JP6461754B2 - Optical fiber test apparatus and optical fiber test method - Google Patents

Description

  The present invention relates to a technique for inputting and outputting light from the side of an optical fiber.

  The side optical input / output technology of an optical fiber has a structure in which another optical fiber (probe fiber) is abutted against the side surface of a bent portion (bending portion) of an optical fiber bent at a certain angle. (See Patent Document 1, Patent Document 2, and Non-Patent Document 1). Hereinafter, in this specification, “side light input” means that light is input from the probe fiber to the bent portion of the optical fiber, and “side light output” means that light is transmitted from the bent portion of the optical fiber to the outside. It means leaking.

  This side light input / output technology is applied to “core control” for specifying a desired optical fiber from among a large number of optical fibers. FIG. 1 is a diagram for explaining the operation of contrasting core wires. Test light is coupled only to a specific optical fiber among the plurality of optical fibers. Then, the optical fiber is bent at a desired position, and the specific optical fiber through which the test light leaks is identified. In the operation / maintenance operation of the optical fiber cable, the core control performed by the field worker using the test light is an indispensable operation for avoiding erroneous disconnection / incorrect connection of the core.

  In the conventional contrast control method, the test light is transmitted from the communication building to the optical access network via an integrated distribution module (IDM) that is installed in the communication building in advance. However, in the access network using the PON (Passive Optical Network) method, when the test light transmitted from the communication building passes through the splitter, the test light is branched, and the test light propagates to a plurality of core wires. It is difficult to identify (see FIG. 2). Therefore, it is possible to combine the test light with a specific optical fiber by the side light input technology downstream from the optical splitter, and to compare the cores with the side light output technology at a desired location without placing personnel in the communication building. It has been studied (see FIG. 3, Patent Document 1, Patent Document 2, and Non-Patent Document 1).

JP 2004-325310 A JP 2009-025211 A

Iwata et al., “Examination of core-line contrast transmitter using side light input technology”, IEICE technical report. OPE, Optoelectronics 112 (449), 55-58, 2013-02-21

  However, in the conventional method of contrasting the cores using the side input technique, the bending loss increases due to the bending of two places formed by the test light input device and the light receiving device, which affects the communication light. was there.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical fiber test apparatus and an optical fiber test method that can perform a core contrast without affecting the communication light passing through the optical fiber core.

  The optical fiber test apparatus according to the present invention reduces the bending amount of the optical fiber core wire by using test light having a wavelength that is likely to leak.

Specifically, the optical fiber testing apparatus according to the present invention is:
A test light source that outputs test light having a wavelength shorter than the cutoff wavelength of the optical fiber;
Arranged in the optical fiber core, bending the optical fiber core to form a first bent portion, so that the test light from the test light source propagates in one direction of the optical fiber core, A side light input section for performing side light input of the test light to the first bent section;
The optical fiber core wire is disposed in the direction in which the test light propagates from the position where the side light input portion is disposed, the second optical fiber core wire is bent to form a second bent portion, and the second bent portion A side light output unit for leaking the test light from the optical fiber core;
Is provided.

Moreover, the optical fiber testing method according to the present invention forms two bent portions at the desired positions by bending the optical fiber core wire,
In one of the bent portions, a test light having a wavelength shorter than a cutoff wavelength of the optical fiber core wire is subjected to side light input to the optical fiber core wire toward the other of the bent portion,
On the other side of the bent portion, the test light leaked from the optical fiber core wire is detected.

  By using light having a wavelength shorter than the cutoff wavelength of the optical fiber core, the test light propagates in the optical fiber core in the fundamental mode and the higher-order mode. Since the light propagating through the optical fiber in the higher-order mode is likely to leak to the outside, the amount of bending of the optical fiber core wire at the portion where the core wires are compared can be reduced. For this reason, the communication light propagating in the fundamental mode has a smaller total loss received at the bent portion even if two bent portions are formed.

  Specifically, the optical fiber core wire is formed by a first bent portion formed by the side light input portion on the optical fiber core wire and a second bent portion formed by the side light output portion on the optical fiber core wire. It is preferable that the total loss of the communication light propagating through is 2 dB or less.

  Therefore, the present invention can provide an optical fiber test apparatus and an optical fiber test method capable of performing a core contrast without affecting the communication light passing through the optical fiber core.

  In addition, a conventional light source for test light (wavelength 1650 nm) used for contrast control of a core wire is expensive, and a light receiving device for detecting the test light is also required. For this reason, the conventional method for contrasting core wires also has a problem in that the cost of opening / maintenance operation of the optical fiber cable is high.

  In the optical fiber testing apparatus according to the present invention, the wavelength of the test light output from the test light source is visible light. A light source that generates visible light is not expensive. Moreover, since it is visible light, a light receiving device is unnecessary. Therefore, the optical fiber test apparatus according to the present invention can reduce the cost of the operation / maintenance operation of the optical fiber cable.

  Furthermore, the light receiving device used in the conventional contrast control of the optical fiber sandwiches the optical fiber cores one by one and imparts bending. Therefore, since only one piece can be detected at a time, it is a problem that the work efficiency of the contrast control is poor.

  The optical fiber test apparatus according to the present invention includes a plurality of the optical fiber core wires, and the side light input portion includes a first bent portion formed in one of the optical fiber core wires, and the side light output portion. The portion is characterized in that the second bent portion is formed in all the optical fiber core wires.

  In the present optical fiber test apparatus, test light is input to only one desired optical fiber core wire at the first bending portion. For this reason, since test light leaks only from the one optical fiber core wire in the second bent portion, a desired optical fiber core wire can be easily identified even if the number of optical fiber core wires is large, Work efficiency can be improved.

  Moreover, the optical fiber test apparatus according to the present invention includes a plurality of the optical fiber core wires, and the side light input portion includes a first bent portion formed in all the optical fiber core wires, and the side light The output unit is characterized in that a second bent portion is formed on all the optical fiber cores, and the test light source outputs the test light having discriminability for each of the optical fiber cores.

  In the present optical fiber test apparatus, test light having different wavelengths is input to each optical fiber core wire in the first bending portion. For this reason, the optical fiber core wire can be easily identified by confirming the wavelength of the test light leaked from the optical fiber core wire in the second bending portion, and the working efficiency can be improved. Note that the “test light having distinctiveness” may be “test light having different blinking speeds” or “test light modulated by signals having different patterns” in addition to “test light having different wavelengths” as described above. .

  The present invention can provide an optical fiber test apparatus and an optical fiber test method capable of performing a core contrast without affecting the communication light passing through the optical fiber core.

It is a figure explaining the operation | work of a core line contrast. It is a figure explaining the core line contrast work in the access network using a PON system. It is a figure explaining the core line contrast work in the access network using a PON system. It is a figure explaining the optical fiber test device concerning the present invention. It is a figure explaining the side light input part of the optical fiber test equipment concerning the present invention. It is a figure explaining the side light output part of the optical fiber testing apparatus which concerns on this invention. It is a figure explaining the side light output part of the optical fiber testing apparatus which concerns on this invention. It is the photograph which image | photographed the test light (visible light with a wavelength of 650 nm) leaking from the side light output part of the optical fiber testing apparatus which concerns on this invention. It is a figure explaining the optical fiber test device concerning the present invention. It is a figure explaining the optical fiber test device concerning the present invention. It is a figure explaining the optical fiber test device concerning the present invention. It is a figure explaining the side light input part of the optical fiber test equipment concerning the present invention. It is a figure explaining the side light output part of the optical fiber testing apparatus which concerns on this invention.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are embodiments of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
FIG. 4 is a conceptual diagram illustrating the optical fiber test apparatus 301 of the present embodiment. The optical fiber test apparatus 301
A test light source 10 for outputting test light having a wavelength shorter than the cutoff wavelength of the optical fiber core wire 50;
The optical fiber core wire 50 is arranged to bend the optical fiber core wire 50 to form a first bent portion 51 so that the test light from the test light source 10 propagates in one direction of the optical fiber core wire 50. , A side light input unit 20 for performing side light input of the test light to the first bending part 51;
The optical fiber core wire 50 is disposed in the direction in which the test light propagates from the position where the side light input portion 20 is disposed, the optical fiber core wire 50 is bent to form a second bent portion 52, and the second bent portion A side light output section 30 for leaking the test light from the optical fiber core wire 52 of 52,
Is provided.

  In order to propagate the test light through the optical fiber 50 in the higher order mode, the test light source 10 outputs light having a wavelength shorter than the cutoff wavelength of the optical fiber. Here, it is preferable that the wavelength of the test light output from the test light source 10 is visible light (for example, a wavelength of 650 nm).

  FIG. 5 is a diagram illustrating the side light input unit 20. The optical fiber core wire 50 is pressed against the cylindrical portion 2 which is a cylindrical rigid body, and the first bent portion 51 is formed. The refractive index matching agent 4, which is a transparent gel-like member, is formed with a certain thickness so as to cover the first bent portion 51 that is in close contact with the cylindrical portion 2. The end face of the probe fiber 5 is abutted against the first bent portion 51 so as to be inserted into the refractive index matching agent 4, thereby forming the optical system of the side light input portion 20. Here, the probe fiber 5 is aligned at such a position that the test light can enter the optical fiber core wire 50 most efficiently.

  Further, the formation of the first bent portion 51 is bent to such an extent that the communication light propagating through the optical fiber core wire 50 is not affected (no loss is given). For example, the first bending portion 51 is formed by giving the optical fiber core wire 50 bending so that the loss of communication light having a wavelength of 1550 nm is 1 dB or less.

  FIG. 6 is a diagram illustrating the side light output unit 30. For example, the optical fiber core wire 50 is sandwiched between the transparent blocks (31A, 31B) that transmit the visible light having the concavo-convex shape, and the second bent portion 52 is formed. The test light leaking from the second bending part 52 is detected by a light receiver. If the test light is visible light, the operator can visually recognize the leakage of the test light. If the leaked light is weak, a highly sensitive CCD camera may be used.

  The transparent blocks (31A, 31B) are formed so as to be bent to the extent that they do not affect (do not cause loss) the communication light propagating through the optical fiber core wire 50 to form the second bent portion 52. . For example, the transparent blocks (31A, 31B) are formed so as to give the optical fiber 50 a bend in which the loss of communication light having a wavelength of 1550 nm is 1 dB or less.

  The optical fiber test apparatus 301 gives two bent portions (51, 52) to the optical fiber core wire 50. Therefore, in the optical fiber test apparatus 301, the first bent portion 51 formed by the side light input unit 20 on the optical fiber core wire 50 and the second bent portion 52 formed by the side light output unit 30 on the optical fiber core wire 50. The total loss of communication light having a wavelength of 1550 nm propagating through the optical fiber core 50 is set to 2 dB or less.

  That is, the amount of bending at the first bending portion 51 and the second bending portion 52 is reduced, and loss to communication light is avoided. On the other hand, since the test light propagates through the optical fiber core wire 50 in a higher mode other than the fundamental mode, it leaks even if the bending amount at the second bending portion 52 is small. Since the optical fiber test apparatus 301 has a small loss of communication light due to the first bending part 51 and the second bending part 52, it does not affect the communication even during the core wire contrast operation.

  Therefore, the optical fiber test apparatus 301 can perform the core control at a low cost only at the work site without affecting the communication light passing through the optical fiber core 50.

[Example of side light output section]
FIG. 7 is a diagram for explaining a specific configuration of the side light output unit 30. FIG. 7A is a perspective view of the side light output unit 30. FIG. 7B is a side view of the side light output unit 30 (viewed from the α direction in FIG. 7A). The transparent blocks (31A, 31B) are made of, for example, acrylic. The corners indicated by the arrows of the transparent blocks (31A, 31B) are rounded to R30 mm so as not to cause microbend loss.

  A gap 32 is provided between the transparent block 31A and the transparent block 31B. The gap 32 is set to 0.25 mm or more so that no side pressure is applied to the optical fiber core 50 (when the diameter (including the coating) of the optical fiber core 50 is 250 μm). The transparent block 31A and the transparent block 31B are formed in a wave shape so that the bending radius of the optical fiber core wire 50 is 2 mm to 30 mm when the optical fiber core wire 50 is sandwiched. For example, if the bending radius of the optical fiber 50 is 2 mm or more and the bending angle is 160 ° or less, the loss of communication light having a wavelength of 1550 nm is 1 dB or less. If the bending radius is 15 mm or more, the loss of communication light having a wavelength of 1550 nm is 0.1 dB or less even when the bending angle is 90 °.

  FIG. 8 shows a photograph of the test light (visible light having a wavelength of 650 nm) leaking from the side light output unit 30 designed in this way. The test light leaks to such an extent that the loss at a wavelength of 1550 nm can be visually confirmed even when the bending is about 0.1 dB (bending that does not affect communication).

  In addition, when detecting leakage of the test light with the CCD camera instead of the visual work of the operator, as shown in FIG. 7B, a transparent block (31A, It is desirable to cover 31B) with a light shielding material.

(Embodiment 2)
FIG. 9 is a diagram for explaining the optical fiber testing apparatus 302 of the present embodiment. The difference between the optical fiber test apparatus 302 and the optical fiber test apparatus 301 described in the first embodiment is as follows.
There are a plurality of optical fiber cores 50,
The side light input part 20 forms the first bent part 51 in one of the optical fiber core wires 50,
The side light output part 30 forms the second bent part 52 in all the optical fiber core wires 50.

  In the side light output unit 30, the test light leaks only from the optical fiber core wire 50 combined with the test light in the side light input unit 20. That is, the specific optical fiber core 50 can be easily recognized from the plurality of optical fiber cores 50. The test light may be blinked so that it can be easily recognized visually. Therefore, the optical fiber test apparatus 302 can perform the core control at a low cost only at the work site without affecting the communication light passing through the optical fiber core 50.

(Embodiment 3)
FIG. 10 is a diagram for explaining the optical fiber test apparatus 303 of the present embodiment. The difference between the optical fiber test apparatus 303 and the optical fiber test apparatus 301 described in the first embodiment is as follows.
There are a plurality of optical fiber cores 50,
The side light input part 20 forms the first bent part 51 in all the optical fiber core wires 50,
The side light output part 30 forms the second bent part 52 in all the optical fiber core wires 50,
The test light source 10 outputs the test light having discriminability for each optical fiber core wire 50.

  In the optical fiber test apparatus 303, test light having different wavelengths (different colors) is coupled to each optical fiber core wire 50 by the side light input unit 20. For this reason, the test light leaking in the side light output unit 30 is different for each optical fiber core 50, and the operator can easily identify the wire numbers of the plurality of optical fiber cores 50. Therefore, the optical fiber test apparatus 303 can perform the core control at a low cost only at the work site without affecting the communication light passing through the optical fiber core 50.

  In addition, although it demonstrated as a thing which differs in the color of test light as "test light which has discriminability" here, since it should just be able to identify a plurality of optical fiber core wires collectively, changing the blinking speed of test light, The flashing pattern of the test light may be changed, or a combination of these may be used.

(Example)
FIG. 11 shows an embodiment of the optical fiber test apparatus 301. The optical fiber core 50 is a core wire having an MFD (mode field diameter) of 9.39 μm and a diameter of 0.25 mm. The light emission power of the test light source 10 is +4 dBm.

  FIG. 12 is a diagram illustrating the configuration of the side light input unit 20. In the present embodiment, the first bent portion 51 is formed in the optical fiber core wire 50 using the transparent block (21A, 21B). Since the transparent block 21 </ b> B is used, the visible light from the probe fiber 5 passes through the transparent block 21 </ b> B and is coupled to the first bent portion 51. The probe fiber 5 is a GI50 fiber (graded index fiber 50 μm). The shape of the first bending portion 51 is a bending radius R = 2 mm and a bending angle θ = 16 ° (bending loss is 0.95 dB). The input efficiency in the 1st bending part 51 is -41.5 dB in visible light 0.65 micrometer.

  FIG. 13 is a diagram illustrating the configuration of the side light output unit 30. In the present embodiment, the second bent portion 52 is formed in the optical fiber core wire 50 using transparent blocks (31A, 31B). Since the transparent block 31B is used, the visible light leaked from the second bent portion 52 can be seen by the operator through the transparent block 31B. The second bending portion 52 has a bending radius R = 2 mm and a bending angle θ = 16 ° (bending loss is 0.95 dB).

  The side light input unit 20 and the side light output unit 30 are installed in the optical fiber core wire 50, and light is transmitted from a light source of 1550 nm. And when the intensity | strength of the light which propagated the optical fiber core wire 50 with the power meter was measured, the total bending loss of the 1st bending part 51 and the 2nd bending part 52 was 2 dB or less.

  In the embodiment described with reference to FIGS. 11 to 13, the bending shape and bending angle of the first bending portion 51 and the second bending portion 52 are the same, and the total bending loss of the first bending portion 51 and the second bending portion 52 is 1550 nm. 2 dB or less. For this reason, the optical fiber test apparatus 301 does not affect communication. On the other hand, visible light incident from the probe fiber propagates through the optical fiber core wire 50 in a higher order mode, and therefore easily leaks at the second bending portion 52. Therefore, it is possible to easily contrast the cores simply by visually confirming the visible light leaking from the target optical fiber core.

[Appendix]
The following describes the optical fiber testing apparatus of the present embodiment.
(the purpose)
In the conventional method of contrasting the cores using the side input technique, bending loss occurs due to bending at two places formed by the test light input device and the light receiving device, which affects communication. Further, the light source of the test light (wavelength 1650 nm) used in the conventional contrast control is expensive, and a light receiving device is required to detect the test light, which is expensive. Further, in the conventional light receiving device, the optical fiber core wires are sandwiched one by one to bend. Therefore, only one piece can be detected, and work efficiency is poor.

(Solving issues)
This optical fiber test equipment
(1): For inputting test light having a wavelength shorter than the cut-off wavelength of the optical fiber core (minimum wavelength for blocking higher-order modes) from the side of the bent optical fiber core at a desired position. It has a bent portion and a probe, propagates a second or higher order mode of the optical fiber core, and detects light leaked from the bent portion of the optical fiber core bent at a desired position.
(2): The wavelength of the input test light is visible light (wavelength of 360 nm or more and 830 nm or less).
(3): Loss of communication light when inputting / outputting test light is 2 dB or less.
(4): The test light leaked from the bent portion is confirmed visually or through a camera.

(Effect of the invention)
According to the present invention, the following operational effects are exhibited.
(1) The light receiving device for detecting the test light is simplified and the cost can be reduced.
(2) Since it can be confirmed by visual observation, the core wire contrast work is simple and the work efficiency is improved.
(3) The cores can be contrasted only outside (construction site) without affecting communications.
(4) Visible light can be input from a desired position of the optical fiber core wire.
(5) Since a visible light source that is less expensive than the test light source is used, it is economical.
(6) One optical fiber core under the optical splitter can be easily identified.
(7) It is possible to identify / select one of a plurality of optical fiber cores for visual confirmation.
(8) A plurality of optical fiber cores can be identified simultaneously.
(9) Bending loss can be reduced and the influence on communication can be reduced as compared with the core line contrast work using the conventional side light input / output technology.

2: Cylindrical part 4: Refractive index matching agent 5: Probe fiber 10: Test light source 20: Side light input part 21A: Transparent block 21B: Transparent block 30: Side light output part 31A: Transparent block 31B: Transparent block 32 : Gap 50: Optical fiber core wire 51: 1st bending part 52: 2nd bending part 301, 302, 303: Optical fiber test equipment

Claims (6)

A test light source that outputs test light that is visible light having a shorter wavelength than the cutoff wavelength of the optical fiber;
Arranged in the optical fiber core, bending the optical fiber core to form a first bent portion, so that the test light from the test light source propagates in one direction of the optical fiber core, A side light input section for performing side light input of the test light to the first bent section;
The optical fiber core wire is disposed in the direction in which the test light propagates from the position where the side light input portion is disposed, the second optical fiber core wire is bent to form a second bent portion, and the second bent portion A side light output unit having a structure in which the test light leaks from the optical fiber core wire of the second bending portion and the test light leaked from the optical fiber core wire of the second bent portion can be visually confirmed from the outside or by a camera ;
An optical fiber testing apparatus comprising: The optical fiber test apparatus according to claim 1, wherein the structure of the side light output unit is a transparent block .   Communication light propagating through the optical fiber core by the first bent portion formed by the side light input portion on the optical fiber core and the second bent portion formed by the side light output portion on the optical fiber core wire. The total optical loss is 2 dB or less, and the optical fiber test apparatus according to claim 1 or 2. A plurality of the optical fiber core wires,
The side light input part forms a first bent part in one of the optical fiber core wires,
4. The optical fiber testing device according to claim 1, wherein the side light output unit forms a second bent portion in all the optical fiber core wires. 5. A plurality of the optical fiber core wires,
The side light input part forms a first bent part in all the optical fiber core wires,
The side light output part forms a second bent part in all the optical fiber core wires,
The optical fiber test apparatus according to claim 1, wherein the test light source outputs the test light having discriminability for each of the optical fiber core wires. Forming two bent portions at desired positions by bending the optical fiber core wire with a predetermined structure ;
In one of the bent portions , a test light which is visible light having a wavelength shorter than a cutoff wavelength of the optical fiber core is subjected to side light input to the optical fiber toward the other of the bent portion,
An optical fiber test method in which the test light leaked from the optical fiber core wire is visually confirmed from the outside of the predetermined structure or by a camera at the other of the bent portions.