JP3129831B2 - Optical line identification method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for identifying an optical line used for optical communication at an end thereof.

[0002]

2. Description of the Related Art As a method for identifying an optical line, the refractive index of a core of the optical line is partially changed, and the position of this change is referred to as OTDR.
A method of detecting at the end of a line using a measuring method is known (The 1991 Autumn Meeting of the Institute of Electronics, Information and Communication Engineers, Document B-59).
1 "Remote fiber identification method for optical line database").

[0003]

However, according to this method, the identification code portion provided on the optical line extends over several hundred meters. For example, in the example in the above-mentioned document, recording an 8-bit identification code on an optical line requires 50 m per bit and a total length of 400 m. Therefore, it is difficult to attach an identification code to an optical line having a short length. Also, in order to record an identification code over several hundred meters on an optical line, this must be performed during the manufacturing process of the optical line, which is not practical.

[0004]

In order to solve such a problem, an identification method according to the present invention comprises providing a plurality of reflectors on an optical line, and determining the relative positions of the plurality of reflectors for each optical line. By changing the combination to form an identification mark, the relative position of the reflecting portion is detected based on the reflected light when the inspection light is incident on these optical lines, and the optical line is identified based on the detection result. .

[0005] Instead of providing the identification mark directly in the optical line, a branch line having the identification mark may be added to the optical line.

[0006]

When the inspection light is incident from one end of the optical line, the light is reflected by a plurality of reflecting portions serving as identification marks and returns to the incident end. The combination of the relative positions of the reflection units is set to be different for each optical line, and the optical path difference of the reflected light from each reflection unit is measured by an interferometer, or the time difference until the reflected light from each reflection unit returns is measured. If, for example, the relative positions of the plurality of reflecting portions constituting the identification marker are detected, the optical path can be identified based on the detection result.

[0007]

FIG. 1 is a configuration diagram showing an optical line facility management system to which an optical line identification method according to the present invention is applied. Office building 1
A terminal box 2 for switching connection of an optical line is provided between the terminal box 2 and the subscriber home 3. A plurality of optical lines, one ends of which are connected to the transmission device 4 in the office 1, are bundled as an optical fiber cable 9 and extend to the terminal box 2. The other end of each optical line is connected to one end of the optical line extending to each subscriber's home 3 via an optical connector 10 in the terminal box 2, whereby the transmission device 4 in the office building 1 is connected to each end. This means that each of the subscriber homes 3 is connected by one optical line.

In the optical connector 10, the connection can be manually switched arbitrarily. When this switching is performed, first, the identification information reading device (code reading device) 5 placed in the station building 1 checks the route information of the optical line by an identification method described later, and the route information is checked by the control device 6. To the local controller 11 in the terminal box 2, and the display device 12 notifies the worker at the site of the information. The operator performs desired connector switching based on the route information. After the switching work is completed, the code reader 5 reads the identification mark of the optical path again, confirms the route information on the side of the station 1, and displays this route information on the display device 12 from the control device 6 via the local controller 11. Thus, the operator confirms whether or not the switching has been performed.

FIG. 2 is a block diagram showing the internal configuration of the code reading device 5 and its peripheral devices. The code reading device 5 includes a light emitting unit 20 and a light receiving unit 21. The operation of these units is controlled by a computer 22 and a timing control circuit 23 that constitute the control circuit 6.

The light emitting section 20 includes a light source 24 that emits light having an appropriate spectral width such as white light, an acousto-optic element 25 that controls on / off of light emitted from the light source 24, and an input / output of the acousto-optic element 25. The light emitted from the light source 24 is transmitted through the lens 26, the acousto-optic device 25, and the lens 27.
, And is incident on one end of the optical fiber 40 as inspection light. The optical fiber 40 is a branch optical line that connects the optical fiber 50, which is a measured optical line, and the code reading device 5, and is connected to the measured optical line 50 via the connection unit 38. The connection means 38 is for selectively connecting the optical fiber 40 to any one of a number of optical paths 50 to be measured.

The light receiving section 21 includes a Michelson interferometer 30
An A / D conversion circuit 36 that converts the output signal of the Michelson interferometer 30 into a digital value and supplies the digital value to the computer 22; and an input light to the Michelson interferometer 30 based on a signal from the timing control circuit 23. And an acousto-optic element 31 for controlling the on / off state as main components. Reference numerals 32 and 33 indicate lenses, respectively, and reference numeral 34 indicates an optical fiber. The Michelson interferometer 30 includes a moving mirror 300, a fixed mirror 301, a beam splitter 302, a moving mirror moving mechanism 303, a moving mirror position reading device 304, a light receiver 305, and lenses 306 and 307. Michelson interferometer 30 from optical fiber 34
Is split by the beam splitter 302,
One is guided to the fixed mirror 301 and the other is guided to the movable mirror 302. The light reflected by each mirror is split by beam splitter 3
It returns to 02 and overlaps, causing interference. This interference light enters the light receiver 305 via the lens 307 and is converted into an electric signal. At this time, an interference waveform called an interferogram can be obtained by moving the movable mirror 300 to change the optical path length difference in the interferometer. This is the principle of operation of the Michelson interferometer 30, and the relative positions of the plurality of reflectors forming the identification mark 39 are detected by using this principle.

Each optical line 50 has a unique identification mark (code) 39 written in the line. The identification marker 39 is composed of a plurality of reflecting portions, and has a combination of relative positions of the reflecting portions for each optical path. The reflection part constituting the identification mark 39 is formed by providing a notch in the optical line 50 to make the refractive index discontinuous. FIG. 3 shows an example of the identification mark 39. The identification mark 39 is composed of four notches 51 to 54, and based on the notch 51, the notches 52, 53, and 54 are 3 mm, 10 mm,
15 mm apart. Therefore, when the inspection light from the light emitting unit 20 is incident on the optical line 50, the reflected light from the identification marker 39 that reaches the light receiving unit 21 has an optical path difference for each notch serving as the reflecting unit. By detecting this optical path difference with the Michelson interferometer 30, the relative positions of the notches 51 to 54 can be detected.

The identification marks 39 are provided on the optical line between the station 1 and the terminal box 2 and the optical line between the terminal box 2 and the subscriber's house 3 in FIG. When a plurality of terminal boxes are interposed between the office building 1 and the subscriber's house 3, an identification mark is also provided on the optical line between the terminal boxes.

Next, a method of reading the identification mark 39 will be described. For example, four reflecting portions 51 to 5 as shown in FIG.
Assuming that the inspection light is incident on the optical path 50 with the identification mark made of No. 4, an interferogram as shown in FIG. That is, the main maximum is obtained when the optical path difference is zero, and the sub-maximum is obtained at the optical path differences for all the sets of the two reflecting sections selected from the reflecting sections 51 to 54. Specifically, the optical path difference is 3 mm, 5 mm, 7
mm, 10 mm, 12 mm, and 15 mm, the sub-maximum appears.

FIG. 2B shows the result of the observation corresponding to the code information. That is, from the observation result of FIG.
Bit code information can be obtained. The content of the code information can be set to a desired value by appropriately selecting the number and position of the reflecting portions.

In this embodiment, the optical line connecting the office 1 and the subscriber's house 3 is composed of two sectioned optical lines connected by a terminal box 2. Since the identification signs are provided on each of the divided optical lines, it is necessary to distinguish and recognize these. The acousto-optic device 31 is used for that purpose. That is, the timing control circuit 23 causes the pulse-like inspection light to be incident on the optical path to be measured, and temporally cuts out the reflected light for each identification marker by the acousto-optic element 31 based on the incident timing of the inspection light. This allows
The reflected light from the identification marks at different points on the same optical path can be distinguished. The computer 22 can obtain an interferogram for each identification marker by taking in the light intensity data of the reflected light while distinguishing the reflected light for each identification marker. The cut-out of the reflected light can also be achieved by using an optical gate (optical deflector) instead of the acousto-optic element 31.

As shown in FIG. 5, instead of directly writing the identification mark in the optical line, a branch optical line 101 on which the identification mark 100 is written may be added using a fiber coupler 102 or the like.

FIG. 6 is a block diagram showing an apparatus for performing an identification method according to another embodiment of the present invention. While the above embodiment detects the relative position of the reflecting portion based on the interference effect of the reflected light, this embodiment detects the relative position of the reflecting portion by measuring the difference in the arrival time of the reflected light. Is what you do. The light emitting section 20 is provided with a semiconductor laser 66 capable of emitting pulse light having a short pulse width and a drive circuit 65 for the semiconductor laser 66. In the light receiving unit 21,
A light receiving element 61, an A / D conversion circuit with memory 62, and an averaging circuit 63 are provided. Reference numerals 64 and 67
Is a lens. In this example, a pulse-like inspection light is incident on the optical line 50, and the temporal change in the intensity of the reflected light is measured to read out the code information corresponding to the relative position of each reflecting portion. FIG. 7 is a graph showing an example of the measurement result.
The vertical axis represents reflected light intensity, and the horizontal axis represents time. In this example, the reflected light from the identification marker provided with four reflecting portions including the reference reflecting portion (the reflecting portion closest to the incident side of the inspection light) is measured, and the reflected light 71 from the reference reflecting portion is measured. Arrives first, and then the respective reflected lights 72, 73, 74 from the three reflectors arrive in the order closer to the reference reflector. If it is assumed that reflectors other than the reference reflector can be provided only at five points that are sequentially spaced at equal intervals from the reference reflector, 5-bit identification is performed based on whether or not a reflector is provided at each point. A sign can be created, and the example of FIG. 7 shows code information “01101”.

[0019]

As described above, according to the identification method of the present invention, the combination of the relative positions of the plurality of reflecting portions constituting the identification mark is set to be different for each optical line, and this relative position is detected. Thus, the optical path can be easily and accurately identified. Therefore, it is very effective for confirming the connection at the time of the switching operation in the terminal box.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an optical line facility management system to which the identification method of the present invention is applied.

FIG. 2 is a block diagram showing the internal configuration of the code reading device and its peripheral devices.

FIG. 3 is a diagram showing a specific example of an identification mark.

FIG. 4 is an explanatory diagram of a method of converting an interferogram into binary code information.

FIG. 5 is a diagram showing a branch optical path for an identification sign.

FIG. 6 is a block diagram showing another configuration example of the code reading device.

FIG. 7 is a graph showing an example of the measurement result.

[Explanation of symbols]

1 ... office building, 2 ... terminal box, 3 ... subscriber home, 4 ... transmission device,
5 code reader, 6 controller, 20 light emitting unit, 2
DESCRIPTION OF SYMBOLS 1 ... Light-receiving part, 30 ... Michelson interferometer, 39 ... identification mark, 50 ... Optical line, 51-54 ... Reflection part (notch).

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Fumio Otsuki 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Yutaka Katsuyama 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Japan (56) References JP-A-4-84727 (JP, A) JP-A-4-309904 (JP, A) JP-A-2-181101 (JP, A) JP-A-2-20803 ( JP, A) JP-A-2-230105 (JP, A) JP-A-2-230106 (JP, A) Proceedings of the Conference of the Institute of Electronics, Information and Communication Engineers, 1991 [Autumn 4] (1991) p. 4.51 (58) Field surveyed (Int. Cl. ⁷ , DB name) G02B 6/00 G01M 11/00 H04B 10/08

Claims (6)

(57) [Claims] 1. When a plurality of reflecting portions are provided on an optical line, and a combination of relative positions of the plurality of reflecting portions is changed for each optical line to serve as an identification mark, and when inspection light is incident on these optical lines. The optical path difference of the reflected light from each of the reflecting portions
An optical line identification method for detecting the relative position of the reflection section based on the measured optical path difference, and identifying the optical path based on the detection result. 2. A branch line is added to each of the optical lines,
A plurality of reflecting portions are provided on these branch lines, and the combination of the relative positions of the plurality of reflecting portions is changed for each optical line to serve as an identification marker, and each of the above-described respective portions when inspection light is incident on the optical line. Measure the optical path difference of the reflected light from the reflector with an interferometer
An optical line identification method for detecting a relative position of the reflection section based on the measured optical path difference and identifying an optical path based on the detection result. 3. A plurality of reflecting portions are provided at each of a plurality of positions on an optical line, and a combination of the relative positions of the plurality of reflecting portions is changed for each position of each optical line to form an identification mark. Measures the time difference until the reflected light from each of the reflection parts returns when the pulsed inspection light is incident on the road
An optical line identification method for detecting the relative position of the reflection section for each of the identification markers based on the measured time difference, and identifying the optical line based on the detection result. 4. A branch line is added at a plurality of positions on an optical line, a plurality of reflection portions are provided on these branch lines, and a combination of relative positions of the plurality of reflection portions is changed for each of the branch lines. The reflected light from each of the reflection portions when the pulse-like inspection light is incident on the optical line is
Measure the time difference before returning, and based on the measured time difference
There detecting the relative position of the reflective portion of each of the identification label,
A method for identifying an optical line based on the detection result. 5. The optical line identification method according to claim 3, wherein the optical line is formed by cascading a plurality of section lines, and the identification mark is provided for each of the section lines. 6. The method for identifying an optical line according to claim 1, wherein the reflecting portion is a notch provided in the optical line.