JPH05160493A - Light amplifier and light transmission system - Google Patents

Abstract

PURPOSE:To enable rapid disposal by a controller by issuing a warning by automatically deciding abnormal places. CONSTITUTION:The light quantity of the optical signal which has been amplified by a rare earth dope optical fiber 3 is monitored by an optical output monitoring circuit 6. The amplified optical output monitoring circuit 6, becoming less than a specified value, switches an optical switch 7 over to a warning signal transmitting circuit 8 side, in response to the light quantity. The warning signal transmitting circuit 8 outputs the optical signal having a specified pattern as a warning signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical amplifier which amplifies input light by exciting an amplifying optical fiber with light emitted from a light emitting means for excitation, and an optical transmission system which performs relay transmission using this optical amplifier. Regarding

[0002]

2. Description of the Related Art In recent years, an optical amplifier, which is capable of directly amplifying an optical signal without converting it into an electric signal, a so-called optical fiber amplifier has been developed.

FIG. 4 is a block diagram showing a configuration example of an optical fiber amplifier. As shown in this figure, the optical fiber amplifier comprises a pumping laser oscillator 1, a multiplexer 2, a rare earth-doped optical fiber 3 and an optical filter 4.

The input optical signal is multiplexed with the laser light emitted from the pumping laser oscillator 1 by the multiplexer 2,
It is input to the rare earth-doped optical fiber 3. The rare earth-doped optical fiber 3 is excited by the laser light emitted from the excitation laser oscillator 1 and stimulated emission occurs. The optical signal is amplified by this stimulated emission. The output of the rare earth-doped optical fiber 3 is sent to a transmission line or the like after the optical filter 4 cuts the excitation light to extract only the optical signal. If the wavelength of the optical signal is, for example, 1.55 μm, the wavelength of the laser light emitted from the excitation laser oscillator 1 is 1.48 μm. The rare earth element doped in the rare earth element-doped optical fiber 3 is, for example, Er (erbium).

Thus, the optical fiber amplifier as described above has a simple structure. Therefore, by using the above optical fiber amplifier as a repeater, an optical transmission system having a simple structure can be constructed.

However, in the case of an optical transmission system that relays a plurality of optical fiber amplifiers, one of the optical fiber amplifiers fails, or an abnormality occurs such as a break in the optical transmission line between the optical fiber amplifiers, When the level of the optical signal on the receiving side has dropped, the occurrence of an abnormality can be easily known based on the drop in the receiving level, but it is difficult to determine the location of the abnormality, so it is difficult to investigate. Takes time.

[0007]

As described above, the prior art is as follows.
When an abnormality occurs, it is difficult to determine the location of the abnormality and it takes a lot of time to investigate. For this reason, there has been a problem that the system administrator cannot take prompt measures.

The present invention has been made in consideration of such circumstances, and the purpose thereof is to be able to automatically determine the location of an abnormality and issue an alarm. An object of the present invention is to provide an optical amplifier and an optical transmission system capable of performing quick treatment.

[0009]

The first invention is an optical output monitoring means such as an optical output monitoring circuit for monitoring whether or not the light quantity of an optical signal after being amplified is equal to or more than a predetermined quantity, An alarm unit such as an alarm signal transmission circuit that outputs a predetermined alarm signal in response to the fact that the light amount of the optical signal after being amplified is detected by the optical output monitoring unit to be lower than a predetermined amount. It was equipped with an optical amplifier.

In a second aspect of the invention, each of a plurality of optical amplifiers such as an optical fiber amplifier monitors whether or not the light amount of the optical signal after being amplified by the corresponding optical amplifier is a predetermined amount or more. For example, the optical output monitoring means such as an optical output monitoring circuit and the optical output monitoring means in the corresponding optical amplifier have detected that the light amount of the optical signal after being amplified by the corresponding optical amplifier has decreased below a predetermined amount. Depending on,
And a warning unit for sending an optical signal corresponding to the optical amplifier of the optical signals of a preset pattern to each of the plurality of optical amplifiers to the transmission line, and When the optical signal is transmitted from any of the alarm means and reaches the transmission line downstream of the plurality of optical amplifiers via the transmission line, an abnormality occurs based on the pattern of the optical signal that has arrived. An optical transmission system is configured by providing a transmission line monitoring means for determining which of the plurality of optical amplifiers the optical amplifier is.

[0011]

According to the first aspect of the present invention, it is monitored whether or not the light amount of the optical signal after being amplified is equal to or more than a predetermined amount, and the predetermined amount is detected in response to the detection that the light amount is lower than the predetermined amount. An alarm signal is output.

According to the second aspect of the invention, each of the plurality of optical amplifiers monitors whether or not the light amount of the optical signal after being amplified is equal to or more than a predetermined amount, and it is determined that the light amount is lower than the predetermined amount. In response to the detection, the optical signal corresponding to the corresponding optical amplifier among the optical signals having the preset pattern for each of the plurality of optical amplifiers is transmitted to the transmission line. Further, on the downstream side of the plurality of optical amplifiers in the transmission line, an optical amplifier in which an abnormality has occurred based on the pattern of the optical signal in which the optical signal is transmitted from any of the alarm means is one of the plurality of optical amplifiers. It is determined which of the two.

Therefore, the presence or absence of abnormality of the optical amplifier is automatically detected, and an alarm signal or an abnormality of the optical amplifier is determined from the determination result of which of the plurality of optical amplifiers the abnormality occurs. You can get to know it easily.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the optical transmission system according to the present embodiment. In the figure, 10 and 20 are terminal repeaters. The terminal repeaters 10 and 20 are connected via an optical transmission line 50 formed by an optical fiber OF and optical fiber amplifiers 30 and 40. Reference numeral 60 is a transmission line monitoring device, which branches and inputs the optical signal reaching the terminal repeater 20. FIG. 2 shows the optical fiber amplifiers 30 and 4
It is a block diagram which shows the concrete structure of 0. The same parts as those in FIG. 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

Reference numeral 5 in the figure denotes a demultiplexer, which demultiplexes the optical signal transmitted through the optical filter 5 and supplies the demultiplexed optical signal to the optical output monitoring circuit 6 and the optical switch 7. The optical output monitoring circuit 6 monitors the light amount of the given optical signal and controls the switching of the optical switch 7 based on the monitoring result. Reference numeral 8 is an alarm signal transmission circuit that transmits an optical signal of a predetermined pattern as an alarm signal. The warning signal has different patterns in the warning signal transmitting circuit 8 of the optical fiber amplifier 30 and the warning signal transmitting circuit 8 of the optical fiber amplifier 40. Optical switch 7
Under the control of the optical output monitoring circuit 6, sends either the optical signal output from the demultiplexer 5 or the alarm signal output from the alarm signal transmission circuit 8 to the optical fiber OF.

FIG. 3 is a block diagram showing a specific structure of the transmission line monitoring apparatus 60. In the figure, reference numeral 11 is an alarm signal extraction unit for extracting an alarm signal of a specific pattern from the optical signal coming through the optical transmission line 50. Reference numeral 12 denotes the optical fiber amplifier 30 or the terminal repeater 10 and the optical fiber amplifier 30 based on the pattern of the alarm signal extracted by the alarm signal extraction unit.
Between the optical fiber OF and the optical fiber amplifier 40
Alternatively, it is an abnormal point determination unit that determines which of the optical fibers OF between the optical fiber amplifier 30 and the optical fiber amplifier 40 has an abnormality. Reference numeral 13 is a display for visually displaying the determination result of the abnormal point determination unit 12.

Next, the operation of the optical transmission system configured as above will be described. First, the optical signal sent from the terminal repeater 10 is transmitted to the terminal repeater 20 through the optical fiber OF while being relayed and amplified by the optical fiber amplifiers 30 and 40, respectively.

At this time, the optical fiber amplifiers 30 and 40 are
The pumping laser oscillator 1, the multiplexer 2, and the rare-earth-doped optical fiber 3 amplify the optical signal by the same operation as the conventional optical fiber amplifier shown in FIG. Here, in the normal state, the optical switch 7 selects the demultiplexer 5 side, and the optical signal amplified by the rare earth-doped optical fiber 3 is output to the optical fiber OF. Thus, relay amplification is performed as described above.

In the optical fiber amplifiers 30 and 40, while the optical signal is being relayed and amplified as described above, the optical signal transmitted through the optical filter 4 is branched by the demultiplexer 5 and the optical output monitoring circuit 6 is provided. This optical output monitoring circuit 6
The optical quantity of the optical signal, that is, the amplified optical signal is monitored by. When the light output monitoring circuit 6 detects that the light quantity of the light signal has become lower than a predetermined value, it switches the light switch 7 to the alarm signal transmission circuit 8 side. As a result, the optical signal transmitted through the optical filter 4 is blocked, and the alarm signal output by the alarm signal transmission circuit 8 is output to the optical fiber OF instead.

Specifically, for example, the optical fiber amplifier 40
When the pumping laser oscillator 1 is deteriorated and the output light amount thereof decreases, the amplification factor of the rare earth-doped optical fiber 3 decreases, and the light amount of the output light of the rare earth-doped optical fiber 3 decreases. Further, when an abnormality occurs in the optical fiber OF between the optical fiber amplifier 30 and the optical fiber amplifier 40, the amount of light reaching the optical fiber amplifier 30 is reduced, so that the amount of output light of the rare earth-doped optical fiber 3 is also reduced. When the light quantity of the output light of the rare earth-doped optical fiber 3 is decreased in this way, the optical output monitor circuit 6 detects this decrease in the light quantity and switches the optical switch 7 of the optical fiber amplifier 40 to select the alarm signal transmission circuit 8. .. As a result, the alarm signal output from the alarm signal transmission circuit 8 of the optical fiber amplifier 40 is sent to the optical fiber OF. Assuming that the pattern assigned to the optical fiber amplifier 30 is A and the pattern assigned to the optical fiber amplifier 40 is B, the alarm signal transmission circuit 8 of the optical fiber amplifier 40 outputs an alarm signal of pattern B. , This is the optical fiber O
Sent to F.

In this way, the optical fiber amplifiers 30, 4 are
The alarm signal output from any one of
Is transmitted to reach the transmission path monitoring device 60. In the transmission path monitoring device 60, the alarm signal extraction unit 11 extracts the alarm signal thus arrived and gives it to the abnormal point determination unit 12.
The abnormal point determination unit 12 determines which one of the optical fiber amplifiers 30 and 40 the pattern of the given alarm signal is assigned to, and based on this, the above-mentioned occurrence points are detected by the optical fiber amplifier 30 or Terminal repeater 10
And the optical fiber OF between the optical fiber amplifier 30 and the optical fiber amplifier 30, and the optical fiber OF between the optical fiber amplifier 40 and the optical fiber amplifier 30. Specifically, the abnormal point determination unit 12
Determines whether the alarm signal is the pattern A or the pattern B when the alarm signal is given from the alarm signal extraction unit 11. When the alarm signal is the pattern A, the optical fiber amplifier 30 or the terminal device 10 and the optical signal are transmitted. It is determined that an abnormality has occurred in the optical fiber OF between the optical fiber amplifier 30 and the optical fiber amplifier 30, and when the pattern is B, the optical fiber amplifier 40 or the optical fiber amplifier 30 and the optical fiber amplifier 4 are detected.
It is determined that an abnormality has occurred in the optical fiber OF between 0 and 0. That is, when the alarm signal of the pattern B is output from the optical fiber amplifier 40 as in the above-described specific example, the abnormal point determination unit 12 causes the optical fiber amplifier 40 or between the optical fiber amplifier 30 and the optical fiber amplifier 40. It is determined that an abnormality has occurred in the optical fiber OF.
The result of the determination made by the abnormal portion determination unit 12 as described above is visually displayed on the display unit 13.

Thus, according to this embodiment, the optical fiber amplifiers 30 and 40 monitor their own abnormalities, and when the abnormalities occur, the fact is notified to the transmission line monitoring device 60. Then, the transmission path monitoring device 60 visually displays the presence / absence of an abnormality, the occurrence location, etc. on the display unit 13 based on the notification.
Therefore, the administrator can easily know the location where the abnormality has occurred by looking at the display unit 13, and can take prompt action.

Further, in the present embodiment, the optical fiber amplifier 3
A different pattern of alarm signals is assigned to each of 0 and 40, and when an abnormality occurs, this alarm signal is transmitted to the optical transmission line 50.
Therefore, it is not necessary to provide a new signal transmission line for notifying the transmission line monitoring device 60 of the occurrence of an abnormality, and thus it is possible to prevent the configuration from becoming complicated.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the alarm signal is an optical signal and is transmitted using the optical transmission line 50. However, a transmission line for transmitting the alarm signal may be separately provided, and the signal form is also an optical signal. It is not limited to. Further, in the above embodiment, the location of the abnormality can be specified by making the alarm signal pattern different, but if an alarm signal transmission path is provided for each optical fiber amplifier, a single alarm signal pattern can be obtained. It can also be

Further, in the above embodiment, the optical transmission system having two optical fiber amplifiers is illustrated, but the present invention can be applied to an optical transmission system having three or more optical fiber amplifiers. Further, in the above embodiment, the transmission line monitoring device 60 is arranged separately from the terminal station repeater 20, but the function of the transmission line monitoring device 60 may be built in the terminal station repeater 20. In addition, various modifications can be made without departing from the scope of the present invention.

[0026]

According to a first aspect of the present invention, an optical output monitoring means such as an optical output monitoring circuit for monitoring whether or not the light amount of an optical signal after being amplified is equal to or more than a predetermined amount, and this optical output monitoring. The optical signal is provided with an alarm means such as an alarm signal transmission circuit which outputs a predetermined alarm signal in response to the detection that the light amount of the optical signal after the amplification is made lower than the predetermined amount by the means. Configured the amplifier.

According to the second invention, each of a plurality of optical amplifiers such as an optical fiber amplifier monitors whether or not the light amount of the optical signal after being amplified by the corresponding optical amplifier is equal to or more than a predetermined amount. For example, the optical output monitoring means such as an optical output monitoring circuit and the optical output monitoring means in the corresponding optical amplifier have detected that the light amount of the optical signal after being amplified by the corresponding optical amplifier has decreased below a predetermined amount. Depending on,
And a warning unit for sending an optical signal corresponding to the optical amplifier of the optical signals of a preset pattern to each of the plurality of optical amplifiers to the transmission line, and When the optical signal is transmitted from any of the alarm means and reaches the transmission line downstream of the plurality of optical amplifiers via the transmission line, an abnormality occurs based on the pattern of the optical signal that has arrived. An optical transmission system is configured by providing a transmission line monitoring means for determining which of the plurality of optical amplifiers the optical amplifier is.

According to these, an optical amplifier and an optical transmission system can be provided in which an abnormal place can be automatically determined and an alarm can be issued, whereby a prompt treatment can be performed by an administrator.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an optical transmission system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a specific configuration of optical fiber amplifiers 30 and 40 in FIG.

3 is a block diagram showing a specific configuration of a transmission line monitoring device 60 in FIG.

FIG. 4 is a diagram illustrating a conventional technique.

[Explanation of symbols]

10, 20 ... Terminal repeater, 30, 40 ... Optical fiber amplifier, 50 ... Optical transmission line, 60 ... Transmission line monitoring device, 1 ... Excitation laser oscillator, 2 ... Multiplexer, 3 ... Rare earth-doped optical fiber, 4 ... Optical filter, 5 ... Demultiplexer, 6 ... Optical output monitoring circuit, 7 ... Optical switch, 8 ... Warning signal transmitting circuit, OF ...
Optical fiber.

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Claims (2)

[Claims] 1. An optical amplifier that amplifies an optical signal by exciting an amplifying optical fiber with light emitted from an exciting light emitting means, is the amount of light of the optical signal amplified by the optical amplifier equal to or more than a predetermined amount? Optical output monitoring means for monitoring whether or not the optical output monitoring means outputs a predetermined alarm signal in response to the fact that the light amount of the optical signal amplified by the optical amplifier is detected to be lower than a predetermined amount. An optical amplifier, comprising: 2. An optical transmission system having a plurality of optical amplifiers for amplifying input light by exciting an amplifying optical fiber with light emitted by an exciting light emitting means, wherein the optical amplifier relays and transmits the optical signal. Optical output monitoring means provided in each of the optical amplifiers for monitoring whether the light amount of the optical signal amplified by the corresponding optical amplifier is equal to or more than a predetermined amount, and provided in each of the plurality of optical amplifiers, The optical output monitoring means in the amplifier detects that the amount of light of the optical signal amplified by the optical amplifier is lower than a predetermined amount, and is preset for each of the plurality of optical amplifiers. An alarm means for sending an optical signal corresponding to the corresponding optical amplifier of the optical signals of the pattern to the transmission path, and an alarm means provided on the downstream side of the transmission path with respect to the plurality of optical amplifiers. When the optical signal is transmitted from a different position and arrives via a transmission line, it is determined which one of the plurality of optical amplifiers the abnormal optical amplifier is based on the pattern of the incoming optical signal. An optical transmission system comprising: a transmission path monitoring means for determining.