JP2018009799A - Optical fiber evaluation jig and optical fiber evaluation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber evaluation jig capable of simultaneously inspecting plural optical fibers or multi-core optical fibers by connecting fibers to an optical fiber characteristics analyzer, and an evaluation method thereof.SOLUTION: Disclosed optical fiber evaluation jig simultaneously measures optical characteristics of plural optical fibers to be tested of the number equal to the number of branches of optical splitters in such manner that, after forming differences in length on a pigtail which is connected to the branching side of an optical splitter, the optical fibers to be tested are connected to the optical fiber evaluation jig formed with the differences in length and the optical fiber characteristics analyzer is connected to the pigtail of the optical fiber evaluation jig at the multiplexing side.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an evaluation jig that collectively evaluates characteristics of a plurality of optical lines and an evaluation method thereof.

  In an optical fiber production site, there is generally a process of 100% inspection before shipment. In 100% inspection, a loss test is performed using an optical line characteristic analyzer such as an optical time domain reflectometer (OTDR). In recent years, research on spatial multiplexing optical fiber technology has been actively conducted, and the market development of multi-core optical fibers having a plurality of cores is expected.

Hirotaka Takahashi, Fumihiko Ito, Chihiro Kito, and Kunihiro Toge, “Individual loss distribution measurement in 32-pumped PON using pulsating pulsating pulsating pulsating pulsating pulsating pulsating pulsating pulsating pons pulsing pulsating pulsating pulsating pulsating pons pulsing pulsating pons pulsing pulsating pulsating pulsating pons pulsing pulsating pons pulsing pulsating pons? Express 21, 6739-6748 (2013) Chihiro Kito, Naka Takahashi, Kunihiro Toge, Tetsuya Manabe, Fumihiko Ito, “Applicability of far-end reflection Brillouin analysis to disconnection fault monitoring”, IEICE Technical Report, OFT 2014-40 (2014) Hiroshi TAKAHASHI, Chihiro KITO, Kunihiro TOGE and Tetsuya MANABE, "Centralized Measurement of Actual Splice Loss for Installed Optical Fiber Cable Networks Using End-reflection-assisted Brillouin Analysis", Proceedings of the 63rd IWCS Conference, 87-91 (2014)

  At the production site of optical fiber cores, all the cables are connected to the OTDR for inspection, so that it takes a long time to evaluate the loss, which increases the production cost of the optical fiber cores. Therefore, it is required to reduce the inspection time per core or reduce the inspection operation by the inspection worker. In addition, when multi-core optical fibers are distributed in the general market, it is possible to ship after conducting a loss test for each core following the current inspection process for single-core optical fibers. Since the inspection cost is expected to increase only, it is necessary to reduce the inspection operation of all core inspections.

  The present invention has been made for the above circumstances, and provides an optical fiber evaluation jig and an evaluation method thereof that can be inspected collectively by connecting a plurality of optical fibers or multi-core optical fibers to an optical line characteristic analyzer. Objective.

  In order to achieve the above object, the present invention provides an optical splitter in which a plurality of optical fibers or multi-core optical fibers are connected to an optical line characteristic analyzer using an optical splitter so that return light from these optical fibers does not overlap. The optical path length from the optical fiber to each optical fiber was adjusted.

Specifically, the first optical fiber evaluation jig according to the present invention is:
N (N is an integer of 2 or more) demultiplexing side pigtails, each of which has an optical fiber core to be connected to one end;
One multiplexing side port to which the optical line characteristic analyzer is connected and N branching side ports to which the other ends of the N demultiplexing pigtails are respectively connected, and light from the multiplexing side port 1 × N light that is coupled to the branching-side pigtail of the branching-side port, combines the light coupled from the branching-side pigtail to the branching-side port, and outputs the combined light to the multiplexing-side port A splitter,
With
The difference between any two round-trip optical path lengths of the N demultiplexing side pigtails is larger than the spatial extension of the pulse width of the return light from the optical fiber under test received by the optical line characteristic analyzer. Features.

In the first optical fiber evaluation method using the first optical fiber evaluation jig, an optical line characteristic analyzer is connected to the multiplexing side port of the 1 × N optical splitter of the first optical fiber evaluation jig,
Connecting each of the one ends of the N branching pigtails to the core of the optical fiber under test,
An optical pulse is incident on the multiplexing side port of the 1 × N optical splitter from the optical line characteristic analyzer.

  When the evaluation object is a multi-core optical fiber, the N demultiplexing-side pigtails have a multi-core optical fiber connection device at the one end.

  The first optical fiber evaluation jig and the first optical fiber evaluation method are used when evaluating optical fibers or multi-core optical fibers whose lengths are close to each other. By setting the difference in the length of each pigtail as described above, the return light of the test light incident on each optical fiber or each core from the optical line characteristic analyzer does not overlap even if they are combined by the optical splitter. For this reason, the optical line characteristic analyzer can receive the return light from each optical fiber or each core separately, and can perform a collective evaluation.

  Therefore, this invention can provide the optical fiber evaluation jig | tool which can test | inspect collectively by connecting a some optical fiber or multi-core optical fiber to an optical-line characteristic analyzer, and its evaluation method.

  Here, it is preferable that the N demultiplexing-side pigtails are respectively identified, and the line length becomes longer or shorter in order from the first to the Nth. By doing in this way, it is possible to easily identify the return light from which optical fiber or the return light from which core of the multi-core optical fiber.

The second optical fiber evaluation jig according to the present invention is:
N demultiplex side pigtails each connected to one end of the core of the optical fiber under test;
A line length difference variable mechanism that is arranged in each of the N demultiplexing-side pigtails to arbitrarily change the line length;
One multiplexing side port to which the optical line characteristic analyzer is connected and N branching side ports to which the other ends of the N demultiplexing pigtails are respectively connected, and light from the multiplexing side port 1 × N light that is coupled to the branching-side pigtail of the branching-side port, combines the light coupled from the branching-side pigtail to the branching-side port, and outputs the combined light to the multiplexing-side port A splitter,
Is provided.

The second optical fiber evaluation method using the second optical fiber evaluation jig is as follows:
An optical line characteristic analyzer is connected to the multiplexing side port of the 1 × N optical splitter of the second optical fiber evaluation jig,
Connecting each of the one ends of the N branching pigtails to the core of the optical fiber under test,
The optical line characteristic analyzer receives the difference between any two of the reciprocal optical path lengths consisting of the demultiplexing side pigtail and the core of the optical fiber to be tested connected to the demultiplexing side pigtail by the variable line length difference mechanism. Set larger than the spatial spread of the pulse width of the return light from the optical fiber to be tested,
An optical pulse is incident on the multiplexing side port of the 1 × N optical splitter from the optical line characteristic analyzer.

  When the evaluation object is a multi-core optical fiber, the N demultiplexing-side pigtails have a multi-core optical fiber connection device at the one end.

  The second optical fiber evaluation jig and the second optical fiber evaluation method can also be used when evaluating optical fibers having different lengths. Each pigtail is provided with a line length difference variable mechanism capable of changing the optical path length, and the reciprocal optical path length difference of “pigtail + optical fiber under test” is set as described above by using the line length difference variable mechanism. Thus, the return light of the test light incident on each optical fiber or each core from the optical line characteristic analyzer does not overlap even if they are combined by the optical splitter. For this reason, the optical line characteristic analyzer can receive the return light from each optical fiber or each core separately, and can perform a collective evaluation.

  Therefore, this invention can provide the optical fiber evaluation jig | tool which can test | inspect collectively by connecting a some optical fiber or multi-core optical fiber to an optical-line characteristic analyzer, and its evaluation method.

  In both the first optical fiber evaluation method and the second optical fiber evaluation method, a reflection end that reflects light may be installed at an end of the optical fiber under test opposite to an end to which the demultiplexing-side pigtail is connected. preferable. The dynamic range during far-end reflection Brillouin analysis can be expanded.

  The present invention can provide an optical fiber evaluation jig and an evaluation method thereof in which a plurality of optical fibers or multi-core optical fibers are connected to an optical line characteristic analyzing apparatus and can be collectively inspected.

It is a figure explaining the optical fiber evaluation jig | tool which concerns on this invention, and the optical fiber evaluation method using the same. It is a figure explaining the optical fiber evaluation jig | tool which concerns on this invention, and the optical fiber evaluation method using the same. It is a figure explaining the requirements in the case of performing an optical fiber evaluation method with the optical fiber evaluation jig concerning the present invention. It is a figure explaining the requirements in the case of performing an optical fiber evaluation method with the optical fiber evaluation jig concerning the present invention. It is a figure explaining the optical fiber evaluation jig | tool which concerns on this invention, and the optical fiber evaluation method using the same. It is a figure explaining the optical fiber evaluation jig | tool which concerns on this invention, and the optical fiber evaluation method using the same.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples 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. 1 is a diagram for explaining an optical fiber evaluation jig 301 (first optical fiber evaluation jig) and an optical fiber evaluation method using the same according to the present embodiment. The optical fiber evaluation jig 301 is
N (N is an integer greater than or equal to 2) branching side pigtails 12 each connected to one end of the core of the optical fiber 200 under test;
One multiplexing side port to which the optical line characteristic analyzing apparatus 100 is connected and N branching side ports to which the other ends of the N demultiplexing pigtails 12 are respectively connected are provided from the multiplexing side port. 1 × N that splits the light and couples it to the branching-side pigtail 12 of the branching-side port, combines the light coupled from the branching-side pigtail 12 to the branching-side port, and outputs it to the multiplexing-side port An optical splitter 11;
Is provided.
In the optical fiber evaluation jig 301, the difference between any two reciprocal optical path lengths of the N demultiplexing side pigtails 12 is the pulse width of the return light from the optical fiber 200 to be tested received by the optical line characteristic analyzer 100. It is characterized by being larger than the spatial extent.

  An optical fiber multi-core evaluation system using the optical fiber evaluation jig 301 connects the optical line characteristic analyzer 100 to the multiplexing side port of the 1 × N optical splitter 11, and separates the demultiplexing side pigtail 12. The test optical fiber 200 is connected to the end using the connection terminal 13. The demultiplexing pigtail 12 has a line length difference in advance.

  This will be specifically described. When the lengths of the optical fibers 200 to be tested are different, the length of the optical fiber to be tested 200 # i connected to the i-th (i is a natural number equal to or less than N) branching pigtail 12 # i and the branching pigtail The total length of 12 # i and the length of the optical fiber under test 200 # j connected to the j-th (j is a natural number less than N and i ≠ j) branch-side pigtail 12 # j and the branch-side pigtail 12 The line length of each branching pigtail 12 is set so that the total length of #j is different. The pigtail is an optical fiber.

  Further, when the lengths of the optical fibers 200 under test are equal, the line lengths of the demultiplexing side pigtails 12 are different so that the length of the demultiplexing side pigtail 12 # i is different from the length of the demultiplexing side pigtail 12 # j. Is set. Note that the N demultiplexing side pigtails 12 are respectively identified, and it is preferable that the line length becomes longer or shorter in order from the first to the Nth. Specifically, the demultiplexing side pigtail length is set in order so that the length of the demultiplexing side pigtail 12 # i is shorter (or longer) than the length of the demultiplexing side pigtail 12 # i + 1. By setting in this way, it becomes easy to associate the evaluation result of the optical line characteristic analyzing apparatus 100 with each optical fiber 200 to be tested. Since the present invention can be applied to collective evaluation of tape cores, it is desirable that the core numbers of the tape cores and the core numbers of the branch pigtails be easily matched.

  Next, how to determine the line length difference of the branching pigtail 12 will be described. The same applies when the lengths of the optical fibers under test 200 are different and when the lengths of the optical fibers 200 under test are equal.

The requirements of the optical fiber multi-fiber batch evaluation system of this embodiment are as follows.
[Requirements]
Relative spatial extent W _p of the pulse width of probe light and the received signal at the optical line characterization system, the direction of any two reciprocating optical path length difference ΔL to be branched by the optical splitter is increased.

  By adjusting the length of the demultiplexing side pigtail 12 in consideration of the line length difference of the plurality of optical fibers 200 to be tested connected to the multi-core collective evaluation system so as to satisfy the requirements, for example, non-patent With the technique disclosed in Document 1, it is possible to collectively evaluate the optical line characteristics of a plurality of core wires. The above requirements will be further described with reference to FIGS. For simplicity, the case where N = 2 and the lengths of the optical fibers 200 to be tested are equal as shown in FIG. 3 will be described.

Due to the difference in the length of the demultiplexing-side pigtail 12, the difference in the reciprocal optical path length between the two cores is ΔL. Moreover, spatial spread of the probe light pulse emitted from the optical line characteristic analyzing apparatus 100 is W _p. At this time, when the above-mentioned requirement (ΔL> W _p ) is satisfied between ΔL and W _p , the spatial positional relationship between the received light probe pulses returned from the two optical fibers 200 to be tested is as shown in FIG. . That is, as shown in FIG. 4, if the light receiving probe pulse is not superimposed, it is possible to associate the light receiving probe signal with the core information from the difference in the return time of the probe light (positional difference). For example, when the technique disclosed in Non-Patent Document 1 is used as the optical line characteristic analyzing apparatus 100, loss information of the optical fiber under test 200 can be obtained by Brillouin gain analysis of the probe pulse returned from each optical fiber under test 200. .

Subsequently, an optical fiber evaluation method (first optical fiber evaluation method) using the optical fiber evaluation jig 301 will be described.
In the optical fiber evaluation method, the optical line characteristic analyzing apparatus 100 is connected to the multiplexing side port of the 1 × N optical splitter 11 of the optical fiber evaluation jig 301, and one or less N ends of the N demultiplexing side pigtails 12 are connected. Each of the optical fibers 200 to be tested is connected to the core of each of the optical fibers, and an optical pulse is incident on the multiplexing side port of the 1 × N optical splitter 11 from the optical line characteristic analyzer 100.

  The optical line characteristic analyzing apparatus 100 can use, for example, a technique specialized in the loss test method of the optical fiber under test disclosed in Non-Patent Document 1. With the technique of Non-Patent Document 1, it is possible to collectively evaluate the optical loss distribution, Brillouin frequency shift distribution, connection loss, and far-end return loss of the non-measuring optical fiber connected to the multi-core batch evaluation system of the present invention.

  The technique disclosed in Non-Patent Document 1 uses pulsed light as test light, and identifies light-receiving pulsed light from each core wire at the bottom of the branch based on the difference in round-trip time of the pulsed light. For this reason, when analyzing the characteristics of the optical line by the technique of Non-Patent Document 1 using the optical fiber multi-core evaluation system of the present embodiment, the length of the branching pigtail 12 is set as described above. It is necessary to provide a reciprocating optical path length difference equal to or greater than the pulse width with respect to the total length of the different or branching pigtail 12 and the optical fiber 200 under test.

  Further, the optical line characteristic analyzing apparatus 100 can use, for example, a disconnection failure monitoring technique using Brillouin analysis disclosed in Non-Patent Document 2. Since the technique disclosed in Non-Patent Document 2 is based on the premise that the reflected test light generated at the far end of the optical fiber under test is used, the light reflecting end 14 is connected to the far end of the optical fiber under test also in this embodiment. May be.

ここで、Ｐ_{ｐｒｏｂｅ}［ｄＢｍ］とＰ_ｐｕｍｐ［ｄＢｍ］はそれぞれ、ＦＵＴ（被試験光ファイバ）に入射するプローブ光とポンプ光のピークパワーを示す。また、βはブリルアン利得係数である。Ｐ_ｄは受光器の最少受光感度を示す。また、右辺の最終項はｎ回の平均化による効果を示す。 Here, the effect of connecting the light reflecting end 14 will be described by taking as an example the case where the technique of Non-Patent Document 2 is used for the optical line characteristic analyzing apparatus 100. In the technique of Non-Patent Document 2, when the reflectance R [dB] is taken into consideration, the one-way dynamic range (SWDR) in the loss measurement is given by Equation (1).

Here, P _probe [dBm] and P _pump [dBm] indicate the peak powers of the probe light and the pump light incident on the FUT (optical fiber to be tested), respectively. Β is a Brillouin gain coefficient. P _d indicates the minimum light receiving sensitivity of the light receiver. The last term on the right side shows the effect of averaging n times.

  From the equation (1), it can be seen that the one-way dynamic range deteriorates by one third of the amount of change [dB] in reflectance. That is, for example, when the total reflection end having a reflectance of 100% is connected to the far end of the optical fiber to be tested, and when the far end of the optical fiber to be tested is cut vertically and Fresnel is reflected at the interface with the air (reflection loss− 14 dB), using the total reflection end means that the one-way dynamic range is improved by 14 / 3≈4.7 dB.

Next, in order to clarify the effect of the present invention quantitatively, a case where the present invention is implemented by the technique of Non-Patent Document 1 and a case where a plurality of core wires are sequentially measured by OTDR will be compared. As a premise, there is no restriction on the output optical power in both test apparatuses, and the restriction on the unmeasured optical fiber incident power in both test methods is equally determined by the stimulated Brillouin scattering threshold. That is, there is no need to consider the branching loss of the optical splitter used in the present invention. According to Non-Patent Document 3, when the distribution measurement point X in the technique of Non-Patent Document 1 is 100 points and the probe light power when the Brillouin interaction occurs is 0 dBm or more, the technique of Non-Patent Document 1 is a signal compared to OTDR. The noise-to-noise ratio (SNR) increases by about 40 dB. Further, the technique of Non-Patent Document 1 can collectively measure the N centers by using the present invention. When it is converted into the SNR improvement effect that N-core batch measurement is possible, it is ₁₀ log ₁₀ (√N) [dB]. That is, the SNR improvement effect of a total of 40 + ₁₀ log ₁₀ (√N) [dB] can be expected by combining the present invention and the technique of Non-Patent Document 1 rather than measuring one by one with OTDR.

  As described above, the optical fiber evaluation jig 301 provides a difference in length to the demultiplexing-side pigtail, causes a difference in the reciprocal optical path length including the optical fiber to be connected, and is disclosed in Non-Patent Document 1. The optical fiber collective multi-fiber evaluation is realized by (that is, the optical measurement technique for identifying the information of the branched core wire using the difference in the reciprocal optical path length difference).

(Embodiment 2)
FIG. 2 is a diagram for explaining an optical fiber evaluation jig 302 (second optical fiber evaluation jig) and an optical fiber evaluation method using the same according to the present embodiment. The optical fiber evaluation jig 302 is
N branch-side pigtails 12 each connected to one end of the core of the optical fiber 200 under test;
A line length difference varying mechanism 18 that is arranged in each of the N branching pigtails 12 and arbitrarily varies the line length;
One multiplexing side port to which the optical line characteristic analyzing apparatus 100 is connected and N branching side ports to which the other ends of the N demultiplexing pigtails 12 are respectively connected are provided from the multiplexing side port. 1 × N that splits the light and couples it to the branching-side pigtail 12 of the branching-side port, combines the light coupled from the branching-side pigtail 12 to the branching-side port, and outputs it to the multiplexing-side port An optical splitter 11;
Is provided.
The variable line length difference mechanism 18 is, for example, a variable optical delay device using a spatial optical system, a fixed optical delay device, or a device for inserting a delay optical fiber.

  The difference between the optical fiber evaluation jig 302 and the optical fiber evaluation jig 301 in FIG. 1 is the length of the demultiplexing side pigtail 12 and the variable line length difference mechanism 18. The length of the demultiplexing side pigtail 12 of the optical fiber evaluation jig 301 in FIG. 1 is fixed, but the length of the demultiplexing side pigtail 12 of the optical fiber evaluation jig 302 can be freely adjusted by the line length difference variable mechanism 18. Can change. For this reason, the optical fiber evaluation jig 301 in FIG. 1 may not satisfy the above-mentioned requirements depending on the length of the optical fiber 200 to be tested. Even in the optical fiber 200 to be tested, the above-mentioned requirements can be satisfied by adjusting the optical path length by the variable line length difference mechanism 18.

When performing optical fiber collective multi-core evaluation using the optical fiber evaluation jig 302, a step of adjusting the line length difference variable mechanism 18 is required. That is, the optical fiber evaluation method (second optical fiber evaluation method) of the present embodiment is:
The optical line characteristic analyzer 100 is connected to the multiplexing side port of the 1 × N optical splitter 11 of the optical fiber evaluation jig 302,
The one end of each of the N branching pigtails 12 is connected to the core of each of the N or less optical fibers 200 to be tested;
The optical fiber under test 200 in which the optical line characteristic analyzer 100 receives the difference between any two of the reciprocal optical path lengths of the demultiplexing-side pigtail 12 and the optical fiber 200 under test connected by the variable line length difference mechanism 18. Set larger than the spatial spread of the pulse width of the return light from
An optical pulse is incident on the multiplexing side port of the 1 × N optical splitter 11 from the optical line characteristic analyzer 100.

  As described in the first embodiment, even when the optical fiber evaluation jig 302 of the present embodiment is used, the optical fiber collective multi-core evaluation by the technique disclosed in Non-Patent Document 1 or Non-Patent Document 2 can be realized. .

(Embodiment 3)
FIG. 5 is a diagram for explaining an optical fiber evaluation jig 303 (first optical fiber evaluation jig) of the present embodiment and an optical fiber evaluation method using the same. The optical fiber evaluation jig 303 is different from the optical fiber evaluation jig 301 described in FIG. 1 in that the multi-core optical fiber connection device 15 is provided at the one end of the N branching pigtails 12. The optical fiber evaluation jig 303 is used when the optical fiber under test is the multi-core optical fiber 201.

  As in the first embodiment, the optical line characteristic analyzing apparatus 100 can use a technique specialized in a loss test method for an optical fiber under test disclosed in Non-Patent Document 1, for example. The optical line characteristic analyzing apparatus 100 can collectively evaluate the light loss distribution, Brillouin frequency shift distribution, connection loss, and far end return loss of the multicore optical fiber 201 connected to the multicore optical fiber connection device 15.

  The cores of the multi-core optical fiber 201 are considered to have the same length. Therefore, in order to realize multi-core collective evaluation of a multi-core optical fiber with the technology disclosed in Non-Patent Document 1, the round-trip optical path length including the multi-core optical fiber 201 is only determined by the difference in the length of the demultiplexing side pigtail 12. It is necessary to satisfy the above-mentioned requirements.

  At this time, the N demultiplexing pigtails 12 are identified, and it is preferable that the line length becomes longer or shorter in order from the first to the Nth. As described in the first embodiment, the evaluation result of the optical line characteristic analyzer 100 and the core of the multi-core optical fiber 201 can be easily associated.

Subsequently, an optical fiber evaluation method (first optical fiber evaluation method) using the optical fiber evaluation jig 303 will be described.
In this optical fiber evaluation method, the optical line characteristic analyzing apparatus 100 is connected to the multiplexing side port of the 1 × N optical splitter 11 of the optical fiber evaluation jig 303, and one end of each of the N demultiplexing side pigtails 12 has the number of cores. The optical fiber is connected to each core of N or less multi-core optical fibers 201, and an optical pulse is incident from the optical line characteristic analyzer 100 to the multiplexing side port of the 1 × N optical splitter 11.

  As described in the first embodiment, the multi-core batch multi-core evaluation of the multi-core optical fiber by the technique disclosed in Non-Patent Document 1 or Non-Patent Document 2 is realized using the optical fiber evaluation jig 303 of the present embodiment. be able to.

(Embodiment 4)
FIG. 6 is a diagram for explaining an optical fiber evaluation jig 304 (second optical fiber evaluation jig) and an optical fiber evaluation method using the same according to this embodiment. The optical fiber evaluation jig 304 is different from the optical fiber evaluation jig 302 described in FIG. 2 in that the multi-core optical fiber connection device 15 is provided at the one end of the N branching pigtails 12. The optical fiber evaluation jig 304 is used when the optical fiber under test is the multi-core optical fiber 201.

  In the optical fiber evaluation jig 303 of FIG. 5, the above requirements may not be satisfied depending on the length of the multi-core optical fiber 201. However, in the case of the optical fiber evaluation jig 304, such a multi-core optical fiber is used. If the optical path length is adjusted by the line length difference varying mechanism 18 in 201, the above requirement can be satisfied.

When performing multi-core batch multi-core evaluation of a multi-core optical fiber using the optical fiber evaluation jig 304, a step of adjusting the line length difference variable mechanism 18 is required. That is, the optical fiber evaluation method (second optical fiber evaluation method) of the present embodiment is:
The optical line characteristic analyzer 100 is connected to the multiplexing side port of the 1 × N optical splitter 11 of the optical fiber evaluation jig 304,
The one end of the N demultiplexing pigtails 12 is connected to each core of the multi-core optical fiber 201 having N or less cores,
The multi-core optical fiber 201 in which the optical line characteristic analyzing apparatus 100 receives the difference between any two of the round-trip optical path lengths composed of the demultiplexing-side pigtail 12 and the core of the multi-core optical fiber 201 connected thereto by the line length difference variable mechanism 18. Set larger than the spatial spread of the pulse width of the return light from
An optical pulse is incident on the multiplexing side port of the 1 × N optical splitter 11 from the optical line characteristic analyzer 100.

  As described in the first embodiment, the multi-core batch multi-core evaluation of the multi-core optical fiber by the technology disclosed in Non-Patent Document 1 and Non-Patent Document 2 is realized even if the optical fiber evaluation jig 304 of the present embodiment is used. can do.

(Effect of the present invention)
As described above, the present invention provides a length difference in the pigtail connected to the demultiplexing side of the optical splitter, connects the optical fiber under test to the optical fiber evaluation jig provided with the line length difference, and the optical line characteristics. By connecting the analyzing device to the combining-side pigtail of the optical fiber evaluation jig, it is possible to collectively measure the optical characteristics of the optical fibers under test that match the number of branches of the optical splitter.

  Therefore, according to the present invention, a plurality of optical fibers to be tested are connected to the demultiplexing side of the optical splitter, and the optical characteristics of the optical fibers to be tested are collectively measured by collectively measuring from the center of the optical splitter. Since measurement is possible, it is possible to provide an optical fiber multi-core evaluation system capable of reducing the inspection operation and inspection time of the optical fiber.

11: optical splitter 12: demultiplexing side pigtail 13: connection terminal 14: light reflecting end 15: multi-core optical fiber connection device 18: line length difference variable mechanism 100: optical line characteristic analyzer 200: optical fiber 201 under test: multi-core Optical fibers 301 to 304: Optical fiber evaluation jig

Claims (7)

N (N is an integer of 2 or more) demultiplexing side pigtails, each of which has an optical fiber core to be connected to one end;
One multiplexing side port to which the optical line characteristic analyzer is connected and N branching side ports to which the other ends of the N demultiplexing pigtails are respectively connected, and light from the multiplexing side port 1 × N light that is coupled to the branching-side pigtail of the branching-side port, combines the light coupled from the branching-side pigtail to the branching-side port, and outputs the combined light to the multiplexing-side port A splitter,
With
The difference between any two round-trip optical path lengths of the N demultiplexing side pigtails is larger than the spatial extension of the pulse width of the return light from the optical fiber under test received by the optical line characteristic analyzer. A characteristic optical fiber evaluation jig. N demultiplex side pigtails each connected to one end of the core of the optical fiber under test;
A line length difference variable mechanism that is arranged in each of the N demultiplexing-side pigtails to arbitrarily change the line length;
One multiplexing side port to which the optical line characteristic analyzer is connected and N branching side ports to which the other ends of the N demultiplexing pigtails are respectively connected, and light from the multiplexing side port 1 × N light that is coupled to the branching-side pigtail of the branching-side port, combines the light coupled from the branching-side pigtail to the branching-side port, and outputs the combined light to the multiplexing-side port A splitter,
An optical fiber evaluation jig comprising:   The optical fiber evaluation jig according to claim 1, wherein each of the N branching pigtails includes a multi-core optical fiber connection device at the one end.   The N number of said demultiplexing side pigtails are identified, respectively, and the line length becomes longer or shorter in order from the first to the Nth. 4. An optical fiber evaluation jig according to 3. An optical fiber evaluation method for evaluating an optical fiber,
An optical line characteristic analyzing apparatus is connected to the multiplexing side port of the 1 × N optical splitter of the optical fiber evaluation jig according to claim 3 or claim 4 quoting claim 1 or claim 1,
Connecting each of the one ends of the N branching pigtails to the core of the optical fiber under test,
An optical fiber evaluation method, wherein an optical pulse is incident on the multiplexing side port of the 1 × N optical splitter from the optical line characteristic analyzer. An optical fiber evaluation method for evaluating an optical fiber,
An optical line characteristic analyzer is connected to the multiplexing side port of the 1 × N optical splitter of the optical fiber evaluation jig according to claim 2,
Connecting each of the one ends of the N branching pigtails to the core of the optical fiber under test,
The optical line characteristic analyzer receives the difference between any two of the reciprocal optical path lengths consisting of the demultiplexing side pigtail and the core of the optical fiber to be tested connected to the demultiplexing side pigtail by the variable line length difference mechanism. Set larger than the spatial spread of the pulse width of the return light from the optical fiber to be tested,
An optical fiber evaluation method, wherein an optical pulse is incident on the multiplexing side port of the 1 × N optical splitter from the optical line characteristic analyzer.   7. The optical fiber evaluation method according to claim 5, wherein a reflection end that reflects light is installed at an end opposite to an end to which the demultiplexing-side pigtail of the optical fiber under test is connected.

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