JPH04211204A - Separation of light transmission passage brakdown position and optical filter type separator used for this - Google Patents

Abstract

PURPOSE:To carry out separation of a breakdown position between a transmission device and a light passage at a minimum loss, on a small scale, simply and minutely by inserting a (j) optical filter into an optical fiber at an angle within range of 0-4.7 C against the surface crossing at right angles to the axial center of the optical fiber. CONSTITUTION:An optical filter type separator 11 is constituted of a communication light-passing test light blocking type optical filter 14, a reinforcing part 15 to reinforce the optical filter 14 and a cord part 18 having an optical fiber 17 in the axial center. The optical filter 14 passes a communication light lambda0 by using optical interference by means of a multilayer film consisting of titan oxide, silicon oxide and/or the like, and reflects a test pulse light lambdat having different wavelength from the communication light lambda0. Thereby, in the case the optical filter 14 is inserted by selecting a proper angle G against the optical fiber 17, a large part of a blocking light (test pulse light) can be inserted again into the optical fiber without diffusing itself, so that the reflection volume can be made large against the test pulse light lambdat.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention makes it possible to easily detect whether a failure is in the optical line or the transmission equipment in an optical transmission system, and in the case of a failure in the optical line, to locate the failure location. The present invention relates to a method for isolating the location of a fault in an optical transmission line and an optical filter type separator used in this method.

0002

[Prior Art] Conventionally, there is a method of detecting whether the cause of failure is in the optical line or the transmission equipment using an optical pulse tester, that is, a method of isolating the failure between the optical line and the transmission equipment. , Japanese Patent Application No. 58-71089 is provided. FIG. 14 is a diagram for explaining the conventional method, in which reference numeral 1 denotes an optical transmitter of a transmission device;
2 is an optical fiber constituting an optical line, 3 is an optical receiver of the transmission device, and 4b is an optical filter provided on the optical receiver 3 side. light λ
It is configured to allow communication light λ0 to pass therethrough and reflect communication light λ0. 4a is an optical filter provided on the optical transmitter 1 side, and has the same configuration as the optical filter 4b. Further, 5 is a reflecting mirror that totally reflects the test light λt, 6 is an optical pulse tester, and this optical pulse tester 6 includes an optical pulse transmitter 7 that outputs the test light λt, a multiplexer/demultiplexer 8, and It consists of an optical pulse receiver 9 that receives the test light λt reflected by the reflecting mirror 5.

According to the above conventional method, when searching for a fault location, if a fault such as a break has occurred in the optical fiber 2, the test light (reflected light) λt is transmitted to the optical pulse receiver 9.
Since the signal is not received in the optical fiber 2, it can be confirmed that the cause of the failure is in the optical fiber 2. On the other hand, when the test light (reflected light) λt is received by the optical pulse receiver 9,
It can be seen that there is no cause of failure in the optical fiber 2, but that the cause of failure is in the transmission device.

0004

By the way, in the above conventional method, the optical fiber 2, the optical filter 4b, the reflecting mirror 5,
Since a lens system with an insertion loss of 3 dB or more was used for the connection between the optical receiver 3 and the optical receiver 3, it was difficult to miniaturize the configuration and reduce the cost, and this resulted in high optical signal loss. . The same can be said for the connection component between the optical filter 4a on the optical transmitter 1 side and the optical pulse tester 6, so as long as it is configured with a lens system, the loss of the entire system can be reduced. It was extremely difficult to realize economicalization and miniaturization. Further, in the conventional method described above, although it is possible to detect that the cause of the failure is in the optical path, it is not possible to detect the location of the failure. Furthermore, there was no consideration at all about branched optical lines that could be applied to video distribution services and the like. The present invention has been made in view of the above circumstances, and is a method for locating a fault in an optical transmission line, which enables the location of a fault between a transmission device and an optical line to be isolated in a small, simple, and detailed manner with low loss. The object of the present invention is to provide an optical filter type segmenter for use therewith.

[0005]

Means for Solving the Problems In order to solve the above problems, the invention according to claim 1 provides an optical fiber and an optical filter that reflects one of two lights of different wavelengths and transmits the other. and the optical filter is inserted into the optical fiber at an angle in the range of 0 to 4.7°C with respect to a plane perpendicular to the axis of the optical fiber. There is.

[0006] The invention according to claim 2 is characterized in that the wavelengths of the two lights are in the range of 1.2 to 1.7 μm.

[0007] The invention according to claim 3 is characterized in that the relative refractive index of the cladding portion of the optical fiber is in the range of 1.4 to 1.6.

[0008] The invention according to claim 4 is characterized in that the spot size of the optical fiber is 4.25 to 5.25 μm.

According to a fifth aspect of the invention, the spot size of the optical fiber is 4.25 to 5.25 μm, the relative refractive index of the cladding is 1.4 to 1.6, and the wavelengths of the two lights are It is characterized by a range of 1.2 to 1.7 μm.

According to a sixth aspect of the invention, the optical filter transmits light having a shorter wavelength among the two lights,
It is characterized by reflecting light with longer wavelengths.

[0011] In the invention according to claim 7, the two lights are:
Light in the wavelength band of 1.25 to 1.35 μm and light in the wavelength band of 1.50 to 1
．． It is characterized by light in a wavelength band of 60 μm.

According to an eighth aspect of the invention, the angle between the optical filter and a plane perpendicular to the axis of the optical fiber is 1.4.
It is characterized by being in the range of ~2.8 degrees.

[0013] The invention according to claim 9 provides a method for isolating a fault location of an optical transmission line, which isolates a fault location between an optical line and an optical receiver of a transmission device using an optical pulse tester, in which the optical pulse test A test pulse light having a wavelength different from that of the communication light is inserted from the device into the optical path through an optical coupler, and the test is performed using an optical filter type splitter that is installed immediately before the optical receiver and reflects only the test pulse light. The light level and position of the reflected light of the pulsed light are detected, and the detected light level and position are compared with the light level and position of the reflected light that have been previously measured on the optical path in a normal state. As a result of the comparison, if there is a change in the optical level or position, it is determined that there is a failure in the optical path and the location of the failure is determined, and if there is no change, it is determined that there is no failure in the optical path. The present invention is characterized in that by determining the location of the failure between the optical line and the optical receiver of the transmission device.

Furthermore, the invention of the fault location isolation method according to claim 10 is such that an optical branching device is provided in the middle of the optical path, and each optical fiber provided on the subscriber side of the optical path branched by the branching device is provided. A method for locating a fault in an optical transmission line, in which each of the above-mentioned optical filter type separators is installed immediately before the receiver, and the fault location between the optical line and the optical receiver of the transmission device is isolated using an optical pulse tester. , a test pulse light having a wavelength different from that of the communication light is inserted from the optical pulse tester into the optical path via an optical coupler, and a light that reflects only the test pulse light is installed immediately before each of the optical receivers. Detecting the light level and position of each reflected light of the test pulse light by the filter-type separator, and detecting the detected light level and position,
Compare the light level and position of each reflected light that has been measured in advance for the optical path and each branched optical path in a normal state, and if there is a change in the optical level or position as a result of the comparison. determines that there is a failure in the optical line where fluctuations are occurring, determines the location of the failure, and if no fluctuations occur, determines that there is no failure in the optical line, so that the optical line and the transmission device It is characterized by being able to isolate the location of the failure with the optical receiver.

[0015]

[Operation] According to the above structure, since the insertion loss is low and the structure is made using a small optical member, the entire system can be made smaller, more economical, and have lower loss, and the detection accuracy is improved. can be achieved. Furthermore, the location of the failure can be determined in more detail. Furthermore, it can also be applied to branched optical paths.

[0016]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)

FIG. 1 is a diagram showing the configuration of a transmission apparatus applied to a method for isolating the location of a fault in an optical transmission line, which is a first embodiment of the present invention. In this diagram, a conventional transmission system (
Components corresponding to those in FIG. 14) are designated by the same reference numerals, and their description will be omitted. In FIG. 1, 10 is an optical coupler, 11 is an optical filter type segmenter, 12 is a CPU (central processing unit) that controls the optical pulse tester 6, and 13 is a database that stores various data. As shown in FIG. 2, the optical filter type segmenter 11 has an optical filter 14 of communication light passage test light blocking type, a reinforcing part 15 for reinforcing the optical filter 14, and an optical fiber 17 at its axis. It is composed of a code section 18. The optical filter 14 utilizes light interference caused by a multilayer film made of titanium oxide, silicon oxide, etc. to pass the communication light λ0.
It is formed so as to reflect the test pulse light λt having a wavelength different from 0.

If the optical filter 14 is inserted into the optical fiber 17 at an appropriate angle θ, most of the blocking light (test pulse light) λt is not scattered, as shown in FIG. It is reinserted into the fiber 2, and the amount of reflection of the test pulse light λt can be increased. Next, a method of designing this filter angle θ will be described. This filter angle θ needs to be determined as shown below so that the required return loss can be obtained for the test light λt and the communication light λ0.

(i) Return loss of test light λt;

002
1] In the optical filter type segmenter 11 shown in FIG.
When the reflected light is re-injected into the optical fiber 17, it is considered that the reflected light is attenuated equivalently by the connection loss of the optical fiber 17 whose angle is shifted by 2θ. Therefore, the return loss Lrt of the test light λt is the sum of this loss and the passage loss It. The formula for calculating splice loss due to angular deviation is MARCUSE (B.S.T.
．． J, 56, 5, 1977), the return loss Lrt is expressed by the following equation.

[0022]

[Math 1]

Here, n is the relative refractive index of the cladding portion of the optical fiber 17, w is the spot size, and λ is the wavelength of the test light. FIG. 3 shows the relationship between Lrt and θ calculated using the first equation and compared with experimental results. As is clear from the figure,
The calculation results and the experimental results are almost in agreement, and therefore, it can be seen that the return loss can be estimated from the calculation results of the first equation. The broken line in the figure shows the target characteristics set so that the method of this example can be applied even if the optical fiber is broken near the splitter 11 and a large Fresnel reflection (14.3 dB) occurs. There is. From this, the insertion angle θ needs to be 2.8 degrees or less.

(ii) Return loss of communication light λ0;

00
25. Reflection of the communication light λ0 is mainly caused by ripples in the transmission band of the optical filter 14. Therefore, the return loss Lrs of the communication light λ0 is expressed by the following equation based on the ripple y% and the first equation.

[0026]

[Math 2]

FIG. 4 shows the relationship between Lrs and θ due to changes in the ripple component. The broken line in the figure shows the target characteristics set to be similar to that of an optical connector for communication.If the ripple of the optical filter 14 is about 1.5%, the insertion angle θ is 1.4 degrees or more. It is necessary to Therefore, from FIGS. 3 and 4, in order to satisfy the target characteristics, the filter angle needs to be approximately 1.4 to 2.8 degrees.

FIG. 5 shows an optical filter type cutter 1 of this example.
The target values of return loss and communication loss for No. 1 are compared with the actual values of the prototype. Here, in the prototype, the filter angle θ was set to 2.0 degrees.

From FIG. 5, it can be seen that the prototype results fully satisfy the target characteristics. Therefore, the filter angle is 1
．． It can be said that the optimum value is about 4 to 2.8 degrees. As is clear from FIG. 5, this optical filter type segmenter 11 has a diameter of 1.31μ.
The m wavelength band can be used for the communication light λ0, and the 1.55 μm wavelength band can be used for the test pulse light λt, and the transmission loss can be reduced to 0.5 dB or less, about 1/6 or less compared to the conventional method. Further, by employing the above-mentioned optimum angle range, the return loss for the test pulse light λt by the optical filter type segmenter 11 can always be smaller than the Fresnel return loss that occurs when the optical path fails.

In the database 13, the test pulse light λt introduced from the optical pulse tester 6 into the optical path (optical fiber 2) under normal conditions is reflected by the optical filter type splitter 11, The data (light level and reflection point (position)) reintroduced and detected by the optical pulse tester 6 is stored through the CPU 12.

FIG. 6 shows an example of the configuration of a connector-mounted optical filter type segmenter. In this figure, the reference numeral 41 is
For example, a ferrule made of zirconia or the like, 42 a knob, 43 a plug frame, 44 a spring, 45 a sleeve, 46 a stop ring, 47 a caulking ring, 48
49 is a ring, 49 is a rubber holder, 50 is a reinforcing portion, and 51 is a bare core wire. Further, here, the optical filter 14 used is a thin one having a thickness of several + μm or less. By mounting it in the connector in this way, it is possible to achieve miniaturization, economy, low loss, and high reliability.

Next, the operation of this example will be explained with reference to the flowchart of FIG. When an abnormality occurs in the transmission path, the optical transmitter 1 or the optical receiver 3 issues an alarm. When the inspector learns of the occurrence of an abnormality in the transmission line from this alarm, he puts the optical pulse tester 6 into operation (step SA1). From this point on, the CPU 12 performs step SA.
2, the test pulse light λt is introduced from the optical pulse tester 6 into the transmission line (optical fiber 2), and the light level of the reflected light (of the test pulse light λt) from the filter-type splitter 11 is calculated accordingly. Detect the reflection position.

Next, the CPU 12 reads the aforementioned normal measurement data (reflection level, reflection position) from the database 13, and compares it with the current detection data (reflection level, reflection position) (step SA3). First, it is compared whether there is a difference in the reflection level between the normal measurement and the current measurement (step SA4). As a result of the comparison,
If a conclusion of ``YES'' is obtained, that is, if a difference is detected, it is determined that there is a failure in the optical line (optical fiber 2), but in order to recognize the failure position, the process proceeds to step SA5.
Determine whether the position of the reflection has shifted (step S
A5).

As a result of the judgment, when a conclusion of "NO" is obtained, that is, when the position of the reflection is not shifted, the process proceeds to step SA6, and the cause of the failure is in the optical path, and the failure position is in the optical path. It recognizes that it is near the filter type segmenter 11 and outputs the recognition result.

On the other hand, in step SA5, when a "YES" conclusion is obtained as a result of the determination, that is, when the reflection position is shifted, the process proceeds to step SA7, and the cause of the failure is on the optical path side. It recognizes that the fault position is the new reflection position and outputs the recognition result.

On the other hand, in step SA4, "NO"
When the conclusion is reached, that is, when no difference is detected between the normal data and the reflection level, the process moves to step SA8, and it is determined whether the reflection position has shifted. Then, when the conclusion of "YES" is obtained as a result of the judgment, that is, when the position of the reflection is shifted and detected, the process moves to step SA7, and the cause of the failure is on the optical path side, and the failure position is the new reflection. It recognizes that it is the position and outputs this recognition result.

The result of the determination in step SA8 is "N
If the result is "O", that is, if the position of the reflection is not shifted, the process proceeds to step SA9, where it is recognized that the transmission device (optical receiver) is out of order, and the recognition result is output.

According to the above configuration, the insertion loss of the optical filter type separator 11 is extremely low, and the reflection level always changes when an optical line fails, so that the failure can be isolated with 100% probability. Also, regarding the failure position (reflection position),
It can be recognized with high precision.

(Second example)

Next, a second embodiment of the present invention will be described. FIG. 8 is a diagram showing a second embodiment of the present invention,
The difference between this second embodiment and the first embodiment (FIG. 1) is that an optical filter 19 is provided between the optical transmitter 1 and the optical coupler 10 to block the reflected light of the test pulse light λt. This is the point where it is inserted. This optical filter 19 has the same configuration as the one shown in FIG.
The difference is that the angle of about 9 degrees is used. According to the configuration of the second embodiment, in addition to the same effects as the first embodiment, it is possible to eliminate the influence of reflected light on the optical transmitter 1, so that when the level of the test pulse light λt is high, This has the advantage of preventing failures such as destruction of the light-emitting element and light-receiving element of the transmission device.

(Third Example)

Next, a third embodiment of the present invention will be described. FIG. 9 is a diagram showing a third embodiment of the present invention,
This third embodiment is different from the second embodiment (FIG. 8) described above in that a 1:n optical splitter 20 such as a star coupler is inserted between the optical fiber 2 and the optical receiver. On the subscriber side of the optical splitter 20, branch fibers 2-1 and 2-2 are connected.
, ..., 2-n, n optical receivers 3-1, 3-2, ..., 3-n are connected, and an optical filter type splitter 11-1 is connected immediately before them. , 11-2, . . . , 11-n are inserted.

[0043] Optical receiver 3-1 installed at each subscriber's home,
The distance between 3-2, ..., 3-n and the optical distributor 20 is
In general, it is considered that each is different, so when the reflection level and position of each optical filter type segmenter 11-1, 11-2, ..., 11-n are measured with the optical pulse tester 6 during normal operation, the figure The results shown in 10 are obtained. Here, the horizontal axis is the distance from the optical pulse tester 6 to the reflection position, the vertical axis is the reflection level, and ls is the position of the optical distributor 20. The distance from the optical pulse tester 6 to the reflection position is l1, l2, ..., l
Let m(l1<l2<...<lm) and the corresponding reflection levels be y1, y2,..., ym, then l1, l2,...
..., lm correspond to the optical filter type segmenters 11-1, 11-2, ..., 11-n in order of shortest distance from the optical distributor 20, respectively. For example, it can be seen that the reflection level y1 is the reflection from the optical filter type splitter installed at the subscriber closest to the optical distributor 20, and the reflection level ym is the reflection from the optical filter type divider installed at the subscriber closest to the optical distributor 20. It can be seen that is the reflection from the optical filter type segmenter installed at the m-th subscriber (counting from the shortest one).

FIG. 11 shows the measurement results of the amount of reflection by the optical pulse tester 6 when the branch fiber 2-2 (connecting the second nearest subscriber to the optical distributor 20) is cut. As shown in this figure, the reflection level y2 at the distance l2 becomes below the noise level, and a Fresnel reflection y2' is newly measured at the distance l2'. Therefore, from this figure,
It can be seen that a failure has occurred in the branch fiber 2-2, and the failure location is l2'.

Further, FIG. 12 shows the measurement results by the optical pulse tester 6 when the optical fiber 2 between the optical coupler 10 and the optical distributor 20 is cut. In this case, reflection from all reflectors disappears (below the noise level), and Fresnel reflection y0' due to the cutting point is newly created between the optical distributor 20 and the station side (between 0 and lS).
is measured. Therefore, the occurrence of a failure in the optical fiber 2 and the location of the failure can be known.

Next, the operation of this example will be explained with reference to the flowchart of FIG. When an abnormality occurs in the transmission path, an alarm is issued from the optical transmitter 1 or one of the plurality of optical receivers 3. When the inspector learns of the occurrence of an abnormality in the transmission line from this alarm, he puts the optical pulse tester 6 into operation (step SB1). From this, C
The PU 12 proceeds to step SB2, and the optical pulse tester 6
The test pulse light λt is introduced into the transmission line (optical fiber 2) from each filter-type splitter 11-1, 11-2,...,
The light level and reflection position of the reflected light (of the test pulse light λt) from 11-n are detected.

Next, in step SB3, CPU1
2 reads the aforementioned normal measurement data (reflection level, reflection position) from the database 13 and compares it with the current detection data (reflection level, reflection position). First, it is determined whether there is a difference in the reflection level between the normal measurement and the current measurement (step SB4).

(a) "YES" in step SB4
When it is determined that "YES" is determined in step SB4,
That is, if there is a difference in the reflection level, step S
Proceed to B5. In step SB5, the number of optical fibers with a difference in reflection level is the number of branches from the optical distributor 20 (the number of subscribers).
Determine whether it matches n.

■When the determination in step SB5 is ``YES'', the result of the determination in step SB5 is ``YES''.
S'', that is, when the number of reflection levels at which a difference has occurred matches the number n of branches from the optical distributor 20, the process advances to step SB7. In step SB7, the CPU 12 recognizes that the cause of the failure is in the optical fiber 2 from the optical splitter (star coupler) 20 to the office side, that the failure position is the new reflection position, and outputs the recognition result.

■When the determination in step SB5 is "NO" On the other hand, if the determination result in step SB5 is "NO",
In other words, the number of reflection levels where a difference has occurred is the number of branches n
If they do not match, the CPU 12 proceeds to step SB8. Then, in step SB8, it is determined whether the measured reflection position is shifted between the normal time and the current time. When "NO" is obtained as a result of this judgment, that is, when the position of the reflection is not shifted, step SB9
Then, it recognizes that the cause of the failure is in a specific branch fiber from the optical splitter (star coupler) 20 to the subscriber side, and that the failure location is near the optical filter type splitter, and outputs the recognition result. do. Here, a plurality of branch fibers 2-1
, 2-2, . . . , 2-n, the method by which the CPU 12 identifies the failed branch fiber is as described with reference to FIG. On the other hand, when the result of the determination in step SB8 is "YES", that is, when the position of the reflection is shifted, the CPU 12 executes step SB1.
0, it is recognized that the cause of the failure is in a specific branch fiber from the optical splitter (star coupler) 20 to the subscriber side, and that the failure position is the new reflection position, and this recognition result is output. The method for identifying a faulty branched fiber is as described with reference to FIG. 11.

(a) When "NO" is determined in step SB4 If "NO" is determined in step SB4, that is, if there is no difference in the reflection level, the process advances to step SB6. In step SB6, it is determined whether the position of the reflection has shifted. The result of this judgment is “YE”
S'', that is, when the position of the reflection is shifted and detected, the process moves to step SB11, and the cause of the failure is in a specific branch fiber from the optical splitter (star coupler) 20 to the subscriber side, and the failure position is determined. Recognizing that is the new reflection position,
This recognition result is output. The method for identifying a faulty branched fiber is as described with reference to FIG. 11. On the other hand, if the result of the determination in step SB6 is "NO", that is, if the position of the reflection is not shifted, the process proceeds to step SB12, where it is recognized that the transmission device (optical receiver) is malfunctioning, Output recognition results. According to the above configuration, it can also be applied to the case of isolating the failure location of a branched optical line.

Note that the present invention can of course be applied even when the optical transceivers are replaced in the system configuration diagrams of FIGS. 1, 8, and 9. In addition, since the optical fiber 2 is actually multi-core, there are a large number of optical couplers 10, and one of them is
Choose your heart. Therefore, by inserting an optical matrix switch between the optical coupler 10 and the optical pulse tester 6, it is possible to automate fault isolation.

Further, in the first embodiment described above, the filter angle θ of the optical filter 14 is set within the optimum angle range of 1.4 to 2.
Although the case where the filter angle is set to 8 degrees has been described, the filter angle according to the present invention is not limited to the above-mentioned optimum angle range. 16 to 20 are characteristic diagrams showing theoretical values of return loss with respect to filter angle. Among these figures, FIG. 16 shows the case where the spot size W is fixed to 5.0 μm, the wavelength λ of light is fixed to 1.55 μm, and the relative refractive index n of the grading part is varied in the range of 1.3 to 1.6. Figure 17 shows the relationship diagram when the relative refractive index n is 1.5 and the wavelength λ of light is 1.
．． Each was fixed at 55 μm, and the spot size W was set to 4.
FIG. 18 is a diagram showing the relationship when changing from 5 to 5.25 μm, when the relative refractive index n is 1.5 and the spot size W is 5.0 μm.
m, and the wavelength of light λ is 1.2 to 1.7 μm.
It is a relationship diagram when it changes within the range of.

As shown in FIGS. 16 to 18, the relative refractive index n
=1.4-1.6, spot size W=4.25-5.
25. In the fluctuation range of wavelength λ = 1.2 to 1.7,
The maximum value that the filter angle θ can take is the relative refractive index n=1.4,
In the case of the combination of spot size W=4.25 and wavelength λt=1.7, θ=3.88 degrees (see FIG. 19). In this case, the light with wavelength λt=1.7μm is the test light λt
used as.

Similarly, the minimum values that the filter angle θ can take are: relative refractive index n=1.6, spot size W=5.
25 μm and wavelength λ=1.2 μm, θ=1.14 degrees (see FIG. 20). In this case, the light with wavelength λ=1.2 μm is used as communication light λ0. Therefore, if the spot size W and the light used are appropriately selected, the optimal range of the filter angle can be expanded from 1.14 degrees to 3.9 degrees.

[0056] In the above, system fluctuations have been taken into account, but
If it is not necessary to take into account system fluctuations due to temperature and other factors, the maximum value of the filter angle θ can be further increased to 4.7 degrees, which can isolate the return loss of 14.3 dB that occurs when cutting the optical fiber. Assuming that an ideal filter without expanding ripples can be created, the minimum value of the filter angle θ will be 0 degrees. Therefore, if no system variations occur, the optimal range of filter angles is further from 0 degrees to 4 degrees.
．． Expand to 66 degrees.

[0057]

Effects of the Invention As explained above, the present invention uses an optical coupler to insert test pulse light and an optical filter-type separator composed of a single optical filter to determine the level of reflected light and the reflection position. Since the method makes a determination based on changes, it can also be applied to branched optical line configurations, and can provide more accurate and detailed failure information than conventional methods. Furthermore, since it is configured using small optical members, the entire system can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a transmission device applied to a method for isolating the location of a fault in an optical transmission line, which is a first embodiment of the present invention.

FIG. 2 is a diagram showing the configuration of the optical filter type segmenter of the same example.

FIG. 3 is a diagram showing the relationship between filter angle θ and return loss.

FIG. 4 is a diagram showing the relationship between filter angle θ and return loss.

FIG. 5 is a diagram showing the target customization and trial production results of the optical filter type cutter.

FIG. 6 is a cross-sectional view showing the configuration of a connector-mounted optical filter type segmenter.

FIG. 7 is a flowchart showing the procedure of the optical filter type separation method of the same example.

FIG. 8 is a block diagram showing the configuration of a transmission device applied to a second embodiment of the invention.

FIG. 9 is a block diagram showing the configuration of a transmission device applied to a third embodiment of the present invention.

FIG. 10 is a diagram for explaining a third embodiment.

FIG. 11 is a diagram for explaining a third embodiment.

FIG. 12 is a diagram for explaining a third embodiment.

FIG. 13 is a flowchart for explaining the fault location isolation operation of the third embodiment.

FIG. 14 is a diagram illustrating a conventional method for isolating the location of a fault in an optical transmission line.

FIG. 15 is a diagram showing an arrangement of optical filters applied to a conventional fault location isolation method.

FIG. 16 is a diagram showing the relationship between filter angle θ and return loss.

FIG. 17 is a diagram showing the relationship between filter angle θ and return loss.

FIG. 18 is a diagram showing the relationship between filter angle θ and return loss.

FIG. 19 is a diagram showing the relationship between filter angle θ and return loss.

FIG. 20 is a diagram showing the relationship between filter angle θ and return loss.

[Explanation of symbols]

1. Optical transmitter 2 Optical fiber 2-1 to 2-n Branch fiber 3. Optical fiber 3-1~3-n Optical receiver 4a Optical filter 4b Optical filter 6. Optical pulse tester 7. Optical pulse transmitter 8 Optical multiplexer/demultiplexer 9 Optical pulse receiver 10 Optical coupler 11 Optical filter type cutter 12 CPU 13 Database 15 Reinforcement part 14 Optical filter 17 Optical fiber 18 Code section 19 Optical filter 20 Optical distributor (star coupler) λ0 Communication light λ1 Test pulse light

Claims (10)

[Claims] [Claim 1] An optical fiber and two fibers with different wavelengths.
an optical filter that reflects one of the two lights and transmits the other; An optical filter type segmenter, characterized in that the filter is inserted into the optical fiber. [Claim 2] The wavelengths of the two lights are 1.2 to 1.7.
2. The optical filter type segmenter according to claim 1, wherein the optical filter is in the range of .mu.m. 3. Claim 1, wherein the relative refractive index of the cladding portion of the optical fiber is in the range of 1.4 to 1.6.
The optical filter type segmenter described. 4. The spot size of the optical fiber is 4.
．． Claim 1 characterized in that it is 25 to 5.25 μm.
The optical filter type segmenter described. 5. The spot size of the optical fiber is 4.
．． 25-5.25μm, relative refractive index of cladding part is 1.4
~1.6, and the wavelengths of the two lights are 1.2 to 1.7
2. The optical filter type segmenter according to claim 1, wherein the optical filter has a range of .mu.m. 6. The light according to claim 1, wherein the optical filter transmits the light with a shorter wavelength of the two lights and reflects the light with a longer wavelength. Filter type cutter. 7. The two lights have a power of 1.25 to 1.35.
7. The optical filter type segmenter according to claim 6, wherein the light is in a wavelength band of 1.50 to 1.60 .mu.m. 8. The optical filter type cutter according to claim 7, wherein an angle between the optical filter and a plane perpendicular to the axis of the optical fiber is in the range of 1.4 to 2.8 degrees. Divider. 9. A method for isolating a fault location in an optical transmission line, which uses an optical pulse tester to isolate a fault location between an optical line and an optical receiver of a transmission device, wherein Regarding the reflected light of the test pulse light by an optical filter type splitter that inserts a test pulse light of a certain wavelength into the optical path via an optical coupler and reflects only the test pulse light, which is installed immediately before the optical receiver. , detect the light level and position, and detect the detected light level and position,
Compare the optical level and position of the reflected light that have been previously measured for the optical path under normal conditions, and if the comparison shows that the optical level or position has changed, it is determined that there is a failure in the optical path. and determine the location of the fault, and if no fluctuation occurs, determine that there is no fault in the optical path, thereby isolating the location of the fault between the optical path and the optical receiver of the transmission device. A method for isolating the location of a fault in an optical transmission line, characterized by the following. 10. An optical branching device is provided in the middle of the optical path, and the optical filter type splitter is installed immediately before each optical receiver provided on the subscriber side of the optical path branched by the branching device. In the optical transmission line fault location isolation method, which uses an optical pulse tester to isolate the fault location between the optical line and the optical receiver of the transmission device, The test pulse light is inserted into the optical path via an optical coupler, and each reflected light of the test pulse light is reflected by an optical filter type splitter that is installed immediately before each of the optical receivers and reflects only the test pulse light. , the light level and position of each reflected light were measured in advance for the optical path and each branched optical path in a normal state. If there is a change in the light level or position as a result of the comparison, it is determined that there is a failure in the optical path where the change has occurred, and the failure position is determined to confirm that no change has occurred. A method for isolating a fault location in an optical transmission line, characterized in that the fault location between the optical line and an optical receiver of the transmission device is isolated by determining that there is no fault in the optical line.