JP7124374B2 - Optical communication device and its control method - Google Patents

Description

The present invention relates to an optical communication device and its control method, and more particularly to adjustment of a transmission waveform of an optical communication device.

An optical transmission waveform of an optical communication device is adjusted to an optimum waveform mainly by using measuring instruments outside the device during manufacturing. For example, measuring instruments such as an optical power meter, a wavelength system, a communication analyzer, and an optical spectrum analyzer outside the optical communication device are prepared, and optical outputs are input to these measuring instruments. Then, while confirming the state, the drive control circuit, the modulator control circuit, and the coherent DSP (Digital Signal Processor) are individually operated to adjust the optical output waveform to an optimum one.

The number of parameters to be adjusted here is several tens or more, and it is necessary to hold parameter information at the time of adjustment. Furthermore, this adjustment must be made for each modulation scheme of the optical communication device, and the more modulation schemes that are supported, the more time it takes to make the adjustment. Also, the more modulation schemes that are supported, the larger the capacity of the non-volatile memory that stores adjustment parameters.

Japanese Patent Application Laid-Open No. 2002-100000 relates to management control of an optical transceiver module. An optical switch for switching the optical path is inserted in the optical path of the transceiver module, and the optical transceiver circuit of the spare transceiver module is photo-controlled via a variable optical attenuator. It has been proposed to receive the light with a diode. As a result, the correspondence between the control electric signal for the variable optical attenuator and the optical attenuation amount can be held even in the spare transmission/reception module.

WO2009/060522

Due to the recent increase in communication line capacity, there is a growing demand for a higher bit rate per single wavelength. However, in order to transmit high-speed line signals such as 40 Gbps or even 100 Gbps with a single wavelength, it is difficult to obtain sufficient transmission characteristics with conventional intensity modulation/direct detection methods. uses the digital coherent method.

As for modulation schemes, multilevel modulation schemes such as BPSK (Binary Phase Shift Keying), DP-QPSK (Dual Polarization-Quadrature Phase Shift Keying), 8QAM (quadrature amplitude modulation), 16QAM, 32QAM and 64QAM are about to be adopted. In order to support various modulation methods, it is supported as the most important coherent DSP function, but in addition to that, it is important to adjust the optical output according to each modulation method in order to fully utilize its characteristics. Become.

And since there are many adjustment points and the adjustment value or the optimum adjustment value differs for each modulation method, it is necessary to find each adjusted value at the time of manufacture and hold it for operation. be. As a result, since it is necessary to adjust for each modulation scheme, it takes time corresponding to the number of modulation schemes to be supported. In addition, the capacity of the non-volatile memory for holding adjustment values that are different for each modulation method also increases according to the number of supported modulation methods. Therefore, it is important to reduce the adjustment time during manufacturing and to suppress the capacity of the nonvolatile memory for holding adjustment values.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical communication apparatus and a control method thereof that enable automatic adjustment of an optical transmission waveform to an optimum waveform.

To achieve the above object, an optical communication apparatus according to the present invention comprises coherent DSP (Digital Signal Processor) means having a signal quality monitoring function, a modulator for modulating an optical signal to be sent, and a modulator for driving the modulator. modulator drive means; optical switch means for branching an optical signal from the modulator and guiding it to the coherent DSP means; and control means for adjusting and adjusting the state of the modulator.

An optical communication system according to the present invention includes the above-described optical communication device and an optical communication device as a communication partner that is connected to and communicates with the above-described optical communication device via an optical fiber transmission line.

A control method for an optical communication device according to the present invention comprises coherent DSP (Digital Signal Processor) means having a signal quality monitoring function, a modulator for modulating an optical signal to be sent out, and the modulation and optical switch means for branching an optical signal from the modulator and guiding it to the coherent DSP means, comprising:
The modulator driving means is adjusted and the state of the modulator is adjusted according to the monitoring result of the optical signal guided from the modulator.

According to the present invention, it is possible to provide an optical communication device capable of automatically adjusting an optical transmission waveform to an optimum waveform, and a control method thereof.

1 is a configuration diagram for explaining an optical communication system in which the optical communication device of the present invention is used; FIG. 1 is a block diagram of an optical communication device in accordance with a high level embodiment of the present invention; FIG. 1 is a block diagram for explaining an optical transmitter/receiver as an optical communication device according to an embodiment of the present invention; FIG.

Preferred embodiments of the present invention will be described in detail with reference to the drawings. Before describing specific embodiments, optical communication devices according to high-level embodiments of the present invention will be described.

FIG. 1 is a configuration diagram for explaining an optical communication system in which the optical communication device of the present invention is used. FIG. 2 is a block diagram of an optical communication device according to a high level embodiment of the present invention. The optical communication system of FIG. 1 includes an optical communication device 50 and an optical communication device 60 connected to the optical communication device 50 via an optical fiber 70 .

The optical communication device of FIG. 2 includes coherent DSP means 51 , control means 52 , modulator drive means 53 , modulator 54 and optical switch means 55 . The coherent DSP means 51 has a signal quality monitor function. Modulator 54 modulates the optical signal. A modulator driving means 53 drives the modulator 54 . The optical switch means 55 splits the optical signal from the modulator 54 and guides it to the coherent DSP means 51 . The control means 52 adjusts the modulator driving means 53 and the state of the modulator 54 according to the monitoring result of the optical signal guided from the modulator 54 to the coherent DSP means 51 .

According to the optical communication apparatus of FIG. 2, the signal quality monitoring function of the coherent DSP means 51 is used to adjust the modulator driving means 53 according to the monitoring result of the optical signal guided to the coherent DSP means 51. Together, it adjusts the state of the modulator 54 . This enables automatic adjustment of the optical transmission waveform. A more specific embodiment will be described below.

[One embodiment]
FIG. 3 is a block diagram for explaining an optical transmitter/receiver as an optical communication device according to one embodiment of the present invention. The optical transmitter/receiver 100 of FIG. 3 is connected to and communicates with an optical transmitter/receiver of a communication partner via an optical fiber transmission line 101 .

The optical transceiver 100 of FIG. 3 includes a coherent DSP (Digital Signal Processor) 1, a control unit 2, a modulator drive circuit 3, a first ITLA (Integrated Tunable Laser Assembly) 4, a modulator 5, a modulator control It includes a circuit 6 and a first optical switch 7 . Further, the optical transceiver 100 of FIG. 3 includes a nonvolatile memory 8, an ICR (Integrated Coherent Receiver) 10, an ICR control circuit 9, a second ITLA (Integrated Tunable Laser Assembly) 11, a monitor circuit 12, a coupler 13, and a second optical switch 14 .

A modulator drive circuit 3 drives the modulator 5 . A modulator control circuit 6 controls the modulator 5 . A monitor circuit 12 monitors the optical level of the optical path branched from the coupler 13 . The ICR control circuit 9 controls the ICR 10 .

The first ITLA 4 and the second ITLA 11 are wavelength tunable light sources whose frequency can be varied from the outside, and emit laser light having a predetermined wavelength.

The control unit 2 controls the modulator drive circuit 3 , the modulator control circuit 6 , the first optical switch 7 , the second optical switch 14 , the monitor circuit 12 and the ICR control circuit 9 .

(Method for adjusting optical transmission waveform)
A method for adjusting the optical transmission waveform of the optical transmission/reception device 100 of FIG. 3 will be described. After the optical transmitter-receiver 100 of FIG. 3 is powered on, the first optical switch 7 and the second optical switch 14 are operated by the controller 2 until the optical output waveform is stabilized. set in the direction in which the

At this time, if settings are made as described in the following more specific adjustment procedure, the signal quality monitor function of the coherent DSP 1 can monitor the current quality state of the transmission signal. In this state, the signal quality that can be monitored by the coherent DSP 1 by sequentially changing each adjustable parameter of the modulator drive circuit 3 and each adjustable parameter of the modulator control circuit 6 in the desired modulation mode, The optical input level monitored by the monitor circuit 12 branched from the coupler 13 is controlled to the optimum level.

After that, the optical transmitter/receiver 100 of FIG. 3 transmits the main signal on the transmission side to the optical fiber transmission line 101 via the coherent DSP 1, the modulator driving circuit 3, the modulator 5, and the first optical switch 7. . 3 is sent from the optical fiber transmission line 101 to the coherent DSP 1 via the second optical switch 14, the coupler 13, and the ICR 10. FIG. Furthermore, the normal operation of outputting to the outside of the device via the coherent DSP is performed.

(more specific adjustment procedure)
A more specific adjustment procedure for the optical transceiver 100 of FIG. 3 will be described.

(1) Selection of Modulation Mode Information on the modulation mode is obtained from the outside, and adjustment parameters are set in the control section 2 according to the information.

(2) Data signal input from the outside A data signal is input from the outside of the optical transmitter/receiver 100 of FIG.

(3) Set the optical signal loopback state. switch 14.

(4) Temporary adjustment of the optical output of the first ITLA 4, which is the transmission light source, is monitored by the monitor circuit 12 and the optical transmission output is set.

(5) Initial Setting of Modulator 5 Using the initial setting parameters in the nonvolatile memory 8, the modulator drive circuit 3 is adjusted, the modulator control circuit 6 is driven, and the parameters of the modulator 5 are initialized.

(6) Settings on the receiving side (6a) The second ITLA 11, which is a local light source, is set to a desired optical transmission output.

(6b) adjust the output level of the ICR 10; The output level of ICR10 is the input level to coherent DSP1.

(7) Settings on the transmitting side (7a) Adjust the data signal amplitude of the modulator drive circuit 3 using the signal quality monitor function of the coherent DSP 1 . Furthermore, the signal quality monitor function of the coherent DSP 1 is used to adjust the bias of the modulator control circuit 6 .

(7b) The monitor circuit 12 monitors and adjusts the optical transmission output.

(8) Release of optical signal loopback state After confirming that the above parameters satisfy the respective target values, the output (output of modulator 5) on the transmission side of optical transceiver 100 in FIG. The first optical switch 7 and the second optical switch 14 are switched so that the optical signal to the transmission line 101 and from the optical fiber transmission line 101 enters the receiving side (coupler 13).

Parameters relating to the transmission function of the optical transceiver 100 of FIG. 3 include the following. Note that the parameters related to the transmission function are necessary for each modulation mode.
<Sending side>
・Parameters related to optical output bias control (ABC: auto bias control)
・LNOUTMON x2 (X/Y)
・PHDCMON x2 (X/Y)
・Dither x4 (XI/XQ/YI/YQ/XPhase/YPhase)
(Wavelength characteristics) xNumber of wavelengths/optical output/LNOUTMON x2 (X/Y)
・DAC SKEW
<Receiving side>
・LO output (LO: Optical output of Local Oscillator)
・LOS
・OPR
・RX SKEW
・AD input amplitude (description of effect)
According to this embodiment, the following effects are brought about.

The first effect is that the optical output waveform can be adjusted autonomously within the optical transmitter-receiver 100 of FIG. 3, so there is no need to individually adjust and obtain adjustment parameters during manufacturing. Thereby, the time required for adjustment can be suppressed.

The second effect is that the optical transmitter-receiver 100 of FIG. 3 does not need to store adjustment parameters for each modulation scheme, so the capacity of the non-volatile memory can be suppressed.

The first and second effects both contribute to cost reduction when the product is produced.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto. Various modifications are possible within the scope of the invention described in the claims, and it goes without saying that they are also included in the scope of the present invention.

Fields of application of the present invention include optical transmission devices and optical transmission/reception devices in network devices.

1 Coherent DSP
2 control unit 3 modulator drive circuit 4 first ITLA
5 modulator 6 modulator control circuit 7 first optical switch 8 non-volatile memory 9 ICR control circuit 10 ICR
11 Second ITLA
12 monitor circuit 13 coupler 14 second optical switch

Claims (8)

A coherent DSP (Digital Signal Processor) means having a signal quality monitoring function, a modulator for modulating an optical signal to be sent out, a modulator driving means for driving the modulator, and a branching optical signal from the modulator. and optical switch means for guiding to said coherent DSP means, and said modulator driving means according to the monitoring result of the optical signal guided from said modulator.data signal amplitude ofand adjusting the modulatorbias toand a control means for adjusting the fruit,
In adjusting the modulator driving means, it is confirmed that parameters for adjusting the modulator driving means satisfy target values, and the adjustment is completed. ,
Optical communication device. 2. The optical communication device according to claim 1, wherein said control means adjusts the data signal amplitude of said modulator drive means according to said monitor result. further comprising modulator control means for controlling the modulator;
3. The optical communication device according to claim 1, wherein said control means adjusts the bias applied to said modulator by said modulator control means according to said monitoring result. 4. The optical communication device according to any one of claims 1 to 3, further comprising a non-volatile memory that holds parameters for said adjustment for each modulation mode. 5. An optical communication system comprising: the optical communication device according to claim 1 ; and an optical communication device connected to and communicating with said optical communication device via an optical fiber transmission line. . A coherent DSP (Digital Signal Processor) means having a signal quality monitoring function, a modulator for modulating an optical signal to be sent out, a modulator driving means for driving the modulator, and a branching optical signal from the modulator. and optical switch means for guiding to the coherent DSP means,
the modulator driving means in accordance with the monitoring result of the optical signal guided from the modulator;data signal amplitude ofand adjusting the modulatorbias toadjust the death,
In adjusting the modulator driving means, the adjustment is completed by confirming that the parameters for adjusting the modulator driving means satisfy target values. do,
A control method for an optical communication device. 7. The method of controlling an optical communication device according to claim 6 , wherein the data signal amplitude of said modulator driving means is adjusted according to said monitoring result. 8. The method of controlling an optical communication device according to claim 6 , wherein the parameter for said adjustment is held for each modulation mode.

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