JPH03114005A - Method for collating coated optical fiber - Google Patents

Abstract

PURPOSE:To extremely easily identify coated fibers without increasing an insertion loss by bending the part near the light input of a part for detecting the coated fiber to a specific bending radius and collating the coated fiber. CONSTITUTION:The coated optical fiber is collated by so bending the part near the light input of the part 3a for detecting the coated fiber 2 that the bending radius (r) attains 15D<=r<=35D (D denotes the diameter of the coated fiber) at the time of detecting the leak light of the coated fiber to collate the coated fiber by inserting the coated optical fiber into the photodetecting part 3a of a coated fiber collating device. The coated fiber 2 near the light input side of the detecting part is bent at the prescribed radius of bending, by which a clad mode or coating propagation mode is partly generated without imparting the increase of the propagation loss to the coated fiber 2 and, therefore, the quantity of leak light is increased and the collation of the coated fiber is execut ed even for the coated fiber with which the leak light is small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical fiber core comparison method for identifying each core wire in an optical fiber cable.

[Prior Art] Optical fiber cables are widely used as communication paths, and when constructing and maintaining the cables, it is necessary to identify each core wire in the optical fiber cables. Generally, when identifying a core wire that is propagating light, a core wire detector such as an ID sensor is used that receives leakage light emitted from the core wire, converts it into electricity using an APD, PD, etc., and displays it as an electrical signal. A vessel is used.

By the way, in such a fiber comparison method that receives leakage light, it is important to efficiently receive the leakage light without increasing the insertion loss of the fiber. Core wire comparison device (Japanese Patent Application Laid-Open No. 63-1459
No. 39) has been proposed.

This core wire comparator 10 bends and supports the core wire 20 inserted into the detection unit main body 3o by a plurality of support members 4o,
The leakage light emitted from the core wire is sensed by a light receiver 5o made of a linear photodiode, and the electric signal from the light receiver 50 is further judged by an identification device 60 or the like. This fiber optic device 1o is configured to refract the fiber and to make the side of the detecting section body facing the light receiver 50 a mirror surface so that leaked light can be efficiently received by the light receiver 50.

[Problems to be Solved by the Invention] However, the above-mentioned conventional fiber optics have a low coupling loss with the fiber optics, for example, ultraviolet curing resin coating (UV
), it is easy to perform fiber comparison for core wires such as 100% fiber, but it is necessary to perform fiber comparison for fibers that are resistant to bending, have little light leakage, or have a large coupling loss with a fiber calibrator. I couldn't do it.

[Object of the Invention] The present invention solves these conventional problems and makes it possible to perform fiber comparison extremely easily and without increasing insertion loss, even for fibers with little leakage light. The present invention aims to provide a method for comparing optical fiber cores.

[Means for Solving the Problems] The optical fiber core comparison method of the present invention that achieves the above object includes inserting an optical fiber core into a light receiving detection section of a fiber core detector and detecting leakage light from the core wire. When detecting and comparing the core wires, bend the core wire near the optical input of the detection section with a radius r of 15D.
The core wire is compared by bending it so that ≦r≦35D (D represents the diameter of the core wire).

By causing the core wire to bend in this manner, crut mode or sheath propagation occurs, and leakage light increases.

Here, the bending may be approximately semicircular, but it may be wound one or more times if necessary. If the bending radius r is less than 15D, the bending increases the transmission loss of the core wire, which is not preferable. on the other hand,
If the bending radius r is larger than 35D, hardly any bending effect can be obtained. Further, the bending may be done by simply bending and supporting by hand, or by using an appropriate jig.

The optical fiber core wire is coated with ultraviolet curable resin (UV
) Various types of core wires such as core wires and plastic-coated core wires can be used, but the method of the present invention is particularly effective for plastic-coated core wires that have a large coupling loss.

The fiber detector may be any device that inserts a core wire into a light receiving detection section and detects leakage light from the core wire.
A known device such as a D tester is used.

[Function] By bending the core wire near the light input side of the detection unit with a predetermined bending radius, it is possible to partially generate a cladding mode or coated propagation mode without increasing propagation loss in the core wire, thereby reducing the amount of leakage light. It is possible to perform fiber contrast even for a fiber with little leakage light.

[Example] Examples 1 to 3 Nylon coated core wire 1 (black) with a diameter of 0.9 mm (=D)
A core wire control experiment was conducted using a measurement system as shown in FIG. 1 using a length of 1000 m. As light source 2, the center wavelength is 1.3
0±0.03. A czm LED was used, and an ID tester 3 was used as a core calibrator for detecting leakage light. A substantially semicircular bent portion 4 was provided at a distance of 50 cm from the light input side of the detection portion 3a of the ID tester 3 (FIG. 2).

Furthermore, a power meter 5 was installed at the end of the core wire to monitor the increase in loss of the core wire. The bending radius r of the bending part 4 is 18D, 25D.
The results of the core control and the increase in loss when changing to 33D and 33D (Examples 1.2 and 3) are shown in the table.

Comparative Example 1 to Comparative Example 3 Using the same core wire as Examples 1 to 3 and using the same measurement system, the bending part was not provided (Comparative Example 1) and the bending radius of the bending part 4 was 8D and 45D (Comparative Example A core control experiment was conducted for the case 2.3). The results are shown in the table.

As is clear from the margin table below, it was not possible to compare the core wires when no bends were provided, but in Examples 1 to 3 where the prescribed bends were provided, no increase in loss was caused to the core wires. We were able to perform effective core contrast.

[Effects of the Invention] As is clear from the above examples, the fiber comparison method of the present invention can produce fibers with low leakage light that cannot be compared with conventional fiber comparison methods. However, fiber comparison can be performed very easily and effectively.

Further, according to the optical fiber core comparison method of the present invention, fiber core comparison can be performed without increasing loss in the core fiber, so that fiber core comparison can be performed without any problem even if the core wire is being used for communication.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a measurement system to which the fiber comparison method of the present invention is applied, FIG. 2 is a diagram showing the main part thereof, and FIG. 3 is a diagram showing a conventional fiber comparison device. 1... Core wire (optical fiber core wire) 2...
Light source 3...Fiber locator 3a...Light reception detection section 4...Bending (part)

Claims (1)

[Claims] When inserting an optical fiber into a light receiving detection section of a fiber compatibility device and detecting leakage light from the fiber to compare the fiber, bend the fiber near the light input of the detection section of the fiber with a radius r of 15D≦. r≦3
A method for comparing optical fibers, characterized in that the fibers are compared by bending the fibers to a diameter of 5D (D represents the diameter of the fiber).