JP6375242B2 - Optical line inspection apparatus and method - Google Patents

Description

  The present invention relates to an optical line inspection apparatus and method used for inspecting optical characteristics of an optical line using a mechanical splice as an optical fiber connecting means.

  In recent years, in an optical access facility, many mechanical splices are used as optical fiber connection means. The mechanical splice mechanism is a mechanism that connects by mechanical butting of the fiber end faces without connecting by fusion when connecting the optical fibers whose end faces are cut. FIG. 13 shows an example of the configuration. Two optical fiber wires 102 and 103 to be connected are arranged on the V-groove member 104 in a state where the coating is removed, and a refractive index is provided at a butt portion of the end face. The alignment agent 104 is filled, and in this state, the optical fiber strands 102 and 103 are fixed by being pressed by the three-part holding members 105, 106, and 107.

  However, while the mechanical splice mechanism can connect the optical fibers relatively easily, it has been reported that a failure occurs at the connecting portion. For example, if the interval between the end faces of the optical fiber increases with time as shown in FIG. 14A or if there is a cut defect in the end face of the optical fiber as shown in FIG. As a result, the optical performance is degraded (for example, see Non-Patent Documents 1, 2, and 3).

  Therefore, conventionally, in order to investigate the cause of a broken mechanical splice, the broken mechanical splice is cut off from the track and brought to the laboratory. It was made to check the abnormalities of the butt portion and the presence or absence of disconnection (for example, see Non-Patent Document 4).

http://www.fujikura.co.jp/products/tele/o_connector/data/td21010.pdf NTT East Technical Cooperation Center, NTT Technical Journal, Vol.22, No.10, pp.48-50, 2010. Junichi Yajima, Takeshi Watanabe, Mitsuru Kihara, Masanobu Toyonaga, “Analysis of performance degradation of optical fiber joints with cut end faces”, IEICE Technical Report, OFT2010-62 (2011-1) Hosoda Makoto, Watanabe Satoshi, Kihara Mitsuru, Masanobu Toyonaga, “Evaluation of Fault Mechanical Splice Using Short Extra Long Connection Jig”, 2011 IEICE Communication Society Conference, B-10-19

  However, in the analysis method described in Non-Patent Document 3, it is necessary to identify the failed part, cut it off from the actual line, and bring it back to the laboratory. In addition, when cutting, in order to leave the core wire as long as possible on the local line side, the extra length of the removed mechanical splice is usually extremely short. Therefore, for inspection of optical properties, fusion connection or connector connection It is necessary to do. For this reason, it took a lot of time and labor for the analysis work. Furthermore, there is a risk that a normal mechanical splice may be accidentally cut due to an operator's misjudgment, and once it is disconnected, connection loss may occur even if it is reconnected.

  The present invention has been made paying attention to the above circumstances, and the object of the present invention is to make it possible to inspect the optical characteristics of the optical line including the mechanical connection mechanism without partially cutting it, thereby necessitating the inspection. It is an object of the present invention to provide an optical line inspection apparatus and method which can significantly reduce the time and labor and prevent the occurrence of work errors such as erroneous cutting.

To achieve the above object, according to a first aspect of the present invention, there is provided an optical line laid between a first transmission device and a second transmission device, wherein a plurality of optical fibers are connected by a mechanical connection mechanism. wherein an optical line inspection apparatus for inspecting the connection state of the optical fiber due to the mechanical connection mechanism, disposed between the first transmission device and the mechanical connection mechanism of the optical line, the optical line For example, a plurality of bent portions whose bending directions are opposite to each other are continuously formed, whereby the transmission of the optical signal for communication transmitted from the first transmission device to the mechanical connection mechanism is blocked. A probe fiber is disposed opposite to the bent portion closest to the mechanical connection mechanism among the plurality of bent portions formed by the first loss applying means, and the optical fiber is transmitted by the probe fiber. For inspection Side optical input / output means for entering and exiting a signal, an optical signal for inspection which is disposed between the second transmission device of the optical line and the mechanical connection mechanism, and which has passed through the mechanical connection mechanism, and A second loss applying means for interrupting transmission of at least one of the communication optical signals transmitted from the second transmission device; and the probe fiber connected to the probe fiber of the side light input / output means; An optical signal for inspection is incident on the optical line via a bending portion in which the probe fiber is disposed opposite to the probe fiber, and the probe fiber is disposed so as to reflect light reflected by the mechanical connection mechanism of the optical signal for inspection . Light analyzing means for receiving light through the bending portion and the probe fiber and analyzing the received reflected light is provided.

  According to a second aspect of the present invention, the optical analysis means measures the wavelength spectrum of the reflected light and performs a Fourier transform on the measured wavelength spectrum, thereby separating the optical fiber end faces from each other by the mechanical connection mechanism. Based on the waveform of the amplitude at each reflection position of the reflected light, and the processing of calculating the loss due to the mechanical connection mechanism based on the detected value of the received light level of the reflected light Further, at least one of the processes for determining the quality of the connection state by the mechanical connection mechanism is executed.

  According to a third aspect of the present invention, in the automatic control, the first loss applying unit, the second loss applying unit, and the side light input / output unit receive a remote control signal and perform a bending operation of the optical line. In the case of having a mechanism, first, by applying a remote control signal to the first and second loss applying means to bend the optical line, the optical signal is blocked, and after the light is blocked, the side light input Remote control means for applying a remote control signal to the output means to bend the optical path is further provided.

  According to a fourth aspect of the present invention, during the optical fiber connection work by the mechanical connection mechanism, the quality of the optical fiber connection state by the mechanical connection mechanism is determined based on the analysis result by the optical analysis means, The information processing device further includes notification means for reporting information representing the determination result.

  According to a fifth aspect of the present invention, the first or second loss imparting means is formed by continuously forming a plurality of bent portions whose bending directions are opposite to the optical line, and the plurality of bent portions The sum of the bending center angles is set so as to be a bending angle necessary for blocking the optical signal.

  According to the first aspect of the present invention, the connection state of the optical fiber by the mechanical connection mechanism can be inspected without partially cutting off the optical line including the mechanical connection mechanism. Therefore, the time and labor required for the inspection can be greatly reduced. Also, there is no need to worry about accidental cutting of the optical line.

  According to the second aspect of the present invention, in the optical analysis means, among the separation distance between the end faces of the optical fiber by the mechanical connection mechanism, the loss by the mechanical connection mechanism, and the quality of the connection state by the mechanical connection mechanism At least one of them is automatically analyzed, which makes it possible to reduce the load on the inspector and improve the inspection accuracy.

  According to the third aspect of the present invention, firstly, the transmission of the optical signal is blocked by the first and second loss applying means, and after the light is blocked, the side optical input / output means inputs the optical signal for inspection sideways. Output is possible. Accordingly, it is possible to eliminate the influence of the inspection optical signal on the first and second transmission devices and the influence of the communication optical signal on the optical analysis means.

  According to the fourth aspect of the present invention, during the optical fiber connection operation by the mechanical connection mechanism, the quality of the optical fiber connection state by the mechanical connection mechanism is determined based on the analysis result of the reflected light, and the determination Information representing the result is notified in real time to the worker performing the connection work. Therefore, the worker can recognize a connection failure due to a work mistake or the like on the spot, thereby improving the efficiency of the connection work and the reliability after the connection.

  According to the fifth aspect of the present invention, when the optical fiber is bent, the bending angle required for the total bending center angle to block the optical signal is realized by the plurality of bending portions. Therefore, it is possible to disperse the burden on the optical fiber per one bent portion, and it is possible to reduce the possibility of damage to the optical fiber due to bending.

  That is, according to the present invention, the optical characteristics including the mechanical connection mechanism can be inspected without partially cutting, thereby significantly reducing the time and labor required for the inspection, and erroneous cutting and the like. It is possible to provide an optical line inspection apparatus and method capable of preventing work errors from occurring.

The figure which shows the whole structure in one Embodiment of an optical-line inspection apparatus. The figure showing an example of the basic structure of a loss provision part. The figure which shows the structure which inputs / outputs light from the side of a fiber by pinching | interposing a fiber with a small curvature radius (example 2 mm) in a side light input / output mechanism, and matching the focus position of the fiber with a lens in a fiber bending part. The figure which shows an example of the basic composition of a reflected light analysis part. The flowchart for demonstrating the procedure of the test | inspection by the optical-line inspection apparatus shown in FIG. The figure which shows operation | movement of the optical line inspection apparatus which performs order control. A photograph showing the shape of the fiber end face. Measurement result of mechanical splice loss. Waveforms representing a bonded surface of a good sample, a bonded surface of a defective sample, and a PC polished bonded surface of a mechanical splice measured using a side light input / output device. The figure which shows the structure in the case of monitoring the manufacture process of a mechanical splice. A combination example in which the total angle of bending is approximately 360 ° in order to completely block external optical signals. The figure which shows the basic structure of the side light input / output mechanism which integrated the station inner side loss provision part and the fiber bending provision part. The figure which shows the element structure of a mechanical splice. The figure which shows the failure cause of a mechanical splice connection.

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
(Constitution)
FIG. 1 is a diagram showing an overall configuration of an optical line inspection apparatus according to the first embodiment of the present invention. The optical line inspection device includes a mechanical splice 6 disposed in the middle of an optical line laid between an optical line termination (OLT) 2 and an optical network unit (ONU) 3 on the subscriber side. Inspecting the connection state, the inside loss providing unit 40, the side light input / output mechanism 41 and the reflected light analyzing unit 42 provided in the inside inspection unit 4, and the inside loss providing at the subscriber side Part 5.

  The station inner loss imparting unit 40 blocks downlink signal light transmitted from the accommodation station of the station inner transmission apparatus 2 toward the subscriber side transmission apparatus 3. If this portion is not present, the reflected light from the mechanical splice 6 of the strong downstream signal light transmitted from the accommodating station of the intra-station transmission device 2 is incident on the reflected light analysis unit 42 and adversely affects the measurement result.

  On the other hand, the in-home loss providing unit 5 makes the inspection light transmitted from the reflected light analyzing unit 42 enter the subscriber-side transmission device 3 and reflects the upstream signal light transmitted from the subscriber-side transmission device 3. The incident on the light analyzing unit 42 is blocked. If this portion is not present, the inspection light adversely affects the in-home equipment in the subscriber-side transmission device 3, or the upstream signal light transmitted from the in-home equipment is incident on the reflected light analysis unit 42 and adversely affects the measurement result. It is because it exerts.

  The office-side loss giving unit 40 and the house-side loss giving unit 5 are configured as follows. FIGS. 2A and 2B are diagrams showing the basic structure of each. That is, first, as shown in FIG. 2A, the local-side loss imparting unit 40 includes a first block 400 in which a concave curved surface having an arc shape and a convex curved surface having a subsequent arc shape are formed on the top surface, and the first block 400 The second block 401 has a convex curved surface having an arc shape corresponding to the shape and size of the concave curved surface and the convex curved surface of the block, and a concave curved surface having an arc shape following the curved surface. The optical fiber 1 is sandwiched from above and below between the first and second blocks 400 and 401 so as to give an S-shaped bent portion to the optical fiber 1.

  The convex curved surface of the first block 400 and the convex curved surface of the second block 401 of the local-inside loss imparting unit 40 have radiuses of curvature R1, R2 and bending center angles of virtual circles 402, 403 including the curved surfaces. Assuming θ1 and θ2, for example, when R1 = R2 = 2 mm, θ1 + θ2 = approximately 180 degrees is set.

  Similarly, as shown in FIG. 2 (b), the inner-side loss imparting section 5 has a first block 50 having a concave curved surface having an arc shape and a convex curved surface having a subsequent arc shape formed on the upper surface and the first block 50. The second block 51 is provided with a convex curved surface having an arc shape corresponding to the shape and size of the concave curved surface and the convex curved surface of one block 50 and a concave curved surface having an arc shape following the curved surface. The optical fiber 1 is sandwiched from above and below between the first and second blocks 50 and 51 so as to give an S-shaped bent portion to the optical fiber.

  The convex curved surface of the first block 50 and the convex curved surface of the second block 51 of the inner-side loss imparting unit 5 are similar to the local loss imparting unit 40 in the virtual circles 52 and 53 including the curved surfaces. Assuming that the curvature radius is R3, R4 and the bending center angles are θ3, θ4, for example, when R3 = R4 = 2 mm, θ3 + θ4 = approximately 180 degrees is set.

  If comprised as mentioned above, it will become possible in the office inner side loss provision part 40 and the inner side loss provision part 5 to interrupt | block substantially all the signal lights transmitted with the optical fiber 1. FIG.

  Note that both the station-side loss giving unit 40 and the house-side loss giving unit 5 can be configured to include an automatic control mechanism having a drive source such as a motor. In this case, for example, the automatic control mechanism receives a remote control signal sent from the outside, and operates to slide the second block toward the first block and press it with a constant pressure.

  Next, the side light input / output mechanism 41 is configured as follows. FIG. 3 shows the structure. That is, the side light input / output mechanism 41 includes a first block 410 made of a transparent member such as an acrylic resin having an arcuate concave surface formed on the upper surface, and a second block 412 made of a column or cylinder. . Then, the optical fiber 1 is sandwiched between the concave surface portion of the first block 410 and the second block 412 to give the optical fiber 1 an arc-shaped bend.

  The shape and size of the concave portion of the first block 410 and the convex portion of the second block 412 are, for example, when the radius of curvature of the bent portion of the optical fiber is R5 and the bending center angle is θ5, the radius of curvature R5 is about 2 mm. And the bending center angle θ5 is set in a range of approximately 20 degrees to 90 degrees.

  The first block 410 is provided with a hole from the lower surface to the concave surface, and the probe fiber 411 is inserted into the hole. A refractive index matching agent 413 is filled between the probe fiber 411 and the inner wall of the hole to prevent reflection. The probe fiber 411 is obtained by attaching a condensing lens to the distal end portion of the probe optical fiber, and is disposed so that the distal end portion faces a predetermined position of the bent portion 414 of the optical fiber 1.

  If comprised in this way, when inspection light will be emitted from the front-end | tip part of a probe fiber, it will become possible for the said inspection light to inject into the optical fiber 1 from the said bending part, and the reflected light by the said mechanical splice 6 of the said inspection light It is possible to cause a part of the light to leak from the bent portion and enter the probe fiber 411.

  Next, the reflected light analysis unit 42 is configured as follows. FIG. 4 is a block diagram showing the functional configuration. That is, the reflected light analysis unit 42 includes a wavelength tunable laser 420 for outputting inspection light 425 having a predetermined wavelength, and couplers 421, 422 that combine the inspection light 425 and the reflected light 426 transmitted by the probe fiber 411. 423, a fiber connector 424 that connects the coupler 422 among the couplers and the probe fiber 411, an APD (Avalanche photodiode) 427 that detects reflected light 426 for detecting reflected light, and a light reception signal output from the APD 427. It comprises an amplifier 428 for amplification, an A / D converter 429 for converting the received light signal output from the amplifier 428 from an analog signal to a digital signal, and a reflected light analysis terminal 430 for analyzing reflected light.

  The reflected light analysis terminal 430 includes a central processing unit (CPU) and a memory, and performs predetermined processing related to the connection state of the mechanical splice 6. This process is realized by causing the CPU to execute a reflected light analysis program stored in a program memory (not shown).

(Operation)
Next, the flow of the optical line inspection by the apparatus configured as described above will be described with reference to the flowchart shown in FIG.
As the inspection method, OFDR (Optical Frequency Domain Reflectometry) using the same wavelength band as the communication light wavelength is used. The reason is that in the side light input / output mechanism 41, there is a case where a large loss (for example, 23 dB) is caused when the inspection light 425 and the reflected light 426 enter and exit, so that a wavelength tunable laser having a high spectral density is used as the light source. Is advantageous. When the loss in the side light input / output mechanism 41 can be kept low, OLCR (Optical Low Coherence Reflectometry) capable of obtaining high resolution on the premise of a white light source (low spectral density) can be used.

(1) Preparation before the test light is incident on the mechanical splice to be measured First, in step S10, the optical fiber 1 is bent by the local loss applying unit 40 so that the bending center angle θ1 = θ2 = 90 degrees. Forming part. At this time, the radius of curvature is set to R1 = R2 = 2 mm. As a result, transmission of the downstream signal light from the station inner transmission device 2 to the mechanical splice 6 is blocked.

  At the same time, in step S11, a bent portion is formed in the optical fiber 1 by the in-home loss providing unit 5 so that θ3 = θ4 = 90 degrees as in the case of the in-office loss providing unit 40. At this time, the radius of curvature is set to R3 = R4 = 2 mm. Thereby, the transmission of the inspection light 425 to the subscriber side transmission device 3 and the transmission of the upstream signal light from the subscriber side transmission device 3 to the mechanical splice 6 are blocked.

  As described above, the local-side loss imparting unit 40 and the in-home loss imparting unit 5 bend the optical fiber 1 into an S shape by a convex curved surface and a concave curved surface portion continuous thereto, and the central angles of the bending are 90 degrees. The total bending center angle is set to 180 degrees. For this reason, the stress applied to the optical fiber at each bent portion is reduced, thereby making it difficult for the optical fiber 1 to be damaged. It has been confirmed by experiments that the effect of sufficiently blocking light can be obtained even when the total bending center angle is approximately 180 degrees.

  The bending operation of the optical fiber 1 by the station inner loss imparting section 40 and the house inner loss imparting section 5 is a remote operation implemented in the reflected light analyzing terminal 430 of the reflected light analyzing section 42 as shown in FIG. In accordance with the control program, a remote control signal is supplied to the in-house loss providing unit 40 and the in-home loss providing unit 5 using a wired line or a wireless line, whereby the in-office loss providing unit 40 and the in-home loss providing unit 5 are supplied. This is realized by operating the automatic control mechanism, but may be performed manually by an operator.

  Next, in step S <b> 2, it is confirmed whether or not the signal light is blocked in the above-mentioned inside-side loss giving unit 40 and inside-home loss giving unit 5. This is because, for example, the light reception level of the signal light is measured by the station inner side transmission device 2 and the subscriber side transmission device 3, respectively, and the reflected light analysis terminal 430 of the reflected light analysis unit 42 uses a wired line or a wireless line. Is made by getting through.

  When it is confirmed that the signal light is blocked in the step S2, the remote control signal is subsequently sent from the reflected light analysis terminal 430 to the side light input / output mechanism 41 via the wired line or the wireless line in step S3. Supplied. As a result, the automatic control mechanism included in the side light input / output mechanism 41 is operated, whereby the second block 412 is moved downward as shown in FIG. It is formed. At this time, since the probe fiber 411 is fixed in advance in the hole of the first block 410, the distal end portion of the probe fiber 411 is disposed opposite to a predetermined position of the bent portion after the bent portion 414 is formed. It becomes a state. The shape and size of the bending portion are set so that the bending center angle θ5 is in the range of approximately 20 degrees to 90 degrees and the curvature radius is 2 mm.

  In this way, an inspection signal can be made incident on the optical fiber 1 from the probe fiber 411 at the bent portion 414, and the reflected light 426 of the inspection light 425 by the mechanical splice 6 leaks from the bent portion 414. Thus, the light can enter the probe fiber 411.

(2) Measurement of connection state of mechanical splice using inspection light When the bent portion 414 for light leakage is formed in the optical fiber 1 as described above, in step S4, the wavelength of the reflected light analyzing portion 42 is variable. Inspection light 425 is generated from the laser 420. The inspection light 425 is incident on the probe fiber 411 via the couplers 421 and 422 and the optical connector, transmitted through the probe fiber 411, and then emitted from the tip of the probe fiber 411 so that the optical fiber 1 is bent for light leakage. The light is incident on the side 414 sideways. Then, the inspection light 425 is transmitted in the downward direction by the optical fiber 1 and is reflected at each position in the mechanical splice 6. The reflected light is transmitted in the upstream direction by the optical fiber 1, and then a part of the reflected light is emitted from the light leakage bending portion 414 and is incident on the probe fiber 411. Then, the reflected light 426 is transmitted to the reflected light analysis unit 42 via the probe fiber 411, and is received by the APD 427 via the optical connectors and couplers 422 and 423 in the reflected light analysis unit 42 as shown in step S5. Converted to a signal. The electric signal is amplified to a level necessary for A / D conversion by the amplifier 428, converted to a digital signal by the A / D converter 429, and taken into the reflected light analysis terminal 430.

  In the reflected light analysis terminal 430, the following reflected light analysis processing is executed in step S6 according to the reflected light analysis program.

(1) A process of calculating the separation distance between the end faces of the optical fiber by the mechanical splice 6 by measuring the wavelength spectrum of the reflected light 426 and Fourier transforming the measured wavelength spectrum.
(2) A process of detecting the light reception level of the reflected light 426 and calculating the amount of loss due to the mechanical splice 6 based on the detected value.
(3) A time-series waveform change of the reflected light 426, that is, a peak waveform width is detected from a waveform indicating an amplitude change at each reflection position, and the optical splicing between the mechanical splices 6 is detected based on the detected value. Processing for determining whether or not the connection state is good.

  The data obtained by each of the above processes is stored in the memory in the reflected light analysis terminal 430, and then converted into a display form that can be easily understood by the worker 8, and displayed on the display.

(Effect of embodiment)
As described in detail above, in the first embodiment, first, on the inside of the station and the subscriber side of the optical fiber 1 connected using the mechanical splice 6, the inside loss providing unit 40 and the inside loss providing unit 5 are respectively provided. Then, the S-shaped bend is applied to block the signal light from flowing, and then the bent portion 414 is formed by the side light input / output mechanism 41 between the local inner loss applying portion 40 and the mechanical splice 6 of the optical fiber 1. As a result, light can enter and exit from the side of the optical fiber 1. In this state, the inspection light 425 is incident on the optical fiber 1 from the reflected light analysis unit 42 via the side light input / output mechanism 41, and the reflected light 426 of the inspection light 425 by the mechanical splice 6 is transmitted to the side. It is taken out from the direction light input / output mechanism 41, guided to the reflected light analysis unit 42, analyzed by the reflected light analysis terminal 430, and the connection state between the optical fibers by the mechanical splice 6 is determined.

  Therefore, it is possible to inspect the connection state between the optical fibers by the mechanical splice 6 without cutting the optical fiber 1 and taking it home. For this reason, it is possible to greatly reduce the time and labor required for the inspection, and there is no risk of erroneous cutting of the optical fiber 1.

  In addition, in order to show that the defective sample and the good sample of the mechanical splice 6 can be distinguished by the inspection method according to the present embodiment, the mechanical splice as a good sample prepared by cleaving the fiber cutter and the fiber end face are cut using a nipper. Each of the mechanical splices using the optical fiber as the defective sample was inspected by the inspection method of this embodiment, and the result was compared with the inspection result of the conventional inspection method in which the optical fiber was cut and inspected. As a reference, FIG. 7 is a diagram showing the shape of each end face. As is clear from the figure, the cleavage plane using the fiber cutter is a flat surface (FIG. 7 (a)), but the cross section cut using a nipper has an irregular shape (FIG. 7 (b)). I understand.

  FIG. 8 shows a loss measurement result of each sample obtained by cutting and measuring the optical fiber on the optical line as in the prior art. It can be seen that the good sample of the fiber cutter cleavage has a loss of -0.13 dB at the maximum, whereas the loss of the defective sample cut with the nipper reaches about -6 dB.

  FIG. 9 shows the observation result of the fiber joint surface by the reflected light analysis unit 42. For reference for recognizing good samples, the PC polished connector joint surface was also measured. Since the PC polishing connector joint surface (FIG. 9A) is in contact with zero gap, the peak width is observed at 10 μm which is the position resolution of the apparatus. On the other hand, the waveform of the bonded surface of the optical fiber by the mechanical splice 6 which is a good sample (FIG. 9B) is very similar to the waveform of the PC polished bonded surface, is symmetrical and has the same peak width. Therefore, it can be said that it is normal. On the other hand, the waveform (FIG. 9C) of the joint surface of the mechanical splice 6 which is a defective sample has an asymmetric peak shape and a wide shape, and can be determined to be clearly abnormal. That is, by analyzing the peak waveform measured by the reflected light analysis unit 42, it is possible to determine normality / abnormality of the joint portion of the optical fiber by the mechanical splice 6.

  Further, according to the present embodiment, the following effects can also be achieved. That is, the reflected light analyzing unit 42 receives various optical signals including the reflected light 426 in a state where the station inner loss providing unit 40 and the house inner loss providing unit 5 do not block light. Specifically, first, the reflected light analysis unit 42 includes a laser light source (for example, a wavelength range of 1525 nm to 1625 nm, power level +4.6 dBm) that is strongly issued, and the inspection light 425 reaches the joint portion of the mechanical splice. . On the other hand, on the optical fiber 1 between the station inner side transmission device 2 and the subscriber side transmission device 3, a downlink signal for broadcast transmission (for example, wavelength 1550 nm, power level is set from the station inner side transmission device 2 to the subscriber side transmission device 3). +8 dBm) and a downlink signal (for example, wavelength 1490 nm) received by the subscriber-side transmission device 3 is transmitted by bidirectional communication. Therefore, when these light beams are reflected by the mechanical splice 6 to be inspected and the reflected light reaches the reflected light analysis unit 42, it may cause a malfunction, and an accurate result may not be obtained. Furthermore, if the upstream light from the subscriber-side transmission device 3 to the station-side transmission device enters the reflected light analysis unit 42, an accurate result may not be obtained.

  On the other hand, according to the present embodiment, first, the optical signal light is blocked by bending the optical fiber 1 by giving a remote control signal to the station inner loss applying unit 40 and the house inner loss applying unit 5, and after the blocking The sequence control can be performed so as to bend the optical fiber 1 by giving a remote control signal to the side light input / output mechanism 41. Further, there is no fear that the inspection light 425 reaches the subscriber-side transmission device 3 and has an adverse effect.

[Second Embodiment]
The apparatus used in the first embodiment can be used not only for inspection of the mechanical splice 6 after installation, but also for work support in the process of connecting the optical fiber 1 using the mechanical splice. A specific overall configuration is shown in FIG. In the process in which the maintenance worker 8 uses the mechanical splice preparation unit 7 to perform the connection work between the optical fibers by the mechanical splice 6, the gap between the end faces of the optical fiber 1 is expanded beyond a predetermined value. In the reflected light analysis terminal 430, the spread of the gap is detected by performing a Fourier transform on the wavelength spectrum of the reflected light 426, and a warning is given by the production status notification unit 9 connected to the reflected light analysis terminal 430. The worker 8 is notified by generating a sound or the like. Upon receiving this notification, the worker 8 can redo the connection work on the spot. Therefore, it is possible to detect and correct the occurrence of a connection failure in the connection work process, thereby improving the reliability and reducing the operation cost associated with the failure repair at a later date. Since the connection state is inspected using the inspection light 425, the connection work by the mechanical splice 6 is not affected at all.

[Third Embodiment]
Recently, strong light for broadcast transmission (for example, a wavelength of 1550 nm and a power level of about +8 dBm) is used for communication on the optical fiber 1 between the station-side transmission device 2 and the subscriber-side transmission device 3. When such light enters the measurement system, it adversely affects the measurement result, so it is necessary to attenuate the communication light. In the third embodiment, a light blocking mechanism (corresponding to the station inner loss applying unit 40 and the house inner loss applying unit 5 in the present invention) used for blocking communication light without cutting and damaging the optical fiber 1. ) Other configurations will be described.

  According to the experiments of the present inventors so far, when the radius of curvature is 2 mm and the bending angle is 360 degrees, good light blocking performance of −18 to −24 dB at an optical wavelength of 1310 nm and −32 to −46 dB at 1550 nm can be confirmed. ing. The bending angle of 360 degrees can be realized by combining a plurality of loss imparting portions. That is, the total value of the bending center angles formed by the respective loss imparting portions may be 360 degrees.

  FIG. 11 shows an example of a combination in the case where a bending angle of 360 degrees is realized by a plurality of loss imparting portions on the assumption that the curvature radius is 2 mm. FIG. 11A shows a case in which bending of 180 degrees is formed by two loss imparting portions, and the total bending center angle is 360 degrees. Further, FIG. 11B shows a case in which bending of 90 degrees is formed by each of the four loss imparting portions, and the total bending center angle is 360 degrees.

  Here, when a bend is formed in the optical fiber 1, the possibility that the optical fiber to be bent is damaged increases as the bending center angle at one location increases. Therefore, damage to the optical fiber can be suppressed as the number of loss imparting portions for realizing a radius of curvature of 2 mm and a bending angle of 360 degrees is larger. For this reason, it is useful to form a bend by combining a plurality of loss imparting portions.

[Other Embodiments]
The present invention is not limited to the above embodiment. For example, the side light input / output mechanism 41 can perform light input / output from the side of the optical fiber 1 by bending the optical fiber 1, but bending the optical fiber 1 simultaneously causes the optical fiber 1 to bend. Since there is a possibility of giving a loss, as shown in FIG. 12, the bending of the optical fiber by the local loss applying section 40 and the side light input / output mechanism 41 may be performed at one place.

  In addition, the reflected light analysis unit 42 used in the first to third embodiments is most suitable for OFDR at present, but other ones based on methods such as OLCR and OTDR (Optical Time Domain Reflectometry) are used. You may make it do.

  In short, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Optical fiber, 2 ... Office inner side transmission apparatus (OLT), 3 ... Subscriber side transmission apparatus (ONU), 4 ... Station inner side inspection unit, 5 ... Home inner loss provision part, 6 ... Mechanical splice, 7 ... Mechanical splice Production unit, 8 ... worker, 9 ... production status notifying means, 40 ... local side loss applying unit, 41 ... side light input / output mechanism, 42 ... reflected light analysis unit, 410 ... first block, 411 ... probe fiber 412 ... 2nd block, 413 ... Refractive index matching agent, 414 ... Bending part, 420 ... Wavelength variable laser, 421, 422, 423 ... Coupler, 424 ... Fiber connector, 425 ... Inspection light, 426 ... Reflected light, 427 ... APD, 428 ... amplifier, 429 ... A / D converter, 430 ... reflected light analysis terminal.

Claims (5)

A light beam that is laid between the first transmission device and the second transmission device and inspects the connection state of the optical fiber by the mechanical connection mechanism in an optical line in which a plurality of optical fibers are connected by the mechanical connection mechanism. A road inspection device,
By continuously forming a plurality of bent portions which are arranged, in which the bending direction relative to the optical line is opposite between the first transmission device and the mechanical connection mechanism of the optical line, the first First loss imparting means for interrupting transmission of the communication optical signal transmitted from one transmission device to the mechanical connection mechanism;
A probe fiber is arranged opposite to a bent portion closest to the mechanical connection mechanism among the plurality of bent portions formed by the first loss applying means, and the inspection light is applied to the optical line by the probe fiber. Side light input / output means for entering and exiting signals,
An optical signal for inspection that is disposed between the second transmission device of the optical line and the mechanical connection mechanism and passes through the mechanical connection mechanism by partially bending the optical line, and the first Second loss imparting means for blocking transmission of at least one of the communication optical signals transmitted from the two transmission devices;
An optical signal for inspection is incident on the optical line through the bent portion, which is connected to the probe fiber of the side light input / output means and the probe fiber and the probe fiber are arranged to face each other. A light analyzing means for receiving the reflected light of the optical signal by the mechanical connection mechanism through the bending portion and the probe fiber which are opposed to the probe fiber, and analyzing the received reflected light;
Optical line inspection apparatus characterized by comprising.   The light analyzing means measures a wavelength spectrum of reflected light and performs a Fourier transform on the measured wavelength spectrum to calculate a separation interval between the end faces of the optical fibers by the mechanical connection mechanism; and the reflection Processing for detecting a light reception level and calculating a loss by the mechanical connection mechanism based on the detected value, and the mechanical connection mechanism based on the amplitude waveform for each reflection position of the reflected light The optical line inspection apparatus according to claim 1, wherein at least one of processes for determining whether or not the connection state between the optical fibers is good is executed. During connection work of the optical fiber by the mechanical connection mechanism, whether the optical fiber connection state by the mechanical connection mechanism is good or not is determined based on the analysis result by the optical analysis unit, and information indicating the determination result is displayed. optical line test apparatus according to informing means for informing, to the further one of claims 1 or 2, characterized in that it comprises. The first or second loss imparting means continuously forms a plurality of bent portions whose bending directions are opposite to the optical line, and a sum of bending center angles of the plurality of bent portions is the optical signal. optical line inspection apparatus according to any one of claims 1 to 3, characterized in that set so that the bending angle required to block. A light beam that is laid between the first transmission device and the second transmission device and inspects the connection state of the optical fiber by the mechanical connection mechanism in an optical line in which a plurality of optical fibers are connected by the mechanical connection mechanism. An optical line inspection method executed by a road inspection device,
By continuously forming a plurality of bent portions whose bending directions are opposite to the optical line by the first bending mechanism between the first transmission device of the optical line and the mechanical connection mechanism. A first loss imparting process for blocking transmission of an optical signal for communication transmitted from the first transmission device to the mechanical connection mechanism;
A probe fiber is arranged opposite to a bent portion closest to the mechanical connection mechanism among the plurality of bent portions formed by the first loss imparting process of the optical line, and the probe fiber is disposed to the optical line. Side light input / output process for entering and exiting the inspection optical signal,
Inspection light that has passed through the mechanical connection mechanism by partially bending the optical line by a second bending mechanism between the second transmission device of the optical line and the mechanical connection mechanism. A second loss imparting step of blocking transmission of at least one of the signal and the optical signal for communication transmitted from the second transmission device;
Connected to the probe fiber in the side light input / output process, an optical signal for inspection is incident on the optical line through the bending portion in which the probe fiber and the probe fiber are arranged to face each other. An optical analysis process for receiving the reflected light of the optical signal by the mechanical connection mechanism through the bending portion where the probe fiber is opposed and the probe fiber, and analyzing the received reflected light. An optical line inspection method characterized by the above.