JPH11150516A - Wavelength number detection device and light amplifier device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the constitution of hardware and to improve responsiveness by obtaining the number of wavelengths based on a mathematical relation between the level of a WDM(wavelength division multiplex) signal and a difference. SOLUTION: A level measuring means 11 measures the WDM signal level Lt obtained by wavelength-dividing/multiplexing plural (n) light signals whose nominal values A<2> of levels are equal and wavelengths differ. An interference light generation means 12 optically synthesizes reference light constituted of the sum of components whose nominal values of the levels are B<2> with the WDM signal by two phases detached by odd times as much as π radian. Then, two interference light beams are generated. A differential level measuring means 13 measures the difference Ld of the levels of the components distributed near the wavelength of the plural light signals in a wavelength area among the components of interference light. An operation means 14 calculates the number (n) of the wavelengths, which becomes the value obtained by measuring the level Lt of the WDM signal and the difference La by the level measuring means 11 and the interference light generation means 12 under a condition that either the nominal value A<2> or the nominal value B<2> is known.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength number detecting device for determining the number of wavelengths multiplexed on a WDM signal.
The present invention relates to an optical amplifier that amplifies a WDM signal while maintaining the level of each component of these wavelengths constant.

[0002]

2. Description of the Related Art Since a large-capacity optical transmission system is a major technology related to the construction of a multimedia network in the future, a time-division multiplexing (TDM) system and a time-division multiplexing (OTDM) system in the optical domain are required. , Wavelength division multiplexing (WDM)
Research and development are being widely pursued for each of the methods.

[0003] Of these systems, the wavelength division multiplexing system, in particular, allows (1) the transmission speed of an optical signal as a carrier to be set to be the lowest with respect to a desired transmission capacity, and (2) the transmission path. (3) Optical filters and other devices that can realize cross-connection, dropping and insertion in the optical domain regardless of the bit rate and transmission format are highly tolerant to the chromatic dispersion and nonlinear optical effects of optical fibers. (4) It is possible to collectively amplify all wavelength components through optical amplification with high gain over a wide band, making it inexpensive and flexible for various transmission services. Promising as an adaptable method.

FIG. 12 is a diagram showing a first configuration example of an optical amplifying device adapted to the wavelength division multiplexing system. Examples of prior art similar to the configuration example shown in this figure include, for example, “Properties of the Optical Amplifier with ALC for Wavelength Number Fluctuations and Input Level Fluctuations” (1996), p. 577.

In FIG. 1, an optical signal (hereinafter, referred to as “WDM signal”) that has been wavelength-division multiplexed from an optical transmission line 131-1 is provided to an entrance of an optical amplifier 130. The output port is connected to the input port of the optical demultiplexer 132. One output port of the optical demultiplexer 132 is connected to one end of the subsequent optical transmission line 131-2, and the other output port of the optical demultiplexer 132 is built in the optical amplifier 130 via the control unit 133. Connected to the drive input of the excitation light source.

In the control unit 133, the other output port of the optical splitter 132 is connected to the input port of the optical-electrical converter (O / E) 134, and the output of the optical-electrical converter 134 is It is connected to a drive input of the above-mentioned excitation light source via a bandpass filter 135 and a drive unit 136. In the conventional example having such a configuration, the WD provided through the optical transmission line 131-1
The specific wavelength included in the M signal (here, for simplicity,
Assume a single wavelength. ) Is modulated with a sine wave signal of a predetermined frequency (here, it is assumed to be 100 kHz for simplicity).

[0007] The optical amplifier 130 generates an output WDM signal by amplifying the WDM signal.
The output WD is sent to the subsequent optical transmission line 131-2 via the
The M signal is emitted. In the control unit 133, the optical-electrical converter 134 converts a part of the output WDM signal described above into the optical demultiplexer 1.
32, and generates a monitor signal indicating the luminance of the output WDM signal. Also, the bandpass filter 135
Extracts the aforementioned sine wave signal component from the monitor signal component in the frequency domain. Further, the driving unit 136 includes:
The above-described excitation light source is driven in a direction in which the level variation of the component of the sine wave signal is compressed.

Therefore, the gain of the optical amplifier 130 is WD
The variation of the level of the M signal is automatically changed in a direction in which the fluctuation is suppressed, and an output WDM signal having a constant level of each wavelength component is emitted to the subsequent optical transmission line 131-2. FIG.
FIG. 3 is a diagram illustrating a second configuration example of the optical amplifying device adapted to the wavelength division multiplexing method. Examples of prior art similar to the configuration example shown in the figure include, for example, “Output level control method of WDM optical amplifier” (1996), p. 581.

In the figure, components having the same functions and configurations as those shown in FIG. 12 are denoted by the same reference numerals, and description thereof is omitted here. The difference between the optical amplifier shown in FIG. 13 and the optical amplifier shown in FIG.
The optical amplifier 130A having the LC function is
The control unit 140 is provided instead of the control unit 133.
Is provided.

The control unit 140 includes an AO filter 141 arranged in series between the other output port of the optical demultiplexer 132 and a drive input of an excitation light source built in the optical amplifier 130.
It comprises an electrical converter (O / E) 142, a wavelength counter 143, and a driving unit 144, and a sweep control unit 145 directly connected to control inputs of the AO filter 141 and the wavelength counter 143.

In the conventional example having such a configuration, the sweep control unit 145 resets the wavelength number counter 143 at a fixed cycle and outputs a variable frequency signal whose frequency uniformly changes in a predetermined frequency band. Generate "process is repeated.
The AO filter 141 has the characteristic that the pass wavelength band changes according to the frequency of the above-mentioned variable frequency signal.
From the output of the O filter 141, components of individual wavelengths included in the WDM signal supplied via the optical demultiplexer 132 are cyclically extracted in the order of time series, and are obtained as a filtered optical signal.

The optical-to-electrical converter 142 generates an electrical pulse signal indicating the component of each wavelength included in the filtered optical signal, and the wavelength counter 143 counts the pulse signal. Since the maximum value of the count value obtained by the wavelength number counter 143 in this way indicates the number of wavelengths multiplexed in the WDM signal, the driving unit 144 sets the target value of the level to be obtained under ALC to the wavelength. The value is appropriately given to the optical amplifier 130A as a value proportional to the number.

Therefore, with respect to the WDM signal obtained at the output port of the optical amplifier 130A according to the target value, the level of the component per unit wavelength is kept substantially constant even if the number of multiplexed wavelengths increases or decreases. It is.

[0014]

Among the above-mentioned prior arts, the one shown in FIG. 12 is such that the luminance of any of a plurality of wavelength components multiplexed in a WDM signal is determined by the above-described sine wave signal. Because the transmission characteristics deteriorate due to modulation,
Unless the degree of the deterioration is allowed, application is difficult.

In the conventional example shown in FIG.
Since the AO filter 141 is expensive and the response time required to change the pass wavelength band according to the frequency of the given variable frequency signal is long, it is difficult to obtain a desired response.
Further, both of the conventional examples shown in FIGS. 12 and 13 are complicated in configuration and large in scale of hardware, so that the required price-performance ratio cannot be achieved or are not actually applied. In many cases.

However, a point-to-point transmission system to which a wavelength division multiplexing method is applied, an optical ADM (Add / Dro
(p Multiplexer) In the transmission system and optical cross-connect system, the channels corresponding to each wavelength are switched appropriately according to the increase or decrease of the required transmission capacity, so the level of each wavelength multiplexed in the WDM signal increases. Of the transmission characteristics caused by the four-wave mixing in the case where the optical amplifiers 130 and 130A are reduced.
The deterioration of the S / N ratio due to the increase in is not both acceptable.

It is an object of the present invention to provide a wavelength number detecting device in which the number of wavelengths can be accurately obtained at low cost and an optical amplifying device in which automatic level control adapted to a wavelength division multiplexing system is reliably performed. .

[0018]

FIG. 1 is a block diagram showing a first embodiment of the present invention;
It is a principle block diagram of the invention of 5 described.

According to the first aspect of the present invention, the level Lt (∝nA ² ) of a WDM signal obtained by wavelength division multiplexing a plurality of n optical signals having the same nominal value A ² and different wavelengths.
And a reference light consisting of a sum of components distributed in the wavelength region near the individual wavelengths of a plurality of optical signals and having a nominal level of B ² and an odd multiple of π radian with each other. By optically combining with a WDM signal at two separated phases, an interference light generating means 12 for generating two interference lights, and a wavelength among two interference light components generated by the interference light generating means 12 The difference Ld (∝nA) between the levels of components distributed near the wavelengths of a plurality of optical signals in the region.
A difference level measuring means 13 for measuring a B), under either are known condition and the nominal value B ² levels of the nominal value A ² with components of the level of the optical signal, the level of the WDM signal L
t and the difference Ld are the values n measured by the level measurement means 11 and the difference level measurement means 13, respectively.
And a calculating means 14 for calculating

FIG. 2 is a block diagram showing the principle of the present invention. According to a second aspect of the present invention, a plurality of n optical signals which have the same nominal value A ² and have different wavelengths, and are wavelength-division multiplexed to form a WDM signal, are individually distributed in the wavelength region, and Nominal value of B ²
Interference light generating means 21 for generating two interference lights by optically combining the reference light composed of the sum of the components with the WDM signal at two phases separated by an odd multiple of π radian from each other; Among the two interference light components generated by the generation unit 21, the levels L1 and L2 of components distributed in the wavelength region near the wavelengths of the plurality of optical signals, and the difference Ld (∝nAB) between these levels L1 and L2. ), And the difference (∝nA ²⁾ between one of the levels L 1 and L ² and its nominal value B ² under the condition that the nominal value B ² of the component level is known. ) And the difference Ld are calculated by the difference level measuring means 22, respectively, and a calculating means 23 for calculating a plurality n is provided.

FIG. 3 is a block diagram showing the principle of the present invention. The invention of claim 3 is the nominal value A ² levels are the same, and wavelength takes in WDM signal light signals of different n, which are wavelength division multiplexed, a variation in the level of the WDM signal An automatic level control means 31 for absorbing and generating a stabilized WDM signal of a constant level Lt (∝nA ² ); and a stabilized WDM signal generated by the automatic level control means 31 The two interferences are obtained by optically synthesizing reference light, which is composed of the sum of components distributed near each wavelength and having a nominal level of B ^2, at two phases that are an odd multiple of π radians from each other. Interference light generating means 32 for generating light
And a difference level measurement for measuring a difference Ld (∝nAB) between levels of components distributed in the wavelength region near the wavelengths of a plurality of optical signals, out of two components of the interference light generated by the interference light generation means 32. Means 33 and a nominal value A of the level of the optical signal.
Under both of which are known condition of ² and nominal value B ² components of level stabilizing WD of the level and the difference Ld of the WDM signal is generated by the automatic level control means 31, respectively
It is characterized by comprising a level Lt of the M signal and a calculating means 34 for calculating a plurality n which is a value measured by the difference level measuring means 33.

According to a fourth aspect of the present invention, in the wavelength number detecting device according to any one of the first to third aspects, the polarization directions of the interference light are uniformly distributed in all directions. It is characterized by. According to a fifth aspect of the present invention, there is provided the wavelength number detecting device according to any one of the first to third aspects, further comprising: a reference light monitoring unit for measuring a level of the reference light; , 22, and 33 are characterized in that they have means for compressing the variation generated in the difference Ld according to the level change measured by the reference light monitoring means 41.

FIG. 4 is a block diagram showing the principle of the invention according to the sixth, eighth and eleventh aspects of the present invention. According to a sixth aspect of the present invention, there is provided a level measuring device for measuring a level Lt (∝nA ² ) of a WDM signal obtained by wavelength division multiplexing a plurality of n optical signals having the same nominal value A ² and different wavelengths. Means 11;
An optical amplifier 51 for amplifying the WDM signal while performing automatic level control, the reference light is distributed in the vicinity of the individual wavelengths of a plurality of optical signals in the wavelength region, and the nominal value of the level is a sum of the component is B ² By optically combining the WDM signal with two phases at odd phases π radians apart from each other,
An interference light generating unit for generating two interference lights, and a level of a component of the two interference lights generated by the interference light generation unit that is distributed in the wavelength region near the wavelengths of the plurality of optical signals. A difference level measuring means 13 for measuring the difference Ld (∝nAB), and a ratio between the level Lt measured by the level measuring means 11 and the difference Ld measured by the difference level measuring means 14 is obtained. Level Lt obtained in a state where the level of the optical signal is common
And a control means 52 for regulating the automatic level control performed by the optical amplifier 51 during a period equal to the ratio between the difference Ld and the difference Ld.

FIG. 5 is a block diagram showing the principle of the invention according to claims 7, 9 and 11-14. The invention according to claim 7, equal nominal value A ² level, and an optical amplifier that performs an optical signal of a plurality n of different wavelengths are parallel amplification of WDM signal formed by wavelength-division multiplexing to automatic level control 61,
Distributed near the individual wavelengths of a plurality of optical signals in the wavelength region,
And a reference light composed of a sum of components having a nominal level of B ² in two phases separated from each other by an odd multiple of π radians.
An interference light generating means 62 for generating two interference lights by optically combining with the DM signal;
2, the levels L1 and L2 of the components distributed in the wavelength region near the wavelengths of the plurality of optical signals, and the difference Ld (∝nA) between these levels L1 and L2.
B), and a nominal value B ² of the component level is given in advance, and the difference (差 nA ² ) between one of the levels L 1 and L ² and the nominal value B ² is obtained. A ratio between the difference Ld and the difference Ld measured by the level measuring means 63 is obtained, and the ratio is equal to the ratio between the level Lt and the difference Ld obtained in advance in a state where the levels of the optical signals of a plurality of wavelengths are common. Further, a control means 64 for regulating the automatic level control performed by the optical amplifier 61 is provided.

According to an eighth aspect of the present invention, in the optical amplifying apparatus according to the sixth aspect, the control means 52 controls the level Lt (∝nA ² ) measured by the level measuring means 11 and the difference level measuring means 13 Ld (に よ っ て nA)
It is characterized in that it is determined whether or not the value of n that satisfies B) is an integer, and the automatic level control performed by the optical amplifier 51 when the result of the determination is false is regulated.

According to a ninth aspect of the present invention, in the optical amplifying apparatus according to the seventh aspect, the control means 64 controls the difference (∝nA ² )
And the difference Ld measured by the difference level measuring means 63
It is characterized by determining whether or not the value of n that satisfies both (∝nAB) is an integer, and restricts the automatic level control performed by the optical amplifier 61 when the result of the determination is false. FIG.
Is a principle block of the invention according to claims 10 to 14.

According to a tenth aspect of the present invention, a WDM signal obtained by wavelength division multiplexing a plurality of n optical signals having the same nominal level A ² and different wavelengths is fetched, and the WDM signal is obtained.
A constant level Lt (∝
nA ² ), an automatic level control unit 31 for generating a stabilized WDM signal, an optical amplifier 71 for amplifying the WDM signal while performing automatic level control, and a wavelength-converted WDM signal generated by the automatic level control unit 31. A reference light consisting of a sum of components distributed near each wavelength of a plurality of optical signals in the region and having a nominal level of B ² is optically combined at two phases separated by an odd number of π radians from each other. The interference light generating means 32 for generating two interference lights
And a difference level measurement for measuring a difference Ld (∝nAB) between levels of components distributed in the wavelength region near the wavelengths of a plurality of optical signals, out of two components of the interference light generated by the interference light generation means 32. Means 33 and a nominal value A of the level of the optical signal.
Under both of which are known condition of ² and nominal value B ² components of level stabilizing WD of the level and the difference Ld of the WDM signal is generated by the automatic level control means 31, respectively
Arithmetic means 34 for calculating the level Lt of the M signal and a plurality n which is the value measured by the difference level measuring means 33
And control means 72 for judging whether or not the plurality n calculated by the arithmetic means 34 is an integer, and regulating the automatic level control performed by the optical amplifier 71 when the result of the judgment is false. Features.

According to an eleventh aspect of the present invention, in the optical amplifying device according to any one of the sixth to tenth aspects, the polarization direction of the interference light is uniformly distributed in all directions. Features. The invention according to claim 12 is the invention according to claim 6.
11. The optical amplifier according to claim 10, wherein the optical amplifiers 51, 61, 71 are configured as optical fiber amplifiers, generated by the optical amplifiers 51, 61, 71, and the optical amplifiers 51, 61, 71. The ASE light emitted from the entrances of 61 and 71 is converted into interference light generating means 12, 62 and 3
2 is provided with an optical demultiplexing means 81 for giving as reference light.

According to a thirteenth aspect of the present invention, in the optical amplifying device according to any one of the sixth to tenth aspects, the optical amplifiers 51, 61, and 71 monitor or control a subsequent optical transmission line. , And multiplexes and outputs a WDM signal with an optical signal that can be regarded as having a common distribution of components in the wavelength region with the reference light, and emits only the optical signal in parallel Means for generating interference light 1
2, 62 and 32 are characterized in that the optical signals emitted by the optical amplifiers 51, 61 and 71 are applied as reference light.

According to a fourteenth aspect of the present invention, in the optical amplifying device according to any one of the sixth to thirteenth aspects, reference light monitoring means 91 for measuring the level of the reference light is provided, and the differential level measurement is performed. The means 13, 63, and 33 are characterized in that they include means for compressing a variation generated in the difference Ld according to the level change measured by the reference light monitoring means 91.

In the wavelength number detecting device according to the first aspect of the present invention, the level measuring means 11 supplies the nominal value A of the level.
The level Lt (∝nA ² ) of a WDM signal obtained by wavelength division multiplexing a plurality of n optical signals having the same ² and different wavelengths is measured. Further, the interference light generation means 12 distributes the reference light, which is distributed in the wavelength region in the vicinity of the individual wavelengths of the plurality of optical signals and has a nominal level of B ² , to each other by π radians. WDM with two phases separated by an odd number of times
By optically combining with the signal, two interference lights are generated. The difference level measuring means 13 measures the difference Ld (∝nAB) of the level of the component distributed near the wavelengths of the plurality of optical signals in the wavelength region among the components of the interference light. Furthermore, the calculating means 14, under either are known condition and the nominal value B ² levels of the nominal value A ² with components of the level of the optical signal described above, the level of the WDM signal L
t and the difference Ld are the values n measured by the level measurement means 11 and the difference level measurement means 13, respectively.
Is calculated.

That is, the above-mentioned level Lt and difference Ld
The number n of the wavelengths is obtained based on the mathematical relationship between the WDM signal and any one of the optical signals wavelength-division multiplexed into the WDM signal is modulated by the monitor signal, or the WDM
Compared with a conventional example in which the presence or absence of a signal component is scanned in a wavelength region, the hardware configuration is simplified and the response is improved.

In the wavelength number detecting apparatus according to the second aspect of the present invention, the interference light generating means 21 outputs the nominal value A of the level.
² are equal and have different wavelengths, and are WDM multiplexed.
With distributed separately in the wavelength region in the vicinity of the optical signals of a plurality n forming the DM signal, the nominal value of the level at odd times apart two phases of the reference light π together radians consisting sum of components a B ² By optically combining with the WDM signal, two interference lights are generated.

The difference level measurement main unit 22 determines the levels L1 and L2 of the components of the interference light components that are distributed in the wavelength region near the wavelengths of the plurality of optical signals, and calculates the levels L1 and L2 of these components. The difference Ld (∝nAB) of L2 is measured.
Furthermore, the calculating means 23, under conditions nominal value B ² levels of the aforementioned components is known, these levels L1,
L2 either the of the difference Ld difference (αnA ²⁾ with its nominal value B ² calculates the plurality n as a value measured by a differential level measuring means 22, respectively.

Such a difference (∝nA ² ) is determined by the aforementioned WD
M signal level, and the level L
The level measuring means for measuring the level of the WDM signal, which is calculated based on a mathematical relationship between one of the ^first and ^second values and the known nominal value, is provided.
The hardware configuration is simplified as compared with the wavelength number detection device described in (1).

In the wavelength number detecting apparatus according to the third aspect of the present invention, the automatic level control means 31 performs wavelength division multiplexing of a plurality of n optical signals having the same nominal level A ² and different wavelengths. The obtained WDM signal is taken in, and the fluctuation of the level of the WDM signal is absorbed to obtain a constant level L.
Generate a stabilized WDM signal of t (∝nA ² ). Further, the interference light generation means 32 distributes the stabilized WDM signal in the wavelength region in the vicinity of the individual wavelengths of the plurality of optical signals described above,
In addition, two interference light beams are generated by optically synthesizing a reference light beam composed of a sum of components having a nominal level of B ² at two phases separated by an odd number of π radians from each other. The difference level measuring means 33 measures a difference Ld (∝nAB) between the levels of the components of the interference light components distributed in the wavelength region near the wavelengths of the plurality of optical signals described above. Furthermore, the calculating means 34, under both are known condition and the nominal value B ² levels of the nominal value A ² with components of the optical signal level, the level and the difference Ld of WDM signals described above, each automatic The level Lt of the stabilized WDM signal generated by the level control means 31 and a plurality n which are the values measured by the difference level measurement means 33 are calculated.

In the calculation of the number n of wavelengths, the level Lt is kept constant as described above, and therefore the difference between the level Lt and the difference Ld is independent of the level of the WDM signal. Since the mathematical relationship represented by a single equation is satisfied, the operation is performed more efficiently than the wavelength number detection device according to the first or second aspect.

According to a fourth aspect of the present invention, in the wavelength number detecting apparatus according to any one of the first to third aspects, the polarization directions of the interference light are all directions. Since the distribution is uniform, a large deviation may occur in the polarization direction of the WDM signal, or the number n of wavelengths can be obtained with high accuracy even when it is difficult to predict the polarization direction.

According to a fifth aspect of the present invention, in the wavelength number detecting apparatus according to any one of the first to third aspects, the reference light monitoring means 41 controls the level of the reference light. Measuring, the difference level measuring means 13, 2
Reference numerals 2 and 33 compress the fluctuation generated in the difference Ld according to the level change thus measured. That is,
Even if the level of the reference light fluctuates, the difference Ld can be obtained with high accuracy, so the number n of wavelengths calculated based on the difference Ld
Can be obtained with high accuracy.

In the optical amplifying apparatus according to the sixth aspect of the present invention, the level measuring means 11 is a WDM device in which a plurality of n optical signals having the same nominal level A ² and different wavelengths are wavelength division multiplexed. The signal level Lt (∝nA ² ) is measured. The optical amplifier 51 amplifies the WDM signal while performing automatic level control. Further, the interference light generating means 12
Distributed in the vicinity of the individual wavelengths of a plurality of optical signals described above in the wavelength region, and the nominal value of the level is in radians π from each other reference light consisting of the sum of the components is a B ² WDM odd times apart two phases By optically combining with the signal, 2
Generate two interference lights. The difference level measuring means 13 calculates a difference Ld (∝) between the levels of the components distributed near the wavelengths of the plurality of optical signals in the wavelength region among the components of the interference light.
nAB) is measured.

Further, the control means 52 obtains the ratio between the level Lt and the difference Ld measured by the level measuring means 11 and the difference level measuring means 14, respectively. During the period in which is equal to the ratio between the level Lt obtained in advance and the difference Ld in a state in which is common, the automatic level control performed by the optical amplifier 51 is regulated.

Under such a mathematical relationship between the level Lt (∝nA ² ) of the WDM signal and the difference Ld (∝nAB) of the WDM signal, the individual wavelength-multiplexed WDM signal is used. Means that the number (the number of wavelengths) n of these optical signals has changed without changing the level of the optical signal. Therefore, at the output of the optical amplifier 51, even if the number n of the wavelengths changes, the level of each optical signal wavelength-division multiplexed to the WDM signal is kept constant.

In the optical amplifying apparatus according to the seventh aspect of the present invention, the optical amplifier 61 is a WDM signal obtained by wavelength division multiplexing a plurality of n optical signals having the same nominal level A ² and different wavelengths. Is performed in parallel with the automatic level control. Further, the interference light generating means 62, a plurality of the above-described in the wavelength region is distributed to the individual in the vicinity of the wavelength of the optical signal, and the level nominal value component reference light of π radians to each other is a sum of a B ² of Two interference lights are generated by optically combining with a WDM signal at two phases separated by an odd number of times. The difference level measuring means 63 calculates the difference Ld (Ld (L2) between the levels L1 and L2 of the components distributed near the wavelengths of the plurality of optical signals in the wavelength region among these interference light components. ∝nAB). further,
Control means 64 is given a nominal value B ² levels of the aforementioned components in advance, the difference between one of the levels L1, L2 described above and its nominal value B ² (αnA ²⁾ a difference level measuring means 6
3, the ratio between the difference Ld and the difference Ld is obtained during a period in which the ratio is equal to the ratio between these levels Lt and the difference Ld obtained in advance with the levels of the optical signals of a plurality of wavelengths being common. The automatic level control performed by the amplifier 61 is regulated.

Such a difference (∝nA ² ) is determined by the above-mentioned WD
M signal level, and the level L
1, L2 either because one and is calculated based on known mathematical relationship between the nominal value B ² of claim level measuring means 11 for measuring the level of the WDM signal is provided 6
The hardware configuration is simplified as compared with the optical amplifier described in (1).

According to an eighth aspect of the present invention, in the optical amplifying apparatus according to the sixth aspect, the control means 52 controls the difference between the level Lt (∝nA ² ) measured by the level measuring means 11 and the difference. It is determined whether or not the value of n that satisfies the difference Ld (ＡnAB) measured by the level measuring means 13 is an integer, and the automatic level control performed by the optical amplifier 51 is performed when the result of the determination is false. regulate.

The error as an integer of n described above generally increases in a state where the level of a part of a plurality of optical signals wavelength-division multiplexed to a WDM signal is changed. Lt (tnA ² ) and the difference Ld (∝nAB) are also defined when n cannot be regarded as a true integer. Therefore, the gain of the optical amplifier 51 is set to a constant value adapted to the level Lt and the difference Ld in the state where the level of a part of the plurality of optical signals wavelength-division multiplexed to the WDM signal changes. Is done.

In the optical amplifying apparatus according to the ninth aspect, in the optical amplifying apparatus according to the seventh aspect, the control means 64 controls the difference (2nA ² ) and the difference measured by the difference level measuring means 63. It is determined whether the value of n that satisfies both Ld (∝nAB) is an integer, and the automatic level control performed by the optical amplifier 61 is restricted when the result of the determination is false. The error as an integer of n described above is generally expressed as WD
Since the level of some of the plurality of optical signals wavelength-division multiplexed to the M signal increases in a changed state, the level increases mathematically, and the level Lt (∝nA ² ) and the difference Ld (∝nAB) are calculated mathematically. Is its n
Is also defined when cannot be considered a true integer.

Therefore, the gain of the optical amplifier 61 is WD
In a state where the level of a part of the plurality of optical signals wavelength-division multiplexed to the M signal changes, the level Lt in that state is changed.
And a difference Ld. In the optical amplifying device according to the tenth aspect, the automatic level control means 31 converts the WDM signal obtained by wavelength division multiplexing a plurality of n optical signals having the same nominal level A ² and different wavelengths. The stabilized WDM of a constant level Lt (∝nA ² )
Generate a signal. The optical amplifier 71 amplifies the above-described WDM signal while performing automatic level control.

Further, the interference light generating means 32 includes a stabilizing WD
In the M signal, reference light composed of the sum of components distributed in the wavelength region near the individual wavelengths of the above-described plurality of optical signals and having a nominal level of B ² is separated from each other by an odd multiple of π radians. By optically combining two phases, two interference lights are generated. The difference level measuring unit 33 calculates a difference Ld (∝n) between the levels of the components of the interference light components that are distributed in the wavelength region in the vicinity of the wavelengths of the plurality of optical signals.
AB) is measured. Further, the calculating means 34 calculates the nominal value A ² of the level of the optical signal and the nominal value B of the level of the component.
² are known, the level of the WDM signal and the difference Ld are measured by the level Lt of the stabilized WDM signal generated by the automatic level control means 31 and the difference level measurement means 33, respectively. A plurality of values n
Is calculated. The control means 72 determines whether or not the plurality n calculated in this way is an integer, and regulates the automatic level control performed by the optical amplifier 71 when the result of the determination is false.

In the calculation of the number n of wavelengths, the level Lt is kept constant as described above, so that the difference between the level Lt and the difference Ld is independent of the level of the WDM signal. Since the mathematical relationship represented by a single equation is satisfied, the operation is performed more efficiently than in the optical amplifying device according to the sixth to ninth aspects. Therefore, the responsiveness is improved as compared with the optical amplifying device according to the sixth to ninth aspects, and the gain of the optical amplifier 71 is a level of a part of a plurality of wavelength division multiplexed optical signals to the WDM signal. Is changed, the level Lt in that state is changed.
And the difference Ld is set to a constant value.

According to an eleventh aspect of the present invention, in the optical amplifying device according to any one of the sixth to tenth aspects, the polarization direction of the interference light is one in all directions. Distributed in a similar manner.

That is, even when there is a possibility that a large deviation occurs in the polarization direction of the WDM signal, or when it is difficult to predict the WDM signal, the automatic level control performed by the optical amplifiers 51, 61, and 71 is performed on the WDM signal. It is regulated with high accuracy while adapting to the combination of the number and the level of the wavelength division multiplexed optical signals. In the optical amplifying device according to the twelfth aspect, in the optical amplifying device according to any one of the sixth to tenth aspects, the optical demultiplexing means 81 is an optical amplifier configured as an optical fiber amplifier. 51, 61, 7
1 and emitted from its entrance
The SE light is provided to the interference light generating means 12, 62, 32 as reference light.

Since such ASE light has components distributed in the wavelength region in the vicinity of individual optical signals wavelength-division multiplexed to WDM signals, it can be applied as reference light. That is, since the optical amplifiers 51, 61, and 71 are also used as the light source of the reference light, the hardware configuration is simplified as compared with a configuration in which such a light source is separately provided.

According to a thirteenth aspect of the present invention, in the optical amplifying apparatus according to any one of the sixth to tenth aspects, the optical amplifiers 51, 61, and 71 are provided.
Forms a transmission line that is used for monitoring or controlling the subsequent optical transmission line, and multiplexes and outputs an optical signal whose distribution of components in the wavelength region can be regarded as common with the reference light to a WDM signal, , And emits only the optical signal in parallel.
The interference light generating means 12, 62, 32 applies such an optical signal as reference light.

That is, since the optical amplifiers 51, 61, and 71 are also used as a light source for the reference light, the hardware configuration is simplified as compared with a configuration in which such a light source is separately provided. According to a fourteenth aspect of the present invention, in the optical amplifying device according to any one of the sixth to thirteenth aspects, the reference light monitoring means 91 measures the level of the reference light and calculates the difference Level measuring means 13, 63,
33 compresses a variation generated in the difference Ld according to the level change measured in this way.

That is, even if the level of the reference light fluctuates, the difference Ld can be obtained with high accuracy.
The automatic level control performed by 71 is regulated with high accuracy based on the difference Ld.

[0057]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 7 is a block diagram of the first embodiment.
FIG. 7 is a diagram showing an embodiment corresponding to the invention described in FIG. In the drawing, components having the same functions and configurations as those shown in FIG. 13 are denoted by the same reference numerals, and description thereof is omitted here. The difference between the present embodiment and the conventional example shown in FIG. 13 is that the optical demultiplexer 132 is disposed in front of the optical amplifier 130 and the control unit 140 instead of the control unit 100 is the other of the optical demultiplexer 132 And the drive input of the pumping light source built in the amplifier 130.

The control unit 100 further comprises: an optical demultiplexer 101 having an input port connected to the other output port of the optical splitter 132;
An optical receiver 102-t having an entrance connected to one exit of the optical demultiplexer 101; an optical coupler 103 having one entrance connected to the other exit of the optical demultiplexer 101; A reference light source 104 whose port is connected to the other input port of the optical coupler 103, and photodetectors 102-i1 and 102-i2 whose input ports are connected to two output ports of the optical coupler 103, respectively.
And the two inputs are these receivers 102-i1, 102-i2
, And two inputs are connected to the output of the subtractor 105 and the output of the photodetector 102-t, respectively, and the outputs are driven by an excitation light source built in the optical amplifier 130A. ALC control unit 1 connected to the input
06.

The correspondence between the present embodiment and the block diagrams shown in FIGS.
Reference numeral 101 and the light receiver 102-t correspond to the level measuring means 11, reference light source 104 and optical coupler 103 correspond to the interference light generating means 12, and light receivers 102-i1 and 102-i2 and the subtracter 105 measure the difference level. A corresponding to means 13
The LC control unit 106 corresponds to the calculation unit 14 and the control unit 52, and the optical amplifier 130A corresponds to the optical amplifier 51.

FIG. 8 is a diagram showing the constructions of the first to fourth embodiments.
The operation of the present embodiment corresponding to the invention described in Item 4 will be described. Hereinafter, the operation of the present embodiment corresponding to the first and sixth aspects of the present invention will be described with reference to FIGS. 7 and 8. FIG. The optical receiver 102-t photoelectrically converts the WDM signal supplied from the optical transmission line 131-1 through the optical demultiplexers 132 and 101, and converts the current Is indicating the power of the WDM signal into an ALC signal.
This is given to the control unit 106.

[0062] Here, the current Is is as described above, different wavelength λ1~λn amplitude A of the electric field is a common, and the propagation velocity v and the time t relative to ^{E1 = Ae j (2 π v} / λ 1) ^{when t = Ae j ω 1t · ·} · En = Ae j optical signal E1~En represented by the formula ^{(2 π v / λ n)} t = Ae j ω nt are wavelength division multiplexed as WDM signal , relative to the conversion efficiency k of the light receiver 102-t, is given by the equation ^{_{I t = knA 2 ··· (1}} ).

The reference light source 104 has the wavelength λ
1~λn has a component of the wavelength λr uniformly distributed in a wavelength range of distribution, and for each field Er of these components is constant amplitude ^{B, Er = Be j (2} π v / λ ^{r) t} = Ae ^j ω ^rt The reference light represented by the equation is constantly emitted.

The optical coupler 103 includes optical demultiplexers 132, 10
By combining the above-described reference light with the WDM signal supplied from the optical transmission line 131-1 via the optical path 1 at two phases different from each other by 180 degrees, two optical signals (hereinafter, referred to as "interference light") are generated. I do. Receiver 102-i1, 102-
i2 converts currents I ₁ and I ₂ indicating individual powers by subtracting the currents I ₁ and I ₂ from each other by photoelectrically converting these interference lights.
Give to.

Note that these currents I ₁ and I ₂ are
If the conversion efficiency of the 02-i1,102-i2 is equal to the conversion efficiency k of the light receiver 102-t _{may, I 1 = k ((E1} + ... + En) + Er) ((E1 * + ... + En *) + Er *) = K (nA ² + B ² + 2AB (cos [(ω ₁ −ω _r ) t] +... + Cos [(ω _n −ω _r ) t]) + 2A ² (cos [(ω ₁ −ω ₂ ) t] + cos [ (ω ₁ -ω ₃ ) t] + ... + cos [(ω ₁ -ω _n ) t] + cos [(ω ₂ -ω ₃ ) t] + ... + cos [(ω _n-1 -ω _n ) t] _{··· (2) I 2 = k} ((E1 + ... + En) -Er) ((E1 * + ... + En *) -Er *) = k (nA 2 + B 2 -2AB (cos [(ω 1 -ω r ) t] + ... + cos [(ω _n -ω _r ) t]) + 2A ² (cos [(ω ₁ -ω ₂ ) t] + cos [(ω ₁ -ω ₃ ) t] +… + cos [(ω _1- ω _n ) t] + cos [(ω ₂ −ω ₃ ) t] +... + cos [(ω _n−1 −ω _n ) t].

The subtractor 105 calculates the difference between the currents I ₁ and I ₂ to obtain I _d = I ₁ −I ₂ = 4 kAB (cos [(ω ₁ −ω _r ) t] +... + Cos [(ω _n -ω _r ) t]) is generated as a difference signal I _d .

[0067] However, the difference signal I _d is the proximity of the actual wavelength region of the light receiver 102-i1,102-i2 is effectively operate the DC component, and as described above, the wavelength λ1~λn
Since the components of the reference light are uniformly distributed in the wavelength region where is distributed, it is given by the following formula: I _d = 4nkAB (3)

For the sake of simplicity, the maximum value n of the number n of wavelengths
As equation I _t = I _d = 1 is satisfied when the expression of n = n _max is satisfied with respect to _max, the advance and the amplitude B obtained as a known value conversion efficiency k are both "1" When normalization is performed (hereinafter, processing for realizing such normalization is simply referred to as “normalization processing”), the currents I _t and I _t shown in the above equations (1) and (3) are obtained.
_d is represented by the formula ^{_{I t = nA 2 / n max}} ··· (4) I d = nA / n max ··· (5).

[0069] Therefore, if the number n of wavelengths "n _max" following either kept integral with the power of the component of the wavelength λ1~λn drops uniformly X (<1) times the upper Equation (4)
The value of the current I _t shown in is the value of X times, and the above equation
(5) the value of the current I _d shown in becomes a X ^1/2 times the value,
If the number n of the wavelength is reduced to X (<1) times the value of the current I _t and the current I _d are both X times the value.

[0070] Furthermore, the relationship between such a current I _t and the current I _d is to the number n of wavelengths is not "1", "n
_The same holds true for any value of “ _max ”. That is, the currents I _t and I _{d represented} by the above equations (4) and (5)
When the number n of the wavelengths multiplexed by the wavelength division multiplexing on the WDM signal changes and the powers of the components of these wavelengths do not change together, one of the plots on the straight line shown by the thin line in FIG. It takes a value corresponding to the number of wavelengths, but when the powers of all the wavelength components increase or decrease uniformly, as shown by the thick line in FIG. Take any value on the curve.

The ALC control unit 106 controls the amplitude B and
And the conversion efficiency k are given in advance, and are expressed by the above equations (1) and (3).
Current I_t, I_dBased on these amplitude B and conversion efficiency k
By performing the "normalization process" described above,
The current I shown in equations (4) and (5) _t, I_dIs calculated. Further
In addition, the ALC control unit 106 calculates
Current I_t, I_dThe combination of “
Any previously plotted for the number of individual wavelengths above
Or not "
Is true, it is wavelength division multiplexed into the WDM signal.
Means that the number of wavelengths changed has changed.
No request is made to 30 to change its gain.
No.

However, if the result of the above determination is false,
In this case, the current I _t Fluctuations are compensated
Request to change the gain in the direction of But
Therefore, the gain of the optical amplifier 130 is
Keeps constant if the number of multiplexed wavelengths increases or decreases
Conversely, all the powers of these wavelength components
If it fluctuates, it will change in a direction to compensate for the fluctuation.
It is.

FIG. 9 shows claims 2, 4, 5, 7, 9, 11
FIG. 15 is a diagram showing an embodiment corresponding to the inventions described in Nos. 14 to 14; In the figure, components having the same functions and configurations as those shown in FIG. 7 are denoted by the same reference numerals, and description thereof is omitted here. The difference between the present embodiment and the embodiment shown in FIG. 7 lies in the configuration of a control unit 110 provided in place of the control unit 100.

The difference between the control unit 110 and the control unit 100 is that one input port of the optical coupler 103 is directly connected to the other output port of the optical splitter 132 and the optical splitter 101 is provided. In addition, a constant (indicated by “B ² ”) indicating the level of the reference light constantly emitted from the reference light source 104 is given to one input, and the output of the light receiver 102-i1 is applied to the other input. The subtractor 111 connected to the input is the photodetector 102-t
In that it is provided in place of

The correspondence between the present embodiment and the block diagrams shown in FIG. 2 and FIG.
The reference light source 104 and the optical coupler 103 correspond to the interference light generating units 21 and 62, the light receivers 102-i1 and 102-i2 and the subtractor 105 correspond to the difference level measuring units 22 and 63, and the ALC control unit 106 calculates The optical amplifier 130A corresponds to the optical amplifier 61, corresponding to the means 23 and the control means 64.

The operation of this embodiment according to the second and seventh aspects of the present invention will be described below with reference to FIGS. Although the optical demultiplexer 101 is not arranged in front of the optical coupler 103, the insertion loss of the optical demultiplexer 101 is generally negligibly small, so that the optical coupler 103, the reference light source 104, and the photodetector 102-i1 are used. , 102-i2 and the subtractor 105 are provided from the optical transmission line 131-1 to the optical demultiplexer 132 in the same manner as in the embodiment according to the first, sixth and eighth aspects.
Depending on the WDM signal applied through obtaining the current I _d shown in previously described equation (3).

Further, the light receiver 102-i 1 is provided in the first embodiment.
As in the embodiment corresponding to the invention described in 6, 8,
To generate a current I _1. Subtractor 111, an amplitude B of the electric field of the reference light E _r (or square value of the amplitude B) is given in advance, the square of the amplitude B from the current I ₁ generated by the light receiver 102-i1 as described above generating a correction current I _c by subtracting a current value corresponding to the value B ^2.

[0078] The value of such a correction current I _c is
Among the components of the current I _{1 represented by} the above-described equation (2), the terms having the coefficients “2AB” and “2A ² ” are distributed in a wavelength range that is significantly separated from the DC component, so that they are actually since not obtained at the output of the photodetector 102-i1, equal from the current I ₁ which does not contain these ingredients KNA ² whose square value B ² described above is formed by subtraction.

[0079] Thus, the value of the correction current I _c corresponds to I _t represented by the above formula (1). As described above, according to the present embodiment, the optical demultiplexer 101 and the photodetector 102-t
Since it is determined with high reliability on the basis of the arithmetic value of I _t is simple based on the configured hardware without included, as compared to the embodiment of the invention according to claim 1, 6, 8 Hardware scale is reduced and responsiveness is enhanced.

Hereinafter, the operation of this embodiment according to the present invention will be described with reference to FIGS. 7 and 9. The feature of this embodiment lies in the following processing procedure performed by the ALC control unit 106. The ALC control unit 106 calculates the number n of wavelengths that satisfies either of the above-described equations (4) and (5) or any of the similar already-described equations (6), and the number of wavelengths n is the nearest number. An error δ with respect to an integer is obtained. Furthermore, AL
The C control unit 106 compares the absolute value of the error δ with a predetermined threshold M, and when the former exceeds the latter, the same as in the embodiment corresponding to the invention according to claims 6 and 7. Thus, the automatic level control performed by the optical amplifier 130A is restricted.

That is, a state in which the level of only a part of the wavelength division multiplexed wavelength-division multiplexed WDM signal has changed is identified as a section indicated by a circle in FIG. 8 or FIG. Then, the optical amplifier 13
The gain of 0A is maintained at the value set previously.
Therefore, according to the present embodiment, the gain of the optical amplifier 130A is set to an appropriate value even when the level of some of the wavelengths multiplexed into the WDM signal fluctuates. The level of each optical signal corresponding to the wavelength is maintained at a substantially constant value.

FIG. 10 is a diagram showing an embodiment corresponding to the third to fifth and tenth to fourteenth aspects of the present invention. In the figure, components having the same functions and configurations as those shown in FIG. 7 are denoted by the same reference numerals, and description thereof is omitted here. The difference between this embodiment and the conventional example shown in FIG. 7 is that a control unit 120 is provided instead of the control unit 100.

The difference between the configurations of the control unit 120 and the control unit 100 is that a level stabilizing unit 121 is provided instead of the optical demultiplexer 101, and the light receiving unit 102-t is not provided. Note that the correspondence between the present embodiment and the block diagrams shown in FIGS. 3 and 6 is such that the optical demultiplexer 132 and the level stabilizing unit 121 correspond to the automatic level control unit 31, and the reference light source 104 and the optical coupler 103. Corresponds to the interference light generating means 32, the light receivers 102-i1, 102-i2 and the subtractor 105 correspond to the difference level measuring means 33,
The C control unit 106 corresponds to the calculation unit 34 and the control unit 72, and the optical amplifier 130A corresponds to the optical amplifier 71.

FIG. 11 is a diagram for explaining the operation of the present embodiment corresponding to the third to fifth and tenth to fourteenth aspects of the present invention. Hereinafter, referring to FIG. 10 and FIG.
The operation of the present embodiment corresponding to the invention described in FIG. The level stabilizing unit 121 supplies the WDM signal to the optical coupler 103 while absorbing a level fluctuation of the WDM signal supplied via the optical demultiplexer 132.

The reference light source 104, the optical coupler 103,
Photoreceiver 102-i1,102-i2 and the subtracter 105, by cooperating in the same manner as the embodiment of the invention according to claim 1, 6, 8, obtains a current I _d. However, as for the current I _d , the level of the WDM signal supplied to the optical coupler 103 is constant as described above, and therefore, between these currents represented by the above-described equations (4) and (5). As shown in FIG. 11, the equation of n = (n _max / I _t ) I _d ² ... (6) obtained by eliminating A from both equations is established.

The ALC control unit 106 calculates the value of n shown in the above equation (6).
values of _max and I _t is given in advance as constants, and by performing a "normalization process" invention similar to the embodiment corresponding to claim 1, 6, 8, shown in the equation (6) The number n of wavelengths is calculated, and it is determined whether or not the number n of wavelengths can be regarded as an integer with a predetermined accuracy. Further, the ALC control unit 106 determines whether the result of the determination is true,
A command is issued to the optical amplifier 130 to cancel the automatic level control.

As described above, according to this embodiment, the level is low.
The current I_t Is kept constant
Therefore, the current I shown in the above-described equations (4) and (5)_t And electricity
Style I _d Mathematical relationship with is summarized in the single equation shown in equation (6) above
The operation to be performed by the ALC control unit 106 is
In the embodiment corresponding to the invention described in the items 1, 6, and 8,
Optical amplifier that is significantly simplified compared to the operations performed
That the automatic level control should be canceled for 130A
Commands are given with equal accuracy.

In this embodiment, the level stabilizing section 1
Although no detailed configuration is shown in FIG. 21, if the level fluctuation is reliably absorbed while the desired accuracy and responsiveness are secured, the level stabilizing unit 121 may be, for example, a variable optical attenuator. And an optical amplifier whose gain can be varied. Hereinafter, FIGS. 7, 9 and 1
This embodiment will be described with reference to FIG.

The feature of this embodiment lies in the following optical characteristics of the reference light source 104. In this embodiment, since the reference light source 104 emits non-polarized reference light, how the polarization plane of the WDM signal provided via the optical transmission line 131-1 changes in the optical transmission line 131-1. Alternatively, even when it is difficult to predict the polarization plane, the amplitude and the distribution of the wavelength region of the interference light obtained by the interference with the reference light can be obtained with high accuracy and stability.

Therefore, according to the present embodiment, a desired performance can be obtained more stably than the embodiments corresponding to the first to third and sixth to tenth aspects of the present invention. Hereinafter, an embodiment corresponding to the invention described in claim 12 will be described with reference to FIGS. 7, 9, and 10. This embodiment and claims 1 to
The difference between the configuration of the present invention and the embodiments corresponding to the inventions described in 4, 6 to 11 is that, as shown by the dotted lines in FIGS. 7, 9 and 10, the extra exit port of the optical demultiplexer 132 is referred to. Light source 1
The point is that it is connected to the corresponding entrance of the optical coupler 103 instead of the optical coupler 104.

The correspondence between the present embodiment and the block diagrams shown in FIGS. 4 to 6 is as described above, except that the optical demultiplexing means 81 corresponds to the optical demultiplexer 132. .
Hereinafter, the operation of this embodiment will be described with reference to FIGS. 7, 9, and 10. The optical amplifier 130A includes an ASE (A) composed of components uniformly distributed over a wavelength range including all wavelengths that can be wavelength-division-multiplexed to a WDM signal to be amplified.
mplified Spontaneous Emission) light is generated internally, and the ASE light is emitted from the entrance.

The optical coupler 103 applies the above-mentioned ASE light as the above-mentioned reference light, and
In the same manner as the embodiments corresponding to the inventions described in 6 to 11, two interference lights are generated, and these interference lights are
-i1, 102-i2. That is, according to the present embodiment, since the reference light is reliably obtained without the provision of the reference light source 104, as long as the deviation of the wavelength range distribution of the component of the ASE light can be tolerated, claims 1 to 4, The hardware configuration is simplified as compared with the embodiments corresponding to the inventions described in 6 to 11.

An embodiment according to the present invention will be described below with reference to FIGS. 7, 9 and 10. The configuration of the present embodiment and the embodiments corresponding to the inventions according to claims 1 to 4 and 6 to 12 is the same as that of the optical amplifier 130A.
Has a monitoring output port for outputting a component of the wavelength λ _s constituting the optical supervisory channel and optical noise accompanying the component, and is indicated by a dotted line in FIGS. 7, 10 and 9. As shown, the monitoring output port is connected to the corresponding input port of the optical coupler 103 instead of the reference light sources 104 and 104A.

The optical amplifier 130A generally has a wavelength λ that individually forms a channel to be applied to transmission of transmission information.
₁ in accordance with the optical signal to [lambda] _n, and emits the optical signal of the wavelength of the wavelength lambda _s to be applied to transmission of information relating to the monitoring control wavelength division multiplexed as WDM signal. The optical amplifier 130A has an optical system (not shown) for forming an optical supervisory channel to be formed by the above-described wavelength λ _s , and the optical system has a wavelength λ s.
_In addition to the optical signal of _s , while generating optical noise distributed in a predetermined wavelength range including the wavelength range in which the wavelengths λ _{1 to} λ _n are distributed, both are emitted to the above-described monitoring emission port. .

Further, the optical coupler 103 generates two interference lights by applying the optical noise emitted in this way as reference light, and uses these interference lights as the light receivers 102-i 1, 102-2. Give to i2. That is, according to the present embodiment, since the reference light is reliably obtained without the provision of the above-described reference light source 104, the first embodiment is provided as long as the deviation of the wavelength range distribution of the ASE light component is allowed. ~ 4,
The hardware configuration is simplified as compared with the embodiments corresponding to the inventions described in 6 to 12.

Hereinafter, embodiments corresponding to the inventions of claims 5 and 14 will be described with reference to FIGS. 7, 9 and 10. FIG. For differences between the present embodiment and the embodiments corresponding to the first to fourth and sixth to eleventh aspects of the present invention, as shown in FIG. 7, FIG. 9 and FIG. A light source 104A is provided, and the reference light source 10A is provided.
4 has a monitor output connected to a corresponding input of the ALC controllers 106, 106.

The reference light source 104A is described in claims 1-4, 6-
In the same manner as in the embodiment corresponding to the invention described in Item 11, the reference light is constantly supplied to the optical coupler 103, and the wavelengths near the wavelengths λ _{1 to} λ _n of the components of the reference light are concurrently provided. The level of the component in the region is measured, and the result is provided to the ALC control units 106 and 106. ALC control unit 106, 1
No. 06 regulates the automatic level control performed by the optical amplifier 130A in the same manner as the embodiment according to the first to fourth and sixth to eleventh aspects of the present invention. Instead of the nominal value of the reference light level (the electric field amplitude B), the level actually measured by the reference light source 104A as described above is applied.

[0098] Thus, according to this embodiment, since the error due to the variation in the level of the reference light source provided to the optical coupler 103 generated current I _d it is compressed, claim 1
As compared with the embodiments corresponding to the inventions described in 4, 6 to 11, the calculation of the number of wavelengths multiplexed to the WDM signal and the determination that one of these wavelengths has disappeared are performed with higher accuracy. Will be

In each of the above embodiments, the reference light,
An ASE light or the like applied in place of the reference light is given as a sum of components distributed flat in the wavelength region. If a component located in the vicinity is included, the demultiplexing in the wavelength region may be comb-shaped. Further, in each of the above-described embodiments, unknown numbers such as the number n of wavelengths having the mathematical relationship shown in the above-described equations are obtained based on arithmetic operations. If desired accuracy and responsiveness can be obtained in the range of power consumption or power consumption, for example, a process of looking up a table in which desired unknowns are registered in advance may be performed instead of the arithmetic operation.

Furthermore, in each of the above-described embodiments, the optical amplifier 130A independently performs automatic level control. For example, the ALC control unit 106 obtains the level of the WDM signal, and based on the level, the optical amplifier 130A The automatic level control may be performed by changing the gain of.

[0101]

As described above, according to the first aspect of the present invention, the hardware configuration is simplified as compared with the conventional example.
In addition, responsiveness is improved.

Further, according to the second aspect of the invention, the hardware configuration is simplified as compared with the first aspect of the invention. Further, according to the third aspect of the invention, the number of wavelengths is calculated more efficiently than the first and second aspects.
According to the fourth aspect of the present invention, a large deviation may occur in the polarization direction of the WDM signal, or the number of wavelengths can be obtained with high accuracy even when it is difficult to predict the polarization direction. Can be

Further, according to the fifth aspect of the present invention, even if the level of the reference light fluctuates, the number of wavelengths can be obtained with high accuracy.
In the invention according to claim 6, the level of each optical signal wavelength-division multiplexed to the WDM signal is kept constant even if the number of wavelengths multiplexed to the WDM signal changes. It is.

Further, according to the invention described in claim 7, the hardware configuration is simplified as compared with the invention described in claim 6. In the inventions according to claims 8 and 9, the gain of the optical amplifier is set to a constant value when the level of a part of a plurality of optical signals wavelength-division multiplexed to the WDM signal changes.

Further, in the invention according to the tenth aspect, the responsiveness is improved as compared with the inventions according to the sixth to ninth aspects, and the gain of the optical amplifier is wavelength division multiplexed to the WDM signal. The value is set to a constant value when the levels of some of the plurality of optical signals change. According to the eleventh aspect of the present invention, even when there is a possibility that a large deviation occurs in the polarization direction of the WDM signal, or when it is difficult to predict the WDM signal, the automatic level control performed by the optical amplifier is performed by the WDM
It is regulated with high accuracy while adapting to the combination of the number and level of optical signals wavelength-division multiplexed to the signal.

Furthermore, in the inventions according to the twelfth and thirteenth aspects, the hardware configuration is simplified as compared with the configuration in which a reference light source is separately provided. Further, in the invention according to claim 14, even if the level of the reference light fluctuates, the automatic level control performed by the optical amplifier is regulated with high accuracy. Therefore,
In the optical transmission system to which these inventions are applied, desired performance and reliability are ensured while flexibly adapting to the characteristics of the optical transmission line and the events occurring in the optical transmission line, and the running cost is reduced. .

[Brief description of the drawings]

FIG. 1 is a principle block diagram of the invention according to claims 1, 4 and 5;

FIG. 2 is a principle block diagram of the invention according to claims 2, 4 and 5;

FIG. 3 is a principle block diagram of the invention according to claims 3 to 5;

FIG. 4 is a principle block diagram of the invention according to claims 6, 8, 11 to 14;

FIG. 5 is a principle block diagram of the invention according to claims 7, 9, 11 to 14;

FIG. 6 is a principle block diagram of the invention according to claims 10 to 14;

FIG. 7 is a diagram showing an embodiment corresponding to the invention described in claims 1, 4 to 6, 8, 11 to 14;

FIG. 8 is a diagram for explaining the operation of the present embodiment corresponding to the invention described in claims 1, 4 to 6, 8, 11 to 14;

FIG. 9 is a diagram showing an embodiment corresponding to the invention described in claims 2, 4, 5, 7, 9, 11 to 14;

FIG. 10 is a diagram showing an embodiment corresponding to the invention described in claims 3 to 5 and 10 to 14;

FIG. 11 is a diagram for explaining the operation of the present embodiment corresponding to the inventions of claims 3 to 5 and 10 to 14;

FIG. 12 is a diagram illustrating a first configuration example of an optical amplifier adapted to a wavelength division multiplexing method.

FIG. 13 is a diagram illustrating a second configuration example of the optical amplifying device adapted to the wavelength division multiplexing method.

[Explanation of symbols]

 11 level measuring means 12, 21, 32, 62 interference light generating means 13, 22, 33, 63 difference level measuring means 14, 23, 34 calculating means 31 automatic level control means 41, 91 reference light monitoring means 51, 61, 71 Optical amplifier 52, 64, 72 Control means 81 Optical demultiplexing means 100, 110, 120, 133, 140 Control unit 101, 132 Optical demultiplexer 102 Optical receiver 103 Optical coupler 104, 104A Reference light source 105, 111 Subtractor 106 ALC Control unit 121 Level stabilizing unit 130, 130A Optical amplifier 131 Optical transmission line 134, 142 Optical-to-electrical converter (O / E) 135 Bandpass filter 136, 144 Drive unit 141 AO filter 143 Wavelength counter 145 Sweep control unit

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI // H01S 3/096 3/10

Claims (14)

[Claims] 1. A level nominal value A ² is equal to, and W an optical signal of a plurality n of different wavelengths, which are wavelength division multiplexed
A level measuring means for measuring the level Lt (∝nA ² ) of the DM signal; and a level distribution means for distributing in the wavelength region near each wavelength of the plurality of optical signals and having a nominal level of B ² from the sum of components. By optically synthesizing the reference light with the WDM signal at two phases separated by an odd number of π radians from each other,
Interference light generating means for generating two interference lights, and among the two interference light components generated by the interference light generating means, a level of a component distributed in the wavelength region in the vicinity of the wavelengths of the plurality of optical signals. A difference level measuring means for measuring a difference Ld (∝nAB), and under the condition that one of the nominal value A ² of the level of the optical signal and the nominal value B ² of the level of the component is known, A wavelength detecting device comprising: a calculating means for calculating a plurality n which is a value obtained by measuring the level Lt of the WDM signal and the difference Ld by the level measuring means and the difference level measuring means, respectively. . 2. A plurality of n which are equal in nominal value A ² and have different wavelengths, and are wavelength division multiplexed to form a WDM signal.
The WD in the in the vicinity of the optical signal with distributed separately in a wavelength region, the level of the nominal value is an odd number times spaced two phases of π radian one another reference light is a sum of the component is B ²
Interference light generating means for generating two interference lights by optically combining with the M signal; and among the two interference light components generated by the interference light generation means, the plurality of lights in the wavelength region a level L1, L2 of the components distributed in the vicinity of the wavelength of the signal, and the differential level measuring means for measuring the these levels L1, L2 of the difference Ld (αnAB), the nominal value B ² levels of the components known Under the condition that one of the levels L1 and L2 and its nominal value B ²
And a calculating means for calculating a plurality of n, each of which is a difference between the difference (レ ベ ル nA ² ) and the difference Ld measured by the difference level measuring means. 3. A WDM signal obtained by wavelength division multiplexing a plurality of n optical signals having the same nominal value A ² and having different wavelengths, and taking in a fluctuation in the level of the WDM signal to be constant. WDM of level Lt (∝nA ² )
Automatic level control means for generating a signal, and a stabilized WD generated by the automatic level control means
In the M signal, ^two reference light beams which are distributed in the wavelength region in the vicinity of the individual wavelengths of the plurality of optical signals and have a nominal value of the level B2 and are composed of a sum of components and are separated from each other by an odd multiple of π radians. Interference light generating means for generating two interference lights by optically combining in phase, and the plurality of optical signals in the wavelength region among the components of the two interference lights generated by the interference light generation means Difference level measuring means for measuring the difference Ld (∝nAB) between the levels of components distributed in the vicinity of the wavelength of the optical signal, and both the nominal value A ² of the level of the optical signal and the nominal value B ² of the level of the component Under known conditions, the WD
The level of the M signal and the difference Ld are respectively the level Lt of the stabilized WDM signal generated by the automatic level control means, and the calculating means for calculating a plurality n which is the value measured by the difference level measuring means. A wavelength number detection device, comprising: 4. The wavelength number detecting apparatus according to claim 1, wherein the polarization directions of the interference light are uniformly distributed in all directions. apparatus. 5. The wavelength number detection device according to claim 1, further comprising: a reference light monitoring unit that measures a level of the reference light, wherein the difference level measurement unit includes the reference light monitoring unit. An apparatus for detecting the number of wavelengths, comprising means for compressing a variation generated in a difference Ld according to a change in a level measured by the means. 6. A W obtained by wavelength division multiplexing a plurality of n optical signals having the same nominal level A ² and different wavelengths.
Level measuring means for measuring the level Lt (∝nA ² ) of the DM signal; an optical amplifier for amplifying the WDM signal while performing automatic level control; and a distribution in the wavelength region near each wavelength of the plurality of optical signals. by then, and the nominal value of the level synthesizes the WDM signal and the optically odd times apart two phases in radians π from each other reference light consisting of the sum of the components is a B ^2, 2
Interference light generating means for generating two interference lights, and among the two interference light components generated by the interference light generating means, a level of a component distributed in the wavelength region in the vicinity of the wavelengths of the plurality of optical signals. A difference level measuring means for measuring a difference Ld (∝nAB); a ratio between a level Lt measured by the level measuring means and a difference Ld measured by the difference level measuring means is determined; And control means for regulating the automatic level control performed by the optical amplifier during a period in which the level of the optical signal is common and equal to the ratio between the level Lt and the difference Ld obtained in advance. Optical amplifier. 7. A W obtained by wavelength division multiplexing a plurality of n optical signals having the same nominal level A ² and different wavelengths.
An optical amplifier for performing parallel amplification of DM signal to automatic level control, and distributed in the vicinity of each wavelength of said plurality of optical signals in the wavelength region, and the nominal value of the level is a sum of the component is B ² By optically combining the reference light with the WDM signal at two phases separated by an odd multiple of π radians from each other, 2
Interference light generation means for generating two interference lights; and a level L1 of a component of the two interference light components generated by the interference light generation means, which is distributed in the wavelength region in the vicinity of the wavelengths of the plurality of optical signals. , and L2, and a difference level measuring means for measuring the these levels L1, L2 of the difference Ld (αnAB), the nominal value B ² levels of the components given in advance, either one of the levels L1, L2 And its difference from the nominal value B ² (∝
nA ² ) and the difference Ld measured by the difference level measuring means are determined, and the ratio is determined in advance with these levels Lt and difference Ld obtained in a state where the levels of the optical signals of the plurality of wavelengths are common. Control means for regulating automatic level control performed by the optical amplifier during a period equal to the ratio of the optical amplifier. 8. The optical amplifying device according to claim 6, wherein the control means controls the level Lt (∝nA ² ) measured by the level measurement means.
And the difference Ld (∝
nAB), and determines whether or not the value of n is an integer, and regulates the automatic level control performed by the optical amplifier when the result of the determination is false. 9. The optical amplifying device according to claim 7, wherein the control means determines that the value of n that satisfies both the difference (∝nA ² ) and the difference Ld (∝nAB) measured by the difference level measuring means is satisfied. An optical amplifying device which determines whether or not the value is an integer and regulates automatic level control performed by the optical amplifier when the result of the determination is false. 10. A WDM signal obtained by wavelength division multiplexing a plurality of n optical signals having the same nominal value A ² and having different wavelengths, and absorbing a fluctuation in the level of the WDM signal to maintain a constant level. Automatic level control means for generating a stabilized WDM signal of Lt (∝nA ² ), an optical amplifier for amplifying the WDM signal while performing automatic level control, and a stabilized WD generated by the automatic level control means
In the M signal, ^two reference light beams which are distributed in the wavelength region in the vicinity of the individual wavelengths of the plurality of optical signals and have a nominal value of the level B2 and are composed of a sum of components and are separated from each other by an odd multiple of π radians. Interference light generating means for generating two interference lights by optically combining in phase, and the plurality of optical signals in the wavelength region among the components of the two interference lights generated by the interference light generation means Difference level measuring means for measuring the difference Ld (∝nAB) between the levels of components distributed in the vicinity of the wavelength of the optical signal, and both the nominal value A ² of the level of the optical signal and the nominal value B ² of the level of the component Under known conditions, the WD
Calculating means for calculating the level Lt of the stabilized WDM signal in which the level of the M signal and the difference Ld are respectively generated by the automatic level control means, and a plurality n which are the values measured by the difference level measuring means; Control means for determining whether or not the plurality n calculated by the calculation means is an integer, and regulating automatic level control performed by the optical amplifier when a result of the determination is false. Optical amplifier. 11. The method according to claim 6, wherein
13. The optical amplifying device according to claim 1, wherein the polarization directions of the interference light are uniformly distributed in all directions. 12. The method according to claim 6, wherein
The optical amplifier is configured as an optical fiber amplifier, and supplies the ASE light generated by the optical amplifier and emitted from the entrance of the optical amplifier to the interference light generating means as reference light. An optical amplifier comprising an optical demultiplexer. 13. The method according to claim 6, wherein
In the optical amplifying apparatus described in the paragraph, the optical amplifier forms a transmission line used for monitoring or controlling the subsequent optical transmission line, and the optical signal whose component distribution in the wavelength region can be regarded as common with the reference light. And a means for multiplexing and outputting the WDM signal and outputting only the optical signal in parallel, wherein the interference light generating means applies the optical signal emitted by the optical amplifier as the reference light. An optical amplifying device characterized by the above-mentioned. 14. The semiconductor device according to claim 6, wherein:
The optical amplifying device according to claim 1, further comprising: reference light monitoring means for measuring a level of the reference light, wherein the difference level measuring means is configured to calculate a difference in the difference Ld according to a change in the level measured by the reference light monitoring means. 1. An optical amplifying device comprising means for compressing light.