JPH06347649A - Method for identifying optical path - Google Patents

Abstract

PURPOSE:To provide a method for easily and exactly identifying an optical path at the end part. CONSTITUTION:Plural reflection parts are provided on the optical paths 50 and one reflection part is provided on a position separated by at least the total length of the plural reflection parts apart, an identifying mark 36 is set by changing the relative position of each reflection part for every optical path 50, the reletive position of the reflection part is detected based on the reflected light beam when an inspecting light beam is made incident on these optical paths 50 and the optical path 50 is identified based on the detected result. When the inspecting light beam is made incident from one end of the optical path 50 by means of a light emitting part 20, this beam is reflected by each reflection part of an identifying mark 39 and returns to the incident end. By analyzing this beam by means of e.g., a Michelson interferometer 30, the relative position of the reflection part is detected and the optical path 50 is identified.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art As a method of identifying an optical line, the refractive index of the core of the optical line is partially changed, and this change position is determined by the OTDR.
A method of detecting at the end of a line using a measurement method is known (1991 Autumn Meeting of the Institute of Electronics, Information and Communication Engineers, Document B-59).
1 "Remote fiber identification method for optical fiber 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, it takes 50 m per bit to record an 8-bit identification code on the optical line, and a total length of 400 m is required. Therefore, it is originally difficult to attach an identification code to an optical line having a short length. Further, in order to record the identification code over several hundred meters on the optical line, it is necessary to do this during the manufacturing process of the optical line, which is not practical.

[0004]

In order to solve such a problem, the identification method of the present invention provides a plurality of reflecting portions on the optical line and one reflecting portion at a position distant from at least the entire length thereof. Provided as an identification mark by changing the combination of the relative positions of a plurality of reflecting portions for each optical line, to detect the relative position of the reflecting portion based on the reflected light when the inspection light is incident on these optical lines, The optical line is identified based on the detection result.

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 the plurality of reflecting portions which are identification marks and returns to the incident end. The combination of the relative positions of multiple reflectors and one reflector is different for each optical line, and the optical path difference of the reflected light from each reflector is measured by an interferometer, and the reflected light from each reflector is If the relative positions of the plurality of reflecting portions that form the identification mark are detected by measuring the time difference until returning, the optical line can be identified based on the detection result.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an optical line facility management system to which the optical line identification method of the present invention is applied. Station building 1
A terminal box 2 for switching the connection of the optical line is provided between and the subscriber's house 3. A plurality of optical lines, one end of which is connected to the transmission device 4 in the station building 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 house 3 via the optical connector 10 in the terminal box 2, whereby each of the transmission devices 4 in the station building 1 is connected. This means that the subscriber's home 3 is connected by one optical line.

In the optical connector 10, the connection can be arbitrarily switched manually. When this switching is performed, first, the identification mark reading device (code reading device) 5 placed in the station building 1 checks the route information of the optical line by the identification method described later, and the route information is checked by the control device 6 Is transmitted from the terminal box 2 to the local controller 11 in the terminal box 2, and the display device 12 notifies the operator of the site of the information. The worker switches the desired connector based on the route information. After the switching work is finished, the code reader 5 reads the identification mark of the optical line again to confirm the route information on the side of the station 1, and the route information is displayed on the display device 12 from the control device 6 via the local controller 11. Therefore, the operator confirms whether the switching is good or bad.

FIG. 2 is a block diagram showing the internal structure 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 which is controlled by a computer 22 and a timing control circuit 23 which form a control circuit 6.

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

The light receiving section 21 is a Michelson interferometer 30.
And 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 the input light to the Michelson interferometer 30 based on the signal from the timing control circuit 23. An acousto-optic element 31 for on / off control is provided as a main component. Reference numerals 32 and 33 indicate lenses, 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. Optical fiber 34 to Michelson interferometer 30
The light incident on is split by the beam splitter 302,
One is guided to the fixed mirror 301, and the other is guided to the movable mirror 300. The light reflected by each mirror is the beam splitter 3
Returning to 02, they overlap and cause interference. The interference light enters the light receiver 305 via the lens 307 and is converted into an electric signal. At this time, by moving the movable mirror 300 to change the optical path length difference in the interferometer, an interference waveform called an interferogram can be obtained. This is the operating principle of the Michelson interferometer 30, and by utilizing this principle, the relative positions of the plurality of reflecting portions forming the identification mark 39 are detected.

A unique identification mark (code) 39 is written in each optical line 50 in the optical line. The identification mark 39 is composed of one and a plurality of reflecting portions, and the combination of the relative positions of the reflecting portions is changed for each optical line.
The reflecting portion that constitutes the identification mark 39 is provided with a discontinuity of the refractive index by cutting the optical line 50 and changing the refractive index of the optical fiber. FIG. 3 shows an example of the identification mark 39. In this identification mark 39, a plurality of reflection parts 52 to 56 formed by notching an optical fiber are provided at intervals P, and one reflection part 51 is formed into a plurality of reflection parts 52 to 56.
The position L is separated from the total length n × P of 56.
Therefore, when the inspection light from the light emitting unit 20 is incident on the optical line 50, the reflected light from the identification mark 39 reaching the light receiving unit 21 has an optical path difference for each notch that is a reflecting unit, By detecting this optical path difference with the Michelson interferometer 30, it is possible to detect the relative position of each of the plurality of reflecting portions 52 to 56 with respect to one reflecting portion 51.

The identification mark 39 is provided on each of 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 provided between the station building 1 and the subscriber's home 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, if the inspection light is incident on the optical line 50 having the identification mark 39 composed of one reflecting portion 51 and a plurality of reflecting portions 52 to 56 as shown in FIG. An interferogram as shown in FIG. 4 is obtained by synchronizing with. That is, the maximum is obtained when the optical path difference is zero, and as the optical path difference increases, the sub-maximum is obtained in the portion corresponding to the optical path difference between the plurality of reflecting portions. The interference between the plurality of reflectors occurs between the optical path differences (n-1) p. When the optical path difference is further increased, the sub-maximum due to the interference between the reflected light from one reflecting portion at the position L and the reflected light from the reflecting portion closest to the one reflecting portion of the plurality of reflecting portions (Fig. (Not shown), and then L + p, L + 2p, ..., L +, which are sequentially provided with identification marks.
The sub-maximum is obtained by the optical path difference of (n-1) p.

Therefore, according to this identification method, the identification mark 39 detects whether or not the reflection portion is provided at the designed optical path difference position as the presence or absence of the sub-maximum, and encodes it by a binary number. Will be identified. For example,
If 12 designed optical path difference positions are provided, 4096 optical lines can be identified by the combination of the presence or absence of the reflecting portions.

It is desirable that the Michelson interferometer 30 is constructed in a substance such as liquid or gas which has substantially the same dispersion value of the optical line in the wavelength width used. Since the light that transmits the optical path difference between the reflected light from one reflection part and the multiple reflection parts has an appropriate spectral width, the way the light travels differently in the optical line at each wavelength due to the influence of dispersion in the optical line. do. However, if the optical path difference between the fixed mirror and the moving mirror provided to interfere with this reflected light is in the air, the light affected by the dispersion of the optical line interferes as it is, and the optical path difference shifts at each wavelength. Therefore, the maximum amplitude becomes small. Therefore, if the Michelson interferometer 30 is constructed in the same material as the optical line, the shifts of the respective wavelengths will be restored, and the maximum amplitude can be increased, and the probability of a read error will be reduced. .

Similarly, if the optical line forming the reflecting portion is made of a substance having substantially zero in the wavelength width to be used, the maximum amplitude does not become small because the progress in each wavelength is the same. Read error probability is reduced. In addition,
According to this embodiment, in the plurality of reflecting parts 52 to 56,
The sub-maximum can be obtained also by the optical path difference between one of the reflection parts and the other reflection part. However, since the sub-maximum is L larger than n × p as described above, one reflection The sub-maximum generated by the optical path difference between the portion 52 and the plurality of reflecting portions 52 to 56 does not overlap. Therefore, in this embodiment, the sub-maximum obtained by the optical path difference between one of the plurality of reflecting portions 52 to 56 and the other reflecting portion may be ignored, and no particular problem occurs.

In this embodiment, the optical line connecting the station building 1 and the subscriber's home 3 is composed of two sectioned optical lines connected by the terminal box 2. Since the identification mark is provided on each of the divided optical lines, it is necessary to distinguish them. The acousto-optic element 31 is used for that purpose. That is, the timing control circuit 23 causes the pulsed inspection light to enter the optical path to be measured, and the acousto-optical element 31 temporally cuts out the reflected light for each identification mark with reference to the incident timing of the inspection light. This allows
The reflected lights from the identification marks at different points on the same optical line can be distinguished from each other. The computer 22 can obtain the interferogram for each identification mark by capturing the light intensity data of the reflected light while distinguishing the reflected light for each identification mark. Note that the cutout of the reflected light can also be achieved by replacing the acousto-optic element 31 and controlling the timing of reading the electrical signal from the light receiver 305 using a gate circuit or the like.

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

In order to allow the inspection light to be reflected and returned by the optical fiber (optical line), the refractive index of the clad in the optical fiber may be changed in addition to the above. FIG. 6 (a),
(B) is another embodiment of the identification mark 39 made from this point of view. The embodiment of FIG. 6A shows an example in which the notch 43 is provided in the clad 42 of the reflection part of the optical fiber 41. FIG. 6B shows an example in which the cladding 42 of the reflection part of the optical fiber 41 is removed and a member 44 having another refractive index is attached.

FIGS. 7A to 7D show another embodiment relating to the installation of the identification mark 39. That is, the identification mark 39 is provided at an arbitrary position in the optical line, but it is difficult to provide it on the optical line in the cable. Therefore, in FIGS. 7A to 7D, the identification mark 39 is recognized as an optical connector used for a connecting portion of an optical line.

More specifically, in FIG. 7A, the optical fiber 41 is provided inside one of the pair of optical connectors 45 and 46.
An identification mark 39 having one reflecting portion 51 and a plurality of reflecting portions 52 to 56 is provided in the. FIG. 7B shows an example in which one reflecting portion 51 is not specially provided as in FIG. 7A and the reflection of the coupling portion 58 of the pair of optical connectors 45 and 46 is used. FIG. 7C shows an example in which the identification mark element 59 having the identification mark 39 is inserted between the one optical connector 45 and the other optical connector 46.
Further, in FIG. 7D, the single reflection part 5 of FIG.
An example is shown in which the reflection at the connection end face 60 between the one optical connector 45 and the identification mark element 59 is used instead of 1.

The present invention may be applied to the following embodiments in addition to the above embodiments. That is, a semiconductor laser capable of emitting pulsed light with a short pulse width and its drive circuit are provided in the light emitting section, while an A / D conversion circuit with a memory and an averaging circuit are provided in the light receiving section to generate pulsed inspection light. By entering the optical line 50 and measuring the temporal change in the reflected light intensity, it is possible to read the code information according to the relative position of each reflecting portion.

In addition to the above, the present invention may be modified in design as necessary.

[0025]

As described above, according to the identification method of the present invention, a combination of a plurality of reflecting portions forming an identification mark and a relative position of one reflecting portion is set to be different for each optical line, and this relative position is set. By detecting the position, the optical line can be identified easily and accurately. Therefore, it is extremely effective for checking the connection at the time of switching work in the terminal box.

[Brief description of drawings]

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

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

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

FIG. 4 is a diagram showing a method for identifying a label by an interferogram.

FIG. 5 is a diagram showing a branched optical line for an identification mark.

FIG. 6 is a diagram showing another specific example of the identification mark.

FIG. 7 is a diagram showing a method of writing an identification mark.

[Explanation of symbols]

1 ... Station building, 2 ... Terminal box, 3 ... Subscriber house, 4 ... Transmission device,
5 ... Code reading device, 6 ... Control device, 20 ... Light emitting part, 2
1 ... Light receiving part, 30 ... Michelson interferometer, 39 ... Identification mark, 40, 41 ... Optical fiber, 42 ... Clad, 43 ...
Notch, 44 ... Other member, 45, 46 ... Optical connector,
50 ... Optical line, 51-56 ... Reflecting part (notch), 59
... Identification mark element.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuhiko Katsu 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Houji Hattori 1 Taya-cho, Sakae-ku, Yokohama, Kanagawa Prefecture Sumitomo Denki Kogyo Co., Ltd. Yokohama Works (72) Inventor Fumio Otsuki 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Katsuya Yamashita 1-1-6 Uchiyuki-cho, Chiyoda-ku, Tokyo No. Japan Telegraph and Telephone Corporation

Claims (15)

[Claims] 1. A plurality of reflectors on an optical line, and one reflector provided at a position apart from the entire length of at least the plurality of reflectors, and a combination of relative positions of the plurality of reflectors is changed for each optical line. As an identification mark, the relative position of the one reflecting portion and the plurality of reflecting portions is detected based on the reflected light when the inspection light is incident on these optical lines, and the optical line is based on the detection result. A method of identifying optical lines for identifying. 2. A branch line is added to each of the optical lines,
A plurality of reflecting portions and one reflecting portion are provided on these branch lines at a position distant from the entire length of at least the plurality of reflecting portions, and identification is performed by changing a combination of relative positions of the plurality of reflecting portions for each optical line. As a marker, the relative position of the one reflection part and the plurality of reflection parts 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 inspection. How to identify the optical fiber line. 3. A plurality of reflecting portions at each of a plurality of positions on the optical line and one reflecting portion separated from at least the entire length of the plurality of reflecting portions are provided, and the relative positions of the plurality of reflecting portions for each optical line. As the identification mark by changing the combination of the above, based on the respective reflected light that returns from the respective identification marks when the pulsed inspection light is incident on these optical lines, with a temporal shift according to the position. An optical line identification method for detecting the relative position of the one reflecting portion and the plurality of reflecting portions for each identification mark and the position of the identification mark in the optical line, and identifying the optical line based on the detection result. . 4. Adding each branch line of the optical line,
A plurality of reflecting portions on one of these branched lines and at least one reflecting portion is provided at a position away from the entire length of the plurality of reflecting portions, and a combination of relative positions of the plurality of reflecting portions is provided for each of the branched optical lines. The identification mark is changed to the identification mark based on the respective reflected lights that return from the respective identification marks when the pulsed inspection light is incident on the optical line, with a temporal shift according to the position. An optical line identification method for detecting the relative position of each of the one reflection part and the plurality of reflection parts and the position of an identification mark in the optical line for identifying the optical line based on the detection result. 5. The method of identifying an optical line according to claim 3, wherein the optical line is constituted by a plurality of section line cascade connections, and the identification mark is provided for each section line. 6. The relative position of the reflector is detected by measuring the optical path difference of each of the plurality of reflectors with respect to one reflector with an interferometer and based on the measured optical path difference. The method for identifying an optical line according to any one of 1 to 5. 7. The relative position of the reflecting portion is detected by measuring a time difference until the reflected light from each reflecting portion returns and based on the measured time difference.
The method for identifying an optical line according to any one of 1. 8. The interferometer used for detecting the relative position of the reflecting portion is formed in a substance having substantially the same wavelength dispersion as that of the optical line in the wavelength region of the detection light.
Identification method of the described optical line. 9. The method for identifying an optical line according to claim 6, wherein the optical line is configured by using a substance whose wavelength dispersion is substantially zero at the wavelength of the detection light in the reflecting portion. 10. The method of identifying an optical line according to claim 1, wherein the reflecting portion is a notch provided in the optical line. 11. The method of identifying an optical line according to claim 1, wherein the reflecting portion is a cut surface provided on the optical line. 12. The method for identifying an optical line according to claim 1, wherein the reflecting portion is a reflecting member provided on the outer periphery of the core of the optical fiber in the optical line. 13. The method of identifying an optical line according to claim 1, wherein the reflection part is provided on an optical fiber bonding part of the optical connector of the optical line. 14. The method of identifying an optical line according to claim 1, wherein the reflection part is provided between two optical connectors of a connection part of the optical lines. 15. The light beam according to claim 13, wherein one reflecting portion provided at a position apart from the entire length of the plurality of reflecting portions among the reflecting portions is a connection end face of the optical connector. Road identification method.