JP5031469B2 - Optical fiber upper / lower judgment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable determination of upper part/lower part of an optical fiber with high accuracy without needing carrying of a wiring state diagram of optical fiber core wires or the like or acquiring operation of optical fiber state in a working site while minimizing the effect of measuring error. <P>SOLUTION: A determination light signal from a light source 6 disposed in a communication base station is incident on the other end (core) of an optical fiber 1, optical power of leaked light at an optical fiber connecting point 3 at which respective one-side ends of optical fibers 1 and 2 are mutually connected is measured, and the side larger in optical power is determined as a lower part of the optical fiber when the communication base station is taken as an upper part, and the side lower in optical power as an upper part of the optical fiber. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an optical fiber installed between a communication base station and a subscriber's house or between communication base stations or a communication base station in an installed optical fiber or any one of the communication base stations as an upper part. It is related with the technology which judges the upper part and the lower part.

  Conventionally, when building an optical fiber communication network, or when determining the upper or lower part of an optical fiber at a work site such as the upper part of an electric pole or underground roadway after construction, It was done by preparing and carrying drawings with recorded arrangements, and grasping the status of optical fiber cores used at the work site and whether they were taped in advance. There was a problem that it took.

In addition, as a method for determining the upper and lower portions of a conventional optical fiber, the optical fiber is bent, and the optical power of light leaking from the bent portion is measured from the upstream side and the downstream side with respect to the peak position of the bent portion. There is a method of determining the upper and lower portions of the optical fiber from the difference (see Patent Documents 1 and 2).
JP 2004-325334 A Japanese Patent No. 3711121

  However, in the conventional determination method using the leaked light described above, the difference in the optical power of the leaked light is only about 5 dB, and there is a possibility of erroneous determination due to a measurement error or the like.

  The present invention has been proposed in view of the above-described problems, and eliminates the need to carry the optical fiber core wiring state diagram and the like and to grasp the state of the optical fiber at the work site, and is less susceptible to measurement errors. An object of the present invention is to provide a method capable of determining the upper and lower portions of an optical fiber with high accuracy.

In order to solve the above-described problem, in the present invention, leaked light generated by leakage of a part of light propagating through the core of the optical fiber to the outside of the optical fiber on both sides of the connection point of the optical fiber by the mechanical splice element. The optical power is measured, and the side with the higher optical power is determined as the lower part and the side with the lower optical power is determined as the upper part.

According to the present invention, it is not necessary to carry the optical fiber core wire wiring state diagram or the like and to grasp the state of the optical fiber at the work site, and unlike the both sides of the bending portion, the connection point of the optical fiber by the mechanical splice element Since the difference in the optical power of the leaked light on both sides of the optical fiber is about 10 to 15 dB, it is difficult to be influenced by the measurement error, and the upper and lower portions of the optical fiber can be determined with high accuracy.

  In order to explain the principle of the present invention, the state of light propagation at an optical fiber connection point is shown in FIG. In the figure, 1 and 2 are optical fibers, 3 is an optical fiber connection point, 11 and 21 are cores of optical fibers 1 and 2, 12, 22 are claddings of optical fibers 1 and 2, and α1 is propagated through the core of optical fiber 1. , Α2 is the light propagating through the core of the optical fiber 2, α3 is the light propagating through the cladding or the coating (not shown) (cladding mode), and α4 is the light leaking outside the optical fiber (leakage) Light).

  From the relative refractive index difference between the core 11 and the clad 12, the core propagating light α1 confined in the core 11 propagates in the optical fiber 1 and reaches one end of the optical fiber 1 and exits (from the core 11). The light is incident on one end (core 21) of the optical fiber 2 connected via the optical fiber connection point 3, and is confined in the core 21 as described above, and propagates as transmitted light α2.

  At this time, a part of the core propagation light α1 emitted from one end (core 11) of the optical fiber 1 is scattered due to a gap between the one ends of the optical fibers 1 and 2 at the optical fiber connection point 3, an axial deviation, an angular deviation, and the like. -Leakage, and a part of it is coupled to the clad 22 of the optical fiber 2 and converted into a clad mode α3 propagating outside the core.

  The cladding mode α3 propagating outside the core of the optical fiber is less confined in the optical fiber than the light α1 and α2 propagating through the core, and therefore easily leaks to the outside of the optical fiber through a coating (not shown). The leakage light α4.

Light power P _in the core propagating light α1 described above, between the light power P _u of the optical power P _c and the cladding modes α3 of the transmitted light α2 is

The optical power P _u of the cladding mode α3 is expressed as follows. When the connection loss at the optical fiber connection point 3 is α _s ,

It can be expressed as.

If the coupling efficiency when the leakage light α4 due to the cladding mode α3 is received by the optical power meter is η _u , the optical power P _l when the leakage light α4 is measured by the optical power meter is

It becomes.

Here, when the coupling efficiency η _u is assumed to be 1 and the optical power P _in of the core propagation light α1 is assumed to be 0 dBm, the relationship between the leakage light power P _l and the connection loss α _s is calculated as shown in FIG. It can be seen that the leakage light power decreases as the connection loss decreases.

  In the present invention, the above-described experiment has found that the above-described leakage light power is different between the upper part and the lower part of the optical fiber connection point. Therefore, the upper and lower parts of the optical fiber are determined based on the difference in the leakage light power.

  In the experiment, as shown in FIG. The upper part of the mechanical splice element indicated by symbols (A), (B), and (C) in the state in which 652 single-mode fibers are used and these are mechanically spliced using the mechanical splice element 4 and the mechanical splice connecting tool 5. The connection loss is reduced by changing the distance between the end faces of the optical fibers 1 and 2 in the mechanical splice element 4 with the optical power meter for the leakage light power at the center and the lower part (ie, the upper part of the optical fiber, the connection point and the lower part). It was measured by changing. The experimental results are shown in FIG.

  FIG. 4 shows that the leakage light power is (c)> (b)> (b) for each connection loss, and the difference between the values of (b) and (c) is about 10 to 15 dB. . The reason for this is that the central part (b) of the mechanical splice element 4 has a smaller gap for light leakage than (b) and (b), and the upper part (b) of the mechanical splice element 4 has a connection point. It is considered that the reflected light of the leaked light is dominant and the leaked light leaks directly at the lower part (c) of the mechanical splice element 4.

  FIG. 5 shows a configuration for realizing the optical fiber upper / lower determination method of the present invention based on the above principle. In the figure, 1 and 2 are optical fibers connected at one end thereof, and 3 is an optical fiber. An optical fiber connection point for connecting the fibers 1 and 2, 6 is arranged at a communication base station (not shown), and a means for inputting an optical signal for determination into the optical fiber 1, specifically, the other end of the optical fiber 1 A light source connected to Reference numerals 7 and 8 denote means for measuring the optical power of the leaked light, here known optical power meters, and the light receiving portions on both sides of the optical fiber connection point 3 are connected to the optical fibers 1 and 2 (covering). Used in close proximity or in contact.

  Here, the determination optical signal may be any optical signal that is not significantly attenuated in the optical fibers 1 and 2. For example, if the optical fibers 1 and 2 are not yet in operation, the communication base station Alternatively, an optical signal for communication at a subscriber's house may be used.

  In the above-described configuration, the optical signal for determination from the light source 6 is incident on the other end (core) of the optical fiber 1, and the optical power of the leaked light is measured by the optical power meters 7 and 8, respectively. It can be determined that the side with the higher optical power is the lower part of the optical fiber when the communication base station is taken as the upper part, and the lower side is the upper part of the optical fiber.

  The above description is for determining the upper and lower parts of the optical fiber when the communication base station in the optical fiber installed or installed between the communication base station and the subscriber's home is the upper part. It is also possible to determine the upper and lower portions of the optical fiber installed between the communication base stations or in this case. In this case, the light source 6 is arranged and the communication base station on the side on which the determination optical signal is incident The upper and lower portions of the optical fiber are determined.

  The above explanation corresponds to the case where the optical fibers 1 and 2 are before the start of operation, and no communication base station or communication device in the subscriber's home is connected to the other end. The optical fiber 1 and the light source 6 are coupled using a known optical coupling means such as an optical coupler, and an optical signal for determination from the light source 6 enters the optical fiber 1 for communication from a communication base station. What is necessary is just to superimpose on an optical signal. At this time, as the optical signal for determination, an optical signal having a wavelength different from that of the optical signal for communication in the communication base station or the subscriber's house and modulated at a predetermined frequency is used. It suffices to receive only the modulated light.

  In addition, here, the optical power of the leaked light on both sides of the connection point of the optical fiber is measured simultaneously using two optical power meters, but it is measured separately by switching the arrangement of one optical power meter. You may do it.

Diagram explaining the behavior of propagating light at an optical fiber connection point Graph showing the relationship between leakage optical power and splice loss The figure explaining the experimental system for showing that determination of the upper part and the lower part of an optical fiber is possible by the method of the present invention Figure showing experimental results The figure which shows the structure of the upper / lower part determination method of the optical fiber of this invention

Explanation of symbols

  1, 2: Optical fiber, 3: Optical fiber connection point, 11, 21: Cores of optical fibers 1, 2, 12, 22: Clad of optical fibers 1, 2, 6: Light source, 7, 8: Optical power meter, α1, α2: Core propagation light, α3: Cladding mode, α4: Leakage light.

Claims (2)

Install the communication base station between the communication base station and the subscriber's home or between the communication base stations with a connection point by a mechanical splice element or install the communication base station in the installed optical fiber or any one of the communication base stations It is a method of judging the upper and lower parts of the optical fiber when
Disposed communication base station or one of the communication base station, means for entering the optical signal for determining the optical fiber,
With means for measuring the optical power of the leaked light generated by leaking a part of the optical signal for determination propagating through the core of the optical fiber to the outside of the optical fiber,
The optical power of the leaked light on both sides of the connection point of the optical fiber by the mechanical splice element is measured, respectively, and the upper side of the optical fiber is determined to be the lower side and the lower side of the optical power. Lower judgment method. In the optical fiber upper / lower determination method according to claim 1,
It said optical signal for the determination has different optical signals and the wavelength for communication, and the upper and lower determination method for an optical fiber, characterized in that it is modulated at a predetermined frequency for the optical fiber in operation.

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