JPH1188267A - Optical transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmitter that easily compensates an optical output of an optical transmission circuit for each wavelength with a very smaller scale than that of a conventional transmitter by using a wavelength variable optical band pass filter means so as to detect a wavelength component and a fluctuation component of an optical signal outputted from an optical fiber amplifier in the optical wavelength division transmission system. SOLUTION: Pluralities of transmission electric signals 1011 , 1012 ,...101n are converted respectively into optical signals with different center wavelengths at optical transmission circuits 1021 ,1022 ,...102n and an optical multiplexer 104 is used to apply wavelength multiplex processing to the optical signals to obtain an optical output signal. An optical branching device 105 branches part of the optical output signal and a sweep means 108 sweeps the branched signal within a prescribed wavelength band including the center wavelength of the optical signal to use a wavelength variable optical band pass filter means 107 to extract an original wavelength component of the optical signal from the branched optical output signal. A peak level detection means 109 detects a level of each extracted wavelength component signal and the optical signal sent from an optical transmission circuit is individually controlled depending on the detected level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission apparatus in wavelength division multiplexing transmission for transmitting optical main signals of a plurality of different wavelengths, and in particular, monitors an output optical transmission signal for each wavelength to thereby monitor the monitored wavelength. The present invention relates to an optical transmission device in wavelength division multiplexing transmission for controlling an output signal level corresponding to (1).

[0002]

2. Description of the Related Art With the diversification of uses of optical communication systems, increasing the amount of communication transmission has become an important issue. Optical communication devices aimed at increasing the amount of communication transmission include, in addition to increasing the capacity of the transmission path itself, an optical communication device using a time-division multiplexing transmission system and a wavelength-division multiplexing device using the unique characteristics of light. There is an optical communication device using a transmission method.

The optical communication apparatus using the wavelength division multiplexing transmission system multiplexes optical signals having different center wavelength components on an optical transmitting side provided with an optical multiplexer and outputs the multiplexed optical signals to an optical fiber transmission line. On the optical receiving side including the optical demultiplexer, the received optical signal is again divided into optical signals having different center wavelength components. By performing multiplexing by wavelength in this way,
Increase transmission capacity.

FIG. 11 shows a configuration of such a conventional wavelength division multiplexing optical transmission / reception apparatus. Sender of the optical transceiver includes an optical transmitter circuit _1102, 1102
2 _2, ..., 1102 _n and, the optical light signal outputted from the transmitting circuit 1103 _1, 1103 _2, ..., and an optical multiplexer 1104 which receives 1103 _n. The receiving side of the optical transmitting / receiving apparatus is connected to the transmitting side via an optical fiber transmission line 1106, and includes an optical demultiplexer 1107 and optical signals 1108 ₁ , 1 demultiplexed by the optical demultiplexer 1107.
108 _2, ..., the light receiving circuit 11 which receives the 1108 _n
09 _1, 1109 _2, ..., and a 1109 _n.

Each of the transmitted electric signals 11011 ₁ , 11012 ₂ ,
, 1101 _n are optical transmitting circuits 1102 ₁ , 110 ₁ each composed of, for example, a semiconductor laser for converting an electric signal to an optical signal and an electric circuit for driving the light source.
2 _2, ..., 1102 _n are input to a different center wavelengths lambda ₁ to each other, lambda _2, ..., an optical signal 1103 having a lambda _{n 1,} 11
03 ₂ , ..., 1103 _n . This optical signal 1103 _1, 1103 _2, ..., 1103
_n is multiplexed in the optical multiplexer 1104 and output to the optical fiber transmission line 1106.

[0006] multiplexed light signal transmitted through the optical fiber electrical path 1106, different lambda ₁ again based on the optical demultiplexer 1107, lambda _2, the optical signal 1108 ₁ having a central wavelength of ... lambda _n, 1108 _2, ..., and is demultiplexed to 1108 _n. The demultiplexed optical signals are supplied to optical receiving circuits 1109 ₁ , 1109 ₂ ,.
At 1109 _n , it is converted into an electric signal and received.

FIG. 12 specifically shows the configuration of the optical transmitter of the conventional wavelength division multiplexing optical transmitter / receiver shown in FIG. In this optical transmission device, each transmission electric signal 1
Each of 101 ₁ , 1101 ₂ ,..., 1101 _n is an electric-optical conversion circuit 1202 ₁ , 1202 ₂ ,..., 1202 each composed of, for example, a semiconductor laser for converting an electric signal into an optical signal and an electric circuit for driving the light source. _Entered in _n . Optical signals 1103 having different center wavelengths λ ₁ , λ ₂ ,..., Λ _n converted by these electro-optical conversion circuits.
_{1, 1103 2, ..., 1103} n is an optical multiplexer 1104
The optical signal components of each wavelength are multiplexed. The multiplexed light is amplified by the optical fiber amplifier 1205 and then output from the optical transmission output terminal 1206 as an optical wavelength multiplexed signal light.

However, in such a configuration, Japanese Unexamined Patent Application Publication No.
As pointed out in "Optical transmitter for wavelength division multiplexing transmission" of No. 54367, there is a problem that the output of the optical multiplexer changes depending on the number of wavelengths due to the characteristics of the amplifier.

FIG. 13 shows a conventional optical transmitter for wavelength division multiplexing transmission intended to solve such a problem. However, this optical transmission device shows an example in wavelength division transmission of four wavelengths. This optical transmitter is similar to the optical transmitter shown in FIG.
21 ₁ , 1302 ₂ , 1302 ₃ , 1302 ₄ , an optical multiplexer 1104, an optical fiber amplifier 1305, and an optical transmission output terminal 1307. Further, an optical splitter 1306 is inserted between the optical fiber amplifier 1305 and the optical transmission output terminal 1307, and the optical transmission output terminal 1307 is provided.
Is branched from the optical signal output to the light source 1308.

[0010] The split light 1308 is input to an optical splitter 1309 and is converted into an optical-electrical conversion circuit 13 for each split wavelength component.
11 _1, the 1311 _2, 1311 _3, 1311 ₄ is converted into an electric signal, the output signals from the light-electricity conversion circuit are inputted to the comparator control circuit 1313. The comparison control circuit 1313 outputs control signals 1314 ₁ , 1314 ₂ , 1314 ₃ , 1314 for each wavelength component.
14 ₄ are output, respectively electro-optical conversion circuit 1302
₁ , 1302 ₂ , 1302 ₃ , 1302 ₄ .

[0011] In such an optical transmission apparatus, the transmission electric signal 1301 _1, 1301 _2, 1301 _3, 1301
₄ is an electric / optical conversion circuit 1302 ₁ , 1302 ₂ , 13
02 ₃ , 1302 ₄ . Electrical / optical conversion circuits 1302 ₁ , 1302 ₂ , 1302 ₃ ,
1302 _4, a semiconductor laser for converting each example the electrical signal into an optical signal and drives its light source, the comparison control circuit 1
1314 ₁ , 1314 ₂ , 131 output from 313
4 _3, 1314 ₄ are composed of an electrical circuit controlled the intensity of the light source, the different central wave lambda ₁ together,
Optical signals 1303 ₁ , 130 _{3 having} λ ₂ , λ ₃ , λ ₄
3 _2, 1303 _3, and is converted to 1303 _4. Optical signals 1303 ₁ , 1303 ₂ , 1303 ₃ ,
1303 ₄ via the optical multiplexer 1104 are summarized in the optical wavelength-multiplexed signal light by multiplexing the optical signals of each wavelength, the combined optical signal is amplified by the optical fiber amplifier 1305.

The amplified optical signal is split by an optical splitter 1306 into an optical transmission signal output from an optical transmission output terminal 1307 and an optical signal 1308 which is a part of the optical transmission signal. The optical signal 1308 is split into an optical splitter 1309. Is input to The split optical signal 1308 is again split into optical signals of the original wavelengths λ ₁ , λ ₂ , λ ₃ , and λ _{4 in} the optical demultiplexer 1309, and the optical-electrical conversion circuit 1311 ₁ , 131
1 _2, 1311 _3, 1311 ₄ in the electric signal 131
21 ₁ , 1312 ₂ , 1312 ₃ , 1312 ₄ .

The comparison control circuit 1313 converts the converted electric signals 1312 ₁ , 1312 ₂ , 131 for each wavelength.
2 _3, 1312 based on the _4, so that the intensity of each wavelength of the optical signal after the optical amplification is equal, the control signal 1314 _first intensity before amplification of the optical signal of each wavelength, 1314 _2, 131
4 ₃ , 1314 ₄ are set, and the electrical / optical conversion circuit 1302 is set.
₁ , 1302 ₂ , 1302 ₃ , 1302 ₄ . Electrical-optical conversion circuit 1302 ₁ ,
1302 _2, 1302 _3, the 1302 _4, the optical signal 1303 ₁ to be sent by the control signal 1314 _1, 1314 _2, 1314 _3, 1314 _4, 1303 _2, 1303
_3, the strength of the 1303 ₄ adjusted.

Such adjustment can be performed by changing the injection current of a semiconductor laser diode, for example, if the light source used in the electric / optical conversion circuit constituting the optical transmission circuit is a semiconductor laser diode. Further, in order to determine whether the target optical signal intensity is obtained by the set injection current, it can be performed by receiving and monitoring the backward output light from the semiconductor laser with a monitor light receiver or the like. .

[0015]

However, in such a conventional optical transmission apparatus in wavelength division multiplex transmission,
When multiplexing a plurality of optical signals having different center wavelengths,
There is a problem that the output of the optical signal of each wavelength component fluctuates due to factors such as optical output variation of the optical transmission circuit, gain frequency variation of the optical fiber amplifier, and characteristic deterioration of the optical multiplexer itself. In addition, as shown in FIG. 13, such an optical transmitter has a very large circuit configuration, and the optical demultiplexer 1309 avoids increasing the optical loss as the number of wavelengths to be demultiplexed increases. Can not.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical transmission device which can easily compensate for the optical output of an optical transmission circuit of each wavelength on a very small scale as compared with the prior art.

[0017]

According to the first aspect of the present invention, (a) an optical transmitting means for converting an electric signal to be transmitted into a plurality of optical signals having different center wavelengths and transmitting the same;
An optical multiplexing means for transmitting a multiplexed light obtained by multiplexing these optical signals; (c) a first optical branching means for branching a part of the multiplexed light and extracting a branched light; and (d) an optical transmitting means. A sweeping means for sweeping within a range including the center wavelength of the plurality of transmitted optical signals; and (e) specifying the split light extracted from the first optical splitting means based on the wavelength swept by the sweeping means. (F) a peak value for detecting the intensity peak value of each wavelength component of the output light extracted from the variable wavelength optical pass band filter means; The optical transmission device includes: a detection unit; and (g) an optical transmission control unit that changes the light transmission intensity of the optical transmission unit for each wavelength component to be transmitted based on the peak value detected by the peak value detection unit. Let it.

That is, in the first aspect of the present invention, the wavelength tunable optical pass band filter is used.
By sweeping a predetermined band including the center wavelength of the optical output signal to be extracted by the sweep circuit, a desired wavelength component can be extracted at a constant timing. Therefore, by detecting the peak value of the wavelength component,
Even if the optical output of each wavelength is caused by factors such as the optical output variation of the individual optical transmission circuits and the deterioration of the characteristics of the optical multiplexer,
The intensity of the optical output signal can be easily controlled for each wavelength component with a small-scale circuit configuration.

According to the second aspect of the present invention, (a) optical transmission means for converting an electric signal to be transmitted into a plurality of optical signals having different center wavelengths and transmitting the same, and (b) combining these optical signals. Optical multiplexing means for transmitting multiplexed light, (c) first optical branching means for branching a part of the multiplexed light and extracting branch light, and (d) optical transmission means for transmitting the multiplexed light. (E) extracting an optical signal of a specific wavelength component of the split light extracted from the first optical splitter based on the wavelength swept by the sweeper, within a range including the center wavelength. (F) peak value detection means for detecting the intensity peak value of each wavelength component of the output light extracted from the wavelength variable light pass band filter means; Control for adjusting the intensity of the optical transmission means First storage means for storing a broadcast,
(H) changing the intensity of the output signal of the optical transmitter corresponding to each wavelength for each wavelength component to be transmitted, based on the control information stored in the storage and the intensity peak value detected by the peak value detector; And an optical transmission control means.

That is, in the second aspect of the present invention, the wavelength tunable optical pass band filter is used.
By sweeping a predetermined band including the center wavelength of the optical output signal to be extracted by the sweep circuit, a desired wavelength component can be extracted at a constant timing. Therefore, by detecting the peak value of the wavelength component, even when the optical output of each wavelength is changed due to factors such as the optical output variation of each optical transmission circuit and the deterioration of the characteristics of the optical multiplexer, it is very small. With a large-scale circuit configuration, it is possible to easily control the intensity of the optical output signal for each wavelength component. Further, since a value can be set in the storage means in advance, the compensation range of the optical output can be made variable when comparing the set value with the level of each wavelength component, so that a flexible optical transmitter can be provided. Become.

According to the third aspect of the present invention, (a) optical transmitting means for converting an electric signal to be transmitted into a plurality of optical signals having different center wavelengths and transmitting the same, and (b) multiplexing these optical signals. Optical multiplexing means for transmitting multiplexed light, (c) optical direct amplifying means for directly amplifying light over the entire wavelength band of the optical wavelength of the output light of the optical multiplexing means, and (d) optical direct amplifying optical signal. First optical splitting means for splitting a part to take out split light, (e) sweeping means for sweeping within a range including the center wavelength of the plurality of optical signals transmitted by the optical transmitting means,
(F) a wavelength-variable optical passband filter for extracting an optical signal of a specific wavelength component of the split light extracted from the first optical splitter based on the wavelength swept by the sweeper; A) peak value detecting means for detecting the intensity peak value of each wavelength component of the output light extracted from the tunable optical pass band filter means, and (h) a peak value detected from the peak value detecting means. The optical transmission device is provided with an optical transmission control unit that changes the optical transmission intensity of the optical transmission unit for each wavelength component to be transmitted.

That is, according to the third aspect of the present invention, the wavelength tunable optical pass band filter is used.
By sweeping a predetermined band including the center wavelength of the optical output signal to be extracted by the sweep circuit, a desired wavelength component can be extracted at a constant timing. Thus, when the optical output signal is amplified by the optical direct amplifier for the purpose of improving the S / N ratio, the peak value of the wavelength component is detected, and the optical output fluctuation and optical multiplexing of each optical transmission circuit are detected. The control of the intensity of the optical output signal of only the wavelength component corresponding to the optical output variation of each wavelength due to factors such as deterioration of the characteristics of the optical amplifier and the gain variation depending on the frequency of the optical direct amplification means is achieved with a very small circuit configuration. It can be done easily. As described above, since the optical transmission signal is controlled in units of wavelength, the optical loss of the optical multiplexer or the optical branching device connected to the optical transmission output terminal can be compensated for by the optical direct amplification means. .

According to the fourth aspect of the present invention, (a) optical transmitting means for converting an electric signal to be transmitted into a plurality of optical signals having different center wavelengths and transmitting the same, and (b) multiplexing these optical signals. Optical multiplexing means for transmitting multiplexed light, (c) optical direct amplifying means for directly amplifying light over the entire wavelength band of the optical wavelength of the output light of the optical multiplexing means, and (d) optical direct amplifying optical signal. First optical splitting means for splitting a part to take out split light, (e) sweeping means for sweeping within a range including the center wavelength of the plurality of optical signals transmitted by the optical transmitting means,
(F) a wavelength-variable optical passband filter for extracting an optical signal of a specific wavelength component of the split light extracted from the first optical splitter based on the wavelength swept by the sweeper; ) Peak value detection means for detecting the intensity peak value of each wavelength component of the output light extracted from the wavelength variable type optical pass band filter means, and (h) control information for adjusting the intensity of the light transmission means. First storage means for storing; and (iii) an output signal of the optical transmission means corresponding to each wavelength based on the control information stored in the storage means and the intensity peak value detected by the peak value detection means. An optical transmission control means for changing the intensity for each wavelength component to be transmitted; (v) an output of the optical direct amplification means based on the control information stored in the storage means and the peak value detected from the peak value detection means. It is provided an optical direct amplifier control means for stopping the optical transmission apparatus in wavelength multiplexing transmission.

That is, in the invention according to the fourth aspect, the wavelength tunable optical pass band filter is used.
By sweeping a predetermined band including the center wavelength of the optical output signal to be extracted by the sweep circuit, a desired wavelength component can be extracted at a constant timing. Therefore, when an optical output signal is amplified by an optical direct amplifier for the purpose of improving the S / N ratio, the peak value of the wavelength component is detected, so that the optical output fluctuation or optical multiplexing of each optical transmission circuit is detected. It is possible to easily control the intensity of the optical output signal of only the wavelength corresponding to the optical output variation of each wavelength due to factors such as deterioration of the characteristics of the optical device and gain variation depending on the frequency of the optical direct amplification means. Thus, the optical loss of the optical multiplexer or the optical branching device connected to the optical transmission output terminal can be compensated by the optical direct amplification means. Further, since the optical direct amplification control means is provided, when the optical output from the optical transmission device of the present invention is interrupted, the output of the optical direct amplification means and the output of the optical transmission circuit corresponding to each wavelength can be stopped.

According to a fifth aspect of the present invention, in the optical transmitting apparatus of the first aspect, the optical transmitting means converts the optical signal into an electrical signal once, and converts the electrical signal into an optical signal of a plurality of predetermined wavelengths. And an optical regeneration repeater for outputting.

That is, according to the fifth aspect of the present invention, since the regenerative repeater is provided for all the input optical signals, the optical output fluctuation of each wavelength component can be compensated by a small-scale circuit configuration. S / of the optical signal passing through the optical direct amplification means
Since the N ratio can be improved, the reliability of the transmission signal can be improved.

According to a sixth aspect of the present invention, in the optical transmission device of the second aspect, the output light of the optical transmission unit is controlled based on the control information stored in the storage unit and the peak value detected by the peak value detection unit. It is characterized by comprising a variable light output means for making the output variable.

That is, in the sixth aspect of the present invention, since the optical output variable means is used, not only the optical output fluctuation of each wavelength component can be controlled based on the information stored in the storage means, but also the driving condition of the optical transmission circuit. The optical output signal of each wavelength can be made variable without changing. This is particularly effective when the optical output waveform deteriorates due to driving conditions of a semiconductor laser or the like at a high frequency.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION

[0030]

【Example】

Hereinafter, the present invention will be described in detail with reference to examples.

First Embodiment

FIG. 1 shows an optical transmission system according to a first embodiment of the present invention.
3 shows an outline of the configuration of a communication device. This optical transmission
The device is capable of transmitting each electrical signal 101₁, 101_Two, ..., 10
1_nAnd the optical output intensity from the optical transmission output means 110
Control signal 111 for₁, 111_Two, ..., 111_nEnter
Optical transmission circuit 102 as power₁, 102_Two, ..., 102 _n
And the optical signal to which the optical signal output from the optical transmission circuit is input.
The optical combiner 104 and the multiplexed light from the optical multiplexer are input.
Optical splitter 105 and optical signals from this optical splitter are optically transmitted.
It has an optical transmission output terminal 106 for outputting as a signal.
You. Further, the optical component that splits the split light from the optical transmission signal
A diverter 105 and a wavelength-tunable optical communication system that receives the branched light as input.
Over-band filter means 107 and this tunable optical pass band
Extract optical signal of specific wavelength component from bandpass filter
Means 108 for sweeping the wavelength for the
Of the wavelength component output from the passband filter
A peak value detecting means 109 for detecting a peak value;
A system that adjusts the optical transmission intensity based on the output peak value.
Control signal 111₁, 111_Two, ..., 111_nProducing light
It has transmission output means 110.

Each of the transmission electric signals 101 ₁ , 101 ₂ ,.
101 _n are respectively input to, for example, a semiconductor laser for converting an electric signal into an optical signal and optical transmission circuits 102 ₁ , 102 ₂ ,..., 102 _n each having a circuit configuration for driving the light source, and having different center wavelengths λ ₁ , lambda _2, ..., the optical signals 103 _1, 103 ₂ with lambda _n, ..., is adapted to be converted to 103 _n. Optical signals 103 ₁ , 103 ₂ ,..., 1
03 _n is optically multiplexed by being multiplexed by the optical multiplexer 104. The wavelength-multiplexed optical signal is
The optical splitter 105 splits the light as an optical transmission output signal into the optical transmission output terminal 106 and the branched light that is a part of the optical transmission output terminal 106. The optical signal transmitted to the optical transmission output terminal 106 is directly transmitted to the receiving device as the output of the optical transmitting device.

The split light split by the optical splitter 105 is input to the tunable optical passband filter 107. The sweeping means 108 sweeps the center wavelength of the optical signal extracted from the optical input signal of the wavelength variable optical passband filter means 107 within a certain band. The wavelength tunable optical pass band filter means 107 includes a sweep circuit 10
8, the optical signal having the center wavelength λ _i swept within a certain band can be extracted at a certain timing.

The peak value detecting unit 109, the optical signal extracted at a constant timing, different central wavelengths lambda ₁ to each other, lambda _2, ..., the optical signals 103 _1, 10 with lambda _n
The peak value of the optical signal of λ _i corresponding to 3 ₂ ,..., 103 _n is detected. 111 ₁ , 11 output from the optical transmission output means 110 according to the detected peak value
1 _2, ..., the control signal 111 _n, the output optical signal 103 ₁ of each wavelength each of the optical transmission circuit of the input signal light, 1
03 _2, 103 _3, ..., it is capable of controlling the intensity of 103 _n.

FIG. 2 specifically shows a main part of the configuration of the optical transmission apparatus shown in FIG. The same elements as those of the conventional example shown in FIGS. 11 to 13 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. This optical transmission device transmits the transmission electric signal 2
01 _1, 201 _2, ..., 201 optical transmitter circuit 1302 _{1 n} is inputted, 1302 _2, ..., 1302 _n and the optical multiplexer 1 the optical output signal is input from these optical transmitter circuit
104, and an optical splitter 1306 for splitting the split light 208 from the optical transmission signal output from the optical multiplexer. Further, the wavelength tunable optical passband filter 2 into which the branched light 208 is input and whose wavelength component is swept by the sweep circuit 211.
09, an optical splitter 212 that splits the output light from the wavelength-tunable optical passband filter into two, an optical / electrical circuit 213, 214 that receives each split light, and a sweep circuit 211
A pulse counter 215 that counts a wavelength component swept within a certain wavelength band from the electrical output signal converted by the optical-electrical conversion circuit 214, and a peak value of the wavelength component swept within the certain wavelength band by the sweep circuit 211 From the electrical output signal from the optical-to-electrical conversion circuit 213, an A / D converter 217 for converting the detected peak value into a digital value, It has a comparison processing circuit 218 for comparing with a set value and a memory 219 for storing a reference value for controlling the light output intensity. Also, an optical transmission control circuit 220 that generates a control signal for adjusting the optical output intensity based on the comparison result of the comparison processing circuit, and a D / D converter that converts the control signal output from the optical transmission control circuit 220 into an analog value a converter 221 _1, 221 _2, ..., has a 221 _n.

In such an optical transmission device, each transmission electric signal
No.201₁, 201_Two, ..., 201 _nBut each
Semiconductor laser that converts electrical signals into optical signals and its light source
Optical transmission circuit 1302 having a circuit configuration for driving₁, 13
02_Two, ..., 1302_nEntered in different centers
Wavelength λ₁, Λ_Two, ..., λ_nOptical signal 203 having₁, 20
3_Two, ..., 203_nHas been converted to. This
Optical signal 203₁, 203_Two, ..., 203_nIs an optical multiplex
The signals are multiplexed and wavelength-multiplexed by the optical unit 1104.

The multiplexed optical wavelength multiplex signal is supplied to the optical
By 306, the optical signal output to the optical transmission output terminal 207 as an optical transmission output signal and a part of the optical signal are split into an optical signal output as a split light 208.
The split light 208 is converted into a wavelength-variable optical passband filter 209.
Is input to

The sweep circuit 211 extracts the light input to the tunable optical passband filter 209 in order to extract the optical signals having different center wavelengths from the optical input signal of the tunable optical passband filter 209 at a fixed timing. The central wavelength of the signal is swept within a certain band. The wavelength tunable optical passband filter 209 receives the input branched light 208.
, The wavelength component swept by the sweep circuit 211 can be extracted.

The extracted optical signal is split by an optical splitter 212 and converted into optical / electrical conversion circuits 213 and 214, respectively.
Is converted into an electric signal. The pulse counter 215 counts the number of wavelengths of the electric signal converted by the optical-electrical conversion circuit 214 under the control of the sweep circuit 211. The peak value detector 216 is connected to the sweep circuit 2
11 detects the peak value of the electric signal converted by the optical / electrical conversion circuit 213. As described above, after the peak value of the optical signal of each wavelength is detected by the peak detector 216 controlled by the sweep circuit 211, the analog value is converted into a digital value by the A / D converter 217 which converts the analog value into a digital value. The comparison processing circuit 218
To be entered.

By monitoring the number of wavelengths obtained from the pulse counter 215 and the peak value of each number of wavelengths obtained from the peak value detector 216 via the A / D converter 217,
It is possible to recognize the fluctuation of the optical output intensity due to the wavelength component of the optical output signal, the optical output fluctuation, the specific deterioration of each inserted optical element, and the like.

The comparison processing circuit 218 controls the optical transmission control circuit 220 based on the result of comparison with the set value of the memory 219. Its output, D / A converter 221 ₁ to change the digital value into an analog value, 22
1 _2, ..., through 221 _n, the optical transmitter circuit 1302 _1, 1
302 _2, ..., to control the optical output intensity of the optical transmission circuit in 1302 _n. Therefore, even when the optical output of each wavelength of the optical multiplexed signal light fluctuates, the memory 2
Based on the 19 setting values, control can be performed so as to individually compensate the output of the optical transmission circuit of each wavelength.

The tunable optical passband filter 20 shown in FIG.
In addition, there is a type 9 which can be used continuously for a wide range of wavelengths and has an insertion loss characteristic as small as about 5 dB.

FIG. 3 shows an Acoust-Optic Tunable Filter as an example of such a wavelength-tunable optical passband filter.
(Hereinafter, it is abbreviated as AOTF.) This AOTF is made of LiNbO ₃ (lithium niobate).
On a substrate, an optical waveguide 301 and a polarization separation element (Polarizi
ng Beam Splitter (PBS) 303, a first AO polarization converter region 304, a polarization separation region 306 where a polarization separation element 303 and an electrode 305 are disposed, and a second AO polarization converter It has a region 307 and a polarization multiplexing region 308 in which a polarization splitting element is arranged.
The boundary between the polarization splitting region 302 and the AO polarization converter region 304, the second AO polarization converter region 307, and the polarization multiplexing region 30
Sound wave absorbers 309 are arranged at the boundaries of the eight.

The input optical signal is separated from the optical waveguide 301 into a TE wave and a TM wave by the polarization separation element 303 in the polarization separation area 302, and the first AO polarization converter 30
In 4, only a specific wavelength component λ _i is converted from a TE wave to a TM wave or from a TM wave to a TE wave according to the frequency of the control signal applied to the electrode 305.
This wavelength component passes through the second AO polarization converter 307 and the polarization multiplexing stage 308 again, and finally has a λ
Only the wavelength component of _i can be extracted.

FIG. 4 specifically shows the structure of the AOTF shown in FIG. This AOTF is LiNb
An optical waveguide 402 is arranged on an O ₃ substrate 401,
It has a first polarization separation element region 404, an AO mode converter region 405, and a second polarization separation element region 405. A comb-shaped opposing electrode 403 is provided at the boundary between the first polarization splitting element region 404 and the AO mode converter region 405.
Is arranged.

The wavelength components λ ₁ ,
When the first input light 408 and the second input light 407, which are random polarized light having λ ₂ ,..., λ _n , are input, the TE wave goes straight in the first polarization separation element region 405, respectively.
The TM waves propagate along the intersecting waveguides. Electrode 4
In 03, by applying a frequency near 170 MHz, an optical signal of an optical wavelength component corresponding to this frequency can be extracted. Therefore, when this AOTF is applied to the present invention, the sweep circuit 211 sweeps at a frequency around 170 MHz.

As described above, the AO mode converter area 405
, A first output light 409 having only a λ _i component, and a second output light 409 having a component of λ ₁ , λ ₂ ,..., Λ _n (where n ≠ i). Output light 410 is obtained.

FIG. 5 shows the characteristics of such an AOTF. The characteristics of the AOTF are as follows: when the light wavelength is taken with the abscissa as the unit nm, the wavelength is about 1450 nm to about 15 nm.
Over the 110 nm wavelength range of 60 nm, about 10 n
This shows that an optical signal of an optical wavelength component at m intervals can be extracted.

Further, since the AOTF as shown in FIG. 4 has two stages of AO mode converter regions, a stable filter characteristic can be obtained without depending on the polarization state of the input optical signal. Is available.

As described above, in the optical transmitter of the first embodiment, the sweeping circuit 211 sweeps a predetermined band including the center wavelength of the optical output signal to be transmitted, and uses the wavelength-tunable optical passband filter 209. Can be extracted. Thus, even when each wavelength of the optically multiplexed signal light has an optical output variation due to the loss of the optical multiplexer 1104 and the optical splitters 1306 and 212, the optical transmission circuit of each wavelength is set based on the set value of the memory 219. Can be individually compensated.

Second Embodiment

FIG. 6 shows the configuration of an optical transmission device for optical wavelength division multiplex transmission according to a second embodiment of the present invention. The same elements as those of the conventional example shown in FIGS. 11 to 13 are denoted by the same reference numerals. In this second embodiment, the first
It has almost the same functional configuration as the optical transmission device of the embodiment. Therefore, the same portions as those of the first embodiment shown in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

The configuration of the optical transmitter of the second embodiment is different from the configuration of the optical transmitter of the first embodiment in that a transmission electric signal is input and optical signals having different wavelength components are optically multiplexed. After being multiplexed by the optical amplifier 1104, the optical direct amplifier 605
Is input to the optical splitter 1306 via the.

Each of the transmission electric signals 201 ₁ , 201 ₂ ,.
201 _n, the optical transmitting circuit 1302 ₁ that each example of the circuit configuration for driving the semiconductor laser and its light source which converts electric signals into optical signals, 1302 _2, ..., are input to the 1302 _n, different central wavelengths lambda ₁ to each other, , λ _n are converted into optical signals 203 ₁ , 203 ₂ ,..., 203 _n having λ ₂ ,. This optical signal 203 ₁ , 20
3 _2, ..., 203 _n are optical wavelength multiplexing are multiplexed by the optical multiplexer 1104. The multiplexed optical wavelength multiplex signal is input to the optical direct amplifier 605.

For example, in an optical direct amplifier 605 using an erbium-doped fiber amplifier (hereinafter abbreviated as EDFA), the entire wavelength band of an optical signal is directly optically amplified, and then the optical splitter 1306 outputs an optical signal as an optical transmission output signal. The transmission output terminal 207 is split into a split light 208 as a part thereof. The split light 208 is input to the tunable optical passband filter 209.

The sweep circuit 211 extracts the light input to the tunable optical pass band filter 209 in order to extract the optical signal of the center wavelength at a fixed timing from the optical input signal of the tunable optical pass band filter 209. The central wavelength of the signal is swept within a certain band. The wavelength-tunable optical passband filter 209 can extract the wavelength component swept by the sweep circuit 211 from the input branched light 208.

The extracted optical signal is split by the optical splitter 212 and converted into an electrical signal by the optical / electrical converters 213 and 214, respectively. The pulse counter 215 controls light and light under the control of the sweep circuit 211.
The number of wavelengths of the electric signal converted by the electric conversion circuit 214 is counted. The peak value detector 216 is connected to the sweep circuit 21
1 detects the peak value of the electric signal converted by the optical-electrical conversion circuit 213. As described above, after the peak value of the optical signal of each wavelength is detected by the peak detector 216 controlled by the sweep circuit 211, the analog value is converted into a digital value by the A / D converter 217 which converts the analog value into a digital value. The comparison processing circuit 218
To be entered.

By monitoring the number of wavelengths obtained from the pulse counter 215 and the peak value of each number of wavelengths obtained from the peak value detector 216 via the A / D converter 217,
It is possible to recognize the fluctuation of the optical output intensity due to the wavelength component of the optical output signal, the optical output fluctuation, the specific deterioration of each inserted optical element, and the like.

The comparison processing circuit 218 controls the optical transmission control circuit 220 based on the result of comparison with the set value of the memory 219. Its output, D / A converter 221 ₁ to change the digital value into an analog value, 22
1 _2, ..., through 221 _n, the optical transmitter circuit 1302 _1, 1
302 _2, ..., to control the optical output intensity of the optical transmission circuit in 1302 _n. Therefore, even when the optical output of each wavelength of the optical multiplexed signal light fluctuates, the memory 2
Based on the 19 setting values, control can be performed so as to individually compensate the output of the optical transmission circuit of each wavelength.

Further, since the output of the optical direct amplifier is controlled to be constant, the peak power of each wavelength increases as the number of input wavelengths decreases, and conversely, as the number of input wavelengths increases, the output power of each wavelength increases. Each peak power decreases.

FIG. 7 is a diagram showing the difference in output response characteristics due to the difference in the number of input wavelengths of such an optical direct amplifier. However, according to the present invention, since the intensity of the optical transmission signal can be changed for each wavelength component, the power fluctuation for each wavelength can be compensated by this configuration.

The tunable optical pass band filter 20 shown in FIG.
As an example of Ninth Embodiment 9, there is an AOTF as in the first embodiment, and a description thereof will be omitted.

As described above, the optical transmitter of the second embodiment uses the wavelength-tunable optical pass band filter 209 by sweeping the fixed band including the center wavelength of the optical output signal to be transmitted by the sweep circuit 211. Can be extracted. As a result, each wavelength of the optical multiplexed signal light is converted into the optical multiplexer 1104, the optical splitters 1306, 212, and the optical direct amplifier 8
Memory 2 even when the optical output fluctuates due to the loss of
The output of the optical transmission circuit of each wavelength can be individually compensated based on the 19 setting values. In addition, the optical direct amplifier 605
The light output fluctuation based on the characteristic depending on the number of wavelengths described above can also be compensated.

Third Embodiment

FIG. 8 shows the configuration of an optical transmitter for optical wavelength division multiplexing transmission according to a third embodiment of the present invention. The same elements as those of the conventional example shown in FIGS. 11 to 13 are denoted by the same reference numerals. In the third embodiment, the second
It has almost the same functional configuration as the optical transmission device of the embodiment. Therefore, the same portions as those of the second embodiment shown in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

The configuration of the optical transmitter of the third embodiment differs from the configuration of the optical transmitter of the second embodiment in that the output of the optical direct amplifier 805 is stopped based on the comparison result of the comparison processing circuit 218. In this case, an alarm processing unit 822, an optical output stop circuit 823, and an optical direct amplification control circuit 824 are provided.

Each of the transmission electric signals 201 ₁ , 201 ₂ ,.
201 _n, the optical transmitting circuit 1302 ₁ that each example of the circuit configuration for driving the semiconductor laser and its light source which converts electric signals into optical signals, 1302 _2, ..., are input to the 1302 _n, different central wavelengths lambda ₁ to each other, , λ _n are converted into optical signals 203 ₁ , 203 ₂ ,..., 203 _n having λ ₂ ,. This optical signal 203 ₁ , 20
3 _2, ..., 203 _n are optical wavelength multiplexing are multiplexed by the optical multiplexer 1104. The multiplexed optical wavelength multiplexed signal is input to an optical direct amplifier 805 controlled by an optical direct amplification control circuit 824.

For example, an optical direct amplifier 80 using an EDFA
In 5, after the entire wavelength band of the optical signal is directly optically amplified,
The optical splitter 1306 splits the light as an optical transmission output signal into an optical transmission output terminal 207 and a split light 208 as a part thereof. The split light 208 is input to the tunable optical passband filter 209.

The sweep circuit 211 extracts the light input to the tunable optical passband filter 209 in order to extract the optical signal of the center wavelength at a fixed timing from the optical input signal of the tunable optical passband filter 209. The central wavelength of the signal is swept within a certain band. The wavelength-tunable optical passband filter 209 can extract the wavelength component swept by the sweep circuit 211 from the input branched light 208.

The extracted optical signal is split by the optical splitter 212 and converted into an electrical signal by the optical / electrical converters 213 and 214, respectively. The pulse counter 215 controls light and light under the control of the sweep circuit 211.
The number of wavelengths of the electric signal converted by the electric conversion circuit 214 is counted. The peak value detector 216 is connected to the sweep circuit 21
1 detects the peak value of the electric signal converted by the optical-electrical conversion circuit 213. As described above, after the peak value of the optical signal of each wavelength is detected by the peak detector 216 controlled by the sweep circuit 211, the analog value is converted into a digital value by the A / D converter 217 which converts the analog value into a digital value. The comparison processing circuit 218
To be entered.

By monitoring the number of wavelengths obtained from the pulse counter 215 and the peak value of each number of wavelengths obtained from the peak value detector 216 via the A / D converter 217,
It is possible to recognize the fluctuation of the optical output intensity due to the wavelength component of the optical output signal, the optical output fluctuation, the specific deterioration of each inserted optical element, and the like.

The comparison processing circuit 218 controls the optical transmission control circuit 820 based on the result of comparison with the set value of the memory 219. Its output, D / A converter 221 ₁ to change the digital value into an analog value, 22
1 _2, ..., through 221 _n, the optical transmitter circuit 1302 _1, 1
302 _2, ..., to control the optical output intensity of the optical transmission circuit in 1302 _n. Therefore, even when the optical output of each wavelength of the optical multiplexed signal light fluctuates, the memory 2
Based on the 19 setting values, control can be performed so as to individually compensate the output of the optical transmission circuit of each wavelength.

The alarm processing unit 822 includes the pulse counter 21
5, the presence or absence of an optical output signal of each wavelength is detected based on the number of wavelengths of the optical output signal detected from the peak value detector 216 and the optical signal level of each wavelength. Based on the detection result of the presence or absence of the optical output signal of each wavelength, the optical output stop circuit 823 determines that the output of the signal of a certain wavelength is cut off, and the optical transmission circuits 1302 ₁ , 1302 ₂ ,.
The optical transmission circuit and the optical direct amplifier 80 of the corresponding wavelength out of _n
5 to output a control signal for stopping the output.

The optical transmission control circuit 820 receives the control signal from the optical output stop circuit 823 and
2 _1, 1302 _2, ..., thereby making it possible to stop the output of 1302 _n. The optical direct amplification control circuit 824 can stop the output of the optical direct amplifier 805 in response to the control signal from the optical output stop circuit 823.

The wavelength tunable optical pass band filter 20 shown in FIG.
As an example of Ninth Embodiment 9, there is an AOTF as in the first embodiment, and a description thereof will be omitted.

As described above, in the optical transmitter of the third embodiment, the sweeping circuit 211 sweeps a predetermined band including the center wavelength of the optical output signal to be transmitted, and uses the wavelength variable optical pass band filter 209. Can be extracted. As a result, each wavelength of the optical multiplexed signal light is converted into the optical multiplexer 1104, the optical splitters 1306, 212, and the optical direct amplifier 8
Memory 2 even when the optical output fluctuates due to the loss of
The output of the optical transmission circuit of each wavelength can be individually compensated based on the 19 setting values.

The provision of the alarm processing section 822 makes it possible to completely stop the outputs of the optical direct amplifier 805 and the optical transmission circuits 1302 ₁ , 1302 ₂ ,..., 1302 _n when the optical transmission signal is interrupted. .

Fourth Embodiment

FIG. 9 shows the configuration of an optical transmission device for optical wavelength division multiplex transmission according to the fourth embodiment of the present invention. The same elements as those of the conventional example shown in FIGS. 11 to 13 are denoted by the same reference numerals. In the fourth embodiment, the third
It has almost the same functional configuration as the optical transmission device of the embodiment. Therefore, the same portions as those of the third embodiment shown in FIG. 8 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

The configuration of the optical transmission apparatus of the fourth embodiment is different from the configuration of the optical transmission apparatus of the third embodiment in that a transmission signal is an optical signal and an optical regenerative repeater circuit 902 is used instead of the optical transmission circuit.
_1, 902 _2, ..., in that it is inserted 902 _n.
Optical reproduction relay circuit _{902 1, 902 2, ...,} 902 n may,
It is composed of an optical-to-electrical conversion circuit and an electrical-to-optical conversion circuit. The optical signal, which is a transmission signal, is once converted into an electrical signal, amplified, and then converted back to an optical signal, thereby obtaining an S / N ratio as a transmission signal. To improve.

Each of the transmission optical signals 901 ₁ , 901 ₂ ,..., 9
01 _n are optical regeneration repeater circuits 902 ₁ , 902 ₂ ,.
2 _n , once converted into an electric signal, and then set again at different center wavelengths λ ₁ , λ ₂ ,.
optical signals 203 _1, 203 ₂ with _n, ..., it is adapted to be converted to 203 _n. This optical signal 203 ₁ , 20
3 _2, ..., 203 _n are optical wavelength multiplexing are multiplexed by the optical multiplexer 1104. The multiplexed optical wavelength multiplexed signal is input to an optical direct amplifier 805 controlled by an optical direct amplification control circuit 824.

For example, an optical direct amplifier 80 using an EDFA
In 5, after the entire wavelength band of the optical signal is directly optically amplified,
The optical splitter 1306 splits the light as an optical transmission output signal into an optical transmission output terminal 207 and a split light 208 as a part thereof. The split light 208 is input to the tunable optical passband filter 209.

The sweep circuit 211 extracts the light input to the tunable optical pass band filter 209 in order to extract the optical signal of the central wavelength at a fixed timing from the optical input signal of the tunable optical pass band filter 209. The central wavelength of the signal is swept within a certain band. The wavelength-tunable optical passband filter 209 can extract the wavelength component swept by the sweep circuit 211 from the input branched light 208.

The extracted optical signal is split by the optical splitter 212 and is converted into an electrical signal by the optical / electrical converters 213 and 214, respectively. The pulse counter 215 controls light and light under the control of the sweep circuit 211.
The number of wavelengths of the electric signal converted by the electric conversion circuit 214 is counted. The peak value detector 216 is connected to the sweep circuit 21
1 detects the peak value of the electric signal converted by the optical-electrical conversion circuit 213. As described above, after the peak value of the optical signal of each wavelength is detected by the peak detector 216 controlled by the sweep circuit 211, the analog value is converted into a digital value by the A / D converter 217 which converts the analog value into a digital value. The comparison processing circuit 218
To be entered.

By monitoring the number of wavelengths obtained from the pulse counter 215 and the peak value of each number of wavelengths obtained from the peak value detector 216 via the A / D converter 217,
It is possible to recognize the fluctuation of the optical output intensity due to the wavelength component of the optical output signal, the optical output fluctuation, the specific deterioration of each inserted optical element, and the like.

The comparison processing circuit 218 controls the optical transmission control circuit 920 based on the result of comparison with the set value of the memory 219. Its output, D / A converter 221 ₁ to change the digital value into an analog value, 22
1 _2, ..., through 221 _n, an optical regenerative repeater circuit 902 _1,
In 902 ₂ ,..., 902 _n , the optical output intensity of the optical regenerative repeater circuit is controlled. Therefore, even when the optical output of each wavelength of the optical multiplexed signal light fluctuates, control can be performed based on the set value of the memory 219 so as to individually compensate the output of the optical transmission circuit of each wavelength.

The alarm processing unit 822 includes the pulse counter 21
5, the presence or absence of an optical output signal of each wavelength is detected based on the number of wavelengths of the optical output signal detected from the peak value detector 216 and the optical signal level of each wavelength. Based on the detection result of the presence or absence of the optical output signal of each wavelength, the optical output stop circuit 823 determines that the output of the signal of a certain wavelength is cut off.
A control signal for stopping the output of the optical transmission circuit and the optical direct amplifier 805 of the corresponding wavelength among the optical regenerative repeaters 902 ₁ , 902 ₂ ,..., 902 _n is output.

The optical transmission control circuit 920 receives the control signal from the optical output stop circuit 823 and
02 _1, 902 _2, ..., thereby making it possible to stop the output of 902 _n. The optical direct amplification control circuit 824 can stop the output of the optical direct amplifier 805 in response to the control signal from the optical output stop circuit 823.

The wavelength tunable optical pass band filter 20 shown in FIG.
As an example of the ninth example, there is an AOTF as in the third embodiment, and a description thereof is omitted.

As described above, in the optical transmitting apparatus of the fourth embodiment, the sweeping circuit 211 sweeps a predetermined band including the center wavelength of the optical output signal to be transmitted, and uses the tunable optical passband filter 209. Can be extracted. As a result, each wavelength of the optical multiplexed signal light is converted into the optical multiplexer 1104, the optical splitters 1306, 212, and the optical direct amplifier 8
Memory 2 even when the optical output fluctuates due to the loss of
The output of the optical transmission circuit of each wavelength can be individually compensated based on the 19 setting values.

The provision of the alarm processing section 822 makes it possible to completely stop the output of the optical direct amplifier 805 and the optical transmission circuits 1302 ₁ , 1302 ₂ ,..., 1302 _n when the optical transmission signal is interrupted. . Further, since the input optical signal can be regenerated and relayed, the input signal of the optical multiplexer 1104 and the optical direct amplifier 805 can
Since the / N ratio can be improved, the reliability of the transmitted transmission signal can be improved.

Fifth Embodiment

FIG. 10 shows the configuration of an optical transmitter for optical wavelength division multiplexing transmission according to a fifth embodiment of the present invention. The same elements as those of the conventional example shown in FIGS. 11 to 13 are denoted by the same reference numerals. The fifth embodiment has almost the same functional configuration as the optical transmitter of the fourth embodiment. Therefore, the same parts as those of the fourth embodiment shown in FIG. 9 are denoted by the same reference numerals, and the description thereof will be appropriately omitted.

[0096] The point at which configuration of the optical transmitting apparatus of the fifth embodiment is different from the configuration of the optical transmitting apparatus of the fourth embodiment, an optical regenerative repeater circuit 902 _1, 902 _2, ..., relayed by 902 _n Before the optical signal is multiplexed by the optical multiplexer 1104, the optical output variable section 102 controlled by the optical transmission control circuit 1020
5 _1, 1025 _2, ..., it is that 1025 _n is inserted.

[0097] Each optical transmission signal 901 _1, 901 _2, ..., 9
01 _n are optical regeneration repeater circuits 902 ₁ , 902 ₂ ,.
2 _n , once converted into an electric signal, and then set again at different center wavelengths λ ₁ , λ ₂ ,.
optical signals 203 _1, 203 ₂ with _n, ..., it is adapted to be converted to 203 _n. This optical signal 203 ₁ , 20
3 _2, ..., 203 _n are controlled by the light transmission control circuit 1020, for example, an optical variable output unit 1025 such as an optical attenuator
₁ , 1025 ₂ ,..., 1025 _n through the optical multiplexer 1
The optical signals are multiplexed by the optical modulator 104 and wavelength-division multiplexed. The multiplexed optical wavelength multiplexed signal is input to an optical direct amplifier 805 controlled by an optical direct amplification control circuit 824.

For example, an optical direct amplifier 80 using an EDFA
In 5, after the entire wavelength band of the optical signal is directly optically amplified,
The optical splitter 1306 splits the light as an optical transmission output signal into an optical transmission output terminal 207 and a split light 208 as a part thereof. The split light 208 is input to the tunable optical passband filter 209.

The sweep circuit 211 extracts the light input to the tunable optical passband filter 209 in order to extract an optical signal having a central wavelength at a fixed timing from the optical input signal of the tunable optical passband filter 209. The central wavelength of the signal is swept within a certain band. The wavelength-tunable optical passband filter 209 can extract the wavelength component swept by the sweep circuit 211 from the input branched light 208.

The extracted optical signal is split by the optical splitter 212, and is converted into an electrical signal by the optical / electrical converters 213 and 214, respectively. The pulse counter 215 controls light and light under the control of the sweep circuit 211.
The number of wavelengths of the electric signal converted by the electric conversion circuit 214 is counted. The peak value detector 216 is connected to the sweep circuit 21
1 detects the peak value of the electric signal converted by the optical-electrical conversion circuit 213. After the peak value of the optical signal of each wavelength is detected by the peak detector 216 controlled by the sweep circuit 211, the analog value is converted into a digital value by the A / D converter 217 which converts the analog value into a digital value. The comparison processing circuit 218
To be entered.

By monitoring the number of wavelengths obtained from the pulse counter 215 and the peak value of each number of wavelengths obtained from the peak value detector 216 via the A / D converter 217,
It is possible to recognize the fluctuation of the optical output intensity due to the wavelength component of the optical output signal, the optical output fluctuation, the specific deterioration of each inserted optical element, and the like.

In the comparison processing circuit 218, based on the result of comparison with the set value of the memory 219, the optical transmission control circuit 1020
Is controlled. The output is a D / A converter 221 ₁ , 2 which changes a digital value to an analog value.
21 _2, ..., through 221 _n, the light output variable 102
5 _1, 1025 _2, ..., so as to control the optical output intensity of 1025 _n. Therefore, even when the optical output of each wavelength of the optical multiplexed signal light fluctuates, control can be performed based on the set value of the memory 219 so as to individually compensate the output of the optical transmission circuit of each wavelength.

The alarm processing section 822 includes the pulse counter 21
5, the presence or absence of an optical output signal of each wavelength is detected based on the number of wavelengths of the optical output signal detected from the peak value detector 216 and the optical signal level of each wavelength. Based on the detection result of the presence or absence of the optical output signal of each wavelength, the optical output stop circuit 823 determines that the output of the signal of a certain wavelength is cut off.
A control signal for stopping the output of the optical transmission circuit and the optical direct amplifier 805 of the corresponding wavelength among the optical regenerative repeaters 902 ₁ , 902 ₂ ,..., 902 _n is output.

The optical transmission control circuit 1020 receives the control signal from the optical output stop circuit 823 and can stop the output of the optical regenerative repeater circuits 902 ₁ , 902 ₂ ,..., 902 _n. I have. The optical direct amplification control circuit 824 can stop the output of the optical direct amplifier 805 in response to the control signal from the optical output stop circuit 823.

The wavelength-tunable optical pass band filter 2 shown in FIG.
As an example of 09, there is an AOTF as in the fourth embodiment, and a description thereof will be omitted.

As described above, in the optical transmitter of the fifth embodiment, the sweeping circuit 211 sweeps a predetermined band including the center wavelength of the optical output signal to be transmitted, and uses the wavelength-tunable optical pass band filter 209. Can be extracted. As a result, each wavelength of the optical multiplexed signal light is converted into the optical multiplexer 1104, the optical splitters 1306, 212, and the optical direct amplifier 8
Memory 2 even when the optical output fluctuates due to the loss of
The output of the optical transmission circuit of each wavelength can be individually compensated based on the 19 setting values.

The provision of the alarm processing section 822 makes it possible to completely stop the output of the light direct amplifier 805 and the optical transmission circuits 1302 ₁ , 1302 ₂ ,..., 1302 _n when the optical transmission signal is interrupted. . Further, since the input optical signal can be regenerated and relayed, the input signal of the optical multiplexer 1104 and the optical direct amplifier 805 can
Since the / N ratio can be improved, the reliability of the transmission signal can be improved.

Further, by making the output of the optical transmission circuit variable by using an optical attenuator or the like, the optical output signal of each wavelength can be made variable without changing the driving conditions of the optical transmission circuit. This is particularly effective when the optical output wave meter deteriorates due to driving conditions of a semiconductor laser or the like at a high frequency.

[0109]

As described above, according to the first aspect of the present invention, the wavelength variable type optical pass band filter means is used, so that the center wavelength of the optical output signal to be extracted by the sweep circuit is included. By sweeping within a certain band, a desired wavelength component can be extracted at a certain timing. Therefore, by detecting the peak value of the wavelength component, even when the optical output of each wavelength is changed due to factors such as the optical output variation of each optical transmission circuit and the deterioration of the characteristics of the optical multiplexer, the corresponding wavelength is changed. Only the intensity of the optical output signal can be controlled on a small scale and easily. This makes it possible to compensate for the optical output output from the optical transmission circuit to the optical receiver.

According to the second aspect of the present invention, since the wavelength-variable optical pass band filter is used, a predetermined band including the center wavelength of the optical output signal to be extracted by the sweep circuit is swept. By doing so, a desired wavelength component can be extracted at a certain timing. Therefore, by detecting the peak value of the wavelength component,
Even if the optical output of each wavelength is caused by factors such as the optical output variation of the individual optical transmission circuits and the deterioration of the characteristics of the optical multiplexer,
The intensity of the optical output signal of only the corresponding wavelength can be controlled on a small scale and easily. Thus, the optical output output from the optical transmission circuit to the optical receiver can be compensated. Further, since a value can be set in the storage means in advance, the compensation range of the optical output can be made variable when comparing the set value with the level of each wavelength component, so that a flexible optical transmitter can be provided. Become.

In the third aspect of the present invention, the wavelength variable optical pass band filter is used, so that the sweep circuit sweeps a predetermined band including the center wavelength of the optical output signal to be extracted. Thereby, a desired wavelength component can be extracted at a certain timing. Therefore,
When an optical output signal is amplified by an optical direct amplifier for the purpose of improving the S / N ratio and improving the reliability of a transmission signal, individual optical transmissions are detected by detecting the peak value of the wavelength component. It is easy to control the intensity of the optical output signal of only the wavelength corresponding to the optical output variation of each wavelength due to factors such as the optical output variation of the circuit, the deterioration of the characteristics of the optical multiplexer, and the gain variation depending on the frequency of the optical direct amplifier. Becomes possible. Thus, the optical loss of the optical multiplexer or the optical branching device connected to the optical transmission output terminal can be compensated by the optical direct amplification means.

In the fourth aspect of the present invention, since the wavelength variable type optical pass band filter is used, the sweep circuit sweeps a predetermined band including the center wavelength of the optical output signal to be extracted. Thereby, a desired wavelength component can be extracted at a certain timing. Therefore,
When the optical output signal is amplified by an optical direct amplifier for the purpose of improving the S / N ratio, the peak value of the wavelength component is detected, and thus the optical output fluctuation of each optical transmission circuit and the optical multiplexer are reduced. It is possible to easily control the intensity of the optical output signal of only the wavelength corresponding to the optical output variation of each wavelength due to factors such as characteristic deterioration and gain variation depending on the frequency of the optical direct amplification means. Thus, the optical loss of the optical multiplexer or the optical branching device connected to the optical transmission output terminal can be compensated by the optical direct amplification means. Further, since the optical direct amplification control means is provided, when the optical output from the optical transmission device of the present invention is interrupted, the output of the optical direct amplification means and the output of the optical transmission circuit corresponding to each wavelength can be stopped. become.

According to the fifth aspect of the present invention, the first aspect is provided.
In addition to the effects of the described invention, since a regenerative repeater circuit is provided for an input optical signal, the S / N ratio of an optical output signal can be improved even if the transmission distance is increased, and the reliability of the transmission signal is improved Can be improved.

Further, according to the invention of claim 6, in addition to the effect of the invention of claim 2, since the optical variable means is provided before input to the multiplexer, the driving conditions of the optical transmission circuit can be changed. The intensity of the optical output signal from the optical transmission circuit can be changed. This is particularly effective when characteristics are degraded at high frequencies, such as when a semiconductor laser is used.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an outline of a configuration of an optical transmission device according to a first embodiment of the present invention.

FIG. 2 is a block diagram specifically illustrating a main part of a configuration of the optical transmission device according to the first embodiment.

FIG. 3 is a diagram illustrating the principle of an AOTF as a wavelength-tunable optical passband filter used in the first embodiment.

FIG. 4 is a diagram showing the structure of an AOTF as a wavelength variable optical pass band filter used in the first embodiment.

FIG. 5 is a diagram showing characteristics of an AOTF as a wavelength variable optical pass band filter used in the first embodiment.

FIG. 6 is a block diagram illustrating a configuration of an optical transmission device according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a difference in output response characteristics due to a difference in the number of input wavelengths of the optical direct amplification means used in the second embodiment.

FIG. 8 is a block diagram illustrating a configuration of an optical transmission device according to a third embodiment of the present invention.

FIG. 9 is a block diagram illustrating a configuration of an optical transmission device according to a fourth embodiment of the present invention.

FIG. 10 is a block diagram illustrating a configuration of an optical transmission device according to a fifth embodiment of the present invention.

FIG. 11 is a block diagram showing an outline of a conventional wavelength multiplex transmission optical transmitting / receiving apparatus.

FIG. 12 is a block diagram illustrating a configuration of a conventional optical transmission device.

FIG. 13 is a block diagram showing a configuration of a conventional optical transmission device for wavelength multiplex transmission.

[Explanation of symbols]

101 _{1 to} 101 _n transmission electric signal 102 _{1 to} 102 _n optical transmission circuit 103 _{1 to} 103 _n optical signal 104 optical multiplexer 105, 212, 1306 optical splitter 106 optical transmission output terminal 107 wavelength tunable optical pass band filter means 108 Sweep means 109 Peak value detection means 110 Optical transmission output means 111 _{1 to} 111 _n Control signal 213,214 Opto-electric conversion circuit 215 Pulse counter 216 Peak value detector 217 A / D converter 218,1313 Comparison processing circuit 219 Memory 220 Optical transmission control circuits 221 _{1 to} 221 _n D / A converters 301, 402 Optical waveguides 302, 306 Polarization separation regions 303 Polarization separation elements (PBS) 304 First AO polarization converters 305, 403 Electrodes 307 Second AO polarization Transducer 308 Polarization combining area 309 Sound absorber 401 Li NbO ₃ (lithium niobate) substrate 404 First polarization separation element region 405 AO mode converter region 406 Second polarization separation element region 605, 1305 Optical fiber amplifier 805 Optical direct amplifier 822 Alarm processing unit 823 Optical output stop circuit 824 Optical direct amplification control circuit 901 _{1 to} 901 _n Transmission optical signal 1025 _{1 to} 1025 _n Optical output variable section 1106 Optical fiber transmission line

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04B 10/08 H04J 14/00 14/02

Claims (6)

[Claims] 1. An optical transmitting means for converting an electric signal to be transmitted into a plurality of optical signals having different center wavelengths and transmitting the same, an optical multiplexing means for transmitting a multiplexed light obtained by multiplexing these optical signals, First optical splitting means for splitting a part of the wave light to extract split light, sweeping means for sweeping within a range including the center wavelength of the plurality of optical signals transmitted by the optical transmitting means, and sweeping by the sweeping means Based on the given wavelength,
A wavelength tunable optical passband filter for extracting an optical signal of a specific wavelength component of the split light extracted from the optical branching means; and each wavelength component of the output light extracted from the wavelength tunable optical passband filter. Peak value detection means for detecting an intensity peak value of the light transmission control means for changing the light transmission intensity of the light transmission means for each wavelength component to be transmitted based on the peak value detected from the peak value detection means; An optical transmission device for wavelength division multiplex transmission, comprising: 2. An optical transmitting means for converting an electric signal to be transmitted into a plurality of optical signals having different center wavelengths and transmitting the same, an optical multiplexing means for transmitting multiplexed light obtained by multiplexing these optical signals, First optical splitting means for splitting a part of the wave light to extract split light, sweeping means for sweeping within a range including the center wavelength of the plurality of optical signals transmitted by the optical transmitting means, and sweeping by the sweeping means Based on the given wavelength,
A wavelength tunable optical passband filter for extracting an optical signal of a specific wavelength component of the split light extracted from the optical branching means; and each wavelength component of the output light extracted from the wavelength tunable optical passband filter. Peak value detecting means for detecting the intensity peak value of the first, first storing means for storing control information for adjusting the intensity of the light transmitting means, control information stored in the storing means, and the peak value detecting means Wavelength-division multiplexing transmission, comprising: an optical transmission controller that changes the intensity of the output signal of the optical transmitter corresponding to each wavelength for each wavelength component to be transmitted, based on the intensity peak value detected by Optical transmission device. 3. An optical transmitting means for converting an electric signal to be transmitted into a plurality of optical signals having different center wavelengths and transmitting the same, an optical multiplexing means for transmitting multiplexed light obtained by multiplexing these optical signals, Direct optical amplification means for directly amplifying light over the entire wavelength band of the optical wavelength of the output light of the wave means, first optical branching means for branching a part of the optically directly amplified optical signal and extracting branched light, A sweeping means for sweeping within a range including a center wavelength of the plurality of optical signals transmitted by the optical transmitting means, and a first sweeping means based on the wavelength swept by the sweeping means.
A wavelength tunable optical passband filter for extracting an optical signal of a specific wavelength component of the split light extracted from the optical branching means; and each wavelength component of the output light extracted from the wavelength tunable optical passband filter. Peak value detection means for detecting the intensity peak value of the light transmission control means for changing the light transmission intensity of the light transmission means based on the peak value detected from the peak value detection means for each wavelength component to be transmitted. An optical transmission device for wavelength division multiplex transmission, comprising: 4. An optical transmitting means for converting an electric signal to be transmitted into a plurality of optical signals having different center wavelengths and transmitting the same, an optical multiplexing means for transmitting multiplexed light obtained by multiplexing these optical signals, Direct optical amplification means for directly amplifying light over the entire wavelength band of the optical wavelength of the output light of the wave means, first optical branching means for branching a part of the optically directly amplified optical signal and extracting branched light, A sweeping means for sweeping within a range including a center wavelength of the plurality of optical signals transmitted by the optical transmitting means, and a first sweeping means based on the wavelength swept by the sweeping means.
A wavelength tunable optical passband filter for extracting an optical signal of a specific wavelength component of the split light extracted from the optical branching means; and each wavelength component of the output light extracted from the wavelength tunable optical passband filter. Peak value detecting means for detecting the intensity peak value of the first, first storing means for storing control information for adjusting the intensity of the light transmitting means, control information stored in the storing means, and the peak value detecting means Based on the intensity peak value detected by the optical transmission control means for changing the intensity of the output signal of the optical transmission means corresponding to each wavelength for each wavelength component to be transmitted, the control information stored in the storage means and the Based on the peak value detected from the peak value detecting means, the optical direct amplification control means for stopping the output of the optical direct amplification means, Optical transmitter. 5. An optical regenerative repeater for converting the optical signal into an electrical signal, converting the optical signal into an electrical signal having a plurality of predetermined wavelengths, and outputting the electrical signal. An optical transmitter in the wavelength division multiplexing transmission according to the above. 6. Based on control information stored in said storage means and a peak value detected by said peak value detection means,
3. The optical transmission apparatus according to claim 2, further comprising an optical output variable unit that varies output light of the optical transmission unit.