WO2019168092A1 - Optical receiver and optical reception method - Google Patents

Optical receiver and optical reception method Download PDF

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Publication number
WO2019168092A1
WO2019168092A1 PCT/JP2019/007791 JP2019007791W WO2019168092A1 WO 2019168092 A1 WO2019168092 A1 WO 2019168092A1 JP 2019007791 W JP2019007791 W JP 2019007791W WO 2019168092 A1 WO2019168092 A1 WO 2019168092A1
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Prior art keywords
optical
signal
optical signal
frequency
determination condition
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PCT/JP2019/007791
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French (fr)
Japanese (ja)
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裕太 五江渕
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日本電気株式会社
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
    • H04B10/077—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using a supervisory or additional signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60—Receivers
    • H04B10/61—Coherent receivers

Definitions

  • the present invention relates to an optical receiver and an optical reception method, and more particularly to an optical receiver and an optical reception method having a function of determining the state of an optical signal to be received.
  • a general optical receiver that receives an optical signal and demodulates a data signal outputs an alarm indicating that the optical signal cannot be detected to the outside of the optical receiver.
  • Such an alarm is called an “optical signal loss alarm” or an “optical signal loss alarm”.
  • the optical signal loss alarm is issued when the power (intensity) of the received optical signal is less than a predetermined threshold, and is canceled when the intensity of the received optical signal is greater than or equal to the threshold. If the intensity of the optical signal falls below a threshold during reception of the optical signal, the optical receiver issues an optical signal loss alarm. When the optical signal loss alarm is issued, for example, the processing of the data signal in the circuit at the subsequent stage of the optical receiver is stopped.
  • the optical receiver determines that the optical signal has been received. As a result, the optical signal loss alarm is canceled. The processing of the data signal is resumed by releasing the optical signal loss alarm.
  • Patent Document 1 discloses a configuration of an optical receiver used in a digital coherent system.
  • Patent Document 2 discloses a configuration in which a bias voltage of an optical modulator is controlled by superimposing a dither signal in an optical transmitter.
  • a general optical receiver uses only the intensity of the received optical signal as a cancellation condition for the optical signal loss alarm. For this reason, even if the received optical signal is an unmodulated optical signal or noise that does not contain data, the optical signal loss alarm is canceled when the intensity exceeds the alarm threshold. As a result, for example, a signal that does not include data is processed after the optical receiver, and abnormal data may be output from the optical receiver. That is, the general optical receiver has a problem that the reception state of the optical signal may not be appropriately determined. (Object of invention) An object of this invention is to provide the technique for determining suitably the reception state of an optical signal.
  • the optical receiver of the present invention is Detecting means for receiving an optical signal modulated by a data signal and detecting a frequency component of the signal superimposed on the optical signal; Photoelectric conversion means for converting the optical signal into an electrical signal and outputting the electrical signal; Control means for determining the content of the predetermined information based on a predetermined determination condition including a first condition relating to the detected frequency component; Is provided.
  • the optical receiving method of the present invention includes: Receiving an optical signal modulated by a data signal; Detecting the frequency component of the signal superimposed on the optical signal; Converting the optical signal into an electrical signal; Determining and determining the content of predetermined information based on a predetermined determination condition including a first condition relating to the detected frequency component; It is characterized by that.
  • the present invention provides an optical receiver and an optical reception method capable of suitably determining the reception state of an optical signal.
  • FIG. 3 is a block diagram illustrating a configuration example of a detection unit 101.
  • FIG. It is a block diagram which shows the structural example of the optical receiver 200 of 2nd Embodiment. It is a block diagram which shows the structural example of the optical transmission system 10 of 3rd Embodiment. It is a block diagram which shows the structural example of the optical receiver 300 of 3rd Embodiment. It is a flowchart which shows the example of the determination procedure of cancellation
  • FIG. 1 is a block diagram illustrating a configuration example of an optical receiver 100 according to the first embodiment of this invention.
  • the optical receiver 100 includes a detection unit 101, a photoelectric conversion unit 102, and a control unit 103.
  • the detection unit 101 serves as a detection unit that receives an optical signal that is modulated by a data signal and on which a signal having a predetermined frequency is superimposed, and that detects a frequency component of the superimposed signal.
  • the photoelectric conversion unit 102 serves as a photoelectric conversion unit that converts an optical signal into an electrical signal and outputs the electrical signal.
  • the photoelectric conversion unit 102 may include a general configuration of a digital coherent receiver (coherent detection unit, photodiode, transimpedance amplifier).
  • a signal (frequency signal) indicating a frequency component included in the optical signal is input from the detection unit 101 to the control unit 103.
  • the control part 103 can know the detected frequency component, the aspect of a frequency signal is arbitrary.
  • the control unit 103 determines the reception state of the optical signal based on the detected frequency component. For example, the control unit 103 determines that a desired optical signal is received when the detected frequency component includes a predetermined frequency. As a result, the optical receiver 100 can suitably determine the reception state of the optical signal.
  • the control unit 103 may output an optical signal loss alarm (LOS) based on the determination result of the optical signal reception state. Further, the control unit 103 may include a predetermined frequency table corresponding to a desired optical signal, and determine whether or not the detected frequency component is a signal based on the predetermined frequency with reference to the table. That is, the control unit 103 determines the content of the predetermined information based on a predetermined determination condition including the first condition regarding the detected frequency component.
  • LOS optical signal loss alarm
  • FIG. 2 is a block diagram illustrating a configuration example of the detection unit 101.
  • the detection unit 101 includes a coupler 111, a light receiving element 112, and an extraction circuit 113.
  • the coupler 111 branches a part of the optical signal input to the optical receiver 100 and outputs it to the light receiving element 112. The remainder of the input optical signal is output to the photoelectric conversion unit 102.
  • the light receiving element 112 is, for example, a photodiode, and converts the optical signal branched by the coupler 111 into an electrical signal.
  • the light receiving element 112 is a relatively low-speed light receiver.
  • the extraction circuit 113 detects the frequency component of the signal superimposed on the optical signal based on the AC component of the electrical signal output from the light receiving element 112.
  • the extraction circuit 113 outputs a signal (frequency signal) indicating the detected frequency component to the control unit 103.
  • the frequency component of the signal superimposed on the optical signal may be based on a dither signal superimposed on the optical signal for bias control of the optical modulator on the optical signal transmission side.
  • the functions of the detection unit 101 and the photoelectric conversion unit 102 may be controlled by the control unit 103.
  • FIG. 3 is a block diagram illustrating a configuration example of the optical receiver 200 according to the second embodiment of this invention.
  • the optical receiver 200 includes a detection unit 101A, a photoelectric conversion unit 102, and a control unit 103.
  • the configuration of the detection unit 101A is basically the same as that of the detection unit 101 of the first embodiment.
  • the light receiving element 112 and the extraction circuit 113 included in the detection unit 101A detect the intensity of the optical signal in addition to the frequency component of the signal superimposed on the optical signal.
  • the configuration and function of the photoelectric conversion unit 102 are the same as those in the first embodiment.
  • the control unit 103 receives a signal (frequency signal) indicating a frequency component included in the optical signal and a signal (optical intensity signal) indicating the intensity of the optical signal from the detection unit 101A.
  • a signal optical intensity signal
  • the detection unit 101A may generate a light intensity signal based on the magnitude of the DC component of the electrical signal generated by the light receiving element 112.
  • the control unit 103 receives the frequency signal and the optical intensity signal from the detection unit 101A, and determines the reception state of the optical signal based on the frequency component and the intensity of the optical signal included in the optical signal.
  • the control unit 103 determines that a desired optical signal is received when the frequency component included in the optical signal has a predetermined frequency and the intensity of the optical signal is equal to or greater than a predetermined threshold.
  • the optical receiver 200 can suitably determine the reception state of the optical signal.
  • the control unit 103 may output an optical signal loss alarm (LOS) based on the determination result of the optical signal reception state.
  • the control unit 103 may include a table of predetermined frequencies and predetermined thresholds corresponding to a desired optical signal, and determine the reception state of the optical signal with reference to the table.
  • the optical receiver 200 determines the reception state based on the frequency component included in the optical signal and the light intensity of the optical signal, thereby comparing the reception state with the optical receiver 100 according to the first embodiment. Can be more suitably determined. For example, when the optical receiver 200 receives an optical signal that includes a predetermined frequency component but has a low intensity and is difficult to demodulate a data signal, the control unit 103 detects an optical signal loss alarm based only on the presence or absence of the frequency component. Can be prevented from being released inappropriately.
  • FIG. 4 is a block diagram illustrating a configuration example of the optical transmission system 10 according to the third embodiment of this invention.
  • the optical transmission system 10 includes an optical transmitter 310 and an optical receiver 300.
  • the optical transmission line 320 connects the optical transmitter 310 and the optical receiver 300.
  • the optical transmitter 310 includes an optical modulator 301 that modulates continuous light, a control circuit 302 that outputs to the optical modulator 301 a data signal that is data for modulating continuous light and a dither signal that is used to control the optical modulator. Is provided.
  • the data signal is a digital signal transmitted by the optical transmission system 10.
  • the data signal is input to the control circuit 302 from the outside of the optical transmitter 310.
  • the optical modulator 301 sends an optical signal modulated with the data signal to the optical transmission line 320.
  • An optical fiber can be used as the optical transmission line 320.
  • the optical modulator 301 is generally composed of an optical waveguide.
  • a technique for superimposing a dither signal on a modulated optical signal for controlling the optical modulator 301 is known.
  • the dither signal is a low-frequency signal having a frequency F0 that is sufficiently slower than the data signal.
  • the amplitude of the dither signal is set so as not to affect the quality of the data signal.
  • the optical signal output from the optical modulator 301 is sent to the optical transmission line 320 with the dither signal superimposed. Therefore, the optical receiver 200 receives the optical signal on which the dither signal is superimposed.
  • the AC component when the output of an optical modulator on which a dither signal is superimposed is detected by a light receiver, the AC component includes a frequency F0 of the dither signal or a frequency 2F0 that is twice that frequency.
  • the optical transmitter can optimally adjust the bias voltage of the optical modulator by controlling the bias voltage of the optical modulator 301 so that the frequency of 2F0 is detected by the light receiver.
  • the optical receiver 300 determines whether the received light includes the F0 or 2F0 frequency based on the frequency of the dither signal as one of the conditions for issuing and canceling the optical signal loss alarm. Use.
  • the optical receiver 300 demodulates the data signal from the optical signal (received light) received from the optical transmission path 320.
  • the optical receiver 300 issues an optical signal loss alarm when it is not determined that the received light is detected, and cancels the optical signal loss alarm when it is determined that the received light is detected.
  • FIG. 5 is a block diagram illustrating a configuration example of the optical receiver 300.
  • the optical receiver 300 receives an optical signal using digital coherent technology.
  • the optical receiver 300 includes a detection unit (Detector, DET) 201, an optical reception circuit 210, and a control unit 203.
  • the detection unit 201 has the same configuration as the detection unit 101A of the second embodiment. That is, the detection unit 201 outputs a signal (frequency signal) indicating a frequency component included in the received light and a signal (light intensity signal) indicating the intensity of the received light to the control unit 203.
  • the optical receiving circuit 210 includes a photoelectric conversion unit 202, a laser diode (LD) 204, and a signal processing unit 205.
  • the laser diode 204 is a local oscillator for coherent detection.
  • the photoelectric conversion unit 202 is an integrated optical receiving circuit, and coherently detects the received light and converts it into an analog data signal.
  • the photoelectric conversion unit 202 is also called a coherent receiver (Integrated Coherent Receiver, ICR).
  • the photoelectric conversion unit 202 includes a 90-degree optical hybrid (HYB) 221, a light receiving element (PD) 222, and an amplifier (TIA) 223.
  • the 90-degree optical hybrid 221 causes the light from the laser diode 204 to interfere with the optical signal input from the detection unit 201, and outputs a beat signal to the light receiving element 222.
  • the 90-degree optical hybrid 221 is also called a coherent detection unit.
  • the light receiving element 222 converts the beat signal into a photocurrent.
  • the amplifier 223 converts the photocurrent input from the light receiving element 222 into a voltage, and outputs an analog data signal.
  • the amplifier 223 is also called a trans-impedance amplifier (Trans-ImpedanceedAmplifier).
  • the analog data signal is output to the control unit 203 and the signal processing unit 205.
  • the configurations and functions of the 90-degree optical hybrid 221, the light receiving element 222, and the amplifier 223 are well known, and details of these configurations are not directly related to the present invention, and thus detailed description thereof is omitted.
  • the signal processing unit 205 includes an analog-to-digital converter (Analog to Digital Converter, ADC) 251 and a digital signal processor (Digital Signal Processor, DSP) 252.
  • the analog-digital converter 251 converts the analog data signal input from the photoelectric conversion unit 202 into a digital signal.
  • the digital signal processor 252 performs dispersion compensation processing and decoding processing on the digital signal input from the analog-digital converter 251, and demodulates and outputs the digital data signal.
  • the digital data signal is a data signal input to the optical transmitter 310. Since the dispersion compensation process and the decoding process in the digital signal processor 252 are general processes performed by a digital coherent optical receiver, detailed description thereof is omitted.
  • control unit 203 determines that the received light is not normally received, the control unit 203 issues an optical signal loss alarm. In the following, the conditions for canceling the optical signal loss alarm being issued will be described.
  • the detection unit 201 outputs a frequency signal indicating the frequency component of the received light and a light intensity signal indicating the intensity of the received light.
  • a frequency signal and a light intensity signal are input to the control unit 203.
  • the control unit 203 detects the intensity of received light from the light intensity signal. If the intensity of the received light is equal to or greater than a predetermined threshold (first threshold), the control unit 203 determines that the condition for canceling the optical signal loss alarm is satisfied with respect to the intensity of the received light.
  • the first threshold is, for example, ⁇ 18 dBm.
  • the control unit 203 detects the presence or absence of the dither signal superimposed by the optical transmitter 310 based on the frequency signal.
  • the detection unit 201 detects a frequency (2F0) twice the dither signal. Therefore, the frequency signal also includes information that a frequency (2F0) twice that of the dither signal has been detected. If the frequency signal indicates that the frequency signal includes 2F0, the control unit 203 determines that the optical signal modulated by the optical transmitter 310 is received. Note that when the bias voltage of the optical modulator 301 is not optimized, the frequency signal includes the frequency (F0) of the dither signal. Therefore, the control unit 203 may determine that the received light is a signal modulated by the optical transmitter 310 if the frequency signal includes the frequency of F0.
  • the control unit 203 detects the amplitude of the analog data signal from the amplitude of the AC component of the analog data signal at the input of the analog-digital converter 251.
  • the amplitude of the analog data signal may be either an average value or a peak-to-peak value. If the amplitude of the analog data signal is equal to or greater than a predetermined threshold (second threshold), the control unit 203 determines that the condition for canceling the optical signal loss alarm is satisfied with respect to the amplitude of the analog data signal.
  • the second threshold is, for example, 500 mVppd (differential peak-to-peak, differential amplitude).
  • the control unit 203 cancels the optical signal loss alarm.
  • the control unit 203 does not cancel the optical signal loss alarm.
  • FIG. 6 is a flowchart showing an example of a determination procedure for canceling the optical signal loss alarm.
  • the control unit 203 issues an optical signal loss alarm.
  • the control unit 203 receives a light intensity signal and a frequency signal from the detection unit 201 (step S02). If the light intensity signal indicates that the intensity of the received light is less than the first threshold (step S03: No), the control unit 203 determines that the received light is not normally received, and an optical signal loss alarm Is not canceled (step S09). If the light intensity signal indicates that the intensity of the received light is greater than or equal to the first threshold (step S03: Yes), the control unit 203 extracts the frequency included in the frequency signal (step S04).
  • step S05: No If the frequency signal does not include the 2F0 frequency (step S05: No), the control unit 203 does not cancel the optical signal loss alarm (step S09).
  • the control unit 203 detects the amplitude of the analog data signal at the input of the analog-digital converter 251 (step S06). As described above, it may be determined in step S05 whether the dither signal includes the frequency F0.
  • step S07: No If the amplitude of the analog data signal is less than the second threshold value (step S07: No), the control unit 203 does not cancel the optical signal loss alarm (step S09). If the amplitude of the analog data signal is greater than or equal to the second threshold (step S07: Yes), the control unit 203 determines that the received light is being received normally, and cancels the optical signal loss alarm (step S08). .
  • control unit 203 may always receive the light intensity signal, the frequency signal, and the analog data signal.
  • the control unit 203 continues to issue an optical signal loss alarm based on the intensity of the received light, the amplitude of the analog data signal, and the frequency component (that is, the dither signal) of the signal superimposed on the received light. Or cancel.
  • the control unit 203 can determine that the received light is an optical signal modulated by the optical transmitter 310. That is, the optical receiver 300 can appropriately determine the reception state of the optical signal, and can cancel the optical signal loss alarm when the optical receiver 300 receives the modulated light.
  • the optical receiver 300 also determines the reception state of the optical signal using the intensity of the received light and the amplitude of the analog data signal. For this reason, it can suppress that the optical signal loss warning is cancelled
  • the cancellation condition of the optical signal loss alarm may be defined only by the amplitude of the analog data signal input to the analog-digital converter 251.
  • an optical transmitter and an optical receiver are arranged on the same plane in order to conform to the specifications of CFP2 (CFP: C-Form-factor Pluggable), which is a standard of MSA (Multi-Source Agreement).
  • CFP2 C-Form-factor Pluggable
  • MSA Multi-Source Agreement
  • the optical receiver 300 of the present embodiment determines the reception state of the optical signal based on the intensity of the received light and the presence or absence of the dither signal in addition to the amplitude of the analog data signal. For this reason, the optical receiver 300 of this embodiment can determine suitably the reception state of an optical signal. Specifically, the optical receiver 300 can suppress erroneous cancellation of the optical signal loss alarm even when the amplitude of the analog data signal increases due to signal interference or signal wraparound.
  • the optical receiver 300 described in the third embodiment receives a wavelength division multiplexing (WDM) optical signal.
  • the configuration of the optical receiver 400 shown in FIG. 7 is the same as that of the third embodiment, but the processing in the control unit 203 is different.
  • the control unit 203 selects the wavelength of the laser diode 204 from the received WDM optical signal so that one optical carrier wave having a desired wavelength including the data signal to be received is received.
  • the detection unit 201 Since the WDM optical signal includes a plurality of optical carriers, the detection unit 201 outputs an optical intensity signal indicating the total intensity of all the optical carriers included in the WDM optical signal. For this reason, when the optical receiver 400 is receiving a WDM optical signal, it is impossible to know the intensity of an optical carrier wave having a desired wavelength from the optical intensity signal output from the detection unit 201. On the other hand, when the low-frequency signal having the frequency F0 is superimposed only on the optical carrier wave of the desired wavelength, the optical carrier wave of the desired wavelength is received by detecting the frequency 2F0 or F0 from the frequency signal. Can be determined. Therefore, in the present embodiment, the control unit 203 determines the reception state of the optical signal based on the frequency signal output from the detection unit 201 and the amplitude of the analog data signal input to the analog-digital converter 251.
  • FIG. 8 is a flowchart showing an example of a determination procedure for canceling the optical signal loss alarm in the present embodiment.
  • step S03 which determines whether the intensity
  • Other procedures are the same as those in FIG.
  • the execution order of steps S05 and S07 may be switched. Moreover, these procedures may be processed in parallel.
  • FIG. 9 is a block diagram illustrating a configuration example of the optical receiver 500 according to the fifth embodiment.
  • a detection unit (TAP) 205 is placed outside the optical reception circuit 210 in place of the detection unit 201. It is different in point.
  • the detection unit 205 is a relatively low-speed light receiver that branches a part of the received light, receives one of the light by a light receiving element, and outputs a light intensity signal indicating the intensity of the received light.
  • the detection unit 205 is also called a tap PD.
  • the other of the branched received light is output to the photoelectric conversion unit 202.
  • the detection unit 205 may have a wavelength selection function.
  • a detection unit 205 having a wavelength selection function outputs a frequency signal and an optical intensity signal of an optical carrier wave having a selected wavelength.
  • the detection unit 205 having a wavelength selection function is realized by, for example, transmitting the branched received light through a wavelength variable filter that can control the transmission wavelength from the outside and receiving the light with a light receiving element.
  • the detection unit 205 can notify the control unit 203 of the intensity of the optical carrier wave of the desired wavelength and the frequency of the dither signal as the light intensity signal and the frequency signal. Therefore, in this case, the optical receiver 500 can cancel or continue the optical signal loss alarm by the procedure based on FIG. 6 of the third embodiment. That is, the detection unit 205 selects an optical carrier wave having a desired wavelength from the WDM optical signal according to an instruction from the control unit 203, and outputs a light intensity signal and a frequency signal to the control unit 203.
  • the control unit 203 obtains the intensity of the optical carrier wave having a desired wavelength from the light intensity signal received from the detection unit 205, and examines the frequency included in the dither signal from the frequency signal (steps S02 to S05 in FIG. 6). Further, the control unit 203 obtains the amplitude of the analog data signal at the input of the analog / digital converter 251 (steps S06 to S07 in FIG. 6). The determination procedure for canceling or continuing the optical signal loss alarm is the same as in FIG.
  • the optical receiver 500 can cancel or continue the optical signal loss alarm according to the procedure of FIG. 8 of the fourth embodiment. That is, the detection unit 205 outputs a frequency signal indicating a frequency component included in the WDM optical signal to the control unit 203.
  • the control unit 203 checks whether or not the frequency signal input from the detection unit 205 includes a frequency (2F0 or F0) corresponding to the dither signal superimposed on the optical carrier wave having a desired wavelength (step S04 in FIG. 8). -S05). Further, the control unit 203 obtains the amplitude of the analog data signal at the input of the analog / digital converter 251 (steps S06 to S07 in FIG. 8).
  • the determination procedure for canceling or continuing the optical signal loss alarm is the same as in FIG.
  • the optical receiver 500 can appropriately determine the reception state of the optical signal and issue and cancel the optical signal loss alarm.
  • the functions and procedures described in the above embodiments may be realized by executing a program by a central processing device (Central Processing Unit, CPU) included in the optical receivers 100, 200, 300, 400, and 500. .
  • the program is recorded on a fixed, non-temporary recording medium.
  • a semiconductor memory or a fixed magnetic disk device is used, but is not limited thereto.
  • the CPU is a computer provided in the control unit 103 or 203, for example, but may be provided in the digital signal processor 252.
  • Appendix 1 Detecting means for receiving an optical signal modulated by a data signal and detecting a frequency component of the signal superimposed on the optical signal; Photoelectric conversion means for converting the optical signal into an electrical signal and outputting the electrical signal; Control means for determining the content of the predetermined information based on a predetermined determination condition including a first condition relating to the detected frequency component; An optical receiver.
  • Appendix 2 The optical receiver according to appendix 1, wherein the control means includes, as the first condition, that the frequency component includes any one of a predetermined frequency and a frequency twice as high as the predetermined frequency.
  • the optical receiver according to appendix 2 wherein the predetermined frequency is a frequency of a dither signal superimposed on an amplitude of the optical signal when the optical signal is transmitted.
  • the detection means further detects the light intensity of the optical signal, The optical receiver according to any one of appendices 1 to 3, wherein the control unit includes the determination condition that the light intensity is equal to or higher than a first threshold value.
  • the photoelectric conversion means outputs the data signal demodulated from the optical signal to the control means, The optical receiver according to any one of appendices 1 to 3, wherein the control means includes, in the determination condition, that an amplitude of the data signal is equal to or greater than a second threshold value.
  • the detection means further detects the light intensity of the optical signal,
  • the control means includes If the determination condition is not satisfied, an alarm indicating that the optical signal is off is issued, Canceling the alarm when the determination condition is satisfied, The optical receiver according to any one of appendices 1 to 7.
  • An optical transmitter that outputs an optical signal modulated by a data signal and a dither signal having a predetermined frequency to an optical transmission line;
  • An optical transmission system comprising: the optical receiver according to any one of appendices 1 to 8 that receives the optical signal from the optical transmission path.
  • Appendix 10 Receiving an optical signal modulated by a data signal; Detecting the frequency component of the signal superimposed on the optical signal; Converting the optical signal into an electrical signal; Determining the content of predetermined information based on a predetermined determination condition including a first condition relating to the detected frequency component; Optical reception method.
  • Appendix 11 The optical reception method according to appendix 10, wherein the first condition includes that the frequency component includes any one of a predetermined frequency and a frequency twice as high as the predetermined frequency.
  • Appendix 12 The optical reception method according to appendix 11, wherein the predetermined frequency is a frequency of a dither signal superimposed on an amplitude of the optical signal when the optical signal is transmitted.
  • Appendix 13 further, Detecting the light intensity of the optical signal; The optical reception method according to any one of appendices 10 to 12, wherein the determination condition includes that the light intensity is equal to or greater than a first threshold value.
  • Optical transmission system 100 200, 300, 400, 500 Optical receiver 101, 101A, 201 Detection unit 102, 202 Photoelectric conversion unit 103, 203 Control unit 111 Coupler 112 Light receiving element 113 Extraction circuit 200 Optical receiver 204 Laser diode ( LD) 205 Detection part (TAP) 210 Optical receiver circuit 221 90-degree optical hybrid 222 Light receiving element (PD) 223 Amplifier (TIA) 251 Analog-to-digital converter (ADC) 252 Digital signal processor (DSP) 301 Optical modulator 302 Control circuit 310 Optical transmitter 320 Optical transmission line

Abstract

This optical receiver, in order to suitably determine the reception state of an optical signal, comprises: a detection unit that receives an optical signal modulated by a data signal and detects a frequency component of a signal superimposed on the optical signal; a photoelectric conversion unit that converts the optical signal into an electrical signal and outputs the same; and a control unit that determines the content of prescribed information on the basis of prescribed determination conditions including a first condition pertaining to the detected frequency component.

Description

光受信機及び光受信方法Optical receiver and optical receiving method
　本発明は光受信機及び光受信方法に関し、特に、受信する光信号の状態を判定する機能を備える光受信機及び光受信方法に関する。 The present invention relates to an optical receiver and an optical reception method, and more particularly to an optical receiver and an optical reception method having a function of determining the state of an optical signal to be received.
　光信号を受信してデータ信号を復調する一般的な光受信機は、受信する光信号が失われると、光信号が検出できないことを示す警報を光受信機の外部へ出力する。このような警報は、「光信号断警報」あるいは「光信号ロス警報」と呼ばれる。光信号ロス警報は、受信する光信号のパワー（強度）が所定の閾値未満の場合に発出され、受信する光信号の強度が当該閾値以上の場合に解除される。光信号の受信中に光信号の強度が閾値未満に低下すると、光受信機は光信号ロス警報を発出する。光信号ロス警報が発出されると、例えば、光受信機の後段の回路におけるデータ信号の処理が停止される。その後、光信号の強度が上昇して警報閾値以上となると、光受信機は、光信号が受信されたと判定する。その結果、光信号ロス警報は解除される。光信号ロス警報の解除により、データ信号の処理が再開される。 When a received optical signal is lost, a general optical receiver that receives an optical signal and demodulates a data signal outputs an alarm indicating that the optical signal cannot be detected to the outside of the optical receiver. Such an alarm is called an “optical signal loss alarm” or an “optical signal loss alarm”. The optical signal loss alarm is issued when the power (intensity) of the received optical signal is less than a predetermined threshold, and is canceled when the intensity of the received optical signal is greater than or equal to the threshold. If the intensity of the optical signal falls below a threshold during reception of the optical signal, the optical receiver issues an optical signal loss alarm. When the optical signal loss alarm is issued, for example, the processing of the data signal in the circuit at the subsequent stage of the optical receiver is stopped. Thereafter, when the intensity of the optical signal increases and becomes equal to or higher than the alarm threshold, the optical receiver determines that the optical signal has been received. As a result, the optical signal loss alarm is canceled. The processing of the data signal is resumed by releasing the optical signal loss alarm.
　本発明に関連して、特許文献１は、デジタルコヒーレント方式で用いられる光受信機の構成を開示する。また、特許文献２は、光送信機においてディザ（dither）信号を重畳することで光変調器のバイアス電圧を制御する構成を開示する。 In connection with the present invention, Patent Document 1 discloses a configuration of an optical receiver used in a digital coherent system. Patent Document 2 discloses a configuration in which a bias voltage of an optical modulator is controlled by superimposing a dither signal in an optical transmitter.
特開２０１０－２４５７７２号公報JP 2010-245772 A 国際公開第２０１６／１０３６３３号International Publication No. 2016/103633
　一般的な光受信機は、光信号ロス警報の解除条件として受信した光信号の強度のみを用いている。このため、受信した光信号がデータを含まない無変調の光信号あるいは雑音であった場合でも、その強度が警報閾値以上となると光信号ロス警報が解除される。その結果、例えば、光受信機の後段でデータを含まない信号が処理され、光受信機から異常なデータが出力される恐れがある。すなわち、一般的な光受信機には、光信号の受信状態を好適に判定できない場合があるという課題があった。
（発明の目的）
　本発明は、光信号の受信状態を好適に判定するための技術を提供することを目的とする。 A general optical receiver uses only the intensity of the received optical signal as a cancellation condition for the optical signal loss alarm. For this reason, even if the received optical signal is an unmodulated optical signal or noise that does not contain data, the optical signal loss alarm is canceled when the intensity exceeds the alarm threshold. As a result, for example, a signal that does not include data is processed after the optical receiver, and abnormal data may be output from the optical receiver. That is, the general optical receiver has a problem that the reception state of the optical signal may not be appropriately determined.
(Object of invention)
An object of this invention is to provide the technique for determining suitably the reception state of an optical signal.
　本発明の光受信機は、
　データ信号により変調された光信号を受信し、前記光信号に重畳された信号の周波数成分を検出する検出手段と、
　前記光信号を電気信号に変換して出力する光電変換手段と、
　前記検出した周波数成分に関する第１の条件を含む所定の判定条件に基づいて所定の情報の内容を決定する制御手段と、
を備える。 The optical receiver of the present invention is
Detecting means for receiving an optical signal modulated by a data signal and detecting a frequency component of the signal superimposed on the optical signal;
Photoelectric conversion means for converting the optical signal into an electrical signal and outputting the electrical signal;
Control means for determining the content of the predetermined information based on a predetermined determination condition including a first condition relating to the detected frequency component;
Is provided.
　本発明の光受信方法は、
　データ信号により変調された光信号を受信し、
　前記光信号に重畳された信号の周波数成分を検出し、
　前記光信号を電気信号に変換し、
　前記検出した周波数成分に関する第１の条件を含む所定の判定条件に基づいて所定の情報の内容を決定判定する、
ことを特徴とする。 The optical receiving method of the present invention includes:
Receiving an optical signal modulated by a data signal;
Detecting the frequency component of the signal superimposed on the optical signal;
Converting the optical signal into an electrical signal;
Determining and determining the content of predetermined information based on a predetermined determination condition including a first condition relating to the detected frequency component;
It is characterized by that.
　本発明は、光信号の受信状態を好適に判定することができる光受信機及び光受信方法を提供する。 The present invention provides an optical receiver and an optical reception method capable of suitably determining the reception state of an optical signal.
第１の実施形態の光受信機１００の構成例を示すブロック図である。It is a block diagram which shows the structural example of the optical receiver 100 of 1st Embodiment. 検出部１０１の構成例を示すブロック図である。3 is a block diagram illustrating a configuration example of a detection unit 101. FIG. 第２の実施形態の光受信機２００の構成例を示すブロック図である。It is a block diagram which shows the structural example of the optical receiver 200 of 2nd Embodiment. 第３の実施形態の光伝送システム１０の構成例を示すブロック図である。It is a block diagram which shows the structural example of the optical transmission system 10 of 3rd Embodiment. 第３の実施形態の光受信機３００の構成例を示すブロック図である。It is a block diagram which shows the structural example of the optical receiver 300 of 3rd Embodiment. 光信号ロス警報の解除の判定手順の例を示すフローチャートである。It is a flowchart which shows the example of the determination procedure of cancellation | release of an optical signal loss warning. 第４の実施形態の光受信機４００の構成例を示すブロック図である。It is a block diagram which shows the structural example of the optical receiver 400 of 4th Embodiment. 光信号ロス警報の解除の判定手順の例を示すフローチャートである。It is a flowchart which shows the example of the determination procedure of cancellation | release of an optical signal loss warning. 第５の実施形態の光受信機５００の構成例を示すブロック図である。It is a block diagram which shows the structural example of the optical receiver 500 of 5th Embodiment.
　（第１の実施形態）
　図１は、本発明の第１の実施形態の光受信機１００の構成例を示すブロック図である。光受信機１００は、検出部１０１、光電変換部１０２及び制御部１０３を備える。検出部１０１は、データ信号により変調され所定の周波数の信号が重畳された光信号を受信し、重畳された信号の周波数成分を検出する、検出手段を担う。光電変換部１０２は、光信号を電気信号に変換して出力する光電変換手段を担う。光電変換部１０２は、デジタルコヒーレント受信機の一般的な構成（コヒーレント検波部、フォトダイオード、トランスインピーダンスアンプ）を含んで構成されてもよい。制御部１０３には、光信号に含まれる周波数成分を示す信号（周波数信号）が検出部１０１から入力される。なお、検出された周波数成分を制御部１０３が知ることができるのであれば、周波数信号の態様は任意である。 (First embodiment)
FIG. 1 is a block diagram illustrating a configuration example of an optical receiver 100 according to the first embodiment of this invention. The optical receiver 100 includes a detection unit 101, a photoelectric conversion unit 102, and a control unit 103. The detection unit 101 serves as a detection unit that receives an optical signal that is modulated by a data signal and on which a signal having a predetermined frequency is superimposed, and that detects a frequency component of the superimposed signal. The photoelectric conversion unit 102 serves as a photoelectric conversion unit that converts an optical signal into an electrical signal and outputs the electrical signal. The photoelectric conversion unit 102 may include a general configuration of a digital coherent receiver (coherent detection unit, photodiode, transimpedance amplifier). A signal (frequency signal) indicating a frequency component included in the optical signal is input from the detection unit 101 to the control unit 103. In addition, as long as the control part 103 can know the detected frequency component, the aspect of a frequency signal is arbitrary.
　制御部１０３は、検出された周波数成分に基づいて光信号の受信状態を判定する。制御部１０３は、例えば、検出された周波数成分が所定の周波数を含む場合に、所望の光信号が受信されていると判定する。その結果、光受信機１００は、光信号の受信状態を好適に判定できる。制御部１０３は光信号の受信状態の判定結果に基づき、光信号ロス警報（ＬＯＳ）を出力してもよい。また、制御部１０３は、所望の光信号に対応する所定の周波数のテーブルを備え、検出された周波数成分が所定の周波数に基づく信号かどうかを、当該テーブルを参照して判定してもよい。すなわち、制御部１０３は、検出した周波数成分に関する第１の条件を含む所定の判定条件に基づいて所定の情報の内容を決定する。 The control unit 103 determines the reception state of the optical signal based on the detected frequency component. For example, the control unit 103 determines that a desired optical signal is received when the detected frequency component includes a predetermined frequency. As a result, the optical receiver 100 can suitably determine the reception state of the optical signal. The control unit 103 may output an optical signal loss alarm (LOS) based on the determination result of the optical signal reception state. Further, the control unit 103 may include a predetermined frequency table corresponding to a desired optical signal, and determine whether or not the detected frequency component is a signal based on the predetermined frequency with reference to the table. That is, the control unit 103 determines the content of the predetermined information based on a predetermined determination condition including the first condition regarding the detected frequency component.
　図２は、検出部１０１の構成例を示すブロック図である。検出部１０１は、カプラ１１１、受光素子１１２、抽出回路１１３を備える。カプラ１１１は、光受信機１００に入力された光信号の一部を分岐して受光素子１１２へ出力する。入力された光信号の残余は光電変換部１０２へ出力される。受光素子１１２は例えばフォトダイオードであり、カプラ１１１で分岐された光信号を電気信号に変換する。受光素子１１２は比較的低速な受光器である。 FIG. 2 is a block diagram illustrating a configuration example of the detection unit 101. The detection unit 101 includes a coupler 111, a light receiving element 112, and an extraction circuit 113. The coupler 111 branches a part of the optical signal input to the optical receiver 100 and outputs it to the light receiving element 112. The remainder of the input optical signal is output to the photoelectric conversion unit 102. The light receiving element 112 is, for example, a photodiode, and converts the optical signal branched by the coupler 111 into an electrical signal. The light receiving element 112 is a relatively low-speed light receiver.
　抽出回路１１３は、受光素子１１２が出力する電気信号の交流成分に基づいて、光信号に重畳された信号の周波数成分を検出する。抽出回路１１３は、検出された周波数成分を示す信号（周波数信号）を、制御部１０３へ出力する。なお、光信号に重畳された信号の周波数成分は、光信号の送信側で光変調器のバイアス制御のために光信号に重畳されるディザ信号に基づくものであってもよい。検出部１０１及び光電変換部１０２の機能は、制御部１０３によって制御されてもよい。 The extraction circuit 113 detects the frequency component of the signal superimposed on the optical signal based on the AC component of the electrical signal output from the light receiving element 112. The extraction circuit 113 outputs a signal (frequency signal) indicating the detected frequency component to the control unit 103. The frequency component of the signal superimposed on the optical signal may be based on a dither signal superimposed on the optical signal for bias control of the optical modulator on the optical signal transmission side. The functions of the detection unit 101 and the photoelectric conversion unit 102 may be controlled by the control unit 103.
　（第２の実施形態）
　図３は、本発明の第２の実施形態の光受信機２００の構成例を示すブロック図である。光受信機２００は、検出部１０１Ａ、光電変換部１０２及び制御部１０３を備える。検出部１０１Ａの構成は、第１の実施形態の検出部１０１と基本的に同様である。ただし、検出部１０１Ａが備える受光素子１１２及び抽出回路１１３は、光信号に重畳された信号の周波数成分に加えて、光信号の強度をも検出する。光電変換部１０２の構成及び機能は第１の実施形態と同様である。 (Second Embodiment)
FIG. 3 is a block diagram illustrating a configuration example of the optical receiver 200 according to the second embodiment of this invention. The optical receiver 200 includes a detection unit 101A, a photoelectric conversion unit 102, and a control unit 103. The configuration of the detection unit 101A is basically the same as that of the detection unit 101 of the first embodiment. However, the light receiving element 112 and the extraction circuit 113 included in the detection unit 101A detect the intensity of the optical signal in addition to the frequency component of the signal superimposed on the optical signal. The configuration and function of the photoelectric conversion unit 102 are the same as those in the first embodiment.
　制御部１０３には、光信号に含まれる周波数成分を示す信号（周波数信号）及び光信号の強度を示す信号（光強度信号）が検出部１０１Ａから入力される。なお、光信号に含まれる周波数成分及び光信号の強度を制御部１０３が知ることができるのであれば、周波数信号及び光強度信号の態様は任意である。検出部１０１Ａは、受光素子１１２が生成する電気信号の直流成分の大きさに基づいて、光強度信号を生成してもよい。 The control unit 103 receives a signal (frequency signal) indicating a frequency component included in the optical signal and a signal (optical intensity signal) indicating the intensity of the optical signal from the detection unit 101A. In addition, as long as the control part 103 can know the frequency component contained in an optical signal, and the intensity | strength of an optical signal, the aspect of a frequency signal and an optical intensity signal is arbitrary. The detection unit 101A may generate a light intensity signal based on the magnitude of the DC component of the electrical signal generated by the light receiving element 112.
　制御部１０３は、検出部１０１Ａから周波数信号及び光強度信号を受信し、光信号に含まれる周波数成分及び光信号の強度に基づいて光信号の受信状態を判定する。制御部１０３は、光信号に含まれる周波数成分が所定の周波数であり、光信号の強度が所定の閾値以上である場合に、所望の光信号が受信されていると判定する。その結果、光受信機２００は、光信号の受信状態を好適に判定することができる。本実施形態においても、制御部１０３は光信号の受信状態の判定結果に基づき、光信号ロス警報（ＬＯＳ）を出力してもよい。また、制御部１０３は、所望の光信号に対応する所定の周波数及び所定の閾値のテーブルを備え、当該テーブルを参照して光信号の受信状態を判定してもよい。 The control unit 103 receives the frequency signal and the optical intensity signal from the detection unit 101A, and determines the reception state of the optical signal based on the frequency component and the intensity of the optical signal included in the optical signal. The control unit 103 determines that a desired optical signal is received when the frequency component included in the optical signal has a predetermined frequency and the intensity of the optical signal is equal to or greater than a predetermined threshold. As a result, the optical receiver 200 can suitably determine the reception state of the optical signal. Also in this embodiment, the control unit 103 may output an optical signal loss alarm (LOS) based on the determination result of the optical signal reception state. The control unit 103 may include a table of predetermined frequencies and predetermined thresholds corresponding to a desired optical signal, and determine the reception state of the optical signal with reference to the table.
　本実施形態の光受信機２００は、光信号に含まれる周波数成分及び光信号の光強度に基づき受信状態を判定することにより、第１の実施形態の光受信機１００と比較して、受信状態をより好適に判定することができる。例えば、光受信機２００は、所定の周波数成分を含むが強度が小さいためデータ信号の復調が困難な光信号を受信した場合に、制御部１０３が周波数成分の有無のみに基づいて光信号ロス警報を不適切に解除することを防ぐことができる。 The optical receiver 200 according to the present embodiment determines the reception state based on the frequency component included in the optical signal and the light intensity of the optical signal, thereby comparing the reception state with the optical receiver 100 according to the first embodiment. Can be more suitably determined. For example, when the optical receiver 200 receives an optical signal that includes a predetermined frequency component but has a low intensity and is difficult to demodulate a data signal, the control unit 103 detects an optical signal loss alarm based only on the presence or absence of the frequency component. Can be prevented from being released inappropriately.
　（第３の実施形態）
　図４は、本発明の第３の実施形態の光伝送システム１０の構成例を示すブロック図である。光伝送システム１０は、光送信機３１０及び光受信機３００を備える。光伝送路３２０は、光送信機３１０と光受信機３００とを接続する。光送信機３１０は、連続光を変調する光変調器３０１と、連続光を変調するデータであるデータ信号及び光変調器の制御に用いられるディザ信号を光変調器３０１へ出力する制御回路３０２とを備える。 (Third embodiment)
FIG. 4 is a block diagram illustrating a configuration example of the optical transmission system 10 according to the third embodiment of this invention. The optical transmission system 10 includes an optical transmitter 310 and an optical receiver 300. The optical transmission line 320 connects the optical transmitter 310 and the optical receiver 300. The optical transmitter 310 includes an optical modulator 301 that modulates continuous light, a control circuit 302 that outputs to the optical modulator 301 a data signal that is data for modulating continuous light and a dither signal that is used to control the optical modulator. Is provided.
　データ信号は、光伝送システム１０によって伝送されるデジタル信号である。データ信号は光送信機３１０の外部から制御回路３０２に入力される。光変調器３０１は、データ信号で変調された光信号を光伝送路３２０へ送出する。光伝送路３２０として光ファイバを用いることができる。 The data signal is a digital signal transmitted by the optical transmission system 10. The data signal is input to the control circuit 302 from the outside of the optical transmitter 310. The optical modulator 301 sends an optical signal modulated with the data signal to the optical transmission line 320. An optical fiber can be used as the optical transmission line 320.
　光変調器３０１は、一般に、光導波路で構成される。光変調器３０１の制御のために、ディザ信号を変調された光信号に重畳する技術が知られている。ディザ信号は、データ信号よりも充分に低速な周波数Ｆ０の低周波信号である。ディザ信号の振幅はデータ信号の品質に影響を与えないように設定される。光変調器３０１から出力される光信号は、ディザ信号が重畳されたまま光伝送路３２０へ送出される。従って、光受信機２００は、ディザ信号が重畳された光信号を受信する。 The optical modulator 301 is generally composed of an optical waveguide. A technique for superimposing a dither signal on a modulated optical signal for controlling the optical modulator 301 is known. The dither signal is a low-frequency signal having a frequency F0 that is sufficiently slower than the data signal. The amplitude of the dither signal is set so as not to affect the quality of the data signal. The optical signal output from the optical modulator 301 is sent to the optical transmission line 320 with the dither signal superimposed. Therefore, the optical receiver 200 receives the optical signal on which the dither signal is superimposed.
　特許文献２に記載されるように、ディザ信号が重畳された光変調器の出力を受光器で検出すると、その交流成分にはディザ信号の周波数Ｆ０又はその２倍の周波数２Ｆ０が含まれる。そして、光送信機は、受光器で２Ｆ０の周波数が検出されるように光変調器３０１のバイアス電圧を制御することで、光変調器のバイアス電圧を最適に調整できる。後述するように、本実施形態の光受信機３００は、ディザ信号の周波数に基づくＦ０又は２Ｆ０の周波数が受信光に含まれるかどうかを、光信号ロス警報の発出及び解除の条件の１つとして用いる。 As described in Patent Document 2, when the output of an optical modulator on which a dither signal is superimposed is detected by a light receiver, the AC component includes a frequency F0 of the dither signal or a frequency 2F0 that is twice that frequency. The optical transmitter can optimally adjust the bias voltage of the optical modulator by controlling the bias voltage of the optical modulator 301 so that the frequency of 2F0 is detected by the light receiver. As will be described later, the optical receiver 300 according to the present embodiment determines whether the received light includes the F0 or 2F0 frequency based on the frequency of the dither signal as one of the conditions for issuing and canceling the optical signal loss alarm. Use.
　光受信機３００は、光伝送路３２０から受信した光信号（受信光）からデータ信号を復調する。光受信機３００は、受信光が検出されたと判定されない場合は光信号ロス警報を発出し、受信光が検出されたと判定された場合は光信号ロス警報を解除する。 The optical receiver 300 demodulates the data signal from the optical signal (received light) received from the optical transmission path 320. The optical receiver 300 issues an optical signal loss alarm when it is not determined that the received light is detected, and cancels the optical signal loss alarm when it is determined that the received light is detected.
　図５は、光受信機３００の構成例を示すブロック図である。光受信機３００は、デジタルコヒーレント技術を用いて光信号を受信する。光受信機３００は、検出部（Detector、DET）２０１、光受信回路２１０及び制御部２０３を備える。検出部２０１は、第２の実施形態の検出部１０１Ａと同様の構成を備える。すなわち、検出部２０１は、受信光に含まれる周波数成分を示す信号（周波数信号）及び受信光の強度を示す信号（光強度信号）を制御部２０３に出力する。 FIG. 5 is a block diagram illustrating a configuration example of the optical receiver 300. The optical receiver 300 receives an optical signal using digital coherent technology. The optical receiver 300 includes a detection unit (Detector, DET) 201, an optical reception circuit 210, and a control unit 203. The detection unit 201 has the same configuration as the detection unit 101A of the second embodiment. That is, the detection unit 201 outputs a signal (frequency signal) indicating a frequency component included in the received light and a signal (light intensity signal) indicating the intensity of the received light to the control unit 203.
　光受信回路２１０は、光電変換部２０２、レーザダイオード（Laser Diode、LD）２０４及び信号処理部２０５を備える。レーザダイオード２０４は、コヒーレント検波のための局部発振器である。 The optical receiving circuit 210 includes a photoelectric conversion unit 202, a laser diode (LD) 204, and a signal processing unit 205. The laser diode 204 is a local oscillator for coherent detection.
　光電変換部２０２は集積化された光受信回路であり、受信光をコヒーレント検波してアナログデータ信号に変換する。光電変換部２０２は、コヒーレントレシーバ（Integrated Coherent Receiver、ICR）とも呼ばれる。光電変換部２０２は、９０度光ハイブリッド（HYB）２２１、受光素子（PD）２２２及び増幅器（TIA）２２３を備える。９０度光ハイブリッド２２１は、レーザダイオード２０４からの光と、検出部２０１から入力された光信号をと干渉させ、ビート信号を受光素子２２２へ出力する。９０度光ハイブリッド２２１は、コヒーレント検波部とも呼ばれる。受光素子２２２はビート信号を光電流に変換する。増幅器２２３は、受光素子２２２から入力された光電流を電圧に変換し、アナログデータ信号を出力する。増幅器２２３は、トランスインピーダンス増幅器（Trans-Impedance Amplifier）とも呼ばれる。アナログデータ信号は、制御部２０３及び信号処理部２０５へ出力される。９０度光ハイブリッド２２１、受光素子２２２及び増幅器２２３の構成及び機能はよく知られており、また、これらの構成の詳細は本発明とは直接関係しないため詳細な説明は省略する。 The photoelectric conversion unit 202 is an integrated optical receiving circuit, and coherently detects the received light and converts it into an analog data signal. The photoelectric conversion unit 202 is also called a coherent receiver (Integrated Coherent Receiver, ICR). The photoelectric conversion unit 202 includes a 90-degree optical hybrid (HYB) 221, a light receiving element (PD) 222, and an amplifier (TIA) 223. The 90-degree optical hybrid 221 causes the light from the laser diode 204 to interfere with the optical signal input from the detection unit 201, and outputs a beat signal to the light receiving element 222. The 90-degree optical hybrid 221 is also called a coherent detection unit. The light receiving element 222 converts the beat signal into a photocurrent. The amplifier 223 converts the photocurrent input from the light receiving element 222 into a voltage, and outputs an analog data signal. The amplifier 223 is also called a trans-impedance amplifier (Trans-ImpedanceedAmplifier). The analog data signal is output to the control unit 203 and the signal processing unit 205. The configurations and functions of the 90-degree optical hybrid 221, the light receiving element 222, and the amplifier 223 are well known, and details of these configurations are not directly related to the present invention, and thus detailed description thereof is omitted.
　信号処理部２０５は、アナログデジタル変換器（Analog to Digital Converter、ADC）２５１及びデジタル信号処理器（Digital Signal Processor、DSP）２５２を備える。アナログデジタル変換器２５１は、光電変換部２０２から入力されたアナログデータ信号をデジタル信号に変換する。デジタル信号処理器２５２は、アナログデジタル変換器２５１から入力されるデジタル信号に対して分散補償処理や復号処理を行い、デジタルデータ信号を復調して出力する。デジタルデータ信号は、光送信機３１０に入力されたデータ信号である。デジタル信号処理器２５２における分散補償処理や復号処理はデジタルコヒーレント方式の光受信機が行う一般的な処理であるので詳細な説明は省略する。 The signal processing unit 205 includes an analog-to-digital converter (Analog to Digital Converter, ADC) 251 and a digital signal processor (Digital Signal Processor, DSP) 252. The analog-digital converter 251 converts the analog data signal input from the photoelectric conversion unit 202 into a digital signal. The digital signal processor 252 performs dispersion compensation processing and decoding processing on the digital signal input from the analog-digital converter 251, and demodulates and outputs the digital data signal. The digital data signal is a data signal input to the optical transmitter 310. Since the dispersion compensation process and the decoding process in the digital signal processor 252 are general processes performed by a digital coherent optical receiver, detailed description thereof is omitted.
　制御部２０３は、受信光が正常に受信されないと判定した場合、光信号ロス警報を発出する。以下では、発出中の光信号ロス警報が解除される条件について説明する。 When the control unit 203 determines that the received light is not normally received, the control unit 203 issues an optical signal loss alarm. In the following, the conditions for canceling the optical signal loss alarm being issued will be described.
　（１）検出部２０１は、受信光の周波数成分を示す周波数信号及び受信光の強度を示す光強度信号を出力する。制御部２０３には、周波数信号及び光強度信号が入力される。制御部２０３は、光強度信号から受信光の強度を検出する。受信光の強度が所定の閾値（第１の閾値）以上であれば、制御部２０３は、受信光の強度に関しては光信号ロス警報の解除条件を満たしていると判定する。第１の閾値は、例えば、－１８ｄＢｍである。 (1) The detection unit 201 outputs a frequency signal indicating the frequency component of the received light and a light intensity signal indicating the intensity of the received light. A frequency signal and a light intensity signal are input to the control unit 203. The control unit 203 detects the intensity of received light from the light intensity signal. If the intensity of the received light is equal to or greater than a predetermined threshold (first threshold), the control unit 203 determines that the condition for canceling the optical signal loss alarm is satisfied with respect to the intensity of the received light. The first threshold is, for example, −18 dBm.
　（２）また、制御部２０３は、光送信機３１０で重畳されたディザ信号の有無を周波数信号に基づいて検出する。光送信機３１０のバイアス電圧が最適化されている場合には、検出部２０１ではディザ信号の２倍の周波数（２Ｆ０）が検出される。従って、周波数信号にも、ディザ信号の２倍の周波数（２Ｆ０）が検出されたという情報が含まれる。そして、制御部２０３は、周波数信号が２Ｆ０の周波数を含むことを示していれば、光送信機３１０で変調された光信号が受信されていると判定する。なお、光変調器３０１のバイアス電圧が最適化されていない場合には、ディザ信号の周波数（Ｆ０）が周波数信号に含まれる。従って、制御部２０３は、周波数信号にＦ０の周波数が含まれていれば、受信光は光送信機３１０で変調された信号であると判定してもよい。 (2) Further, the control unit 203 detects the presence or absence of the dither signal superimposed by the optical transmitter 310 based on the frequency signal. When the bias voltage of the optical transmitter 310 is optimized, the detection unit 201 detects a frequency (2F0) twice the dither signal. Therefore, the frequency signal also includes information that a frequency (2F0) twice that of the dither signal has been detected. If the frequency signal indicates that the frequency signal includes 2F0, the control unit 203 determines that the optical signal modulated by the optical transmitter 310 is received. Note that when the bias voltage of the optical modulator 301 is not optimized, the frequency signal includes the frequency (F0) of the dither signal. Therefore, the control unit 203 may determine that the received light is a signal modulated by the optical transmitter 310 if the frequency signal includes the frequency of F0.
　（３）さらに、制御部２０３は、アナログデジタル変換器２５１の入力におけるアナログデータ信号の交流成分の振幅から、アナログデータ信号の振幅を検出する。アナログデータ信号の振幅は、平均値及びpeak to peak値のいずれでもよい。アナログデータ信号の振幅が所定の閾値（第２の閾値）以上であれば、制御部２０３は、アナログデータ信号の振幅に関しては光信号ロス警報の解除条件を満たしていると判定する。第２の閾値は、例えば５００ｍＶｐｐｄ（differential peak-to-peak、差動振幅）である。 (3) Further, the control unit 203 detects the amplitude of the analog data signal from the amplitude of the AC component of the analog data signal at the input of the analog-digital converter 251. The amplitude of the analog data signal may be either an average value or a peak-to-peak value. If the amplitude of the analog data signal is equal to or greater than a predetermined threshold (second threshold), the control unit 203 determines that the condition for canceling the optical signal loss alarm is satisfied with respect to the amplitude of the analog data signal. The second threshold is, for example, 500 mVppd (differential peak-to-peak, differential amplitude).
　上記の（１）乃至（３）で説明した光信号ロス警報の解除条件が全て満たされた場合に、制御部２０３は、光信号ロス警報を解除する。（１）乃至（３）の光信号ロス警報の解除条件の少なくとも１つが満たされない場合には、制御部２０３は、光信号ロス警報を解除しない。 When all the conditions for canceling the optical signal loss alarm described in (1) to (3) above are satisfied, the control unit 203 cancels the optical signal loss alarm. When at least one of the optical signal loss alarm cancellation conditions (1) to (3) is not satisfied, the control unit 203 does not cancel the optical signal loss alarm.
　図６は、上記の光信号ロス警報の解除の判定手順の例を示すフローチャートである。手順の開始時点では光受信機３００には光信号が入力されておらず、制御部２０３は光信号ロス警報を発出している。光受信機３００に光信号が入力されると（図６のステップＳ０１）、制御部２０３は、検出部２０１から光強度信号及び周波数信号を受信する（ステップＳ０２）。受信光の強度が第１の閾値未満であることを光強度信号が示していれば（ステップＳ０３：Ｎｏ）、制御部２０３は受信光が正常に受信されていないと判定し、光信号ロス警報を解除しない（ステップＳ０９）。受信光の強度が第１の閾値以上であることを光強度信号が示していれば（ステップＳ０３：Ｙｅｓ）、制御部２０３は、周波数信号に含まれる周波数を抽出する（ステップＳ０４）。 FIG. 6 is a flowchart showing an example of a determination procedure for canceling the optical signal loss alarm. At the start of the procedure, no optical signal is input to the optical receiver 300, and the control unit 203 issues an optical signal loss alarm. When an optical signal is input to the optical receiver 300 (step S01 in FIG. 6), the control unit 203 receives a light intensity signal and a frequency signal from the detection unit 201 (step S02). If the light intensity signal indicates that the intensity of the received light is less than the first threshold (step S03: No), the control unit 203 determines that the received light is not normally received, and an optical signal loss alarm Is not canceled (step S09). If the light intensity signal indicates that the intensity of the received light is greater than or equal to the first threshold (step S03: Yes), the control unit 203 extracts the frequency included in the frequency signal (step S04).
　周波数信号に２Ｆ０の周波数が含まれていない場合は（ステップＳ０５：Ｎｏ）、制御部２０３は、光信号ロス警報を解除しない（ステップＳ０９）。周波数信号に２Ｆ０の周波数が含まれている場合は（ステップＳ０５：Ｎｏ）、制御部２０３は、アナログデジタル変換器２５１の入力におけるアナログデータ信号の振幅を検出する（ステップＳ０６）。なお、上述したように、ステップＳ０５においてディザ信号にＦ０の周波数が含まれているかどうかを判定してもよい。 If the frequency signal does not include the 2F0 frequency (step S05: No), the control unit 203 does not cancel the optical signal loss alarm (step S09). When the frequency signal includes the frequency of 2F0 (step S05: No), the control unit 203 detects the amplitude of the analog data signal at the input of the analog-digital converter 251 (step S06). As described above, it may be determined in step S05 whether the dither signal includes the frequency F0.
　アナログデータ信号の振幅が第２の閾値未満であれば（ステップＳ０７：Ｎｏ）、制御部２０３は、光信号ロス警報を解除しない（ステップＳ０９）。アナログデータ信号の振幅が第２の閾値以上であれば（ステップＳ０７：Ｙｅｓ）、制御部２０３は、受信光が正常に受信されていると判定し、光信号ロス警報を解除する（ステップＳ０８）。 If the amplitude of the analog data signal is less than the second threshold value (step S07: No), the control unit 203 does not cancel the optical signal loss alarm (step S09). If the amplitude of the analog data signal is greater than or equal to the second threshold (step S07: Yes), the control unit 203 determines that the received light is being received normally, and cancels the optical signal loss alarm (step S08). .
　なお、Ｓ０３、Ｓ０５及びＳ０７の実施順序は、図６の例に限定されない。また、これらの手順が並列に処理されてもよい。制御部２０３は、光強度信号、周波数信号及びアナログデータ信号を常時受信してもよい。 In addition, the execution order of S03, S05, and S07 is not limited to the example of FIG. Moreover, these procedures may be processed in parallel. The control unit 203 may always receive the light intensity signal, the frequency signal, and the analog data signal.
　以上説明したように、制御部２０３は、受信光の強度、アナログデータ信号の振幅及び受信光に重畳された信号の周波数成分（すなわち、ディザ信号）に基づいて、光信号ロス警報の発出を継続しあるいは解除する。ディザ信号を検出することで、制御部２０３は、受信光が、光送信機３１０で変調された光信号であると判定できる。すなわち、光受信機３００は、光信号の受信状態を好適に判定し、光受信機３００が変調された光を受信した場合に光信号ロス警報を解除できる。また、光受信機３００は受信光の強度及びアナログデータ信号の振幅をも用いて光信号の受信状態を判定する。このため、２Ｆ０又はＦ０の周波数を含む雑音によって光信号ロス警報が誤って解除されることを抑制できる。 As described above, the control unit 203 continues to issue an optical signal loss alarm based on the intensity of the received light, the amplitude of the analog data signal, and the frequency component (that is, the dither signal) of the signal superimposed on the received light. Or cancel. By detecting the dither signal, the control unit 203 can determine that the received light is an optical signal modulated by the optical transmitter 310. That is, the optical receiver 300 can appropriately determine the reception state of the optical signal, and can cancel the optical signal loss alarm when the optical receiver 300 receives the modulated light. The optical receiver 300 also determines the reception state of the optical signal using the intensity of the received light and the amplitude of the analog data signal. For this reason, it can suppress that the optical signal loss warning is cancelled | released accidentally by the noise containing the frequency of 2F0 or F0.
　一般的な光トランシーバにおいては、光信号ロス警報の解除条件がアナログデジタル変換器２５１に入力されるアナログデータ信号の振幅のみで規定される場合がある。一方、近年の光トランシーバでは、ＭＳＡ（Multi-Source Agreement）の規格であるＣＦＰ２（CFP：C Form-factor Pluggable）に仕様を準拠させるために、光送信機と光受信機とが同一平面に並ぶようなピン配列が用いられる。この場合、光送受信機間の電気信号の干渉や、光送信機から光受信機への信号の回り込みの影響で、受信光がない状況であってもアナログデータ信号に雑音が重畳され、光信号ロス警報が誤って解除される場合がある。 In a general optical transceiver, the cancellation condition of the optical signal loss alarm may be defined only by the amplitude of the analog data signal input to the analog-digital converter 251. On the other hand, in recent optical transceivers, an optical transmitter and an optical receiver are arranged on the same plane in order to conform to the specifications of CFP2 (CFP: C-Form-factor Pluggable), which is a standard of MSA (Multi-Source Agreement). Such a pin arrangement is used. In this case, noise is superimposed on the analog data signal even in the absence of received light due to the interference of electrical signals between the optical transceivers and the influence of the signal from the optical transmitter to the optical receiver. The loss alarm may be canceled by mistake.
　本実施形態の光受信機３００は、アナログデータ信号の振幅に加えて、受信光の強度及びディザ信号の有無に基づいて光信号の受信状態を判定する。このため、本実施形態の光受信機３００は、光信号の受信状態を好適に判定することができる。具体的には、光受信機３００は、信号の干渉や信号の回り込みの影響でアナログデータ信号の振幅が増加した場合でも、光信号ロス警報が誤って解除されることを抑制できる。 The optical receiver 300 of the present embodiment determines the reception state of the optical signal based on the intensity of the received light and the presence or absence of the dither signal in addition to the amplitude of the analog data signal. For this reason, the optical receiver 300 of this embodiment can determine suitably the reception state of an optical signal. Specifically, the optical receiver 300 can suppress erroneous cancellation of the optical signal loss alarm even when the amplitude of the analog data signal increases due to signal interference or signal wraparound.
　（第４の実施形態）
　第４の実施形態では、第３の実施形態で説明した光受信機３００が、波長分割多重（Wavelength Division Multiplexing、WDM）光信号を受信する場合について説明する。図７に示す光受信機４００の構成は第３の実施形態と同様であるが、制御部２０３における処理が異なる。本実施形態において、制御部２０３は、受信したＷＤＭ光信号から、受信したいデータ信号を含む所望の波長の１つの光搬送波が受信されるように、レーザダイオード２０４の波長を選択する。 (Fourth embodiment)
In the fourth embodiment, a case will be described in which the optical receiver 300 described in the third embodiment receives a wavelength division multiplexing (WDM) optical signal. The configuration of the optical receiver 400 shown in FIG. 7 is the same as that of the third embodiment, but the processing in the control unit 203 is different. In the present embodiment, the control unit 203 selects the wavelength of the laser diode 204 from the received WDM optical signal so that one optical carrier wave having a desired wavelength including the data signal to be received is received.
　ＷＤＭ光信号は複数の光搬送波を含むため、検出部２０１はＷＤＭ光信号に含まれる全ての光搬送波の合計の強度を示す光強度信号を出力する。このため、光受信機４００がＷＤＭ光信号を受信している場合には、検出部２０１から出力される光強度信号からは所望の波長の光搬送波の強度を知ることができない。一方、所望の波長の光搬送波のみに周波数Ｆ０の低周波信号が重畳されている場合には、周波数信号から２Ｆ０又はＦ０の周波数が検出されることで、所望の波長の光搬送波が受信されていると判定できる。従って、本実施形態では、制御部２０３は、検出部２０１から出力される周波数信号及びアナログデジタル変換器２５１へ入力されるアナログデータ信号の振幅に基づいて光信号の受信状態を判定する。 Since the WDM optical signal includes a plurality of optical carriers, the detection unit 201 outputs an optical intensity signal indicating the total intensity of all the optical carriers included in the WDM optical signal. For this reason, when the optical receiver 400 is receiving a WDM optical signal, it is impossible to know the intensity of an optical carrier wave having a desired wavelength from the optical intensity signal output from the detection unit 201. On the other hand, when the low-frequency signal having the frequency F0 is superimposed only on the optical carrier wave of the desired wavelength, the optical carrier wave of the desired wavelength is received by detecting the frequency 2F0 or F0 from the frequency signal. Can be determined. Therefore, in the present embodiment, the control unit 203 determines the reception state of the optical signal based on the frequency signal output from the detection unit 201 and the amplitude of the analog data signal input to the analog-digital converter 251.
　図８は、本実施形態における、光信号ロス警報の解除の判定手順の例を示すフローチャートである。図８は、図６と比較して、ステップＳ０２において周波数信号のみが受信される。また、受信光の強度が第１の閾値未満であるかどうかを判定する手順（ステップＳ０３）が省略されている。それ以外の手順は、図６と同様である。ステップＳ０５及びＳ０７の実施順序は入れ替わってもよい。また、これらの手順が並列に処理されてもよい。 FIG. 8 is a flowchart showing an example of a determination procedure for canceling the optical signal loss alarm in the present embodiment. In FIG. 8, compared with FIG. 6, only the frequency signal is received in step S02. Moreover, the procedure (step S03) which determines whether the intensity | strength of received light is less than a 1st threshold value is abbreviate | omitted. Other procedures are the same as those in FIG. The execution order of steps S05 and S07 may be switched. Moreover, these procedures may be processed in parallel.
　（第５の実施形態）
　図９は、第５の実施形態の光受信機５００の構成例を示すブロック図である。光受信機５００は、第３及び第４の実施形態の光受信機３００及び４００と比較して、検出部２０１に代えて検出部（TAP）２０５が光受信回路２１０の外部に置かれている点で相違する。検出部２０５は、受信光の一部を分岐して一方を受光素子で受光し、受信光の強度を示す光強度信号を出力する比較的低速な受光器である。検出部２０５は、タップＰＤとも呼ばれる。分岐された受信光の他方は光電変換部２０２へ出力される。検出部２０５は、波長選択機能を備えてもよい。波長選択機能を備える検出部２０５は、選択された波長の光搬送波の周波数信号及び光強度信号を出力する。波長選択機能を備える検出部２０５は、例えば、分岐された受信光を、外部から透過波長を制御できる波長可変フィルタを透過させて受光素子で受信することで実現される。 (Fifth embodiment)
FIG. 9 is a block diagram illustrating a configuration example of the optical receiver 500 according to the fifth embodiment. In the optical receiver 500, as compared with the optical receivers 300 and 400 of the third and fourth embodiments, a detection unit (TAP) 205 is placed outside the optical reception circuit 210 in place of the detection unit 201. It is different in point. The detection unit 205 is a relatively low-speed light receiver that branches a part of the received light, receives one of the light by a light receiving element, and outputs a light intensity signal indicating the intensity of the received light. The detection unit 205 is also called a tap PD. The other of the branched received light is output to the photoelectric conversion unit 202. The detection unit 205 may have a wavelength selection function. A detection unit 205 having a wavelength selection function outputs a frequency signal and an optical intensity signal of an optical carrier wave having a selected wavelength. The detection unit 205 having a wavelength selection function is realized by, for example, transmitting the branched received light through a wavelength variable filter that can control the transmission wavelength from the outside and receiving the light with a light receiving element.
　検出部２０５が波長選択機能を備える場合には、検出部２０５は、所望の波長の光搬送波の強度及びディザ信号の周波数を光強度信号及び周波数信号として制御部２０３に通知できる。従って、この場合、光受信機５００は、第３の実施形態の図６に基づく手順により光信号ロス警報を解除しあるいは継続できる。すなわち、検出部２０５は、制御部２０３からの指示によりＷＤＭ光信号から所望の波長の光搬送波を選択して、光強度信号及び周波数信号を制御部２０３へ出力する。制御部２０３は、検出部２０５から受信した光強度信号から所望の波長の光搬送波の強度を求め、周波数信号からディザ信号に含まれる周波数を調べる（図６のステップＳ０２－Ｓ０５）。また、制御部２０３は、アナログデジタル変換器２５１の入力におけるアナログデータ信号の振幅を求める（図６のステップＳ０６－Ｓ０７）。光信号ロス警報を解除しあるいは継続する判定の手順も図６と同様である。 When the detection unit 205 has a wavelength selection function, the detection unit 205 can notify the control unit 203 of the intensity of the optical carrier wave of the desired wavelength and the frequency of the dither signal as the light intensity signal and the frequency signal. Therefore, in this case, the optical receiver 500 can cancel or continue the optical signal loss alarm by the procedure based on FIG. 6 of the third embodiment. That is, the detection unit 205 selects an optical carrier wave having a desired wavelength from the WDM optical signal according to an instruction from the control unit 203, and outputs a light intensity signal and a frequency signal to the control unit 203. The control unit 203 obtains the intensity of the optical carrier wave having a desired wavelength from the light intensity signal received from the detection unit 205, and examines the frequency included in the dither signal from the frequency signal (steps S02 to S05 in FIG. 6). Further, the control unit 203 obtains the amplitude of the analog data signal at the input of the analog / digital converter 251 (steps S06 to S07 in FIG. 6). The determination procedure for canceling or continuing the optical signal loss alarm is the same as in FIG.
　検出部２０５が波長選択機能を備えない場合には、光受信機５００は、第４の実施形態の図８の手順により、光信号ロス警報を解除し、あるいは継続できる。すなわち、検出部２０５は、ＷＤＭ光信号に含まれる周波数成分を示す周波数信号を制御部２０３へ出力する。制御部２０３は、検出部２０５から入力された周波数信号から、所望の波長の光搬送波に重畳されたディザ信号に対応する周波数（２Ｆ０又はＦ０）が含まれるかどうかを調べる（図８のステップＳ０４－Ｓ０５）。また、制御部２０３は、アナログデジタル変換器２５１の入力におけるアナログデータ信号の振幅を求める（図８のステップＳ０６－Ｓ０７）。光信号ロス警報を解除しあるいは継続する判定の手順も図８と同様である。 When the detection unit 205 does not have a wavelength selection function, the optical receiver 500 can cancel or continue the optical signal loss alarm according to the procedure of FIG. 8 of the fourth embodiment. That is, the detection unit 205 outputs a frequency signal indicating a frequency component included in the WDM optical signal to the control unit 203. The control unit 203 checks whether or not the frequency signal input from the detection unit 205 includes a frequency (2F0 or F0) corresponding to the dither signal superimposed on the optical carrier wave having a desired wavelength (step S04 in FIG. 8). -S05). Further, the control unit 203 obtains the amplitude of the analog data signal at the input of the analog / digital converter 251 (steps S06 to S07 in FIG. 8). The determination procedure for canceling or continuing the optical signal loss alarm is the same as in FIG.
　このように、光受信機５００は、第３及び第４の実施形態と同様に、光信号の受信状態を好適に判定し、光信号ロス警報の発出及び解除を行うことができる。 As described above, similarly to the third and fourth embodiments, the optical receiver 500 can appropriately determine the reception state of the optical signal and issue and cancel the optical signal loss alarm.
　以上の各実施形態に記載された機能及び手順は、光受信機１００、２００、３００、４００及び５００が備える中央処理装置（Central Processing Unit、CPU）がプログラムを実行することにより実現されてもよい。プログラムは、固定された、一時的でない記録媒体に記録される。記録媒体としては半導体メモリ又は固定磁気ディスク装置が用いられるが、これらには限定されない。ＣＰＵは、例えば制御部１０３又は２０３に備えられるコンピュータであるが、デジタル信号処理器２５２に備えられてもよい。 The functions and procedures described in the above embodiments may be realized by executing a program by a central processing device (Central Processing Unit, CPU) included in the optical receivers 100, 200, 300, 400, and 500. . The program is recorded on a fixed, non-temporary recording medium. As the recording medium, a semiconductor memory or a fixed magnetic disk device is used, but is not limited thereto. The CPU is a computer provided in the control unit 103 or 203, for example, but may be provided in the digital signal processor 252.
　なお、本発明の実施形態は以下の付記のようにも記載されうるが、これらには限定されない。 In addition, although embodiment of this invention can be described also as the following additional remarks, it is not limited to these.
　（付記１）
　データ信号により変調された光信号を受信し、前記光信号に重畳された信号の周波数成分を検出する検出手段と、
　前記光信号を電気信号に変換して出力する光電変換手段と、
　前記検出した周波数成分に関する第１の条件を含む所定の判定条件に基づいて所定の情報の内容を決定する制御手段と、
を備える光受信機。
　（付記２）
　前記制御手段は、前記周波数成分が所定の周波数及び前記所定の周波数の２倍の周波数のいずれかの成分を含むことを、前記第１の条件に含む、付記１に記載された光受信機。
　（付記３）
　前記所定の周波数は、前記光信号の送信の際に前記光信号の振幅に重畳されたディザ信号の周波数である、付記２に記載された光受信機。
　（付記４）
　前記検出手段は、さらに、前記光信号の光強度を検出し、
　前記制御手段は、前記光強度が第１の閾値以上であることを前記判定条件に含む、付記１乃至３のいずれかに記載された光受信機。
　（付記５）
　前記光電変換手段は前記光信号から復調された前記データ信号を前記制御手段へ出力し、
　前記制御手段は、前記データ信号の振幅が第２の閾値以上であることを前記判定条件に含む、付記１乃至３のいずれかに記載された光受信機。
　（付記６）（２Ｆ０＋データ信号振幅）＋光強度
　前記検出手段は、さらに、前記光信号の光強度を検出し、
　前記制御手段は、前記光強度が第１の閾値以上であることを、前記判定条件に含む、付記５に記載された光受信機。
　（付記７）
　前記検出手段は、前記データ信号が含まれる波長の光搬送波を選択し、選択された前記光搬送波の強度を前記光強度として出力する、付記４又は６に記載された光受信機。
　（付記８）
　前記制御手段は、
　前記判定条件が充足されない場合には前記光信号が断であることを示す警報を発出し、
　前記判定条件が充足された場合には前記警報を解除する、
付記１乃至７のいずれか１項に記載された光受信機。
　（付記９）
　データ信号及び所定の周波数のディザ信号により変調された光信号を光伝送路へ出力する光送信機と、
　前記光伝送路から前記光信号を受信する付記１乃至８のいずれか１項に記載された光受信機と、を備える光伝送システム。
　（付記１０）
　データ信号により変調された光信号を受信し、
　前記光信号に重畳された信号の周波数成分を検出し、
　前記光信号を電気信号に変換し、
　前記検出した周波数成分に関する第１の条件を含む所定の判定条件に基づいて所定の情報の内容を決定する、
光受信方法。
　（付記１１）
　前記周波数成分が所定の周波数及び前記所定の周波数の２倍の周波数のいずれかの成分を含むことを、前記第１の条件に含む、付記１０に記載された光受信方法。
　（付記１２）
　前記所定の周波数は、前記光信号の送信の際に前記光信号の振幅に重畳されたディザ信号の周波数である、付記１１に記載された光受信方法。
　（付記１３）
　さらに、
　前記光信号の光強度を検出し、
　前記光強度が第１の閾値以上であることを、前記判定条件に含む、付記１０乃至１２のいずれかに記載された光受信方法。
　（付記１４）
　前記光信号から復調された前記データ信号の振幅が第２の閾値以上であることを、前記判定条件に含む、付記１０乃至１２のいずれかに記載された光受信方法。
　（付記１５）
　さらに、
　前記光信号の光強度を検出し、
　前記光強度が第１の閾値以上であることを、前記判定条件に含む、付記１４に記載された光受信方法。
　（付記１６）
　前記データ信号が含まれる波長の光搬送波を選択し、選択された前記光搬送波の強度を前記光強度として出力する、付記１３又は１５のいずれかに記載された光受信方法。
　（付記１７）
　前記判定条件が充足されない場合には前記光信号が断であることを示す警報を発出し、
　前記判定条件が充足された場合には前記警報を解除する、
付記１０乃至１６のいずれかに記載された光受信方法。
　（付記１８）
　光受信機のコンピュータに、
　データ信号により変調された光信号を受信する手順、
　前記光信号に重畳された信号の周波数成分を検出する手順、
　前記光信号を電気信号に変換する手順、
　前記検出した周波数成分に関する第１の条件を含む所定の判定条件に基づいて所定の情報の内容を決定する手順、
を実行させるための光受信機のプログラムが記録された記録媒体。
　以上、実施形態を参照して本発明を説明したが、本発明は上記の実施形態に限定されない。本発明の構成や詳細には、本発明のスコープ内で当業者が理解し得る様々な変更をすることができる。また、以上の実施形態に記載された構成は、必ずしも互いに排他的なものではない。本発明の作用及び効果は、上述の実施形態の全部又は一部を組み合わせた構成によって実現されてもよい。
　この出願は、２０１８年３月２日に出願された日本出願特願２０１８－０３７４５５を基礎とする優先権を主張し、その開示の全てをここに取り込む。 (Appendix 1)
Detecting means for receiving an optical signal modulated by a data signal and detecting a frequency component of the signal superimposed on the optical signal;
Photoelectric conversion means for converting the optical signal into an electrical signal and outputting the electrical signal;
Control means for determining the content of the predetermined information based on a predetermined determination condition including a first condition relating to the detected frequency component;
An optical receiver.
(Appendix 2)
The optical receiver according to appendix 1, wherein the control means includes, as the first condition, that the frequency component includes any one of a predetermined frequency and a frequency twice as high as the predetermined frequency.
(Appendix 3)
The optical receiver according to appendix 2, wherein the predetermined frequency is a frequency of a dither signal superimposed on an amplitude of the optical signal when the optical signal is transmitted.
(Appendix 4)
The detection means further detects the light intensity of the optical signal,
The optical receiver according to any one of appendices 1 to 3, wherein the control unit includes the determination condition that the light intensity is equal to or higher than a first threshold value.
(Appendix 5)
The photoelectric conversion means outputs the data signal demodulated from the optical signal to the control means,
The optical receiver according to any one of appendices 1 to 3, wherein the control means includes, in the determination condition, that an amplitude of the data signal is equal to or greater than a second threshold value.
(Appendix 6) (2F0 + data signal amplitude) + light intensity The detection means further detects the light intensity of the optical signal,
The optical receiver according to appendix 5, wherein the control means includes the determination condition that the light intensity is equal to or greater than a first threshold value.
(Appendix 7)
The optical receiver according to appendix 4 or 6, wherein the detection means selects an optical carrier wave having a wavelength including the data signal, and outputs the intensity of the selected optical carrier wave as the optical intensity.
(Appendix 8)
The control means includes
If the determination condition is not satisfied, an alarm indicating that the optical signal is off is issued,
Canceling the alarm when the determination condition is satisfied,
The optical receiver according to any one of appendices 1 to 7.
(Appendix 9)
An optical transmitter that outputs an optical signal modulated by a data signal and a dither signal having a predetermined frequency to an optical transmission line;
An optical transmission system comprising: the optical receiver according to any one of appendices 1 to 8 that receives the optical signal from the optical transmission path.
(Appendix 10)
Receiving an optical signal modulated by a data signal;
Detecting the frequency component of the signal superimposed on the optical signal;
Converting the optical signal into an electrical signal;
Determining the content of predetermined information based on a predetermined determination condition including a first condition relating to the detected frequency component;
Optical reception method.
(Appendix 11)
The optical reception method according to appendix 10, wherein the first condition includes that the frequency component includes any one of a predetermined frequency and a frequency twice as high as the predetermined frequency.
(Appendix 12)
The optical reception method according to appendix 11, wherein the predetermined frequency is a frequency of a dither signal superimposed on an amplitude of the optical signal when the optical signal is transmitted.
(Appendix 13)
further,
Detecting the light intensity of the optical signal;
The optical reception method according to any one of appendices 10 to 12, wherein the determination condition includes that the light intensity is equal to or greater than a first threshold value.
(Appendix 14)
The optical reception method according to any one of appendices 10 to 12, wherein the determination condition includes that the amplitude of the data signal demodulated from the optical signal is equal to or greater than a second threshold value.
(Appendix 15)
further,
Detecting the light intensity of the optical signal;
The optical reception method according to appendix 14, wherein the determination condition includes that the light intensity is greater than or equal to a first threshold value.
(Appendix 16)
16. The optical reception method according to any one of appendix 13 or 15, wherein an optical carrier having a wavelength including the data signal is selected, and the intensity of the selected optical carrier is output as the optical intensity.
(Appendix 17)
If the determination condition is not satisfied, an alarm indicating that the optical signal is off is issued,
Canceling the alarm when the determination condition is satisfied,
The optical receiving method according to any one of appendices 10 to 16.
(Appendix 18)
To the optical receiver computer,
Receiving an optical signal modulated by a data signal;
Detecting a frequency component of a signal superimposed on the optical signal;
Converting the optical signal into an electrical signal;
A procedure for determining the content of predetermined information based on a predetermined determination condition including a first condition relating to the detected frequency component;
A recording medium on which a program of an optical receiver for executing is recorded.
As mentioned above, although this invention was demonstrated with reference to embodiment, this invention is not limited to said embodiment. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention. Further, the configurations described in the above embodiments are not necessarily mutually exclusive. The operation and effect of the present invention may be realized by a configuration in which all or part of the above-described embodiments are combined.
This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2018-037455 for which it applied on March 2, 2018, and takes in those the indications of all here.
１０　光伝送システム
１００、２００、３００、４００、５００　光受信機
１０１、１０１Ａ、２０１　検出部
１０２、２０２　光電変換部
１０３、２０３　制御部
１１１　カプラ
１１２　受光素子
１１３　抽出回路
２００　光受信機
２０４　レーザダイオード（ＬＤ）
２０５　検出部（ＴＡＰ）
２１０　光受信回路
２２１　９０度光ハイブリッド
２２２　受光素子（ＰＤ）
２２３　増幅器（ＴＩＡ）
２５１　アナログデジタル変換器（ＡＤＣ）
２５２　デジタル信号処理器（ＤＳＰ）
３０１　光変調器
３０２　制御回路
３１０　光送信機
３２０　光伝送路 10 Optical transmission system 100, 200, 300, 400, 500 Optical receiver 101, 101A, 201 Detection unit 102, 202 Photoelectric conversion unit 103, 203 Control unit 111 Coupler 112 Light receiving element 113 Extraction circuit 200 Optical receiver 204 Laser diode ( LD)
205 Detection part (TAP)
210 Optical receiver circuit 221 90-degree optical hybrid 222 Light receiving element (PD)
223 Amplifier (TIA)
251 Analog-to-digital converter (ADC)
252 Digital signal processor (DSP)
301 Optical modulator 302 Control circuit 310 Optical transmitter 320 Optical transmission line

Claims (18)

  1. 　データ信号により変調された光信号を受信し、前記光信号に重畳された信号の周波数成分を検出する検出手段と、
    　前記光信号を電気信号に変換して出力する光電変換手段と、
    　前記検出した周波数成分に関する第１の条件を含む所定の判定条件に基づいて所定の情報の内容を決定する制御手段と、
    を備える光受信機。     Detecting means for receiving an optical signal modulated by a data signal and detecting a frequency component of the signal superimposed on the optical signal;
    Photoelectric conversion means for converting the optical signal into an electrical signal and outputting the electrical signal;
    Control means for determining the content of the predetermined information based on a predetermined determination condition including a first condition relating to the detected frequency component;
    An optical receiver.
  2. 　前記制御手段は、前記周波数成分が所定の周波数及び前記所定の周波数の２倍の周波数のいずれかの成分を含むことを、前記第１の条件に含む、請求項１に記載された光受信機。 2. The optical receiver according to claim 1, wherein the control unit includes, as the first condition, that the frequency component includes any one of a predetermined frequency and a frequency that is twice the predetermined frequency. .
  3. 　前記所定の周波数は、前記光信号の送信の際に前記光信号の振幅に重畳されたディザ信号の周波数である、請求項２に記載された光受信機。 3. The optical receiver according to claim 2, wherein the predetermined frequency is a frequency of a dither signal superimposed on an amplitude of the optical signal when the optical signal is transmitted.
  4. 　前記検出手段は、さらに、前記光信号の光強度を検出し、
    　前記制御手段は、前記光強度が第１の閾値以上であることを前記判定条件に含む、請求項１乃至３のいずれかに記載された光受信機。     The detection means further detects the light intensity of the optical signal,
    4. The optical receiver according to claim 1, wherein the control unit includes the determination condition that the light intensity is equal to or higher than a first threshold value.
  5. 　前記光電変換手段は前記光信号から復調された前記データ信号を前記制御手段へ出力し、
    　前記制御手段は、前記データ信号の振幅が第２の閾値以上であることを前記判定条件に含む、請求項１乃至３のいずれかに記載された光受信機。     The photoelectric conversion means outputs the data signal demodulated from the optical signal to the control means,
    4. The optical receiver according to claim 1, wherein the control unit includes the determination condition that an amplitude of the data signal is equal to or greater than a second threshold value. 5.
  6. 　前記検出手段は、さらに、前記光信号の光強度を検出し、
    　前記制御手段は、前記光強度が第１の閾値以上であることを、前記判定条件に含む、請求項５に記載された光受信機。     The detection means further detects the light intensity of the optical signal,
    The optical receiver according to claim 5, wherein the control unit includes the determination condition that the light intensity is equal to or greater than a first threshold value.
  7. 　前記検出手段は、前記データ信号が含まれる波長の光搬送波を選択し、選択された前記光搬送波の強度を前記光強度として出力する、請求項４又は６に記載された光受信機。 The optical receiver according to claim 4 or 6, wherein the detection means selects an optical carrier having a wavelength including the data signal, and outputs the intensity of the selected optical carrier as the optical intensity.
  8. 　前記制御手段は、
    　前記判定条件が充足されない場合には前記光信号が断であることを示す警報を発出し、
    　前記判定条件が充足された場合には前記警報を解除する、
    請求項１乃至７のいずれか１項に記載された光受信機。     The control means includes
    If the determination condition is not satisfied, an alarm indicating that the optical signal is off is issued,
    Canceling the alarm when the determination condition is satisfied,
    The optical receiver according to claim 1.
  9. 　データ信号及び所定の周波数のディザ信号により変調された光信号を光伝送路へ出力する光送信機と、
    　前記光伝送路から前記光信号を受信する請求項１乃至８のいずれか１項に記載された光受信機と、を備える光伝送システム。     An optical transmitter that outputs an optical signal modulated by a data signal and a dither signal having a predetermined frequency to an optical transmission line;
    An optical transmission system comprising: the optical receiver according to claim 1 that receives the optical signal from the optical transmission path.
  10. 　データ信号により変調された光信号を受信し、
    　前記光信号に重畳された信号の周波数成分を検出し、
    　前記光信号を電気信号に変換し、
    　前記検出した周波数成分に関する第１の条件を含む所定の判定条件に基づいて所定の情報の内容を決定する、
    光受信方法。     Receiving an optical signal modulated by a data signal;
    Detecting the frequency component of the signal superimposed on the optical signal;
    Converting the optical signal into an electrical signal;
    Determining the content of predetermined information based on a predetermined determination condition including a first condition relating to the detected frequency component;
    Optical reception method.
  11. 　前記周波数成分が所定の周波数及び前記所定の周波数の２倍の周波数のいずれかの成分を含むことを、前記第１の条件に含む、請求項１０に記載された光受信方法。 The optical reception method according to claim 10, wherein the first condition includes that the frequency component includes any one of a predetermined frequency and a frequency twice the predetermined frequency.
  12. 　前記所定の周波数は、前記光信号の送信の際に前記光信号の振幅に重畳されたディザ信号の周波数である、請求項１１に記載された光受信方法。 12. The optical reception method according to claim 11, wherein the predetermined frequency is a frequency of a dither signal superimposed on an amplitude of the optical signal when the optical signal is transmitted.
  13. 　さらに、
    　前記光信号の光強度を検出し、
    　前記光強度が第１の閾値以上であることを、前記判定条件に含む、請求項１０乃至１２のいずれかに記載された光受信方法。     further,
    Detecting the light intensity of the optical signal;
    The optical reception method according to claim 10, wherein the determination condition includes that the light intensity is greater than or equal to a first threshold value.
  14. 　前記光信号から復調された前記データ信号の振幅が第２の閾値以上であることを、前記判定条件に含む、請求項１０乃至１２のいずれかに記載された光受信方法。 The optical reception method according to claim 10, wherein the determination condition includes that the amplitude of the data signal demodulated from the optical signal is equal to or greater than a second threshold value.
  15. 　さらに、
    　前記光信号の光強度を検出し、
    　前記光強度が第１の閾値以上であることを、前記判定条件に含む、請求項１４に記載された光受信方法。     further,
    Detecting the light intensity of the optical signal;
    The optical reception method according to claim 14, wherein the determination condition includes that the light intensity is equal to or greater than a first threshold value.
  16. 　前記データ信号が含まれる波長の光搬送波を選択し、選択された前記光搬送波の強度を前記光強度として出力する、請求項１３又は１５のいずれかに記載された光受信方法。 The optical reception method according to claim 13 or 15, wherein an optical carrier having a wavelength including the data signal is selected, and the intensity of the selected optical carrier is output as the optical intensity.
  17. 　前記判定条件が充足されない場合には前記光信号が断であることを示す警報を発出し、
    　前記判定条件が充足された場合には前記警報を解除する、
    請求項１０乃至１６のいずれかに記載された光受信方法。     If the determination condition is not satisfied, an alarm indicating that the optical signal is off is issued,
    Canceling the alarm when the determination condition is satisfied,
    The optical receiving method according to claim 10.
  18. 　光受信機のコンピュータに、
    　データ信号により変調された光信号を受信する手順、
    　前記光信号に重畳された信号の周波数成分を検出する手順、
    　前記光信号を電気信号に変換する手順、
    　前記検出した周波数成分に関する第１の条件を含む所定の判定条件に基づいて所定の情報の内容を決定する手順、
    を実行させるための光受信機のプログラムが記録された記録媒体。     To the optical receiver computer,
    Receiving an optical signal modulated by a data signal;
    Detecting a frequency component of a signal superimposed on the optical signal;
    Converting the optical signal into an electrical signal;
    A procedure for determining the content of predetermined information based on a predetermined determination condition including a first condition relating to the detected frequency component;
    A recording medium on which a program of an optical receiver for executing is recorded.
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JPH0730495A (en) * 1993-07-09 1995-01-31 Sony Corp Bidirectional optical communication equipment
JPH08234251A (en) * 1994-12-29 1996-09-13 At & T Corp Apparatus and method for transmission of light signal
JP2003158497A (en) * 2001-11-21 2003-05-30 Nec Corp Signal cutoff detection circuit and optical receiver using the same
JP2004056187A (en) * 2002-07-16 2004-02-19 Fujitsu Ltd Optical transmission apparatus provided with state detection function
JP2011004269A (en) * 2009-06-19 2011-01-06 Opnext Japan Inc Optical reception module, optical receiver, and electronic circuit
JP2013214977A (en) * 2005-05-23 2013-10-17 Fujitsu Ltd Optical transmitting apparatus, optical receiving apparatus, and optical communication system comprising them

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0340539A (en) * 1989-07-06 1991-02-21 Fujitsu Ltd Device for detecting disconnection of optical signal input
JPH0730495A (en) * 1993-07-09 1995-01-31 Sony Corp Bidirectional optical communication equipment
JPH08234251A (en) * 1994-12-29 1996-09-13 At & T Corp Apparatus and method for transmission of light signal
JP2003158497A (en) * 2001-11-21 2003-05-30 Nec Corp Signal cutoff detection circuit and optical receiver using the same
JP2004056187A (en) * 2002-07-16 2004-02-19 Fujitsu Ltd Optical transmission apparatus provided with state detection function
JP2013214977A (en) * 2005-05-23 2013-10-17 Fujitsu Ltd Optical transmitting apparatus, optical receiving apparatus, and optical communication system comprising them
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