JP4122192B2 - Control method of optical amplifier - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to an effective method and an apparatus equipped with an optical transmission method using an optical amplifier using an optical amplification fiber.
[0002]
[Prior art]
In an optical transmission system, an optical amplifier using an optical amplifying fiber is widely used, and this optical amplifier generally has an automatic output stabilizing function for stabilizing the output. By the way, even if some kind of failure occurs in the optical transmission system and the input optical power to the optical amplifier is greatly reduced, if the automatic output stabilization function of the optical amplifier is activated, the pumping light power is reduced to compensate for the decrease in the input optical power. Increase. In general, the life of the pumping light source is deteriorated by increasing the power of the pumping light emitted and operating at a high load. At this time, the life of the pumping light source is deteriorated. Therefore, a control method and apparatus that does not deteriorate the lifetime of the pumping light source are desired so as to further improve the reliability of the optical transmission system.
[0003]
[Problems to be solved by the invention]
One solution to this problem is to suppress the power of the pumping light when the input light power is reduced (for example, Japanese Patent No. 3050237).
[0004]
According to the above method, when the input light power decreases, the pumping light power is uniformly suppressed and the optical transmission is stopped. However, the optical transmission should be maintained as much as possible in the optical transmission system, and the stop of the optical transmission is a situation that should be avoided unless it is unavoidable to protect the apparatus.
[0005]
Therefore, in view of the above problems, the present invention provides an optical amplifier with a function for determining the pumping light power or operating current of the pumping light source, that is, the load, and performs optical transmission except when it is unavoidable to protect the device when the input light power is reduced. The purpose is to provide a control method that does not require stopping.
[0006]
[Means for Solving the Problems]
In order to solve the above problem, in the method for controlling an optical amplifier according to the present invention, two pumping light sources are connected to a wavelength multi-polymerizer, and one or the other pumping light source is operated to pump light into an optical amplification fiber. Ri Na supplies, in an optical amplifier for controlling the amplified output light constant output power of the input light to the optical amplifying fiber is not less than a predetermined value, and the operating current value of the one excitation light source Is switched over from one excitation light source to the other excitation light source by stopping the one excitation light source and operating the other excitation light source. It is said.
[0013]
[Action]
According to the present invention, when the input light power to the optical amplifier is reduced by monitoring not only the input light power but also the load of the pump light source, more specifically, the power of the pump light or the operating current value, Even if the automatic output stabilization function of the amplifier operates, the operating current of the pumping light source actually increases and the operating current must be suppressed, and the operating current does not increase so much that it must be suppressed. A case can be distinguished. By controlling the distinction, it is possible to prevent the excitation light source from being deteriorated as a result of increasing the load of the excitation light source while maintaining optical transmission as much as possible.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing an embodiment of an optical amplifier according to the present invention.
In FIG. 1, the input light, which is the signal light to be amplified, is incident on the optical branching device 11 and branched there, and a part of it, for example, about 5% of the total input light is incident on the O / E converter 15 as the input monitoring light. Most of the remaining light is incident on the wavelength multi-polymerizer 12. The pumping light is output from the pumping light source 16, is combined with the input light by the wavelength multi-polymerizer 12, and enters the optical amplification fiber 13. At this time, the input light is amplified in the optical amplification fiber 13 and output to the optical branching device 14. This output light is branched by the optical splitter 14, and a part of the output light, for example, about 3% of the output light is incident on the O / E converter 17 as output monitor light, and most of the remaining light is output as the output light of the optical amplifier. It is configured to be output outside the amplifier.
[0015]
The input monitor light incident on the O / E converter 15 is converted from light to electricity in the O / E converter 15 and transmitted as an electric signal to the control circuit 18 which is an electronic circuit. Similarly, the output monitor light incident on the O / E converter 17 is converted from light to electricity by the O / E converter 17 and transmitted to the control circuit 18 as an electric signal. Apart from these, as the load information of the pumping light source 16, the operating current value or pumping light power value of the pumping light source is transmitted to the control circuit 18 as an electrical signal.
[0016]
The optical branching unit 11, the optical branching unit 14, and the wavelength multi-polymerization wave unit 12 are specifically optical couplers. However, the optical branching unit 11 and the optical branching unit 14 have a function of branching incident light to two ports, and have a plurality of wavelengths. The superposition wave generator 12 may be an optical fiber type optical coupler obtained by melting and stretching an optical fiber, or may be a microscopic device such as a mirror or a prism, as long as the function of combining signal light and pumping light having different wavelengths can be obtained. It may be a bulk type using a simple optical component, or an optical waveguide type in which an optical circuit is formed on a quartz substrate or the like. However, because of the demand for high-efficiency and stable operation of the optical amplifier, it is necessary to have a small loss inside the optical coupler and a small change in the output light of each port even if the environmental temperature changes. The pumping light source 16 is preferably a semiconductor laser diode module that satisfies the usage requirements of small size, high output, and long life. In some cases, a photodiode is built in the module to monitor the pumping light power. You may use what is done. The O / E converter 15 and the O / E converter 17 are not particularly limited, and various O / E converters can be used. For example, a photodiode can be used.
[0017]
The optical amplifying fiber 13 is typically an erbium-doped fiber that obtains a stimulated emission effect by adding erbium, but it may be an optical fiber doped with other elements to obtain a stimulated emission effect, and it is also pumped. As long as it is an optical fiber having an optical amplifying action by combining with light, an optical fiber having an optical amplifying action by other physical phenomena is not limited to the stimulated emission action. As for the configuration relating to the pumping light incident on the optical amplification fiber 13, in FIG. 1, the input light and the pumping light, which are signal light to be amplified, are configured to be forward pumping in which they enter from the same end face of the optical amplification fiber. This is only an example, and it may be a configuration of backward pumping in which input light and pumping light are incident from different end faces of the optical amplifying fiber, or pumping light is incident from both ends of the optical amplifying fiber. A bidirectional excitation configuration may also be used.
[0018]
In this optical amplifier, an automatic output stabilization function generally called auto level control is operating in order to stabilize the output light while keeping the output light constant. The pumping light power, that is, the operating current value of the pumping light source is automatically increased / decreased so that the output light is always kept constant. That is, in FIG. 1, it is determined whether the operating current of the excitation light source 16 should be increased or decreased by the output determination control circuit 19 based on an electrical signal transmitted from the O / E converter 17 to the output determination control circuit 19 which is a part of the control circuit 18. Then, an electrical signal relating to increase / decrease of the operating current corresponding to the determination result is transmitted from the output determination control circuit 19 to the excitation light source control circuit 20 which is also a part of the control circuit 18. The output light is controlled to be constant by increasing or decreasing the operating current by the excitation light source control circuit 20.
[0019]
FIG. 2 is a flowchart showing an embodiment of the control of the optical amplifier of the present invention.
When the input light power decreases while the automatic output stabilization function is operating, the pumping light power of the pumping light source is increased to compensate for the decrease in input light power. That is, the operating current value of the excitation light source increases. Here, when the pumping light power is equal to or higher than a predetermined value and the input light power is equal to or lower than the predetermined value, the pumping light power is suppressed to reduce the load on the pumping light source, thereby preventing the life of the pumping light source from being deteriorated. When the pumping light power is less than or equal to a predetermined value, the pumping light power is maintained regardless of whether the input light power is less than or equal to the predetermined value. As a result, the optical transmission is prevented from being stopped unnecessarily except when it is unavoidable to protect the apparatus. As a specific example, the predetermined value of the pumping light power is 100 mW, the predetermined value of the input light power is 0.1 mW, and the pumping light power is suppressed to, for example, 5 mW or less. At this time, the operating current value of the excitation light source decreases from about 500 mA to about 50 mA or less.
[0020]
When the pumping light power is equal to or higher than the predetermined value and the input light power is equal to or higher than the predetermined value, the pumping light power is maintained, but it is determined that the pumping light source is abnormal and an alarm signal is transmitted. Specifically, the alarm signal is transmitted, so that the administrator of the optical transmission system can visually recognize the abnormal state, the abnormality is visually indicated by a lamp, etc. The step includes emitting an electrical signal from the optical amplifier to the control display device.
[0021]
FIG. 3 is a flowchart showing another embodiment of the control of the optical amplifier of the present invention.
Here, when the input light power decreases, the automatic output stabilization function increases the pumping light power to compensate for the decrease in the input light power, and as a result, the operating current value of the pumping light source increases. At this time, if the operating current value of the pumping light source is equal to or greater than a predetermined value and the input light power is equal to or lower than the predetermined value, the operating current of the pumping light source is suppressed to reduce the pumping light source load and prevent the pumping light source life from deteriorating. .
[0022]
If the input light power has not decreased below the predetermined value and the operating current of the pumping light source is equal to or higher than the predetermined value, it is determined that the pumping light source is abnormal, and the pumping light source backup product and the optical amplifier backup product are switched. As a means for switching to a backup product of the excitation light source, for example, in FIG. 1, there are two or more excitation light sources 16 connected to the wavelength multi-polymerizer 12, and the excitation light source that has been operating so far is stopped to perform another excitation. A means for automatically controlling the light source to operate can be exemplified. Further, as means for switching to a backup product of an optical amplifier, for example, there are two or more sets of optical amplifiers shown in FIG. 1, and the input light is passed through an optical amplifier different from the optical amplifier that has been operating so far. A means for automatically controlling so as to obtain output light amplified from can be exemplified.
[0023]
Further, when the input light power is not reduced below the predetermined value and the operating current of the pumping light source is lower than the predetermined value, the operating current of the pumping light source is maintained as a normal state. Furthermore, if the input light power decreases below the predetermined value and the operating current of the pumping light source is below the predetermined value, the operating current of the pumping light source is maintained because there is a possibility that the optical transmission can be maintained although the input light is in an abnormal state. . In this case, it is desirable that the optical amplifier is controlled so that an alarm signal indicating that the input light is in an abnormal state is transmitted.
[0024]
【The invention's effect】
As described above, according to the present invention, when the input light power is reduced, it is confirmed that the pumping light power is a predetermined value or more, and the pumping light power is suppressed. This reduces the load on the excitation light source and prevents the life of the excitation light source from deteriorating. In addition, when the input light power is reduced, the pump light power is maintained when the pump light power is below a predetermined value, so that there is an advantage of avoiding stopping the optical transmission except when it is unavoidable due to protection of the device. .
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an optical amplifier according to the present invention.
FIG. 2 is a flowchart showing an example of control of an optical amplifier according to the present invention.
FIG. 3 is a flowchart showing another example of the control of the optical amplifier according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Optical branching device 12 Wavelength multi-polymerization wave device 13 Optical amplification fiber 14 Optical branching device 15 O / E converter 16 Excitation light source 17 O / E converter 18 Control circuit 19 Output determination control circuit 20 Excitation light source control circuit

Claims (1)

To connect the two excitation light sources to the wavelength division multiplexer multiplexer operates the one or the other excitation light source Ri name by supplying excitation light to the optical amplifier fiber, the light for controlling the amplified output light constant output In the amplifier, when the power of the input light to the optical amplification fiber is not less than a predetermined value and the operating current value of the one excitation light source is not less than the predetermined value, the one excitation light source is stopped, A method of controlling an optical amplifier, wherein the pumping light source to be operated is switched from the one pumping light source to the other pumping light source by operating the other pumping light source.

Images