JP2004159166A - Optical transmission line protection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmission protection device for preventing a fiber fuse phenomenon occurring when a high power of a prescribed optical energy density or above is inputted into an optical transmission line. <P>SOLUTION: The optical transmission line protection device comprises an optical distributor 2 for branching an optical energy transmitted on the optical transmission line side to a branch line 3 at a certain ratio; and a light interception part 2 for generating a fiber fuse 7 in response to storage of an optical energy density of a prescribed value or higher and cutting off the optical transmission line on the basis of this fiber fuse phenomenon. The device does not require power sources and electric circuits at all. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical transmission line protection device, and more particularly, to an optical transmission line protection device used for protecting an optical transmission line such as an optical circuit or an optical line in a wavelength division multiplexing (WDM) optical communication system.
[0002]
[Prior art]
At present, optical fiber communication means is becoming more and more important as information communication means, and further increase in speed and capacity of information communication is desired in the future.
Above all, in order to cope with the increase in capacity, wavelength division multiplexing optical communication has become extremely difficult due to improvements in gain of optical amplifiers, higher output of pump light accompanying the practical use of Raman amplifiers, multi-channel wavelength division multiplexing, etc. The need to handle high energy density laser light has emerged.
[0003]
However, as the output of the light used increases, the following new problems have recently started to occur.
For example, if high-power light of several watts or more is input to an optical fiber in which the optical fibers are not properly connected or the optical fiber is locally bent, the above-described connection point or the local Light energy concentrates on the bends, where they become hot and eventually ignite. This phenomenon is usually called a fiber fuse phenomenon or simply a fiber fuse.
[0004]
Furthermore, recently, it has become clear that the fiber fuse is generated even when the light energy density propagating through the optical fiber becomes higher than a predetermined value. For example, a situation in which the optical output of a light source or an optical amplifier causes unexpected fluctuations or abnormalities, and the laser power transmitted through an optical circuit or optical line (hereinafter collectively referred to as an optical transmission line) instantaneously increases. Occurs, a fiber fuse may be generated at an unspecified location in the optical transmission line (for example, see Patent Documents 1 and 2).
[0005]
In addition, if laser light is continuously input to the optical transmission line in the above-described state, the fiber fuse proceeds from the generated position toward the light source. If no measures are taken to stop the fiber fuse in the middle of the optical transmission line, not only the optical transmission line between the light source and the place where the fiber fuse is generated, but also the optical amplifier circuit, wavelength converter, or All optical circuit components such as add-drop may be damaged in some way. In other words, once a fiber fuse is generated, in the worst case, a self-destruction progress phenomenon occurs over the entire optical transmission path existing on the light source side from that location. If these optical transmission paths are damaged, it takes enormous cost and time to identify and replace a failed component, causing a great inconvenience in information transmission (for example, see Patent Document 3).
[0006]
In order to avoid the trouble caused by the fiber fuse as described above, the light output of the light emitted from the light source or the excitation light may be kept low. However, such measures go against the recent trend of realizing high-speed and large-capacity optical communication systems.
As a countermeasure for protecting the optical transmission line from such a fiber fuse phenomenon, the following methods and apparatuses have been conventionally proposed. For example, an optical monitor or a temperature monitor detects abnormal light emission or temperature in an optical transmission line caused by a fiber fuse phenomenon, and a method of shutting off the output light of a light source by combining the detection signal and an electric control circuit, A method and apparatus for determining the state of a fiber fuse and reducing the light output of a light source.
[0007]
However, in the case of these countermeasures, since it is impossible to predict where the fiber fuse occurs, the arrangement and number of monitors and the electric control circuit become complicated, and it is not easy to construct a protection system. In addition, since these monitors and control circuits are active components, there is a problem that the apparatus becomes expensive.
In addition, even if such a protection system operates properly, the optical transmission line between the location where the fiber fuse is generated and the location where the monitor is placed is all damaged by the progress of the fiber fuse. There is also. In order to minimize the damage caused by the fiber fuse, the number of monitors and the number of electric control circuits may be increased in parallel with the increase in the number of monitors, but this requires a great deal of cost and time.
[0008]
[Patent Document 1]
US Patent Application Publication No. 2002/0114605 (pp. 6-7 and FIG. 1).
[Patent Document 2]
U.S. Patent Application Publication No. 2002/0114608 (pp. 6-7 and FIG. 1).
[Patent Document 3]
US Patent Application Publication No. 2002/0114554 (pp. 8-9 and FIG. 6).
[0009]
[Problems to be solved by the invention]
The present invention has been made in order to solve the problem of the fiber fuse that occurs with the increase in the output of communication using an optical fiber, and can prevent the occurrence of the fiber fuse in the optical transmission line. Another object of the present invention is to provide a passive optical transmission path protection device that can be easily introduced and replaced.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, an optical splitter disposed on a main line of an optical transmission line, an optical splitter disposed on a branch line branched from the optical splitter, and having an optical energy of a predetermined value or more. A fiber fuse generating section that generates a fiber fuse phenomenon when density is accumulated, and a light blocking section that blocks the main line based on the fiber fuse phenomenon generated in the fiber fuse generating section. An optical transmission path protection device is provided.
[0011]
Further, the optical distributor is arranged on the main line of the optical transmission line, and the optical distributor is connected to a branch line branched from the optical distributor, and when a light energy density equal to or higher than a predetermined value is accumulated, the temperature is raised to a desired temperature. The optical transmission line protection device comprising a heat generating part and a light circuit breaker connected to the heat generating part of the branch line, wherein the light breaker includes a variable frame and a fixed frame supporting the main line, The variable gantry is connected to a spring gantry via a spring, and a connecting member is stretched between the variable gantry and the fixed gantry, and the heat generating portion is provided on the connecting member. Is provided.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an example A of the apparatus of the present invention.
The device A includes a main line 1 through which an optical signal propagates, an optical splitter 2 disposed on the main line 1, and a branch line 3 branched from the optical splitter 2. The line 3 functions as a fiber fuse generator. In addition, one of the main lines 1 is connected to the light source 4 via the incident side optical fiber, and the other is connected to the light receiving section 5 via the emission side optical fiber. Here, as the light distributor 2, an optical coupler manufactured by stretching and fusing two optical fibers is used, and also functions as a light blocking unit that blocks the main line 1 by an operation described later.
[0013]
This optical coupler has a structure as shown in FIG. 2, for example. The whole is protected by a package 6. In FIG. 2, the optical fiber running on the upper side is the main line 1, the optical fiber running on the lower side is the branch line 3, and both are optically coupled via the extension fusion part 1c. Is split into the branch line 3 at a certain distribution ratio.
[0014]
For example, the branching ratio in the optical coupler 2 can be set to be the ratio of the main line 95 to the branch line 5, and 5% of the light energy input to the device can flow through the branch line 3. Note that the two terminal portions of the branch line 3 may be simply released, but not to the outside of the device.
In making the optical coupler 2 described above, an optical fiber that causes a fiber fuse phenomenon even at a low optical energy density is selected as the branch line 3. Then, as the main line 1, an optical fiber in which a fiber fuse phenomenon occurs at a higher light energy density than the branch line 3 is selected. In this way, a fiber fuse can be caused in the branch line 3 before the main line 1 causes a fiber fuse.
[0015]
Next, the operation of the device A will be described. Now, it is assumed that high-output light is input to the branch line 2 and a fiber fuse 7 is generated at a certain location. The fiber fuse 7 travels through the branch line 2 toward the light source 4 oscillating at a high output as shown by the arrow, and reaches the optical coupler 5. Then, at that time, the main line side optical fiber 1 of the optical coupler 2 is blown by its own high heat. That is, the light transmission path is light-blocked. Thus, in the case of the device A, the optical coupler 2 also functions as an optical circuit breaker.
[0016]
FIG. 3 shows a device A1 which is a modification of the device A.
In the figure, a small-diameter coil 8 is formed at a specific location on the right side of the optical fiber 3, and a fiber fuse 7 generated at this specific location is run toward the light source 4 to blow the optical coupler 2 located in the apparatus. It is also possible to block light.
More specifically, for example, the above-mentioned optical coupler 2 having a branch ratio of 95: 5 is used, and 95% of the light energy emitted from the light source is used on the optical transmission line side. The fiber fuse 7 is reliably generated at 5% or less of the light energy density that can be safely used on the transmission line side. The generated fiber fuse 7 travels in the direction of the arrow toward the light source 4, and the propagated fiber fuse 7 blows the optical coupler 2 in the middle and interrupts the light of the main line side optical fiber 1.
[0017]
Further, the coil 8 may be placed near the optical coupler 2, and the optical coupler 8 may be blown by the heat of the fiber fuse generated in the coil 8 to block the light (not shown).
FIG. 4 shows another device B of the present invention.
The device B is different from the device A in that a light distributor and a light blocking unit are separately provided. That is, the optical coupler 2 and the optical circuit breaker 9 are separated from each other, and the branch line 3 is connected to the heating section 17 of the optical circuit breaker 9. The optical circuit breaker 9 includes a base 10, a variable mount (traverser) 11, a fixed mount 12, a spring mount 13, and two slide bars 14. The fixed gantry 12 grips and fixes the main line 1 by gripping means (not shown), and the variable gantry 11 has two through holes corresponding to the axial shape of the slide bar 14, and smoothly moves along the slide bar 14. It can move horizontally. The variable gantry 10 and the spring gantry 12 are connected via a spring 15, and when the connecting member 16 described below is not connected, the variable gantry 11 is located at a free end determined by the length of the spring 15. positioned.
[0018]
Next, the variable gantry 11 is laterally moved to the left side of the figure by a predetermined distance via the slide bar 14 and the tension is applied to the spring 15, and the variable gantry 11 and the fixed gantry 12 are connected via the connection member 16. I do. Since the variable gantry 11 is pulled to the right side in the drawing by the elastic force of the spring 15, the connecting member 16 connecting the variable gantry 11 and the fixed gantry 12 and the optical fiber 18 of the main line 1 are fixed without slack.
[0019]
The connecting member 16 used here has a property of generating heat and melting when the light energy density of the branch path 3 reaches a predetermined value. For example, the connecting member 16 is resistant to tensile stress near normal temperature and melts and cuts at high temperature. Metal filaments can be given. The heating section 17 is formed by connecting the branch line 3 to a part of the metal filament 19. With such a structure, the connection member 16 functions as a heat generating portion.
[0020]
Now, when the light energy density on the optical transmission line side reaches a predetermined value, the metal filament 19 connected to the branch line 3 is heated and blown by the heat generated by the metal filament 19. When the tension of the spring 15 is released, the variable gantry 11 moves rightward in the drawing by the restoring force of the spring 15. At the same time, the optical fiber 18 fixed without loosening between the fixed gantry 12 and the variable gantry 11 is pulled and broken, and the light of the main line 1 is blocked.
[0021]
In the above embodiment, the metal filament 19 is used as the connecting member 16 and the heat generating portion 17. However, as another embodiment, the fiber fuse phenomenon itself may be used as the heat generating portion 17. That is, as shown in the conceptual diagram of FIG. 5, the coil 8 may be wound around the connection member 16, and the connection member 16 may be heated and blown by heating when the fiber fuse passes through the coil 8. Further, the coil 8 may be provided near the connection member 16 (not shown).
[0022]
In the case of this embodiment, as the connecting member 16, in addition to the above-described metal filament 19, a solder alloy, a polymer material, or the like having a property that the tensile strength rapidly decreases or melts at a high temperature can be used. . In addition, a shape memory alloy which does not melt but is significantly deformed at high temperatures can be used.
In the above embodiment, when the fiber fuse is generated, the optical fiber 18 is pulled and broken to interrupt the advance of the fiber fuse. However, a spring mechanism that interrupts the advance of the fiber fuse across the optical fiber 18 is used. (Not shown).
[0023]
FIG. 6 shows a device B1 which is a modification of the device B.
This device B1 has a structure in which the main line 1 between the variable gantry 11 and the fixed gantry 12 is used as a PC (Physical Contact) connection 20 without breaking the optical fiber with the optical circuit breaker 9 as in the above embodiment. is there. The PC connection 20 is a method of optically connecting two optical fibers by abutting the end faces 20c and 20c 'of the two optical fibers. Conversely, in order to block light, the butted end surfaces 20c and 20c 'of the two optical fibers may be simply separated. If this light blocking method is used, the original PC connection 20 can be easily restored, and there is an advantage in handling.
[0024]
Also, in any of the above-described embodiments, as shown in a schematic diagram in FIG. 7, mounting and replacement are easy if a unit 23 having both ends of the optical transmission line protection device A or B as connectors 21 and 22 is used. Can be done. Furthermore, if one side is a male connector and the other side is a female connector, it is easy to additionally mount it on an existing system.
[0025]
【The invention's effect】
By using the optical transmission line protection device of the present invention, it is possible to prevent the occurrence of fiber fuses in the optical transmission line, and to safely input high power to the optical transmission line. Further, since this device is a passive optical component, it is inexpensive, and can be easily replaced, so that it has great industrial value.
[Brief description of the drawings]
FIG. 1 shows an example in which an optical fiber is used for detecting light energy density as one embodiment of the present invention.
FIG. 2 is a schematic diagram of an optical coupler used in the present invention.
FIG. 3 is another embodiment in which an optical fiber is used for detecting an optical energy density in the present invention.
FIG. 4 is an embodiment in which an optical distributor and an optical circuit breaker are separated in the present invention.
FIG. 5 is a conceptual diagram of a case where an optical fiber coil is used as a heating unit of a light blocking unit.
FIG. 6 shows another embodiment in which the optical distributor and the optical circuit breaker are separated in the present invention.
FIG. 7 is an embodiment of the present invention in the case where the apparatus main body and the optical connector have a unit structure.
[Explanation of symbols]
1 Main line 2 Optical distributor (optical coupler)
3 branch line 4 light source 5 receiver 7 fiber fuse 8 coil 9 optical circuit breaker 15 spring 17 heating section

Claims (8)

An optical distributor arranged on the main line of the optical transmission line;
A fiber fuse generator that is arranged on a branch line branching from the optical distributor and generates a fiber fuse phenomenon when a light energy density equal to or higher than a predetermined value is accumulated,
An optical transmission line protection device, comprising: a light blocking unit that cuts off the main line based on the fiber fuse phenomenon generated in the fiber fuse generating unit. The optical transmission line protection device according to claim 1, wherein the distributor is an optical coupler including two types of optical fibers having different optical energy densities that cause a fiber fuse phenomenon. The optical transmission line protection device according to claim 1, wherein the fiber fuse generator is configured by winding the optical fiber of the branch line into a coil. An optical distributor arranged on the main line of the optical transmission line;
A heating unit connected to a branch line branching from the optical distributor, and rising to a desired temperature when a light energy density equal to or higher than a predetermined value is accumulated;
An optical transmission line protection device comprising: an optical circuit breaker connected to a heat generating portion of the branch line;
The optical circuit breaker includes a variable gantry and a fixed gantry supporting the main line, the variable gantry is connected to a spring gantry via a spring, and a connection member is provided between the variable gantry and the fixed gantry. An optical transmission line protection device, wherein the optical transmission line protection device is stretched and the heat generating portion is disposed on the connection member. The optical transmission line protection device according to claim 4, wherein a metal filament is used as the connection member and the heat generating portion. The optical transmission line protection device according to claim 4, wherein the heat generating unit is the fiber fuse generating unit according to claim 3. The optical transmission line protection device according to any one of claims 4 to 6, wherein a main line between the fixed gantry and the variable gantry is connected to a PC. The optical transmission line protection device according to claim 1, wherein the optical transmission line protection device is an integrated structure to which the optical connector is connected.

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