coupler that has deteriorated due to the presence of scratches or the like is strengthened.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a fiber coupler according to an embodiment of the present invention will be described below with reference to the accompanying drawings. In the description, the same elements are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 is a flowchart showing a method for manufacturing a fiber coupler according to an embodiment of the present invention, and FIG. 2 is a process chart showing a process for manufacturing a fiber coupler.

In step 201, a part of the coating of the optical fiber core wire 1.2 is removed, and the optical fiber 1as2b from which the coating has been removed is placed in close contact with the optical fiber 1.2 (see FIG. 2(a)).

In step 202, a heating device 3 such as a burner is used to fuse the adhered portion 17 and stretch it in the optical axis direction (see Fig.
)reference).

In step 203, in the process of fusing and stretching,
The optical branching ratio is detected by measuring the light incident from one end of the optical fiber at the other end.

In step 204, when a predetermined branching ratio is obtained, the stretching and fusing of the optical fibers is stopped, and a coupler member having a stretched portion A is formed (see FIG. 2(c)).

In step 205, the combustion gas contains at least carbon and is burnt after stretching to form a carbon film on the surface of the stretched portion of the coupler member (see (d) in the same figure). Specifically, a carbon-containing combustion gas and an oxidizing gas are simultaneously supplied to the burner 4, and the elongated portion A is brought into contact with the combustion flame to form a carbon film. In this case, the burner 4 is placed above the extension part A, and the heat-resistant flat plate 5 is placed opposite the burner 4, sandwiching the extension part A, so that the temperature of the flame decreases and wind pressure is suppressed. combustion conditions can be adjusted. This heat-resistant flat plate 5 is made of quartz glass or the like. Since the burner 4 is supplied with carbon-containing combustion gas and oxidizing gas through separate pipes via flow valves, etc., the flow rates can be adjusted individually.

In step 206, the coupler member is fixed to the protective member 6 with a coupling agent such as Evoquin resin or ultraviolet curing resin,
A fiber coupler is formed (see FIG. 2(e)).

According to this embodiment, it is possible to coat the stretched portion with a carbon film, and it is possible to prevent deterioration of the breaking strength due to an atmosphere such as water vapor that promotes the growth of flaws on the fiber surface.

Note that this invention is not limited to the above embodiments. For example, in this embodiment, a carbon film is formed after stretching, but a carbon film may be formed (carbon coat) before fusing the optical fiber, before stretching, or during stretching.

Furthermore, a carbon film can be formed on the stretched member by reciprocating a burner (flame) along the optical axis of the optical fiber.

In this case, it is more effective to reciprocate while rotating the optical fiber around its optical axis.

Furthermore, the burner may be inclined at a certain angle with respect to the optical axis of the optical fiber to moderate the jet flow of the combustion flame.

Moreover, instead of reciprocating the burners, a plurality of burners may be arranged along the optical axis direction. The temperature gradient in the stretching portion can be reduced, and the excessive loss of the fiber coupler can be reduced.

Furthermore, the carbon-containing combustion gas is not limited to acetylene. For example, alkanes such as methane, ethane, and propane, olefins such as ethylene and propylene, acetylene, aromatic compounds such as benzene, methanol,
It may contain carbon-containing compounds such as alcohols such as ethanol, oxygen-containing compounds other than alcohols such as acetone and dimethyl ether, and halogen-containing compounds such as tetrachloromethane and chloroform.

Note that the present invention can also be applied to a fiber coupler that twists and stretches a plurality of optical fibers.

Next, experimental results of the fiber coupler according to the above embodiment will be explained. This experiment shows whether a carbon film is formed depending on the ratio of carbon-containing combustion gas to oxidizing gas. In this experiment, acetylene (c2H2) was used as the carbon-containing combustion gas and oxygen was used as the oxidizing gas.
A burner with a hole diameter of 0.2 mm was used by moving it back and forth along the optical axis direction at a rate of 10 cm/min. Burners were arranged at intervals of 3 mm in the direction perpendicular to the optical axis of the optical fiber with respect to the stretching section, and quartz glass plates with a thickness of 1 mm were arranged at intervals of 1 mm so as to face the burners. In this experimental device, it has been confirmed that if there is no quartz glass plate, the extended portion will be destroyed by the wind pressure of the combustion flame. The presence or absence of carbon film formation was confirmed using a Raman spectrum and an electron microscope (SEM).

In Experiment A, acetylene was fed at 20 cm3/min and oxygen was fed at 10 cm3/min.
In experiment B, acetylene was supplied at a flow rate of 0 m3/min.
4 cm/min, oxygen was supplied at a flow rate of 1.0 crr+3/min, and in experiment C, acetylene was supplied at a flow rate of 13 cm 2 /min and oxygen at a flow rate of 100 m 3 /min. According to the above experimental examples, it was confirmed that in experimental examples A and B, a carbon film was formed on the surface of the stretched portion.

In the Raman spectrum of Experimental Example A, 1360 Cm” and 1
A peak value appeared at 590 cm −1 , indicating that graphite carbon was formed on the surface. Furthermore, in the electron micrograph, it was confirmed that scale-like carbon was attached to the fiber surface. In Experimental Example B, adhesion of carbon was also confirmed.

According to this experiment, the flow rate ratio of oxygen and acetylene was 1.
If the ratio is 0:(14 to 20), a carbon film can be formed.

〔Effect of the invention〕

Since this invention is configured as explained above,
By coating the extended portion of the fiber coupler with a carbon film, the breaking strength of the fiber coupler can be improved.

Therefore, deterioration of the strength of the fiber due to water vapor or the like can be prevented, and a highly reliable fiber coupler can be manufactured.

Particularly, it is effective in the manufacturing method of fiber type couplers such as branch/multiplexers, branch/multiplexers, etc. used in the field of optical communications.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing a method for manufacturing a fiber coupler according to an embodiment of the present invention, FIG. 2 is a process diagram showing a manufacturing process of this fiber coupler, and FIG. 3 is an experiment according to the present invention. FIG. 4, a diagram showing the results, is a flowchart showing a method for manufacturing a fiber coupler according to the prior art. 1.2...Optical fiber core wire 3...Heating device 4...Burner 5...Heat-resistant flat plate 6...Protection member How to manufacture fiber coupler Part 1 Go to Figure 1 Go to 2 Go to 3＼ノ4 to 51＼ 6 to method (cm3/min) Experimental results Figure 3 Conventional technology not shown

Claims (1)

[Claims] 1. A method for manufacturing a fiber-type coupler, in which a coupler member is formed by fusing and stretching at least two or more optical fibers with their coatings removed using a burner that heats them by supplying combustion gas. A method for manufacturing a fiber coupler, characterized in that the combustion gas contains at least carbon and is combusted to form a carbon film on the surface of the extended portion of the coupler member. 2. The method of manufacturing a fiber coupler according to claim 1, further comprising disposing a heat-resistant flat plate at a position facing the burner and sandwiching the extending portion to adjust the combustion state of the flame of the burner. 3. The method for manufacturing a fiber coupler according to claim 1, wherein the burner is reciprocated along the optical axis direction of the optical fiber to bring the flame into contact with the entire coupler member.