JP5693519B2 - Optical transmitter - Google Patents

Description

  The present invention relates to an optical transmitter that includes a 1: 2 DEMUX that divides a transmission data string by timing synchronization and outputs it, and that has a function of controlling the phase of a clock used for timing synchronization.

  Optical submarine cable transmission systems are broadly classified into relayless transmission systems that are applied to the strait crossing for short distances and relay transmission systems that are applied to the transoceanic sea for long distances. The optical submarine cable transmission system of the relay transmission system is composed of a submarine relay transmission line and land coastal station devices at both ends thereof. In the submarine relay transmission line, the submarine relay apparatus is arranged for each relay span of about 50 km. The configuration is common. In an optical submarine cable transmission system, wavelength division multiplexing optical transmission (WDM) technology is generally used.

  FIG. 9 is a schematic diagram showing the configuration of the WDM apparatus. The WDM apparatus includes a plurality of optical transmitters 200, an optical wavelength multiplexing apparatus 300, an optical wavelength separation apparatus 400, and a plurality of optical receivers 500. The plurality of optical transmitters 200 each include a laser and emit laser beams having different wavelengths. Then, the optical transmitter 200 modulates the laser light to generate a transmission signal, and the optical wavelength multiplexer 300 multiplexes the plurality of transmission signals. Thereafter, the multiplexed transmission signal is transmitted through the optical submarine cable. On the other hand, on the receiving side, the multiplexed transmission signal is separated into optical signals of each wavelength by the optical wavelength demultiplexer 400, each optical signal is received by each of the plurality of optical receivers 500, and is received by a built-in light receiving element. Convert to electrical signal. This technology has the advantage of enabling large-capacity information transmission from a small amount of cable resources.

  In an optical submarine cable transmission system using the WDM technology, the communication capacity can be increased by a method of narrowly multiplexing the wavelength intervals and performing a dense multiplexing or a method of increasing the bit rate of the optical transceiver. At present, optical submarine cable transmission systems having transmission speeds of 40 Gbps and 100 Gbps have been realized.

  On the other hand, if the wavelength interval is narrowed and the multiplexing is made dense, the transmitted light intensity increases. For example, if the transmission light intensity per wave is +10 dBm and the multiplexing number is 64, the transmission light intensity reaches +28 dBm. However, when the intensity of light input to the optical fiber is increased, the nonlinear effect of the fiber becomes noticeable and the transmission characteristics are deteriorated, so that the intensity of transmitted light is limited. Therefore, it is necessary to reduce the transmission light intensity per wave. However, if the transmission light intensity is reduced, the S / N ratio (Signal to Noise) is deteriorated. Therefore, if the transmission light intensity is excessively reduced, the transmission characteristics deteriorate. There is.

  Further, when the bit rate is increased, the spectrum width of the transmission light is increased. For this reason, when OOK (ON-OFF Keying) and DPSK (Differential Phase Shift Keying), which are conventional modulation methods, are used, there is a disadvantage that the wavelength interval cannot be narrowed and the number of wavelength multiplexing cannot be increased.

  As means for solving these problems, a method using a DP-QPSK (Dual Polarization Quadrature Phase Shift Keying) modulation method, which is one of digital coherent methods, has been proposed. In this method, an optical signal is transmitted by placing information on the polarization and four phase changes of light, and in the receiver, local light of the same wavelength is interfered with the received optical signal by the front end module (FE module), After the phase-modulated light is converted into intensity-modulated light, a signal is received by photoelectric conversion. DP-QPSK is a phase modulation method, and balance-detects received light. Therefore, since reception sensitivity can be improved as compared with OOK, good transmission characteristics can be ensured even if transmission light intensity is reduced. Further, since DP-QPSK uses two polarizations and four phases, the modulation rate can be reduced to a quarter compared with generally used OOK and DPSK. Therefore, the spectrum width can be narrowed and the number of wavelength multiplexing can be increased.

  Since DP-QPSK uses two polarizations and four phases, the DP-QPSK modulator has four input terminals. Therefore, for example, after bundling 16 columns of transmission data with a 2-output MUX (Multiplexer), the transmission data sequence from the MUX is divided into 2 with 1: 2 DEMUX (DeMultiplexer) to generate 4 series of data. Input to the QPSK modulator.

  In 1: 2 DEMUX, a clock having a frequency f / 2 that is half the frequency f of the transmission data string is used as a clock used for timing synchronization. At this time, when the input phase is inverted, the output data string is inverted and an incorrect data string is output. A method corresponding to this is disclosed in Patent Document 1, for example. That is, the setting on the transmission side is changed by feeding back the bit error rate information on the reception side. This makes it possible to determine whether the clock phase is correct or incorrect.

US201000069022 [Chapter 6, What is claimed is 1]

  As described above, according to the technique of claim 1 according to Patent Document 1, the receiving side receives data and feeds back the bit error rate information to the transmitting side, thereby determining whether the clock phase of the 1: 2 DEMUX output is correct or incorrect. Is possible. However, the fact that the receiving side is receiving data means that the transmitting side and the receiving side are able to perform data communication with each other, and the determination cannot be made only on the transmitting side. In particular, when establishing a long-distance communication, since it starts from a state of no data communication, there is a problem that it is difficult to apply the above technique.

  The present invention has been made in order to solve the above-described problem, and does not require information on the reception side, and only determines the correctness of the phase of the 1: 2 DEMUX (demultiplexer) output with the configuration on the transmission side. The purpose is to provide a transmitter.

An optical transmitter according to the present invention divides a data string in which transmission data is aggregated and a single data string from the multiplexer into two data strings at a synchronization timing using a clock and outputs the data string A demultiplexer, an electric driver for amplifying a data string from the demultiplexer, an optical modulator for optically modulating the data string amplified by the electric driver, and one of two data strings input to the optical modulator Is a AC pattern and the other is a DC pattern. A data output control unit that outputs transmission data of a fixed pattern to the multiplexer, a phase shifter that shifts the phase of the clock, and a driver ON / OFF that controls output ON / OFF from the electric driver. OFF controller, optical coupler for branching light from the optical modulator, and monitoring the light branched by the optical coupler Equipped with a photodiode and a clock phase controller that controls the shift amount of the phase shifter based on the monitoring result by the photodiode in a state where the driver output ON / OFF is controlled by the driver ON / OFF controller It is.

Further, the optical transmitter according to the present invention, a multiplexer for outputting the data string obtained by aggregating transmission data, a data string of one line from the multiplexer, in synchronization timing using a clock is divided into data two rows Output demultiplexer, an electric driver for amplifying the data string from the demultiplexer, an optical modulator for optically modulating the data string amplified by the electric driver, and two data strings input to the optical modulator. A data output control unit that outputs fixed pattern transmission data, one of which is an AC pattern and the other is a DC pattern, to the multiplexer, a phase shifter that shifts the phase of the clock, and a peak that monitors the peak of the electrical output from the electrical driver A clock phase control that controls the shift amount of the phase shifter based on the monitoring results of the detector and the peak detector. It is obtained by a part.

Further, the optical transmitter according to the present invention, a multiplexer for outputting the data string obtained by aggregating transmission data, a data string of one line from the multiplexer, in synchronization timing using a clock is divided into data two rows Output demultiplexer, an electric driver for amplifying the data string from the demultiplexer, an optical modulator for optically modulating the data string amplified by the electric driver, and two data strings input to the optical modulator. A data output control unit for outputting transmission data of a fixed pattern in which one of them is an AC pattern and the other is a DC pattern to a multiplexer, a phase shifter for shifting the phase of a clock, and a current detection unit for monitoring current consumption of an electric driver A clock phase control unit for controlling the shift amount of the phase shifter based on the monitoring result by the current detection unit. It is.

  According to the present invention, since it is configured as described above, it is possible to determine whether the phase of the demultiplexer output is correct or not with only the configuration on the transmission side without requiring information on the reception side. Thereby, the present invention can also be applied to establishment of long-distance transmission starting from a state in which data is not transmitted between the transmission side and the reception side.

It is a figure (QPSK modulation) which shows the structure of the data signal generation part which concerns on Embodiment 1 of this invention. It is a conceptual diagram explaining 2 division of the transmission data sequence by 1: 2 DEMUX of the data signal generation part which concerns on Embodiment 1 of this invention. It is a figure explaining the transmission data sequence input from 1: 2 DEMUX to the QPSK modulator of the data signal generation part which concerns on Embodiment 1 of this invention. It is a figure (DP-QPSK modulation) which shows the structure of the data signal generation part which concerns on Embodiment 1 of this invention. It is a figure (QPSK modulation) which shows the structure of the data signal generation part which concerns on Embodiment 2 of this invention. It is a figure (DP-QPSK modulation) which shows the structure of the data signal generation part which concerns on Embodiment 2 of this invention. It is a figure (QPSK modulation) which shows the structure of the data signal generation part which concerns on Embodiment 3 of this invention. It is a figure (DP-QPSK modulation) which shows the structure of the data signal generation part which concerns on Embodiment 3 of this invention. It is a figure which shows the structure of the conventional wavelength division multiplexing optical transmission apparatus (WDM).

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a data signal generation unit according to Embodiment 1 of the present invention. The data signal generation unit can be applied to an optical transmitter using 1: 2 DEMUX 3 that divides one transmission data string into two, and FIG. 1 shows a configuration in the case of the QPSK modulation method as an example. .

  As shown in FIG. 1, the data signal generation unit includes a data output control unit 1, 16: 1 MUX (multiplexer) 2, 1: 2 DEMUX (demultiplexer) 3, capacitors 4 and 5, drivers (electric drivers) 6 and 7, Capacitors 8 and 9, laser diode (LD) 10, QPSK optical modulator (optical modulator) 11, phase shifter 12, driver ON / OFF control unit 13, optical coupler 14, photodiode (PD) 15, and clock phase control unit 16 is composed.

  The data output control unit 1 controls transmission data to the 16: 1 MUX 2. Here, the data output control unit 1 outputs 16 columns of transmission data in a fixed pattern such that one of the two data sequences input to the QPSK optical modulator 11 is an AC pattern and the other is a DC pattern: Output to 1MUX2.

  The 16: 1 MUX 2 aggregates 16 columns of transmission data from the data output control unit 1 and outputs one column of data (transmission data sequence). One data row aggregated by the 16: 1 MUX2 is output to the 1: 2 DEMUX3.

  1: 2 DEMUX 3 divides one data string from 16: 1 MUX 2 into two data strings and outputs them. Here, the 1: 2 DEMUX 3 uses a clock having a frequency f / 2 that is half the frequency f of the data string from the 16: 1 MUX 2 to distribute data every 1 bit at the timing of HI and LOW. Divide the data into columns. The data strings divided by the 1: 2 DEMUX 3 are output to the corresponding capacitors 4 and 5, respectively.

  Capacitors 4 and 5 respectively remove DC components of the data string from 1: 2 DEMUX 3. Data strings from which DC components have been removed by the capacitors 4 and 5 are output to the corresponding drivers 6 and 7, respectively.

  The drivers 6 and 7 amplify the data strings (electric signals) from the corresponding capacitors 4 and 5, respectively. The data strings amplified by the drivers 6 and 7 are output to the corresponding capacitors 8 and 9, respectively.

  Capacitors 8 and 9 remove the DC components of the data strings from the corresponding drivers 6 and 7, respectively. The data string from which the DC component is removed by the capacitors 8 and 9 is output to the QPSK optical modulator 11 as an I-ch and Q-ch data string.

  The laser diode 10 emits light. The light emitted by the laser diode 10 is output to the QPSK optical modulator 11.

  The QPSK optical modulator 11 is an LN optical modulator that QPSK modulates the data string from the capacitors 8 and 9 with light from the laser diode 10. The light modulated by the QPSK optical modulator 11 is output to the outside.

  The phase shifter 12 shifts the phase of the clock input to the 1: 2 DEMUX 3. The phase shifter 12 sets a shift amount according to control by the clock phase control unit 16. In many cases, a general MUX has a built-in phase shifter. In that case, a phase shifter inside the MUX may be used.

  The driver ON / OFF control unit 13 controls output ON / OFF of the drivers 6 and 7.

The optical coupler 14 branches the light from the QPSK optical modulator 11 into two. The light branched by the optical coupler 14 is output to the photodiode 15.
The photodiode 15 photoelectrically converts the light from the optical coupler 14 and monitors its output. The monitoring result by the photodiode 15 is output to the clock phase controller 16.
Note that many common optical modulators have functions of an optical coupler and a photodiode, and in that case, an optical coupler and a photodiode inside the optical modulator may be used.

  The clock phase control unit 16 controls the phase shifter 12 based on the monitoring result by the photodiode 15.

Next, the operation of the data signal generation unit configured as described above will be described.
In the QPSK modulation method, as shown in FIG. 1, 16 columns of transmission data are output as one column with 16: 1 MUX2, and are divided into two columns of data with 1: 2 DEMUX3 and output. The DC component is removed by capacitors 4 and 5 and amplified by drivers 6 and 7. The DC component of the output is again removed by the capacitors 8 and 9, input to the QPSK optical modulator 11 as an I-ch and Q-ch data string, and QPSK modulated by the light of the laser diode 10.

  The I-ch and Q-ch data strings to the QPSK optical modulator 11 are determined by the phase timing of the clock of the frequency f / 2 used for the timing synchronization of 1: 2 DEMUX3. Here, as shown in FIG. 2, when the clock phase timing is inverted, the data strings of I-ch and Q-ch are inverted. If QPSK modulation is performed as it is, the receiving side cannot perform decoding correctly, and data cannot be received. Therefore, it is necessary to input the clock to the 1: 2 DEMUX 3 with correct phase timing.

  Therefore, in order to input the clock to the 1: 2 DEMUX 3 at the correct phase timing, the phase shifter 12 is arranged between the 16: 1 MUX 2 and the 1: 2 DEMUX 3, and the phases of the phase are matched by controlling the phase of the clock.

Next, a control method of the phase shifter 12 will be described.
First, the data output control unit 1 sets the data string to 16: 1 MUX2 as a fixed pattern instead of a conventional random pattern. As an example, as shown in FIG. 3, one output (output 1) of 1: 2 DEMUX 3 becomes an alternating pattern (A) of HI (1) and LOW (0), and the other output (output 2). Are fixed patterns so that all become LOW patterns (B) (that is, the data output control unit 1 transmits 16 columns of transmission data of fixed patterns in which alternating patterns (A) and LOW patterns (B) alternate. To 16: 1 MUX2).

  Thus, when the phase timing of the clock input to the 1: 2 DEMUX 3 is correct, the input to the I-ch is an AC pattern, so there is an optical output from the QPSK optical modulator 11, and the input to the Q-ch is a DC pattern. Therefore, there is no optical output from the QPSK optical modulator 11. When the clock phase timing is incorrect, the outputs of I-ch and Q-ch are reversed.

  When the driver ON / OFF control unit 13 turns off the Q-ch driver 7 and the input to the QPSK optical modulator 11 is only I-ch, the QPSK optical modulator is used when the clock phase timing is correct. When there is an optical output from 11 and the phase timing is incorrect, there is no optical output. Conversely, when the output of the I-ch driver 6 is turned off, the opposite phenomenon occurs.

  Then, with the driver ON / OFF control unit 13 controlling the output ON / OFF of the drivers 6 and 7, the optical output of the QPSK optical modulator 11 is branched by the optical coupler 14, and photoelectrically converted by the photodiode 15. , Input to the clock phase controller 16. In the clock phase control unit 16, there is an optical input when the driver ON / OFF control unit 13 turns off the output of the Q-ch driver 7, and conversely when the output of the I-ch driver 6 is turned off. The phase shifter 12 is controlled so that there is no optical input.

  For example, when the output of the laser diode 10 is 13 dBm, the optical input to the photodiode 15 is 0 dBm or more in the case of AC input, and the optical input to the photodiode 15 is -20 dBm or less in the case of DC input. . Therefore, for example, −10 dBm is set as the threshold value as the detection value of the photodiode 15. Then, if the optical input is −10 dBm or less, no optical input is made. If it is determined that there is an optical input of −10 dBm or more, the phase shifter 12 is driven appropriately.

  As described above, according to the first embodiment, whether or not there is optical output from the QPSK modulator 11 when the fixed pattern transmission data is output to the 16: 1 MUX 2 and the drivers 6 and 7 are turned ON / OFF. Since the phase of the clock input to the 1: 2 DEMUX 3 is controlled, the correct phase timing can be obtained without using information on the receiving side. Therefore, the present invention can also be applied to establishment of long-distance transmission starting from a state in which data is not transmitted between the transmission side and the reception side.

  The present invention is not limited to the case of QPSK modulation using 16: 1 MUX2 and QPSK optical modulator 11 as shown in FIG. 1, but 16: 2 MUX (multiplexer) 17 and DP as shown in FIG. The present invention can also be applied to the case of DP-QPSK modulation using a QPSK optical modulator (optical modulator) 18. In FIG. 4, only main components are illustrated, and the suffix “a” is added to the reference numerals of the constituent elements relating to DATA1, and the suffix “b” is attached to the reference numerals of the constituent elements relating to DATA2.

Embodiment 2. FIG.
A data signal generation unit according to Embodiment 2 of the present invention will be described. This data signal generation unit is different from the data signal generation unit according to the first embodiment in terms of a control method for the phase shifter 12.
That is, in the data signal generation unit of the first embodiment, the phase shifter 12 is controlled based on the optical output from the QPSK optical modulator 11. For this purpose, the driver ON / OFF control unit 13, the optical coupler 14, and the photocoupler are used. A diode 15 is required. On the other hand, the data signal generation unit of the second embodiment controls the phase not by the optical output from the QPSK optical modulator 11 but by the peak detection of the electrical output from the drivers 6 and 7, and thus has a simple configuration. It has become.

  FIG. 5 is a diagram showing the configuration of the data signal generation unit according to Embodiment 2 of the present invention. The data signal generation unit according to the second embodiment shown in FIG. 5 deletes the driver ON / OFF control unit 13, the optical coupler 14, and the photodiode 15 from the data signal generation unit according to the first embodiment shown in FIG. Peak detectors 19 and 20 are added. Other configurations are the same, and the same reference numerals are given and description thereof is omitted.

The peak detectors 19 and 20 monitor the peak of the electrical output from the corresponding drivers 6 and 7, respectively. The monitoring results by the peak detectors 19 and 20 are output to the clock phase controller 16. Some drivers have a built-in peak detection unit. In that case, the peak detection unit inside the driver may be used.
The clock phase control unit 16 controls the phase shifter 12 based on the monitoring results from the peak detection units 19 and 20.

Next, the control method of the phase shifter 12 will be specifically described.
Also in the second embodiment, as in the first embodiment, 16 transmission data are output as one data string with 16: 1 MUX2, and are divided into two data strings with 1: 2 DEMUX3, and output. The DC component of each output is removed by capacitors 4 and 5 and amplified by drivers 6 and 7. The DC component of the output is again removed by the capacitors 8 and 9 and input to the QPSK optical modulator 11 as an I-ch and Q-ch data string.
Here, the data output control unit 1 that controls the data string of 16: 1 MUX2 has a fixed pattern in which the alternating pattern (A) of 0 and 1 and the pattern (B) of all 0 as shown in FIG. Outputs transmission data of frequency f. Thus, when the phase timing of the clock of frequency f / 2 is correct, the input to I-ch is an AC pattern and the input to Q-ch is a DC pattern.

  In the first embodiment, the QPSK-modulated output light is branched by the optical coupler 14 and monitored by the photodiode 15. However, in the second embodiment, the outputs of the drivers 6 and 7 are respectively detected by the peak detector 19. , 20 to discriminate AC output or DC output by peak detection. The clock phase control unit 16 then sets the peak value of the peak detection unit 19 of the driver 6 serving as the input of I-ch to a set voltage value (with output), and the peak detection unit 20 of the driver 7 serving as the input of Q-ch. The phase shifter 12 is controlled so that the peak value of becomes zero (no output).

  As described above, according to the second embodiment, the output peaks of the drivers 6 and 7 are monitored and the phase of the clock input to the 1: 2 DEMUX 3 is controlled. The effect can be obtained, and the configuration can be simplified.

  Note that the present invention is not limited to the case of QPSK modulation using the 16: 1 MUX2 and QPSK optical modulator 11 as shown in FIG. 5, but 16: 2 MUX17 and DP-QPSK optical modulation as shown in FIG. The present invention can also be applied to DP-QPSK modulation using the device 18. In FIG. 6, only the main components are illustrated, and the suffix “a” is attached to the reference numerals of the constituent elements related to DATA1, and the suffix “b” is attached to the reference numerals of the constituent elements related to DATA2.

Embodiment 3 FIG.
A data signal generation unit according to Embodiment 3 of the present invention will be described. This data signal generation unit is different from the data signal generation unit according to the first and second embodiments in terms of a control method for the phase shifter 12.
That is, in the data signal generation unit of the first embodiment, the phase shifter 12 is controlled based on the optical output from the QPSK optical modulator 11. For this purpose, the driver ON / OFF control unit 13, the optical coupler 14, and the photocoupler are used. A diode 15 is required. Further, the data signal generation unit of the second embodiment requires an IC for peak detection or a driver with built-in peak detection. On the other hand, the data signal generation unit of the third embodiment controls the phase by detecting the current consumption of the drivers 6 and 7, and has a simplified configuration.

  FIG. 7 is a diagram showing the configuration of the data signal generation unit according to Embodiment 3 of the present invention. The data signal generation unit according to the third embodiment shown in FIG. 7 deletes the driver ON / OFF control unit 13, the optical coupler 14, and the photodiode 15 from the data signal generation unit according to the first embodiment shown in FIG. Current detection units 21 and 22 are added. Other configurations are the same, and the same reference numerals are given and description thereof is omitted.

The current detection units 21 and 22 monitor current consumption of the corresponding drivers 6 and 7, respectively. The monitoring results by the current detection units 21 and 22 are output to the clock phase control unit 16. Some drivers have a built-in current detection unit. In that case, the current detection unit in the driver may be used.
The clock phase control unit 16 controls the phase shifter 12 based on the monitoring results from the current detection units 21 and 22.

Next, the control method of the phase shifter 12 will be specifically described.
Also in the third embodiment, as in the first embodiment, 16 transmission data is output as one data string with 16: 1 MUX2, and two data strings are divided and output with 1: 2 DEMUX3. The DC component of each output is amplified by drivers 6 and 7 by removing capacitors 4 and 5. The DC component of the output is again removed by the capacitors 8 and 9 and input to the QPSK optical modulator 11 as an I-ch and Q-ch data string.
Here, the data output control unit 1 that controls the data string of 16: 1 MUX2 has a fixed pattern in which the alternating pattern (A) of 0 and 1 and the pattern (B) of all 0 as shown in FIG. Outputs transmission data of frequency f. Thus, when the phase timing of the clock of frequency f / 2 is correct, the input to I-ch is an AC pattern and the input to Q-ch is a DC pattern.

In the first embodiment, the QPSK-modulated output light is branched by the optical coupler 14 and monitored by the photodiode 15. In the second embodiment, the outputs of the drivers 6 and 7 are respectively detected by peak detection. In the third embodiment, the current consumption of the drivers 6 and 7 is monitored by the current detectors 21 and 22 to determine whether the input to the drivers 6 and 7 is AC or DC. Here, in the case of DC input, the electric amplitude input to the drivers 6 and 7 is almost 0, and the operation of the drivers 6 and 7 hardly occurs, so that the current consumption becomes very small. On the other hand, in the case of AC input, there is an electric amplitude to be input to the drivers 6 and 7, and since the drivers 6 and 7 operate normally, the current consumption increases.
Then, the clock phase control unit 16 sets a threshold value in the current detection units 21 and 22 so that the case of DC input and the case of AC input can be discriminated. Then, the phase shifter 12 is controlled so that the current consumption of the current detection unit 21 is equal to or greater than the threshold value and the current consumption of the current detection unit 22 is equal to or less than the threshold value.

  As described above, according to the third embodiment, the current consumption of the drivers 6 and 7 is monitored and the phase of the clock input to the 1: 2 DEMUX 3 is controlled. It is possible to obtain the same effects as those described above and to simplify the configuration.

  The present invention is not limited to the case of QPSK modulation using 16: 1 MUX2 and QPSK optical modulator 11 as shown in FIG. 7, but 16: 2 MUX17 and DP-QPSK optical modulation as shown in FIG. The present invention can also be applied to DP-QPSK modulation using the device 18. In FIG. 8, only the main components are illustrated, and suffix “a” is added to the reference numerals of the constituent elements related to DATA1, and suffix “b” is added to the reference numerals of the constituent elements related to DATA2.

  Further, within the scope of the present invention, the invention of the present application can be freely combined with each embodiment, modified with any component in each embodiment, or omitted with any component in each embodiment. .

  1 Data output control unit, 2 16: 1 MUX (multiplexer), 3 1: 2 DEMUX (demultiplexer), 4, 5, 8, 9 capacitor, 6, 7 driver (electric driver), 10 laser diode (LD), 11 QPSK Optical modulator (optical modulator), 12 phase shifter, 13 driver ON / OFF control unit, 14 optical coupler, 15 photodiode (PD), 16 clock phase control unit, 17 16: 2 MUX (multiplexer), 18 DP-QPSK Optical modulator (optical modulator), 19, 20 Peak detector, 21, 22 Current detector.

Claims (8)

A multiplexer that outputs a data string in which transmission data is aggregated;
A demultiplexer that divides and outputs one data string from the multiplexer into two data strings at a synchronization timing using a clock;
An electric driver for amplifying the data string from the demultiplexer,
An optical modulator that optically modulates the data string amplified by the electric driver;
A data output control unit that outputs transmission data of a fixed pattern in which one of the two data strings input to the optical modulator is an AC pattern and the other is a DC pattern to the multiplexer;
A phase shifter for shifting the phase of the clock;
A driver ON / OFF control unit for controlling output ON / OFF from the electric driver;
An optical coupler for branching light from the optical modulator;
A photodiode for monitoring light branched by the optical coupler;
A clock phase control unit that controls a shift amount of the phase shifter based on a monitoring result by the photodiode in a state where output ON / OFF of the driver is controlled by the driver ON / OFF control unit. Transmitter. A multiplexer that outputs a data string in which transmission data is aggregated;
A demultiplexer that divides and outputs one data string from the multiplexer into two data strings at a synchronization timing using a clock;
An electric driver for amplifying the data string from the demultiplexer;
An optical modulator that optically modulates the data string amplified by the electric driver;
A data output control unit that outputs transmission data of a fixed pattern in which one of the two data strings input to the optical modulator is an AC pattern and the other is a DC pattern to the multiplexer;
A phase shifter for shifting the phase of the clock;
A peak detector for monitoring the peak of the electrical output from the electrical driver;
An optical transmitter comprising: a clock phase control unit that controls a shift amount of the phase shifter based on a monitoring result by the peak detection unit. A multiplexer that outputs a data string in which transmission data is aggregated;
A demultiplexer that divides and outputs one data string from the multiplexer into two data strings at a synchronization timing using a clock;
An electric driver for amplifying the data string from the demultiplexer;
An optical modulator that optically modulates the data string amplified by the electric driver;
A data output control unit that outputs transmission data of a fixed pattern in which one of the two data strings input to the optical modulator is an AC pattern and the other is a DC pattern to the multiplexer;
A phase shifter for shifting the phase of the clock;
A current detector for monitoring current consumption of the electric driver;
An optical transmitter comprising: a clock phase control unit that controls a shift amount of the phase shifter based on a monitoring result by the current detection unit. The multiplexer aggregates 16 rows of transmission data into one data row ,
The optical transmitter according to any one of claims 1 to 3, wherein the optical modulator performs QPSK modulation.   A multiplexer that outputs two lines of data aggregated from transmission data;
  For each of the systems, a demultiplexer that divides and outputs a data string from the multiplexer into two data strings at a synchronization timing using a clock;
  An electric driver for amplifying the data string from the demultiplexer;
  An optical modulator that optically modulates the data string amplified by the electric driver;
  For each of the systems, a data output control unit that outputs, to the multiplexer, fixed pattern transmission data in which one of the two data strings input to the optical modulator is an AC pattern and the other is a DC pattern;
  A phase shifter for shifting the phase of the clock;
  A driver ON / OFF control unit for controlling output ON / OFF from the electric driver;
  An optical coupler for branching light from the optical modulator;
  A photodiode for monitoring light branched by the optical coupler;
  A clock phase control unit for controlling a shift amount of the phase shifter based on a monitoring result by the photodiode in a state where the output ON / OFF of the driver is controlled by the driver ON / OFF control unit;
  With optical transmitter.   A multiplexer that outputs two lines of data aggregated from transmission data;
  For each of the systems, a demultiplexer that divides and outputs a data string from the multiplexer into two data strings at a synchronization timing using a clock;
  An electric driver for amplifying the data string from the demultiplexer;
  An optical modulator that optically modulates the data string amplified by the electric driver;
  For each of the systems, a data output control unit that outputs, to the multiplexer, fixed pattern transmission data in which one of the two data strings input to the optical modulator is an AC pattern and the other is a DC pattern;
  A phase shifter for shifting the phase of the clock;
  A peak detector for monitoring the peak of the electrical output from the electrical driver;
  A clock phase control unit for controlling a shift amount of the phase shifter based on a monitoring result by the peak detection unit;
  With optical transmitter.   A multiplexer that outputs two lines of data aggregated from transmission data;
  For each of the systems, a demultiplexer that divides and outputs a data string from the multiplexer into two data strings at a synchronization timing using a clock;
  An electric driver for amplifying the data string from the demultiplexer;
  An optical modulator that optically modulates the data string amplified by the electric driver;
  For each of the systems, a data output control unit that outputs, to the multiplexer, fixed pattern transmission data in which one of the two data strings input to the optical modulator is an AC pattern and the other is a DC pattern;
  A phase shifter for shifting the phase of the clock;
  A current detector for monitoring current consumption of the electric driver;
  A clock phase control unit for controlling a shift amount of the phase shifter based on a monitoring result by the current detection unit;
  With optical transmitter.   The multiplexer aggregates 16 rows of transmission data into two data rows,
  The optical modulator performs DP-QPSK modulation.
  The optical transmitter according to any one of claims 5 to 7, wherein the optical transmitter is provided.

Images