WO2014068978A1 - 光受信器、光受信装置および光受信強度補正方法 - Google Patents
光受信器、光受信装置および光受信強度補正方法 Download PDFInfo
- Publication number
- WO2014068978A1 WO2014068978A1 PCT/JP2013/006435 JP2013006435W WO2014068978A1 WO 2014068978 A1 WO2014068978 A1 WO 2014068978A1 JP 2013006435 W JP2013006435 W JP 2013006435W WO 2014068978 A1 WO2014068978 A1 WO 2014068978A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- signal
- optical
- gain
- voltage
- optical receiver
- Prior art date
Links
Images
Classifications
-
- 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
- H04B10/616—Details of the electronic signal processing in coherent optical receivers
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/04—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only
- H03F3/08—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only controlled by light
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
- H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
- H03F3/4508—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using bipolar transistors as the active amplifying circuit
- H03F3/45085—Long tailed pairs
-
- 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
- H04B10/613—Coherent receivers including phase diversity, e.g., having in-phase and quadrature branches, as in QPSK coherent receivers
Definitions
- the present invention relates to an optical receiver, an optical receiver, and an optical reception intensity correction method, and more particularly, to an optical receiver and an optical receiver using a coherent detection method corresponding to a quadrature phase-shift keying (QPSK) method.
- QPSK quadrature phase-shift keying
- the present invention relates to an apparatus and an optical reception intensity correction method.
- the digital coherent reception method In the digital coherent reception method, light intensity information and phase information are extracted from a received signal and demodulated by a digital signal processing technique. According to the digital coherent reception system, the OSNR tolerance is improved by the coherent reception system, and the waveform distortion compensation is realized by the digital signal processing technique. Therefore, high reliability can be obtained even in an optical communication system exceeding 40 Gbit / s.
- FIG. 7 shows a configuration of a related coherent optical receiver described in Patent Document 1.
- the related coherent optical receiving device 5000 receives an optical reception signal 5001 and local oscillation light 5002 having substantially the same wavelength as the optical reception signal 5001 from the local oscillation light source.
- the local oscillation light 5002 and the optical reception signal 5001 are made to interfere with each other and converted into an electric signal (coherent detection). Since the coherent detection method has strong polarization dependence, only one optical signal having the same polarization state as that of the local oscillation light can be received by one optical receiver.
- a polarization separation unit 5010 is provided at the input unit of the optical reception signal 5001, and the optical reception signal 5001 is separated into two orthogonal polarization components by the polarization separation unit 5010.
- two optical receivers are required to receive one optical signal, but this disadvantage can be compensated by doubling the information transmission amount by polarization multiplexing.
- Each polarized light and local oscillation light 5002 of the optical reception signal 5001 are input to the optical 90-degree hybrid circuit 5100.
- a set of output lights obtained by causing each polarized light and local oscillation light to interfere with each other in the same phase and opposite phase, and in a phase relationship of orthogonal (90 degrees) and inverse orthogonal (-90 degrees).
- a total of four types of output light, that is, one set of output light interfered, is obtained.
- These output optical signals are converted into current signals by two photodiodes 5200 for one set and input to the differential transimpedance amplifier 5300.
- the electrical signals output from the differential transimpedance amplifier 5300 are the in-phase interference component (I component) and the quadrature interference component (Q component) of the optical reception signal and the local oscillation light, respectively.
- the output for each polarization that is, a total of four types of electric signals composed of the I component and Q component of X polarization and the I component and Q component of Y polarization, are converted into an analog / digital converter (ADC) 5400.
- ADC analog / digital converter
- AD analog / digital
- DSP digital signal processor
- the digital signal thus obtained can be subjected to various equalization / determination processes by a digital signal processing technique widely used in wireless communication. After such digital signal processing is performed and error correction processing is performed, an information signal of an ultra high speed (for example, 100 Gbit / s) is output.
- CMRR common mode noise reduction ratio
- the CMRR is lowered by the difference in the received intensity caused by the difference in the intensity of the optical signal and the optical path difference.
- the pulse repetition frequency of the local oscillation light and the surplus components of the harmonics saturate the transimpedance amplifier and lower its linearity.
- highly accurate waveform distortion equalization becomes difficult in subsequent digital signal processing.
- FIG. 8 shows waveforms of output current signals (I PD1 and I PD2 ) of the two photodiodes (PD1 and PD2) in this case.
- the difference in the output current signal between the two photodiodes PD1 and PD2 that are paired is divided into a direct current (DC) component difference and an amplitude component difference.
- An example of a method for compensating for the difference between the DC components is described in Patent Document 1.
- the photocurrent generated in the two photodiodes is detected by the photocurrent detection unit and fed back to the level adjustment unit connected to the differential transimpedance amplifier. It is configured. With this configuration, the level of the signal in a complementary relationship in the two feedback closed loops is adjusted, and the difference in the received intensity of the optical signal is automatically corrected.
- the associated coherent optical receiver does not compensate for the amplitude difference in the output currents of the two photodiodes (PD) in the pair.
- the related coherent optical receiver cannot correct the amplitude difference in the output current signal of the paired photodiodes, which is caused by the difference in the received intensity of the optical signal and the difference in the photoelectric conversion efficiency of the photodiode. Therefore, there is a problem that the common-mode noise component removal ratio (CMRR) is lowered.
- CMRR common-mode noise component removal ratio
- the object of the present invention is that the above-mentioned problem is that, in the related coherent optical receiver, the common-mode noise component removal ratio (CMRR) is lowered due to the difference in optical signal reception intensity and the photoelectric conversion efficiency of the photodiode.
- An object of the present invention is to provide an optical receiver, an optical receiver, and an optical reception intensity correction method for solving the problems.
- the optical receiver of the present invention includes a first photodiode that receives a first optical signal and outputs a positive signal, a second photodiode that receives a second optical signal and outputs a complementary signal, and a positive signal.
- This is the gain of the differential transimpedance amplifier that outputs the amplified positive signal voltage, outputs the complementary signal, and outputs the amplified complementary signal voltage, and the differential transimpedance amplifier with respect to the positive signal.
- a first gain and a gain adjustment unit that adjusts a second gain that is a gain of the differential transimpedance amplifier with respect to the complementary signal.
- the optical reception intensity correction method of the present invention receives a first optical signal, converts it into an electrical signal, outputs a positive signal, receives a second optical signal, converts it into an electrical signal, and outputs a complementary signal
- the positive signal and the complementary signal are multiplied to output the positive signal voltage and the complementary signal voltage, and the first gain with respect to the positive signal voltage and the second gain with respect to the complementary signal voltage are set to the voltage amplitude of the positive signal voltage. Adjustments are made so that the voltage amplitudes of the complementary signal voltages are substantially the same.
- CMRR common-mode noise component removal ratio
- PD photodiodes
- FIG. 1 is a block diagram showing a configuration of an optical receiver according to the first embodiment of the present invention.
- the optical receiver 100 includes a first photodiode 110, a second photodiode 120, a differential transimpedance amplifier 130, and a gain adjustment unit 140.
- the first photodiode 110 receives the first optical signal 11 and outputs a positive signal.
- the second photodiode 120 receives the second optical signal 12 and outputs a complementary signal.
- the differential transimpedance amplifier 130 inputs a positive signal and outputs a multiplied positive signal voltage, and inputs a complementary signal and outputs a multiplied complementary signal voltage.
- the gain adjusting unit 140 adjusts the first gain that is the gain of the differential transimpedance amplifier 130 for the positive signal and the second gain that is the gain of the differential transimpedance amplifier 130 for the complementary signal.
- the first gain for the positive signal voltage and the second gain for the complementary signal voltage are set such that the voltage amplitude of the positive signal voltage and the voltage amplitude of the complementary signal voltage are substantially the same.
- Each can be adjusted. Therefore, according to the optical receiver 100 according to the present embodiment, it is possible to correct the amplitude difference in the output current signal of the paired photodiodes, which is caused by the difference in the received intensity of the optical signal and the difference in the photoelectric conversion efficiency of the photodiode. . As a result, a decrease in the common-mode noise component removal ratio (CMRR) in the optical receiver 100 can be suppressed.
- CMRR common-mode noise component removal ratio
- the differential transimpedance amplifier 130 may include a differential amplifier 131
- the gain adjustment unit 140 may include a variable impedance unit connected to the differential amplifier 131.
- the variable impedance unit may be configured such that the impedance is variable corresponding to the adjustment range of the first gain and the second gain.
- FIG. 2 is a block diagram showing a configuration of the optical receiving apparatus according to the first embodiment of the present invention.
- FIG. 2 shows only one polarization (X) portion of an optical receiver using the coherent detection method (hereinafter referred to as a coherent optical receiver).
- the coherent optical receiver 1000 includes an optical receiver 100 and an optical 90-degree hybrid circuit 400.
- a variable gain amplifier 410, an analog / digital converter (ADC) 420, and a digital signal processing circuit (DSP) 430 are connected to the subsequent stage of the coherent optical receiver 1000.
- ADC analog / digital converter
- DSP digital signal processing circuit
- the first optical signal 11 is a first interference optical signal obtained by interference between the optical reception signal 21 and the first local oscillation light 31 having substantially the same wavelength as the optical reception signal 21. is there.
- the second optical signal 12 is a second interference optical signal obtained by interference between the optical reception signal 21 and the second local oscillation light 32 whose phase is inverted from that of the first local oscillation light 31. That is, the optical 90-degree hybrid circuit 400 causes the optical reception signal 21 and the first local oscillation light 31 to interfere with each other, outputs the first interference optical signal, and interferes with the optical reception signal 21 and the second local oscillation light 32.
- the second interference light signal is output.
- the optical receiver 100 includes the first photodiode 110, the second photodiode 120, the differential transimpedance amplifier 130, and the gain adjustment unit 140 as described above.
- the optical 90-degree hybrid circuit 400 includes an optical phase shifter 210 and an optical mixer 220.
- the optical reception signal 21 is an optical reception signal after being separated into X polarization and Y polarization by the polarization beam splitter.
- the first photodiode 110 and the second photodiode 120 are made to interfere with the optical reception signal 21 and the first local oscillation light 31 or the second local oscillation light 32 in the optical 90-degree hybrid circuit 400. An optical signal is input.
- a gain adjusting unit 140 is connected to the differential transimpedance amplifier 130.
- the gain adjusting unit 140 has a function of adjusting an amplitude difference between output current signals of the first photodiode 110 and the second photodiode 120. That is, the gain adjustment unit 140 individually adjusts the transimpedance gain of the correction loop in the differential transimpedance amplifier 130 having negative feedback so as to cancel the amplitude difference between the output current signals of the two photodiodes. Therefore, at the output of the differential transimpedance amplifier 130, a demodulated signal having a substantially complementary relationship with substantially the same amplitude is obtained.
- the output of the differential transimpedance amplifier 130 is amplified by a variable gain amplifier 410 connected in a subsequent stage, and is subjected to analog-to-digital conversion in an analog / digital conversion unit (ADC) 420. Thereafter, the digital signal processing circuit (DSP) 430 performs digital signal processing such as polarization separation processing, light source frequency offset compensation processing, and phase compensation processing.
- the differential transimpedance amplifier 130 may include a variable gain amplifier 410.
- the optical reception signal 21 is branched into four by an optical coupler.
- the local oscillation light is branched into four by the optical coupler, and the phases of the four branches are shifted by 0, ⁇ , ⁇ / 2, and 3 ⁇ / 2.
- interference light between the optical reception signal 21 and the branched local oscillation light is input to the first photodiode 110 and the second photodiode 120, respectively.
- ⁇ is a phase, and transmission information is put on this phase in the phase modulation method. For example, in the QPSK system, they are 0, ⁇ , ⁇ / 2, and 3 ⁇ / 2.
- a, b, c, and d are coefficients resulting from the quantum efficiency and coupling efficiency of each photodiode (PD) and the loss in the optical 90-degree hybrid circuit 400.
- the second term on the right side of equations (1) to (4) is the DC component (offset component), and the third term is the phase information of the signal.
- the differential signals of Equation (5) and Equation (6), Equation (7), and Equation (8) are the output of the differential transimpedance amplifier 130.
- the light intensity B 2 of the local oscillator light is for at least 10 times the intensity A 2 of the received optical signal, the light intensity B 2 of the local oscillator light is dominant.
- the gain of the differential transimpedance amplifier 130 can be individually adjusted by the gain adjusting unit 140. Assuming that the gain of the differential transimpedance amplifier 130 for each signal is ⁇ , ⁇ , ⁇ , and ⁇ , the output of the differential transimpedance amplifier 130 is represented by the following equations.
- the differential signals of Equation (9) and Equation (10), Equation (11) and Equation (12) appear at the output of the differential transimpedance amplifier 130.
- the gain adjustment unit 140 by adjusting ⁇ , ⁇ , ⁇ , and ⁇ by the gain adjustment unit 140, the difference in the term of the light intensity A (t) 2 of the optical reception signal can be eliminated. That is, the voltage amplitude of the positive signal voltage is adjusted by adjusting the first gain ( ⁇ , ⁇ ) of the differential transimpedance amplifier 130 with respect to the positive signal voltage and the second gain ( ⁇ , ⁇ ) with respect to the complementary signal voltage. And the voltage amplitude of the complementary signal voltage can be made substantially the same.
- the optical receiver 100 has a configuration in which the differential transimpedance amplifier 130 is provided with the gain adjusting unit 140 that adjusts the gain of the differential transimpedance amplifier 130. Therefore, the gain can be adjusted so as to cancel the amplitude difference between the output current signals of the two photodiodes (PD). That is, a good complement signal having no noise and the same amplitude can be obtained as the output of the differential transimpedance amplifier. As a result, it is possible to compensate for the deterioration of the common-mode noise component removal ratio (CMRR) generated in the optical 90-degree hybrid circuit and the photodiode in the differential transimpedance.
- CMRR common-mode noise component removal ratio
- the optical reception intensity correction method according to this embodiment, first, the first optical signal is received, converted into an electrical signal, and a positive signal is output. Similarly, the second optical signal is received, converted into an electrical signal, and a complementary signal is output. Subsequently, the positive signal and the complementary signal are multiplied to output a positive signal voltage and a complementary signal voltage.
- the first gain for the positive signal voltage and the second gain for the complementary signal voltage are adjusted so that the voltage amplitude of the positive signal voltage and the voltage amplitude of the complementary signal voltage are substantially the same.
- the first gain and the second gain can be adjusted by adjusting the impedance of the multiplier having the function of multiplying.
- optical reception intensity correction method it is possible to suppress a decrease in the common-mode noise component removal ratio (CMRR) caused by the difference in optical signal reception intensity and the photoelectric conversion efficiency of the photodiode.
- CMRR common-mode noise component removal ratio
- FIG. 3 is a circuit configuration diagram showing the configuration of the coherent optical receiver 200 according to the second embodiment of the present invention.
- FIG. 3 shows only the I channel (Ix) of one polarization (X) portion of the coherent optical receiver.
- symbol is attached
- the coherent optical receiver 200 includes a first photodiode 110, a second photodiode 120, a differential transimpedance amplifier 130, and a gain adjustment unit 140.
- the coherent optical receiver 200 and the optical 90-degree hybrid circuit 400 constitute a coherent optical receiver.
- the differential transimpedance amplifier 130 includes a differential amplifier 131 to which output current signals of the first photodiode 110 and the second photodiode 120 are input, an emitter follower circuit 132, and two feedback resistors 133.
- the differential amplifier 131 includes a differential pair transistor and a current source.
- the gain adjusting unit 140 includes a variable impedance unit 141 connected to the differential amplifier 131.
- the variable impedance unit 141 has one end connected to the ground side of the differential amplifier 131 and the other end connected to the control terminal 142, and the impedance changes according to the voltage applied to the control terminal 142.
- the variable impedance unit 141 can include either a diode element or a transistor element. Hereinafter, a case where a diode element is used as the variable impedance unit 141 as illustrated in FIG. 3 will be described in more detail.
- a resistance element and a diode element are connected to the emitter side of the differential pair transistor constituting the differential amplifier 131, respectively.
- a control terminal 142 is connected to the anode side of the diode element.
- the reason why the impedance on the emitter side of the differential pair transistor changes is as follows.
- the impedance on the emitter side of the differential pair transistor is determined by the resistance element connected to the emitter side of the differential pair transistor and the internal resistance of the diode element. This is because the internal resistance of the diode element changes by changing the voltage on the anode side of the diode element.
- Transimpedance gain Z T of the differential transimpedance amplifier 130 is represented by the following formula.
- R F is a feedback resistor
- a O is a differential amplifier gain
- R C is the load resistance of the differential amplifier
- the emitter of the impedance of R E is the differential pair transistors
- I C is the current source of the differential amplifier Current.
- FIG. 4 is a circuit configuration diagram for explaining the operation of the coherent optical receiver 200 of the present embodiment.
- the configuration of the coherent optical receiver 200 is the same as that in FIG.
- the potential of the control terminal 142 constituting the gain adjustment unit 140 is Set differently. That is, the potential V 1 of the control terminal 142 to which the first photodiode 110 is connected is smaller than the potential V 2 of the control terminal to which the second photodiode 120 is connected (V 1 ⁇ V 2 ) Set as follows. As a result, the emitter-side impedance RE of the differential pair transistors constituting the differential amplifier 131 has different values.
- the impedance RE 1 on the side to which the first photodiode 110 is connected becomes larger than the impedance RE 2 on the side to which the second photodiode 120 is connected (RE 1 > RE 2 ).
- the transimpedance gain Z of the differential transimpedance amplifier 130 also has a different value from the above equation (13). That is, the gain Z T1 of the differential transimpedance amplifier 130 on the side to which the first photodiode 110 is connected is the gain Z T2 of the differential transimpedance amplifier 130 on the side to which the second photodiode 120 is connected. (Z T1 ⁇ Z T2 ).
- the difference in amplitude between the output current signals of the first photodiode 110 and the second photodiode 120 is canceled, and the output terminals (OUTP, OUTN) of the differential transimpedance amplifier 130 have the same amplitude.
- a positive signal voltage and a complementary signal voltage are output.
- FIG. 5 shows the frequency dependence of the gain (transimpedance gain) of the differential transimpedance amplifier 130. From the figure, the gain Z T1 of the differential transimpedance amplifier 130 on the side to which the first photodiode 110 is connected is the gain of the differential transimpedance amplifier 130 on the side to which the second photodiode 120 is connected. it can be seen that is smaller than the Z T2.
- the gain adjustment unit 140 that adjusts the transimpedance gain of the differential transimpedance amplifier 130 includes a resistance element and a diode element connected to the emitter of the differential pair transistor.
- the present invention is not limited to this, and a gain adjusting unit having another configuration may be used as long as the impedance on the emitter side of the differential pair transistor can be varied, such as a configuration including a transistor element instead of the diode element.
- the gain adjusting unit 140 is configured to adjust the gain of the correction loop of the differential transimpedance amplifier 130 by changing the impedance on the emitter side of the differential pair transistor.
- the present invention is not limited to this, and other configurations, for example, a gain adjusting unit configured to adjust the gain of the differential transimpedance amplifier 130 by changing the load resistance or feedback resistance of the differential pair may be used.
- the gain adjusting unit 140 configured to change the impedance on the emitter side described above, the transimpedance gain can be adjusted without causing a change in the band characteristic of the transimpedance gain. Therefore, the gain adjustment unit 140 has a configuration particularly suitable for practical use.
- the coherent optical receiver 200 is configured such that the differential transimpedance amplifier 130 is provided with the gain adjusting unit 140 that adjusts the gain of the differential transimpedance amplifier 130. Therefore, by adjusting the gain of the differential transimpedance amplifier 130, the amplitude difference between the output signals of the differential transimpedance amplifier 130 caused by the amplitude difference between the output current signals of the two photodiodes (PD) is eliminated. be able to. That is, it is possible to compensate for the deterioration of the common-mode noise component removal ratio (CMRR) generated in the optical 90-degree hybrid circuit or the photodiode in the differential transimpedance.
- CMRR common-mode noise component removal ratio
- FIG. 6 is a circuit configuration diagram showing a configuration of a coherent optical receiver 300 according to the third embodiment of the present invention.
- FIG. 6 shows only the I channel (Ix) of one polarization (X) portion of the coherent optical receiver.
- symbol is attached
- the coherent optical receiver 300 includes a first photodiode 110, a second photodiode 120, a differential transimpedance amplifier 130, and a gain adjustment unit 140.
- the coherent optical receiver 300 according to the present embodiment is different from the coherent optical receiver 200 according to the second embodiment in that the peak detecting unit 310 and the level converting unit 320 are further provided.
- the coherent optical receiver 300 and the optical 90-degree hybrid circuit 400 constitute a coherent optical receiver.
- the first photodiode 110 and the second photodiode 120 are made to interfere with the optical reception signal 21 and the first local oscillation light 31 or the second local oscillation light 32 in the optical 90-degree hybrid circuit 400.
- An optical signal is input (see FIG. 2).
- the optical reception signal 21 is an optical reception signal after being separated into X polarization and Y polarization by the polarization beam splitter.
- the differential transimpedance amplifier 130 includes a differential amplifier 131 to which output current signals of the first photodiode 110 and the second photodiode 120 are input, an emitter follower circuit 132, and two feedback resistors 133.
- the differential amplifier 131 includes a differential pair transistor and a current source.
- the gain adjusting unit 140 includes a variable impedance unit 141 connected to the differential amplifier 131.
- the variable impedance unit 141 has one end connected to the ground side of the differential amplifier 131 and the other end connected to the control terminal 142, and the impedance changes according to the voltage applied to the control terminal 142.
- the variable impedance unit 141 can include either a diode element or a transistor element. Hereinafter, a case where a diode element is used as the variable impedance unit 141 as shown in FIG. 6 will be described in more detail.
- a resistance element and a diode element are connected to the emitter side of the differential pair transistor constituting the differential amplifier 131, respectively.
- a control terminal 142 is connected to the anode side of the diode element.
- the peak detector 310 detects the voltage amplitudes of the positive signal voltage (OUTP) and the complementary signal voltage (OUTN) output from the differential transimpedance amplifier 130, respectively.
- the detected voltage amplitude is fed back to the gain adjustment unit 140.
- the level of the detected voltage amplitude can be converted by the level conversion unit 320 and applied to the control terminal 142 of the gain adjustment unit 140.
- Specific circuit configurations of the peak detection unit 310 and the level conversion unit 320 are not particularly limited, and generally used voltage difference detection circuits, voltage amplification circuits, and the like can be used.
- the operation of the coherent optical receiver 300 of this embodiment will be described.
- the positive signal voltage and the complementary signal voltage having the same amplitude are output to the output terminals (OUTP, OUTN) of the differential transimpedance amplifier 130. Therefore, since the peak detection unit 310 outputs the same potential, the same potential is also set to the control terminal 142 through the level conversion unit 320. At this time, the transimpedance gain of the differential transimpedance amplifier 130 is the same for both the positive signal and the complementary signal.
- a difference occurs in the amplitude of the output current signal of the first photodiode 110 and the second photodiode 120 (for example, I PD1 > I PD2 ) will be considered.
- a positive signal voltage and a complementary signal voltage having different amplitudes are output to the output terminals (OUTP, OUTN) of the differential transimpedance amplifier 130.
- the peak detector 310 detects the positive signal voltage and the complementary signal voltage.
- the level difference corresponding to the amplitude difference detected by the peak detector 310 is converted into an appropriate voltage range (V 1 , V 2 ) by the level converter 320 and input to the control terminal 142.
- V 1 , V 2 the potential V 1 of the control terminal 142 to which the first photodiode 110 is connected is smaller than the potential V 2 of the control terminal to which the second photodiode 120 is connected (V 1 ⁇ V 2 ).
- the gain Z T1 of the differential transimpedance amplifier 130 on the side to which the first photodiode 110 is connected is equal to the side to which the second photodiode 120 is connected.
- the differential transimpedance amplifier 130 is smaller than the gain Z T2 (Z T1 ⁇ Z T2 ). This feedback control is repeated until a positive signal voltage and a complementary signal voltage having the same amplitude are output to the output terminals (OUTP, OUTN) of the differential transimpedance amplifier 130.
- OUTP, OUTN the output terminals of the differential transimpedance amplifier 130.
- the gain of the differential transimpedance amplifier 130 is automatically adjusted.
- the amplitude difference between the output signals of the differential transimpedance amplifier 130 caused by the amplitude difference between the output current signals of the two photodiodes (PD) can be automatically eliminated. That is, it is possible to automatically compensate for the deterioration of the common-mode noise component removal ratio (CMRR) generated in the optical 90-degree hybrid circuit or the photodiode in the differential transimpedance amplifier.
- CMRR common-mode noise component removal ratio
- DESCRIPTION OF SYMBOLS 100 Optical receiver 110 1st photodiode 120 2nd photodiode 130 Differential type transimpedance amplifier 131 Differential amplifier 132 Emitter follower circuit 133 Feedback resistance 140 Gain adjustment part 141 Variable impedance part 142 Control terminal 200, 300 Coherent light Receiver 210 Optical phase shifter 220 Optical mixer 310 Peak detector 320 Level converter 400 Optical 90-degree hybrid circuit 410 Variable gain amplifier 420 Analog-digital converter (ADC) 430 Digital signal processing circuit (DSP) 1000 coherent optical receiver 11 first optical signal 12 second optical signal 21 optical received signal 31 first local oscillation light 32 second local oscillation light 5000 related coherent optical receiver 5001 optical reception signal 5002 local oscillation light 5010 Polarization Separator 5100 Optical 90 Degree Hybrid Circuit 5200 Photodiode 5300 Differential Transimpedance Amplifier 5400 Analog to Digital Converter (ADC) 5500 Digital signal processor (DSP)
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Power Engineering (AREA)
- Optical Communication System (AREA)
- Amplifiers (AREA)
- Dc Digital Transmission (AREA)
Abstract
Description
図1は、本発明の第1の実施形態に係る光受信器の構成を示すブロック図である。光受信器100は、第1のフォトダイオード110、第2のフォトダイオード120、差動型トランスインピーダンスアンプ130、および利得調整部140を有する。
次に、本発明の第2の実施形態について説明する。本実施形態では、光受信器としてコヒーレント検波方式によるコヒーレント光受信器を用いた場合について説明する。図3は、本発明の第2の実施形態に係るコヒーレント光受信器200の構成を示す回路構成図である。図3では、コヒーレント光受信器のうち、一の偏波(X)部のIチャネル(Ix)のみを示す。なお、第1の実施形態による光受信器100と同一の構成については同一の符号を付している。
次に、本発明の第3の実施形態について説明する。本実施形態では、光受信器としてコヒーレント検波方式によるコヒーレント光受信器を用いた場合について説明する。図6は、本発明の第3の実施形態に係るコヒーレント光受信器300の構成を示す回路構成図である。図6では、コヒーレント光受信器のうち、一の偏波(X)部のIチャネル(Ix)のみを示す。なお、第2の実施形態によるコヒーレント光受信器200と同一の構成については同一の符号を付している。
110 第1のフォトダイオード
120 第2のフォトダイオード
130 差動型トランスインピーダンスアンプ
131 差動アンプ
132 エミッタフォロワ回路
133 帰還抵抗
140 利得調整部
141 可変インピーダンス部
142 制御端子
200、300 コヒーレント光受信器
210 光位相器
220 光ミキサ
310 ピーク検出部
320 レベル変換部
400 光90度ハイブリッド回路
410 可変利得アンプ
420 アナログ・デジタル変換部(ADC)
430 デジタル信号処理回路(DSP)
1000 コヒーレント光受信装置
11 第1の光信号
12 第2の光信号
21 光受信信号
31 第1の局部発振光
32 第2の局部発振光
5000 関連するコヒーレント光受信装置
5001 光受信信号
5002 局部発振光
5010 偏波分離部
5100 光90度ハイブリッド回路
5200 フォトダイオード
5300 差動型トランスインピーダンスアンプ
5400 アナログ・デジタル変換部(ADC)
5500 デジタル信号処理部(DSP)
Claims (10)
- 第1の光信号を受光し正信号を出力する第1のフォトダイオードと、
第2の光信号を受光し補信号を出力する第2のフォトダイオードと、
前記正信号を入力して増倍した正信号電圧を出力し、前記補信号を入力して増倍した補信号電圧を出力する差動型トランスインピーダンスアンプと、
前記正信号に対する前記差動型トランスインピーダンスアンプの利得である第1の利得と、前記補信号に対する前記差動型トランスインピーダンスアンプの利得である第2の利得をそれぞれ調整する利得調整手段、とを有する
光受信器。 - 請求項1に記載した光受信器において、
前記第1の光信号は、光受信信号と、前記光受信信号と略同一波長の第1の局部発振光が干渉して得られる第1の干渉光信号であり、
前記第2の光信号は、前記光受信信号と、前記第1の局部発振光と位相が反転した第2の局部発振光が干渉して得られる第2の干渉光信号である
光受信器。 - 請求項1または2に記載した光受信器において、
前記差動型トランスインピーダンスアンプは、差動アンプを備え、
前記利得調整手段は、前記差動アンプに接続された可変インピーダンス手段を備え、
前記可変インピーダンス手段は、前記第1の利得および前記第2の利得の調整範囲に対応してインピーダンスが可変である
光受信器。 - 請求項3に記載した光受信器において、
前記可変インピーダンス手段は、一端が前記差動アンプの接地側に接続され、他端が制御端子に接続されており、前記制御端子に印加される電圧に応じて前記インピーダンスが変化する
光受信器。 - 請求項4に記載した光受信器において、
ピーク検出手段をさらに備え、
前記ピーク検出手段は、前記正信号電圧および前記補信号電圧の電圧振幅をそれぞれ検出し、前記電圧振幅を前記利得調整手段に帰還させる
光受信器。 - 請求項5に記載した光受信器において、
レベル変換手段をさらに備え、
前記レベル変換手段は、前記電圧振幅のレベルを変換して前記制御端子に印加する
光受信器。 - 請求項3から6のいずれか一項に記載した光受信器において、
前記可変インピーダンス手段は、ダイオード素子およびトランジスタ素子のいずれか一方を含む
光受信器。 - 請求項2から7のいずれか一項に記載した光受信器と、光90度ハイブリッド回路を有し、
前記光90度ハイブリッド回路は、前記光受信信号と前記第1の局部発振光を干渉させて前記第1の干渉光信号を出力し、前記光受信信号と前記第2の局部発振光を干渉させて前記第2の干渉光信号を出力する
光受信装置。 - 第1の光信号を受光し、電気信号に変換して正信号を出力し、
第2の光信号を受光し、電気信号に変換して補信号を出力し、
前記正信号と前記補信号を増倍して正信号電圧と補信号電圧を出力し、
前記正信号電圧に対する第1の利得と、前記補信号電圧に対する第2の利得を、前記正信号電圧の電圧振幅と前記補信号電圧の電圧振幅が略同一となるように、それぞれ調整する
光受信強度補正方法。 - 請求項9に記載した光受信強度補正方法において、
前記第1の利得および前記第2の利得の調整は、前記増倍する機能を有する増倍器のインピーダンスを調整することにより行う
光受信強度補正方法。
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2014544320A JPWO2014068978A1 (ja) | 2012-11-01 | 2013-10-30 | 光受信器、光受信装置および光受信強度補正方法 |
US14/439,108 US9509413B2 (en) | 2012-11-01 | 2013-10-30 | Optical receiver, optical receiving device, and method for correcting received optical intensity |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2012-241996 | 2012-11-01 | ||
JP2012241996 | 2012-11-01 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2014068978A1 true WO2014068978A1 (ja) | 2014-05-08 |
Family
ID=50626926
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2013/006435 WO2014068978A1 (ja) | 2012-11-01 | 2013-10-30 | 光受信器、光受信装置および光受信強度補正方法 |
Country Status (3)
Country | Link |
---|---|
US (1) | US9509413B2 (ja) |
JP (1) | JPWO2014068978A1 (ja) |
WO (1) | WO2014068978A1 (ja) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9337937B2 (en) * | 2014-03-10 | 2016-05-10 | Cisco Technology, Inc. | Common mode rejection ratio control for coherent optical receivers |
US10333472B2 (en) * | 2015-09-15 | 2019-06-25 | Firecomms Limited | Optical receiver |
US10209127B2 (en) * | 2015-11-05 | 2019-02-19 | Ciena Corporation | Method and system for balancing optical receiver |
JP6708344B2 (ja) * | 2016-02-29 | 2020-06-10 | 国立研究開発法人情報通信研究機構 | コヒーレント光受信器の同相除去比測定装置,及び測定方法 |
US10944486B2 (en) * | 2017-12-06 | 2021-03-09 | Elenion Technologies, Llc | DC current cancellation scheme for an optical receiver |
CN113644884A (zh) * | 2021-07-27 | 2021-11-12 | 宁波群芯微电子有限责任公司 | 跨阻放大电路及光敏芯片 |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2009069814A1 (ja) * | 2007-11-30 | 2009-06-04 | Nec Corporation | 光受信回路および信号処理方法 |
JP2012010187A (ja) * | 2010-06-25 | 2012-01-12 | Sumitomo Electric Ind Ltd | 増幅回路 |
WO2012117951A1 (ja) * | 2011-03-01 | 2012-09-07 | 日本電気株式会社 | 光受信器および光受信方法 |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7606498B1 (en) * | 2005-10-21 | 2009-10-20 | Nortel Networks Limited | Carrier recovery in a coherent optical receiver |
JP5105005B2 (ja) | 2010-04-21 | 2012-12-19 | 日本電気株式会社 | 光受信器、光受信装置および光受信強度補正方法 |
US8649690B2 (en) * | 2012-05-30 | 2014-02-11 | Cisco Technology, Inc. | Optical communication reception system |
-
2013
- 2013-10-30 US US14/439,108 patent/US9509413B2/en active Active
- 2013-10-30 WO PCT/JP2013/006435 patent/WO2014068978A1/ja active Application Filing
- 2013-10-30 JP JP2014544320A patent/JPWO2014068978A1/ja active Pending
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2009069814A1 (ja) * | 2007-11-30 | 2009-06-04 | Nec Corporation | 光受信回路および信号処理方法 |
JP2012010187A (ja) * | 2010-06-25 | 2012-01-12 | Sumitomo Electric Ind Ltd | 増幅回路 |
WO2012117951A1 (ja) * | 2011-03-01 | 2012-09-07 | 日本電気株式会社 | 光受信器および光受信方法 |
Also Published As
Publication number | Publication date |
---|---|
JPWO2014068978A1 (ja) | 2016-09-08 |
US9509413B2 (en) | 2016-11-29 |
US20150295660A1 (en) | 2015-10-15 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5105005B2 (ja) | 光受信器、光受信装置および光受信強度補正方法 | |
JP5339088B2 (ja) | 光受信回路および信号処理方法 | |
WO2014068978A1 (ja) | 光受信器、光受信装置および光受信強度補正方法 | |
JP5326584B2 (ja) | 遅延処理装置,信号増幅装置,光電変換装置,アナログ/デジタル変換装置,受信装置および受信方法 | |
US8989593B2 (en) | Frequency domain clock recovery | |
JP5246381B1 (ja) | 光信号処理装置、及び光信号処理方法 | |
JP5861765B2 (ja) | 光受信器、及び光受信方法 | |
JP5287516B2 (ja) | デジタルコヒーレント光受信器 | |
US8977140B2 (en) | Optical receiver and optical reception method | |
US8285152B2 (en) | DQPSK optical receiver | |
JP5370133B2 (ja) | 光受信機および受信方法 | |
JP2011250126A (ja) | トランスインピーダンスアンプ及び光レシーバ | |
Chen et al. | Direct-detection based frequency-resolved I/Q imbalance calibration for coherent optical transmitters | |
JP5908872B2 (ja) | コヒーレント通信用光受信器およびその制御方法 | |
EP2418789B1 (en) | Optoelectronic device for differential photoreception, with automatic compensation of phase and amplitude imbalances | |
WO2013057967A1 (ja) | 光受信器、光受信装置および光受信強度補正方法 | |
WO2013015391A1 (ja) | 光受信器、それを用いた光受信装置、および光受信方法 | |
JPWO2020050299A1 (ja) | 光受信装置および受信方法 | |
JPWO2020110956A1 (ja) | 光受信機及び光空間通信システム | |
Ashok et al. | Differentiator based frequency detector for 100-Gb/s analog domain DP-QPSK coherent optical receivers |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 13852135 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2014544320 Country of ref document: JP Kind code of ref document: A |
|
WWE | Wipo information: entry into national phase |
Ref document number: 14439108 Country of ref document: US |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 13852135 Country of ref document: EP Kind code of ref document: A1 |