JPH03157605A - Method for identifying optical fiber - Google Patents

Abstract

PURPOSE:To avert the effect of an adverse influence upon the optical fiber circuit under operation even if this circuit is erroneously subjected to an identification operation by applying ultrasonic oscillation to the optical fiber from the outside thereof. CONSTITUTION:Ultrasonic waves are applied from the outside of the optical fiber 1 to the identifying part 5 at the intermediate point in the longitudinal direction of the optical fiber 1 by an ultrasonic wave applying device 6. This applying device 6 is designed to allow the modulation of the intensity and phase of ultrasonic oscillation by changing the intensity and period of ultrasonic oscillation by means of a controller 10. Even if ultrasonic oscillation are applied to the other optical fiber 1 during use, this method is of an intensity modulation/ direct detection system and, therefore, no adverse influences are exerted at all upon the circuit. The optical fiber 12 for input and the optical fiber 13 for output are connected by a looped wire 14 in a folding station 11. The optical circuit under operation is kept free from the adverse influence even if this circuit is subjected to the identifying operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is applicable, for example, to selecting required optical fibers (including optical fiber cores and tape cores) from among a large number of optical fibers in a laid optical cable. ) is related to a method for identifying a destination fiber.

(Prior Art) With the development of communication networks, various multi-core optical cables are being installed in conduits, building ducts, and the like. A large number of optical fibers are housed within such an optical cable.

If you take out one of these many optical fibers and perform construction work such as a back branch midway in the longitudinal direction, it is necessary to take out the optical fiber that branches at that branch point. Usually, optical fibers are distinguished by color, so they can be identified to some extent by the color, but since the connections may cross in the middle, identification becomes difficult when the number of fibers increases. Moreover, when carrying out construction or repair work on optical cables, it is necessary to distinguish between optical fibers that are being used and optical fibers that are not being used at the construction site.

Conventionally, the optical fiber identification method in such cases was as follows:
There was a method of bending an optical fiber to leak light from it and detecting the leaked light. This identification method was designed to identify the optical fiber in operation without cutting it, and was very convenient because it allowed the optical fiber to be identified while it was in operation.

(Problems with the Prior Art) However, since the above-mentioned identification method bends the optical fiber, if the end fiber in operation is accidentally bent, the line in operation will be affected by loss fluctuations and other adverse effects. In the worst case, a bit error could occur.

(9, Aim of Light) The purpose of the present invention is 2. To realize a method for identifying the destination fiber 11 that can search for the optical fiber required for transport without adversely affecting the line in operation. 3. .

(F stage to solve problems) The present invention applies the principle of the optical system 7 shown in FIG.

The light in Figure 2? In the system 15, when one nose beam from [4D7 is input into a single mode optical fiber (5M fiber) 8 and the light intensity is detected through a transverse photon 9 on the receiving side,
When the polarization state of the LI) light (angle 2 phase of the polarization F axis, etc.) changes in the 5M fiber 8, the detected output optical power changes.・The level fluctuation of the second output light power depends on the polarization state of the output light.Incidentally, in FIG. ':ri field is expressed as follows.

U x "a, e'Q" E, = a, e' am, ay: x @, Rolling wheel δ on 3' axis, λ axis, y
The phase difference ω at the axis and the angular frequency is 1:, and the received power of the light through analysis f9 at the assumed X-axis and principal axis angle θ is expressed by the linear equation 9 1) (θ ) = am” CI) S”θ+ay”sin
``θ+2am a, cosOsinOcnsδ In other words, the received light power P is a function of the principal axis angle θ.

The optical fiber identification method and identification device of the present invention apply the -V principle of the optical system.

The destination fiber identification method of the present invention is to transmit polarized light to the destination fiber 1 of a large number of destination fibers as shown in FIG. By applying vibrations such as sound waves, the polarization state of the polarized light in the groove fiber 7 to fiber 1 is changed, and from the level fluctuation of the output light from the same optical fiber 1 that occurs due to this fluctuation, It is characterized in that it is distinguished from other destination fibers.

(Function) In the optical fiber identification method of the present invention, vibrations such as ultrasonic waves are applied from the outside to the grooved fiber 1 midway in the long hair direction (for example, at a branch point) of any optical fiber l among a large number of optical fibers. At this time, the same optical fiber is used! The angle of the principal axis of polarization of the polarized light transmitted through the optical fiber, the polarization state of the 1i7 phase, etc. vary, and the level of the output optical power emitted from the same optical fiber varies. In this case, if vibrations such as ultrasonic waves are applied to the optical fiber to be searched, the power of the output light passing through the analyzer of the optical fiber will fluctuate, so the desired fiber can be selected from among the many end fibers in the optical cable. l can be identified.

(Example) FIG. 1 is an explanatory diagram of the destination fiber identification method of the present invention.

In the figure, 2 is a light source that generates linearly polarized light (if the light source is not linearly polarized, insert a polarizer to make it linearly polarized)
, 3 are polarization variation light receiving sections that receive light transmitted through the optical fiber 1, and these are provided in the transmitting/receiving station 4. A single mode optical fiber is used as the optical fiber l.

Reference numeral 6 denotes an ultrasonic wave applying device, which is used to apply ultrasonic waves to the grooved fiber l from outside the optical fiber 1 at the identification portion 5 in the middle of the optical fiber l in the long hair direction. This ultrasonic wave applying device 6 is configured so that the intensity and period of ultrasonic vibration can be changed by a controller 10 to perform intensity modulation and phase modulation.

In this case, since the current optical communication system uses an intensity modulation/direct detection method, even if polarization fluctuation occurs in the line in use, it does not have any effect. In other words, even if ultrasonic vibration is applied to another optical fiber in use, there will be no adverse effect on that line.

Reference numeral 11 in FIG.
Connected by 4.

According to an experiment conducted by the inventors, in the experimental system shown in Fig. 3, a stranded fiber 15 with an outer diameter of 0.4 mm was used. 7i in the middle of Iil+5 in the longitudinal direction! 1
When ultrasonic vibration was applied to 5, Doyu fiber bare wire 15
The fluctuations in the received power of the light received through the analyzer 9 are as shown in FIG.

(Effects of the Invention) The optical fiber 1 alternative method of the present invention applies ultrasonic vibration to the optical fiber 1 from the outside, so there is no need to cut or bend the optical fiber 1. Even if you accidentally perform another operation on a line that is currently in operation, it will become a fiber line! ! ! Shadow W cannot reach it.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an example of the identification method of the present invention, Fig. 2 is an explanatory diagram of polarization plane fluctuation in an optical system, and Fig. 3 is an explanatory diagram of an example of the identification method of the present invention.
FIG. 4 is an explanatory diagram of an experimental system of another method, and is an explanatory diagram showing fluctuations in output optical power when ultrasonic vibration is applied to the experimental system of FIG. 3. 1 is an optical fiber 2 is a light source 3 is a polarization variation light receiving section 4 is a transmitting/receiving station 5 is an identification section 6 is an ultrasonic wave applying device

Claims (1)

[Claims] Transmit light to any optical fiber 1 among a large number of optical fibers, and apply vibrations such as ultrasonic waves to the optical fiber 1 from outside the optical fiber 1 to change the polarization state within the optical fiber 1. The optical fiber identification method is characterized in that the same optical fiber 1 is identified from other optical fibers based on the level fluctuation of the light emitted from the same optical fiber 1 that occurs with this fluctuation.