JP2004077233A - Optical fiber pair identifying method and device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber pair identifying method for identifying the pair of fibers without causing a bend loss. <P>SOLUTION: While identifying light enters from a light source 1 into an optical fiber 5 as a subject, an arbitrary location of the optical fiber 5 is oscillated, only an intensity change component having the same polarization direction as return light generated by the identifying light, passes through and is detected by a light receiver 4 through a polarizer 3 for interrupting other components, and the optical fiber 5 is identified. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber contrast method and an optical fiber contrast device used therefor, and is particularly useful when used in construction and maintenance of an optical fiber cable network.
[0002]
[Prior art]
When constructing and maintaining an optical fiber communication network, it is necessary to identify the optical fiber in the manhole (closure), the premises (cabinet), or the site (cable termination) at the work site. This operation is referred to as a cord control, and is usually performed by a method as shown in FIG. This is because a fiber optic reference light (hereinafter referred to as reference light) is incident from the light source 1 installed on the upstream side of the target optical fiber 5, and the optical fiber 5 is bent downstream of the optical fiber 5 using the bent portion 8. In this method, the control light is emitted from the side of the optical fiber while bending, and the light is detected by the light receiver 4 '. In this method, bending is applied to the optical fiber, so that bending loss is inevitable. In particular, an optical fiber cord or a nylon core wire used in a place or a premises has a thick coating, and the bending radius must be reduced in order to emit more control light. As a result, the bending loss increases. In the case of an optical fiber cord or a nylon core wire having a thick coating, even if the bending radius is reduced, it is difficult to reliably control the cords, and they may be damaged. Also, in the case of optical fiber cords and nylon cores in service, the transmission quality may be deteriorated due to the large bending loss.
[0003]
[Problems to be solved by the invention]
As described above, in the conventional optical fiber control, bending loss is unavoidable because the optical fiber is bent, and it is necessary to increase the radiated power of the control light especially in an optical fiber cord with a thick coating or a nylon optical fiber. However, the bending radius must be smaller than that of the thin coated ribbon. As a result, the bending loss may be increased and the transmission quality may be degraded. Further, when an optical fiber cord or nylon core wire having a thick coating is gripped by a bent portion having a small bending radius, there is a problem that the coating or the optical fiber is damaged.
[0004]
An object of the present invention is to provide an optical fiber contrast method capable of performing optical fiber contrast without causing bending loss, and an optical fiber contrast apparatus used in the optical fiber contrast apparatus.
[0005]
[Means for Solving the Problems]
The configuration of the present invention that achieves the above object has the following features.
[0006]
1) In an optical fiber contrast method for specifying a target optical fiber from a plurality of optical fibers,
While the control light is incident on the target optical fiber from the light source, the polarization direction of the return light generated by the control light is changed by applying an external force to an arbitrary position of the target optical fiber,
By passing the return light through a polarizer that transmits only a specific polarization direction, an intensity change occurs in the return light, and the target optical fiber is specified by detecting the intensity change.
[0007]
2) In the optical fiber contrast method described in 1) above,
Applying an external force to an arbitrary portion of the optical fiber so as to vibrate the return light so as to generate a periodic intensity modulation signal.
[0008]
3) In an optical fiber contrast device for specifying an optical fiber of interest from a plurality of optical fibers,
A light source that emits contrast light toward the optical fiber to be compared with the optical fiber,
An optical coupler that causes the control light emitted by the light source to enter the optical fiber, and guides the return light of the control light reflected by the reflection end of the optical fiber to the polarizer,
Of the return light incident through the optical coupler, only a component having the same polarization direction as this passes, and a polarizer that blocks the other,
A light receiver for receiving the return light via the polarizer and detecting the intensity thereof.
[0009]
Embodiment
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0010]
FIG. 1 is a block diagram showing an optical fiber contrast device according to an embodiment of the present invention. In the figure, 1 is a light source, 2 is an optical coupler, 3 is a polarizer, 4 is a light receiver, 5 is an optical fiber, 6 is a reflection end, and 7 is amplitude motion. Here, the light source 1 emits control light. This control light is incident on the optical fiber 5 via the optical coupler 2. The polarizer 3 allows only return light having the same polarization direction to pass therethrough and blocks the others, and is configured such that return light from the reflection end 6 of the optical fiber 5 enters via the optical coupler 2. It is. The return light passing through the polarizer 3 is received by the light receiver 4. Further, the optical fiber 5 is configured so as to be able to perform amplitude movement.
[0011]
In the present embodiment, when performing the core wire contrast, first, the control light is transmitted from the light source 1. The transmitted reference light enters the optical fiber 5 via the optical coupler 2. When an external force is applied to the optical fiber 5 by the gentle amplitude motion 7 with respect to the optical fiber 5 while the control light is being transmitted, the polarization direction of the return light from the reflection end 6 fluctuates. The fluctuating return light is guided from the optical coupler 2 to the polarizer 3 and received by the light receiver 4. Here, since the polarizer 3 allows only the return light having the same polarization direction to pass therethrough and blocks the others, the passing power of the return light also changes with time according to the change in the polarization direction caused by the amplitude motion 7. I do. The change is detected by the light receiver 4 to perform a core line comparison.
[0012]
Here, a verification experiment of the optical fiber contrast method according to the above embodiment will be described with reference to FIG. 2, reference numeral 1 denotes a light source, 2 denotes an optical coupler, 3 denotes a polarizer, 4, 4 ″ denotes a light receiver, 5 ′ denotes an optical fiber code, and 7 denotes an amplitude motion. A continuous light of 1.55 μm was transmitted, and was incident on the optical fiber cord 5 ′ of about 1 km via the optical coupler 2. In the state where the control light was transmitted, the vicinity of the far end of the optical fiber cord 5 ′ was gradually loosened manually. Then, a temporal change of the amount of light returning from the connector end face 6 'and passing through the polarizer 3 was measured by the light receiver 4. At the same time, the control light transmitted through the optical fiber cord 5' was measured. The level change was measured by the light receiver 4 ″.
[0013]
FIG. 3 shows the measurement results of the verification experiment. In the figure, 9 is the transmitted light power in the light receiver 4 ″, 10 is the return light power detected by the light receiver 4 in a state where the amplitude movement 7 is not given, and 11 is the light power in the state where the amplitude movement 7 is given. As shown in the figure, when the gentle amplitude motion 7 is not manually applied, the power of the return light in the light receiver 4 is substantially constant.
On the other hand, when the gentle amplitude motion 7 is manually applied, a fluctuation of about 12 dB occurs between the maximum value and the minimum value. It is sufficiently possible to perform a core wire comparison by detecting this variation. Here, the transmitted power of the control light detected by the light receiver 4 ″ hardly changes regardless of the presence or absence of the amplitude motion 7. This means that there is no loss associated with the amplitude motion 7.
[0015]
As described above, in the present embodiment, by applying an external force to the optical fiber 5, the polarization direction of the return light is changed, and a change in the passing power of the return light having the same polarization direction as the polarizer is detected. It can be seen that the optical fiber 5 can be reliably compared. Further, it can be seen that even if this method is applied to an optical fiber in service, no loss occurs, so that transmission quality is not degraded.
[0016]
Needless to say, it is possible to perform a center line contrast by generating a periodic intensity modulation signal as the amplitude motion 7 and detecting the return light with the light receiver 4 ″.
[0017]
【The invention's effect】
As described in detail with the above embodiments, according to the present invention, the polarization direction of the return light is changed by applying an external force to an arbitrary position of the optical fiber, and the return direction having the same polarization direction as the polarizer is provided therein. A change in light passing power can be detected. As a result, it is possible to reliably control the core without causing bending loss, which is inevitable in the conventional core control method, and to achieve a desired core without deteriorating the transmission quality even with an optical fiber under service. Control treatments can be performed. In addition, it is possible to reliably perform the core wire comparison without damaging the optical fiber cord or the nylon core wire having a thick coating.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an optical fiber contrast device according to an embodiment of the present invention.
FIG. 2 is a block diagram showing an apparatus used for a verification experiment for verifying the effect of the embodiment.
FIG. 3 is a characteristic diagram showing a result of the verification experiment shown in FIG.
FIG. 4 is a block diagram illustrating an embodiment of an optical fiber contrast method according to the related art.
[Explanation of symbols]
Reference Signs List 1 light source 2 optical coupler 3 polarizer 4, 4 ', 4 "light receiver 5 optical fiber 5' optical fiber cord 6 reflection end 6 'connector end face 7 amplitude motion 9 transmitted light power detected by light receiver 4' 10 light receiver 4 Return light power detected by (when amplitude motion 7 is not applied)
11 Return light power detected by light receiver 4 (when amplitude motion 7 is applied)

Claims (3)

In an optical fiber contrast method for identifying an optical fiber of interest from a plurality of optical fibers,
While the control light is incident on the target optical fiber from the light source, the polarization direction of the return light generated by the control light is changed by applying an external force to an arbitrary position of the target optical fiber,
By passing the return light through a polarizer that transmits only a specific polarization direction, a change in intensity occurs in the return light, and the target optical fiber is identified by detecting the change in intensity. Characteristic optical fiber contrast method. In the optical fiber contrast method according to claim 1,
An optical fiber contrast method, wherein an external force is applied to an arbitrary portion of an optical fiber, and the return light vibrates so as to generate a periodic intensity modulation signal. In an optical fiber contrast device that specifies an optical fiber of interest from a plurality of optical fibers,
A light source that emits contrast light toward the optical fiber to be compared with the optical fiber,
An optical coupler that causes the control light emitted by the light source to enter the optical fiber, and guides the return light of the control light reflected by the reflection end of the optical fiber to the polarizer,
Of the return light incident through the optical coupler, only a component having the same polarization direction as this passes, and a polarizer that blocks the other,
A light receiver for receiving the return light passing through the polarizer and detecting the intensity of the return light.

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