WO2013088694A1 - 光受信器及び光受信器の制御方法 - Google Patents
光受信器及び光受信器の制御方法 Download PDFInfo
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- WO2013088694A1 WO2013088694A1 PCT/JP2012/007884 JP2012007884W WO2013088694A1 WO 2013088694 A1 WO2013088694 A1 WO 2013088694A1 JP 2012007884 W JP2012007884 W JP 2012007884W WO 2013088694 A1 WO2013088694 A1 WO 2013088694A1
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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
- H04B10/60—Receivers
- H04B10/61—Coherent receivers
- H04B10/616—Details of the electronic signal processing in coherent optical receivers
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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
- H04B10/25—Arrangements specific to fibre transmission
- H04B10/2575—Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier
-
- 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
-
- 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
- H04B10/614—Coherent receivers comprising one or more polarization beam splitters, e.g. polarization multiplexed [PolMux] X-PSK coherent receivers, polarization diversity heterodyne coherent receivers
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
- H04L27/22—Demodulator circuits; Receiver circuits
- H04L27/227—Demodulator circuits; Receiver circuits using coherent demodulation
Definitions
- the present invention relates to an optical receiver and an optical receiver control method, and more particularly to an optical receiver using a digital coherent reception method and a control method thereof.
- DP-QPSK is an abbreviation for dual-polarization quadrature phase shift keying (polarization multiplexed four-phase shift keying).
- a digital coherent reception method is used for demodulating the signal light modulated by DP-QPSK.
- received signal light received light
- LO light local oscillator light, local oscillation light
- the output of the 90-degree hybrid is received by a light receiving element (photo diode, PD).
- the PD outputs a beat signal of received light and LO light as a photocurrent to a TIA (trans-impedance amplifier).
- the TIA converts the photocurrent output from the PD into a voltage signal and outputs it to an ADC (analog-digital converter, analog-digital converter).
- the beat signal converted into a digital signal by the ADC is output to the signal processing circuit.
- the signal processing circuit performs arithmetic processing on the digital signal output from the ADC and demodulates the transmitted data.
- the conversion efficiency ⁇ indicates the ADC input amplitude obtained with respect to the signal light power input to the PD.
- the amplitude (voltage) V of the signal input to the ADC can be expressed by Equation (1) using the conversion efficiency ⁇ .
- V ⁇ ⁇ (P sig ⁇ P LO ) 1/2 (1)
- V is the amplitude (V) of the signal input to the ADC
- ⁇ is the conversion efficiency (V / W) when converting the signal light into the input signal to the ADC
- P sig is the signal input to the light receiving element.
- the light intensity (W) and P LO are the intensity (W) of the LO light input to the light receiving element.
- the amplitude of the signal input to the ADC is limited by the amplitude of the signal that can be processed inside the ADC.
- the optical receiver is required to normally reproduce an optical signal having an intensity within a range determined by the specifications of the optical transmission system. For this reason, the optical receiver needs to be designed so that the amplitude of the signal input to the ADC is within the allowable range over the entire range in which the intensity of the light input to the receiving apparatus varies.
- the amplitude of the signal input to the ADC is proportional to the square root of the product of the signal light intensity and the LO light intensity. That is, even if the intensity of the signal light is constant, the amplitude of the signal input to the ADC can be controlled by changing the intensity of the LO light. Therefore, even when the range of the input intensity of the signal light is wide, the amplitude of the signal input to the ADC can be kept within the allowable range of the ADC by reducing or increasing the intensity of the LO light.
- Patent Document 1 and Patent Document 2 describe the configuration of an optical receiver that mixes LO light and received light and converts them into an analog electrical signal, and further converts the output into a digital signal. ing.
- the LO light power is changed in the digital coherent reception system, the following problems occur. That is, in an optical module using a semiconductor laser normally used as a light source for LO light, when the power of the LO light source is changed by controlling the drive current, the wavelength and phase of the LO light output from the semiconductor laser fluctuate. However, in the digital coherent reception method, if the wavelength or phase of the LO light varies, a code error may occur due to phase slip. For this reason, if the LO light intensity is directly changed during the operation of the optical receiver, the transmission quality may be deteriorated due to a code error.
- variable optical attenuator at the output of the LO light source, the intensity of the LO light can be controlled while keeping the output of the semiconductor laser constant.
- the configuration in which the variable optical attenuator is provided outside has a problem that it is difficult to reduce the size and cost of the optical receiver because the number of components of the optical receiver increases.
- the method of controlling the amplitude of the signal input to the ADC by decreasing or increasing the intensity of the LO light has a problem that the transmission quality is deteriorated due to a code error, or the optical receiver is downsized. In addition, there is a problem that cost reduction becomes difficult. And patent document 1 and 2 described previously cannot solve these subjects.
- An object of the present invention is to provide a technique for realizing an optical receiver capable of suppressing the occurrence of a code error at the time of signal detection of an optical receiver with a simple configuration and with a wide range of signal light input intensities. is there.
- the optical receiver of the present invention includes a local light oscillation means for generating local oscillation light having a constant intensity, and an optical mixing means for mixing the local oscillation light and the first signal light and outputting them as a second signal light.
- a signal processing circuit for processing the second electrical signal, and the gain is set so that the amplitude of the second electrical signal is within a range of amplitude allowed at the input of the signal processing circuit.
- the control method of the optical receiver of the present invention generates local oscillation light having a constant intensity, mixes the local oscillation light and the first signal light, and outputs them as second signal light. Is converted into an electric signal and output as a first electric signal, the first electric signal is amplified with a predetermined gain and output as a second electric signal, and the amplitude of the second electric signal is within a predetermined range.
- the gain is set so that
- the present invention has an effect that it is possible to suppress the occurrence of a code error at the time of signal detection of an optical receiver in a wide input range of signal light intensity with a simple configuration.
- FIG. 1 is a diagram showing a configuration of an optical receiver 100 according to the first embodiment of the present invention.
- an optical receiver 100 includes PBSs (polarization beam splitters) 3a and 3b, 90-degree hybrids 4a and 4b, an LO light generation unit 9, and PDs (photo diodes) 5a to 5h.
- the optical receiver 100 further includes amplifiers 6a to 6d, ADCs 7a to 7d, a digital signal processing unit 8, a monitor unit 21, and a control unit 22.
- the monitor unit 21 outputs the input received signal light 1 to the PBS 3 a and outputs an electrical signal proportional to the intensity of the received signal light 1.
- the monitor unit 21 includes, for example, an optical branching device and a light receiving element that outputs a current proportional to the intensity of the light branched by the optical branching device.
- the control unit 22 controls the gains of the amplifiers 6a to 6d based on the output of the monitor unit 21.
- the PBSs 3a and 3b separate the signal light output from the monitor unit 21 into X and Y polarizations orthogonal to each other.
- the 90-degree hybrid 4a regenerates an I (inphase) signal and a Q (quadture) signal from each of the polarization separated signal lights.
- the 90-degree hybrid 4a outputs an XI signal and an XQ signal that are outputs of an I signal and a Q signal.
- the 90-degree hybrid 4b outputs a YI signal and a YQ signal.
- the LO light generator 9 generates LO light having a constant intensity.
- PDs 5a to 5h are twin PDs composed of four sets, each set of two PDs.
- the PDs 5a to 5h receive the received light separated into XI, XQ, YI, and YQ by the 90-degree hybrids 4a and 4b through two channels of p (positive) / n (negative), respectively, as a differential current. Output.
- the amplifiers 6a to 6d output the differential current output from the PDs 5a to 5h to the ADCs 7a to 7d as voltage signals.
- TIA can be used as the amplifiers 6a to 6d.
- the ADCs 7a to 7d convert the analog signals output from the amplifiers 6a to 6d into digital signals.
- the digital signal processing unit 8 performs signal processing on the digital signals output from the ADCs 7a to 7d.
- the monitor unit 21 outputs an electrical signal corresponding to the intensity of the input signal light. (Description of operation of the first embodiment) FIG.
- FIG. 2 is a diagram illustrating a relationship between the range of the signal light intensity P sig input to the PDs 5a to 5h and the range of the amplitude V of the signal output from the amplifiers 6a to 6d in the optical receiver 100.
- the horizontal axis in FIG. 2 indicates the intensity P sig of the signal light input to the PDs 5a to 5h, and the vertical axis indicates the amplitude of the electric signal output from the amplifiers 6a to 6d.
- the amplitude of the signals output from the amplifiers 6a to 6d is equal to the amplitude of the signals input to the ADCs 7a to 7d.
- the amplitude of signals input to the ADCs 7a to 7d is generally defined by voltage.
- V min and V max on the vertical axis in FIG. 2 indicate the minimum and maximum values of the amplitude V allowed by the ADCs 7a to 7d.
- P min and P max on the horizontal axis indicate the minimum value and the maximum value of the intensity P sig of the signal light received by the PDs 5a to 5h.
- the minimum value and the maximum value of P sig correspond to the amplitude range of the input signals of the ADCs 7a to 7d. If the range of the intensity of the signal light received by the PDs 5a to 5h is between P min and P max in the light receiving range of the signal light determined by the specifications of the optical receiver 100, the amplifiers 6a to 6d The amplitude of the electrical signal to be output falls between V min and V max .
- FIG. 2 shows the photoelectric conversion processing in the PDs 5a to 5h and the amplifiers 6a to 6d when the intensity P sig of the signal light input to the PDs 5a to 5h is converted into the input amplitude V to the ADCs 7a to 7d.
- the characteristic which integrated the current-voltage conversion process in is shown.
- Equation (1) described above can be written as Equation (2) below.
- V [ ⁇ ⁇ (P LO ) 1/2 ] ⁇ (P sig ) 1/2 (2) That is, by taking (P sig ) 1/2 on the horizontal axis, the relationship between the square root of the intensity P sig of the signal light received by the PDs 5a to 5h and the amplitude V of the electric signal output from the amplifiers 6a to 6d. Is represented by a straight line as shown in FIG. In FIG. 2, (P min ) 1/2 and (P max ) 1/2 are (P sig ) 1/2 when the intensity P sig of the signal light received by the PDs 5a to 5h is the minimum value and the maximum value, respectively. A value of 2 is shown. V min and V max indicate the values of V when the amplitudes of the signals output from the amplifiers 6a to 6d are the minimum value and the maximum value allowed by the ADCs 7a to 7d, respectively.
- the slopes of the straight lines A and B in FIG. 2 are represented by ⁇ ⁇ (P LO ) 1/2 shown in Expression (1).
- the conversion efficiency ⁇ is also expressed as ⁇ PD ⁇ ⁇ amp when the quantum efficiency of the PDs 5a to 5h is ⁇ PD (A / W) and the gains of the amplifiers 6a to 6d are ⁇ amp (V / A).
- the quantum efficiency ⁇ PD of the PDs 5a to 5h may be considered constant for each PD.
- the intensity P LO of the LO light is kept constant.
- the slopes K A and K B of the straight lines A and B are expressed by the following equations when the gains of the amplifiers 6a to 6d at the points P and Q are ⁇ A and ⁇ B , respectively.
- K A [ ⁇ PD ⁇ (P LO ) 1/2 ] ⁇ ⁇ A (3)
- K B [ ⁇ PD ⁇ (P LO ) 1/2 ] ⁇ ⁇ B (4)
- a point where the amplitude satisfies the maximum value (V max ) allowed in the ADCs 7a to 7d is shown.
- the slope K B of the straight line B passing through the point Q corresponds to the gain ⁇ B of the amplifiers 6a to 6d at that time.
- the amplifiers 6a to 6d are used at a constant gain corresponding to the straight line B, when the signal light intensity P sig becomes small, the signals input to the ADCs 7a to 7d even if P sig > P min .
- the amplitude V is below V min (point Q 1 ).
- the optical receiver 100 can control the gain ⁇ amp of the amplifiers 6a to 6d to keep the range of the amplitude V of the signal output from the amplifiers 6a to 6d within the allowable range of the ADCs 7a to 7d. To do.
- the gain ⁇ amp of the amplifiers 6a to 6d it is not necessary to change the intensity P LO of the LO light, and the value of P LO is maintained at a constant value.
- the monitor unit 21 monitors the intensity of the signal light input to the optical receiver 100 and outputs an electric signal having an amplitude proportional to the intensity of the input signal light to the control unit 22.
- the control unit 22 controls the gains ⁇ amp of the amplifiers 6a to 6d based on the amplitude of the electric signal input from the monitor unit 21. For example, when the intensity of the signal light input to the optical receiver 100 is small, the control unit 22, a gain eta A corresponding gain eta # 038 of amplifiers 6a ⁇ 6d to tilt K A of the straight line A in FIG. 2 Control to be. Then, the control unit 22, the intensity of the signal light is increased, and controls so as to approach the gain eta B corresponding gain eta # 038 the inclination K B of the straight line B in FIG.
- the gain ⁇ amp may be controlled so as to smoothly follow the change in the intensity of the signal light input to the optical receiver 100.
- the control unit 22 controls the gains of the amplifiers 6a to 6d to decrease from ⁇ A to ⁇ B according to the value of P sig. May be.
- the intensity of the signal light input to the optical receiver 100 may be divided into a plurality of ranges, and the gain ⁇ amp may be controlled to be a predetermined value for each range corresponding to the intensity of the signal light.
- control unit 22 can keep the range of the amplitude V of the signal output from the amplifiers 6a to 6d within the allowable range of the ADCs 7a to 7d.
- the gains ⁇ amp of the amplifiers 6a to 6d may be controlled so as to output signal light having an intensity in the range of P min to P max as a signal having an amplitude in the range of V min to V max . That is, the adjustment procedure of the gain ⁇ amp by the control unit 22 is not limited to the above.
- the control unit 22 controls the amplifiers 6a to 6d so that the amplitude of the signals output from the amplifiers 6a to 6d does not deviate from the range in which the input amplitude to the ADCs 7a to 7d is allowed by the ADC. Control the gain of 6d. That is, in the optical receiver 100, the amplitudes of the signals input to the ADCs 7a to 7d are maintained within an allowable range by controlling the gains of the amplifiers 6a to 6d while keeping the intensity of LO light constant.
- the PDs 5a to 5h, the amplifiers 6a to 6d, and the ADCs 7a to 7d are provided for each signal (XI, XQ, YI, YQ) path. Therefore, the gains ⁇ amp of the amplifiers 6a to 6d may be controlled to different values according to the characteristics of the components of the path of each signal.
- the control unit 22 sets the gain ⁇ amp of the amplifiers 6a to 6d to the output signal of the amplifiers 6a to 6d without changing the intensity P LO of the LO light. Control is performed so that the amplitude falls within the allowable input range of the ADCs 7a to 7d.
- the optical receiver 100 of the first embodiment can suppress the occurrence of a code error when detecting the signal of the optical receiver with a simple configuration even when the input range of the intensity of the signal light is wide. Play.
- ⁇ amp V / [ ⁇ PD ⁇ (P LO ) 1/2 ⁇ (P sig ) 1/2 ] (6)
- the value of ⁇ amp is expressed as shown in Equation (7).
- any of the quantum efficiencies of the PDs 5a to 5h may be used as a representative.
- the value of the quantum efficiency ⁇ PD used to determine the LO light intensity P LO may be calculated based on part or all of the values of the quantum efficiencies of the PDs 5a to 5h. For example, the average value of the quantum efficiencies of PDs 5a to 5h may be used as the value of the quantum efficiency ⁇ PD .
- the intensity P sig of the signal light input to the PDs 5a to 5h is equal to the intensity of the received signal light 1 input to the optical receiver 100, the loss of the monitor unit 21, the loss of the PBS 3a, and the 90-degree hybrid 4a or 4b. It can be obtained by adding the loss.
- the intensity P LO of the LO light input to the PDs 5a to 5h can be obtained by adding the loss of the PBS 3b and the loss of the 90-degree hybrid 4a or 4b to the intensity of the LO light output from the LO light source 9. it can.
- the gains ⁇ amp of the amplifiers 6a to 6d are changed between the gains corresponding to the slope of the straight line A and the slope of the straight line B, respectively.
- the control characteristic of the gain ⁇ amp is not limited to the above.
- the gains ⁇ amp of the amplifiers 6a to 6d are such that when the intensity of the signal light input to the PDs 5a to 5h changes from P min to P max , the amplitudes of the signals output from the amplifiers 6a to 6d change monotonously. only to be controlled to fall within the range of V max from min.
- FIG. 3 is a diagram illustrating a configuration of the optical receiver 200 according to the second embodiment of this invention.
- the optical receiver 200 includes PBSs 3a and 3b, 90-degree hybrids 4a and 4b, an LO light generator 9, and PDs 5a to 5h.
- the optical receiver 200 further includes amplifiers 6a to 6d, ADCs 7a to 7d, a digital signal processing unit 8, monitor units 31a to 31d, and a control unit 23.
- the configuration of the optical receiver 200 shown in FIG. 3 is different from the configuration of the optical receiver 100 shown in FIG. 1 in that monitor units 31a to 31d are provided instead of the monitor unit 21. . Further, the control 23 controls the gains ⁇ amp of the amplifiers 6 a to 6 d different from the control unit 22 of the optical receiver 100. Of the constituent elements of the optical receiver 200, the same elements as those of the optical receiver 100 are designated by the same reference numerals as those in FIG.
- the monitor units 31a to 31d are arranged between the amplifiers 6a to 6d and the ADCs 7a to 7d.
- the monitor units 31a to 31d output signals corresponding to the amplitudes of the signals output from the amplifiers 6a to 6d to the control unit 23.
- the control unit 23 controls the gain ⁇ amp so that the amplitude V of the signals output from the amplifiers 6a to 6d is within the amplitude range allowed by the ADCs 7a to 7d. .
- control unit 23 may control the gain ⁇ amp so that the amplitude V becomes a constant value within the range of amplitude allowed by the ADCs 7a to 7d.
- control unit 23 may control the gain ⁇ amp so that the amplitude V does not deviate from between the upper limit or the lower limit of the amplitude range allowed by the ADCs 7a to 7d.
- the gain ⁇ amp of the amplifiers 6a to 6d is such that the amplitude of the output signal of the amplifiers 6a to 6d is equal to the ADC 7a while the LO light intensity P LO is kept constant. It is controlled so as to be within an allowable input range of ⁇ 7d.
- the optical receiver 200 of the second embodiment can be used for signal detection of the optical receiver with a simple configuration even when the input range of the intensity of the signal light is wide. There is an effect that generation of a code error can be suppressed.
- the monitor units 31a to 31d are arranged between the amplifiers 6a to 6d and the ADCs 7a to 7d.
- the optical receiver 200 according to the second embodiment has the effect that the gain ⁇ amp of the amplifiers 6a to 6d can be more precisely controlled according to the signal strength for each signal (XI, XQ, YI, YQ) path. Also play.
- the monitor unit has been described as being placed at the input unit of the optical receiver 100 or the outputs of the amplifiers 6a to 6d.
- the position of the monitor unit is not limited as long as the intensity of the signal light input to the optical receiver can be detected.
- a monitor unit may be provided between the PBS 3a and the 90-degree hybrid 4a and between the PBS 3a and the 90-degree hybrid 4b.
- FIG. 4 is a diagram illustrating a configuration of an optical receiver 300 according to the third embodiment of the present invention.
- the optical receiver 300 includes PBSs 3a and 3b, 90-degree hybrids 4a and 4b, an LO light generator 9, and PDs 5a to 5h.
- the optical receiver 300 further includes amplifiers 6a to 6d, ADCs 7a to 7d, and a digital signal processing unit 8.
- the configuration of the optical receiver 300 shown in FIG. 4 is different from the configurations of the optical receivers 100 and 200 shown in FIGS. 1 and 2 in that the monitor units 21, 31a to 31d and the control units 22, 23 are provided. Both are different in that they are lacking. Since the components of the optical receiver 300 are the same as those of the optical receivers 100 and 200, the same reference numerals are given to the components, and description thereof is omitted.
- the gain ⁇ amp of the amplifiers 6a to 6d during operation is constant.
- the amplitude of the output signal of the amplifiers 6a to 6d can be within the allowable input range of the ADCs 7a to 7d even when the gain ⁇ amp of the amplifiers 6a to 6d is kept constant.
- FIG. 5 is a diagram illustrating a relationship between the range of the intensity P sig of the signal light input to the PDs 5a to 5h and the range of the amplitude V of the signal output from the amplifiers 6a to 6d in the optical receiver 300.
- the horizontal axis is the square root (P sig ) 1/2 of the intensity P sig of the signal light input to the PDs 5a to 5h, as in FIG.
- the vertical axis in FIG. 5 indicates the amplitude V of the electric signal output from the amplifiers 6a to 6d.
- the straight lines C and D in FIG. 5 indicate the characteristics when the intensity of the signal light input to the PDs 5a to 5h is converted into the input amplitudes to the ADCs 7a to 7d, as in FIG.
- the slope K C of the straight line C at the point R corresponds to the gain ⁇ amp of the amplifiers 6a to 6d at that time.
- V does not exceed V max (point R 1 ).
- the point at which the amplitude satisfies the maximum value (V max ) allowed by the ADCs 7a to 7d is shown.
- the slope K D of the straight line D at point S corresponds to the gain eta # 038 of amplifiers 6a ⁇ 6d that time.
- the optical receiver 300 of the third embodiment having such a configuration, even when the intensity of the signal light changes from the minimum value to the maximum value of the fluctuation range in a state where the LO light intensity PLO is kept constant.
- the amplitudes of the output signals of the amplifiers 6a to 6d are within the allowable input range of the ADCs 7a to 7d.
- the optical receiver 300 of the third embodiment can receive light with a simple configuration even when the input range of signal light intensity is wide. It is possible to suppress the occurrence of a code error when detecting the signal of the detector.
- the optical receiver 300 according to the third embodiment does not include the monitor unit and the control unit, the configuration is further simplified, and there is an effect that the optical receiver can be reduced in size and price.
- FIG. 6 is a diagram illustrating the configuration of the optical receiver according to the fourth embodiment of the present invention.
- the optical receiver 400 includes a local light oscillation unit 401, an optical mixing unit 402, a light receiving unit 403, an amplification unit 404, and a signal processing circuit 405.
- the local light oscillation unit 401 generates local oscillation light 406 having a constant intensity.
- the light mixing unit 402 mixes the local oscillation light 406 and the first signal light 407 and outputs it as the second signal light 408.
- the light receiving unit 403 converts the second signal light 408 into an electric signal and outputs it as a first electric signal 409.
- the amplifying unit 404 amplifies the first electric signal 409 with a predetermined gain and outputs it as the second electric signal 410.
- the signal processing circuit processes the second electrical signal 410. Then, the gain of the amplifying unit 404 is set so that the amplitude of the second electric signal 410 is within the range of the amplitude allowed at the input of the signal processing circuit 405.
- the intensity of the local oscillation light 406 is kept constant.
- the amplitude of the first electric signal 410 input to the signal processing circuit 405 is allowed at the input of the signal processing circuit 405 even if the intensity of the first signal light 407 changes.
- the gain of the amplifying unit 404 is set so as to fall within the range of
- the optical receiver 400 since the optical receiver 400 does not change the intensity of the local oscillation light 406 even when the intensity of the first signal light 407 changes, the frequency and phase of the local oscillation light 406 do not vary. As a result, the optical receiver 400 does not generate a phase slip between the first signal light 407 and the local oscillation light 406 in the optical mixing unit 402 even when the intensity of the first signal light 407 changes. Thus, it is possible to suppress the occurrence of signal errors during signal detection.
- Optical receiver 1 Received signal light 3a, 3b PBS 4a, 4b 90 degree hybrid 5a-5h PD 6a to 6d amplifier 7a to 7d
- ADC 8 Digital signal processing unit 9 LO light generation unit 21, 31a to 31d Monitor unit 22, 23
- Control unit 401 Local light oscillation unit 402
- Optical mixing unit 403 Light reception unit 404
- Amplification unit 405 Signal processing circuit 406 Local oscillation light 407 First signal Light 408 Second signal light 409 First electric signal 410 Second electric signal
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Abstract
Description
ここで、VはADCへ入力される信号の振幅(V)、ηは信号光をADCへの入力信号に変換する際の変換効率(V/W)、Psigは受光素子へ入力される信号光の強度(W)、PLOは受光素子へ入力されるLO光の強度(W)である。
本発明の第1の実施形態について説明する。図1は、本発明の第1の実施形態である光受信器100の構成を示す図である。図1において、光受信器100は、PBS(polarization beam splitter)3a及び3b、90度ハイブリッド4a及び4b、LO光発生部9及びPD(photo diode)5a~5hを備える。光受信器100は、さらに、アンプ6a~6d、ADC7a~7d、デジタル信号処理部8、モニタ部21及び制御部22を備える。
(第1の実施形態の動作の説明)
図2は、光受信器100における、PD5a~5hに入力される信号光強度Psigの範囲とアンプ6a~6dから出力される信号の振幅Vの範囲との関係を示す図である。図2の横軸はPD5a~5hに入力される信号光の強度Psigを示し、縦軸はアンプ6a~6dが出力する電気信号の振幅を示す。アンプ6a~6dから出力された信号の振幅は、ADC7a~7dへ入力される信号の振幅に等しい。ADC7a~7dへ入力される信号の振幅は、一般に電圧で規定される。
すなわち、(Psig)1/2を横軸に取ることにより、PD5a~5hで受光される信号光の強度Psigの平方根と、アンプ6a~6dが出力する電気信号の振幅Vと、の関係は、図2に示すように直線で表される。図2において、(Pmin)1/2及び(Pmax)1/2は、PD5a~5hで受光される信号光の強度Psigがそれぞれ最小値及び最大値の場合の(Psig)1/2の値を示す。また、Vmin及びVmaxは、アンプ6a~6dから出力される信号の振幅が、それぞれADC7a~7dで許容される最小値及び最大値の場合の、Vの値を示す。
KB=[ηPD×(PLO)1/2]×ηB ・・・(4)
図2の点Pは、(Psig)1/2=(Pmin)1/2、すなわち信号光の強度が最小(Pmin)の場合に、アンプ6a~6dから出力される信号の振幅がADC7a~7dで許容される最小値(Vmin)を満足する点を示す。そして、点Pを通る直線Aの傾きKAはその際のアンプ6a~6dの利得ηAに対応する。しかしながら、アンプ6a~6dを直線Aに対応する一定の利得で使用すると、信号光の強度Psigが大きくなった場合に、Psig<PmaxであってもADC7a~7dへ入力される信号の振幅VがVmaxを超える(点P1)。
=[(ηPD×ηamp)×(PLO)1/2]×(Psig)1/2 ・・・(5)
式(5)から、ηampは下式で求められる。
ここで、LO光の強度の設定の際にηPD×(PLO)1/2が所定の一定値Gとなるように、PLOが調整される。すなわち、PLO=(G/ηPD)2である。そうすると、ηampの値は式(7)のように表される。
式(7)を用いると、量子効率ηPD及びLO光の強度PLOが未知であっても、Psigを変化させた場合のADC入力信号の振幅Vの範囲が許容入力範囲を超えない利得ηampの範囲を求めることができる。このように、PLO=(G/ηPD)2となるとようにPLOを調整することにより、LO光の強度PLOの設定前であっても、利得ηampが制御される範囲を知ることができる。その結果、光受信器の製造時にアンプ6a~6dが使用される利得の範囲で最適な回路の調整が可能となる。さらに、光受信器の製造時に、LO光の強度の設定工程とアンプ6a~6dの利得ηampの設定工程との実施順序を自由に決定することができる。
図3は、本発明の第2の実施形態の光受信器200の構成を示す図である。図3において、光受信器200は、PBS3a及び3b、90度ハイブリッド4a及び4b、LO光発生部9及びPD5a~5hを備える。光受信器200は、さらに、アンプ6a~6d、ADC7a~7d、デジタル信号処理部8、モニタ部31a~31d及び制御部23を備える。
図4は、本発明の第3の実施形態の光受信器300の構成を示す図である。図4において、光受信器300は、PBS3a及び3b、90度ハイブリッド4a及び4b、LO光発生部9及びPD5a~5hを備える。光受信器300は、さらに、アンプ6a~6d、ADC7a~7d、デジタル信号処理部8を備える。
図6は、本発明の第4の実施形態の光受信器の構成を示す図である。光受信器400は、局発光発振部401と、光混合部402と、受光部403と、増幅部404と、信号処理回路405と、を備える。
局発光発振部401は、一定の強度の局部発振光406を発生する。光混合部402は、局部発振光406と第1の信号光407とを混合して、第2の信号光408として出力する。受光部403は、第2の信号光408を電気信号に変換して第1の電気信号409として出力する。増幅部404は、第1の電気信号409を所定の利得で増幅して第2の電気信号410として出力する。信号処理回路は、第2の電気信号410を処理する。そして、第2の電気信号410の振幅が信号処理回路405の入力において許容される振幅の範囲内となるように、増幅部404の利得が設定される。
1 受信信号光
3a、3b PBS
4a、4b 90度ハイブリッド
5a~5h PD
6a~6d アンプ
7a~7d ADC
8 デジタル信号処理部
9 LO光発生部
21、31a~31d モニタ部
22、23 制御部
401 局発光発振部
402 光混合部
403 受光部
404 増幅部
405 信号処理回路
406 局部発振光
407 第1の信号光
408 第2の信号光
409 第1の電気信号
410 第2の電気信号
Claims (9)
- 一定の強度の局部発振光を発生する局発光発振手段と、
前記局部発振光と第1の信号光とを混合して第2の信号光として出力する光混合手段と、
前記第2の信号光を電気信号に変換して第1の電気信号として出力する受光手段と、
前記第1の電気信号を所定の利得で増幅して第2の電気信号として出力する増幅手段と、
前記第2の電気信号を処理する信号処理回路と、を備え、
前記第2の電気信号の振幅が前記信号処理回路の入力において許容される振幅の範囲内となるように前記利得が設定される、光受信器。 - 前記第1の光信号をモニタして前記第1の光信号の電力に対応する信号を出力する第1のモニタ手段をさらに備え、前記利得は前記第1のモニタ手段が出力する信号に基づいて設定される、請求項1に記載された光受信器。
- 前記第2の電気信号をモニタして前記第2の電気信号の振幅に対応する信号を出力する第2のモニタ手段を備え、前記利得は前記第2のモニタ手段が出力する信号に基づいて設定される、請求項1に記載された光受信器。
- 前記局部発振光の電力は、前記第1の電気信号の電力を前記第2の光信号の電力で除した値である量子効率に基づいて設定される、請求項1乃至3のいずれかに記載された光受信器。
- 前記局部発振光の電力の平方根と前記量子効率との積が所定の値となるように前記局部発振光の電力が設定される、請求項4に記載された光受信器。
- 前記第2の電気信号をデジタル信号に変換して前記信号処理回路に出力するADC(analog-digital converter)をさらに備える、請求項1乃至5のいずれかに記載された光受信器。
- 前記利得は、前記ADCに入力される前記第2の電気信号の振幅が、前記ADCにおいて許容される範囲となるように設定される、請求項6に記載された光受信器。
- 受信した信号光を第3の信号光と第4の信号光とに偏波分離する偏波分離手段をさらに備え、
前記光混合手段は、前記第3及び第4の信号光のそれぞれから直交するI(inphese)信号とQ(quadrature)信号を分離して前記第2の信号光として出力する、
請求項1乃至7のいずれかに記載された光受信器。 - 一定の強度の局部発振光を発生し、
前記局部発振光と第1の信号光とを混合して第2の信号光として出力し、
前記第2の信号光を電気信号に変換して第1の電気信号として出力し、
前記第1の電気信号を所定の利得で増幅して第2の電気信号として出力し、
前記第2の電気信号の振幅が所定の範囲内となるように前記利得が設定される、ことを特徴とする、光受信器の制御方法。
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015004828A1 (ja) * | 2013-07-11 | 2015-01-15 | 日本電気株式会社 | 光受信装置およびモニタ信号生成方法 |
CN106471757A (zh) * | 2014-06-12 | 2017-03-01 | 日本电气株式会社 | 光接收装置和光接收方法 |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9209908B2 (en) * | 2012-10-04 | 2015-12-08 | Zte (Usa) Inc. | System and method for heterodyne coherent detection with optimal offset |
JP6281303B2 (ja) * | 2014-02-03 | 2018-02-21 | 富士通株式会社 | 多値強度変復調システムおよび方法 |
CN106487453B (zh) * | 2016-09-28 | 2018-10-16 | 西安电子科技大学 | 一种零中频的微波光子信道化接收机的装置及方法 |
JP6760017B2 (ja) * | 2016-11-28 | 2020-09-23 | 富士通オプティカルコンポーネンツ株式会社 | 光受信器 |
CN117714914A (zh) | 2018-08-02 | 2024-03-15 | 有线电视实验室公司 | 用于相干突发接收的系统和方法 |
JP7489886B2 (ja) * | 2020-10-05 | 2024-05-24 | 富士通オプティカルコンポーネンツ株式会社 | 受信装置及び受信方法 |
CN116260139B (zh) * | 2023-03-29 | 2023-08-22 | 南方电网科学研究院有限责任公司 | 振荡现象的抑制方法、抑制装置以及电子装置 |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008278249A (ja) * | 2007-04-27 | 2008-11-13 | Fujitsu Ltd | 光信号受信装置 |
JP2010245772A (ja) * | 2009-04-03 | 2010-10-28 | Fujitsu Ltd | 光受信機および光受信方法 |
JP2010251851A (ja) * | 2009-04-10 | 2010-11-04 | Fujitsu Ltd | 光伝送システム |
JP2012147078A (ja) * | 2011-01-07 | 2012-08-02 | Fujitsu Ltd | 光伝送装置およびアナログ−デジタル変換装置 |
Family Cites Families (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4697284A (en) * | 1986-05-08 | 1987-09-29 | American Telephone And Telegraph Company, At&T Bell Laboratories | Single-photodiode optical heterodyne mixers |
JPS63244934A (ja) * | 1987-03-30 | 1988-10-12 | Matsushita Electric Ind Co Ltd | アナログ・デジタル変換装置 |
US4900917A (en) * | 1988-07-15 | 1990-02-13 | American Telephone And Telegraph Company, At&T Bell Laboratories | Polarization insensitive optical communication device utilizing optical preamplification |
JPH08154056A (ja) * | 1994-11-28 | 1996-06-11 | Nec Eng Ltd | アナログ−デジタル変換方法及び自動利得調整回路 |
KR100337642B1 (ko) * | 1999-07-06 | 2002-05-23 | 오길록 | 근접장 탐침을 이용한 광 혼합 밀리미터파 생성장치 |
US7233432B2 (en) * | 2001-12-20 | 2007-06-19 | Xtera Communications, Inc. | Pre-emphasized optical communication |
US6819479B1 (en) * | 2001-12-20 | 2004-11-16 | Xtera Communications, Inc. | Optical amplification using launched signal powers selected as a function of a noise figure |
CN1517734A (zh) * | 2003-01-28 | 2004-08-04 | ��ʿ��Ƭ��ʽ���� | 使用片状导光体的通信系统 |
US20060245766A1 (en) * | 2005-04-29 | 2006-11-02 | Taylor Michael G | Phase estimation for coherent optical detection |
US8073345B2 (en) * | 2006-12-22 | 2011-12-06 | Alcatel Lucent | Frequency estimation in an intradyne optical receiver |
JP4888567B2 (ja) * | 2007-11-08 | 2012-02-29 | 富士通株式会社 | コヒーレント光受信機 |
JP2009182841A (ja) * | 2008-01-31 | 2009-08-13 | Sumitomo Electric Ind Ltd | 光受信装置 |
JP4518282B2 (ja) * | 2008-03-06 | 2010-08-04 | 日本電気株式会社 | コヒーレント型光受信器およびその調整方法 |
CN101888274B (zh) * | 2009-05-14 | 2014-06-04 | 华为技术有限公司 | 相干接收机反馈控制方法、装置及系统 |
JP2011250126A (ja) * | 2010-05-26 | 2011-12-08 | Sumitomo Electric Ind Ltd | トランスインピーダンスアンプ及び光レシーバ |
US9048956B2 (en) * | 2010-11-18 | 2015-06-02 | Nec Corporation | Coherent optical receiver device and coherent optical receiving method |
JP5699583B2 (ja) * | 2010-12-17 | 2015-04-15 | 富士通株式会社 | 光受信機及び光受信方法 |
US8768178B2 (en) * | 2011-09-15 | 2014-07-01 | Opnext Subsystems, Inc. | Automatic gain control for high-speed coherent optical receivers |
-
2012
- 2012-12-11 US US14/358,266 patent/US20140348515A1/en not_active Abandoned
- 2012-12-11 JP JP2013549113A patent/JP5812110B2/ja active Active
- 2012-12-11 WO PCT/JP2012/007884 patent/WO2013088694A1/ja active Application Filing
- 2012-12-11 CN CN201280062218.9A patent/CN103999382B/zh active Active
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008278249A (ja) * | 2007-04-27 | 2008-11-13 | Fujitsu Ltd | 光信号受信装置 |
JP2010245772A (ja) * | 2009-04-03 | 2010-10-28 | Fujitsu Ltd | 光受信機および光受信方法 |
JP2010251851A (ja) * | 2009-04-10 | 2010-11-04 | Fujitsu Ltd | 光伝送システム |
JP2012147078A (ja) * | 2011-01-07 | 2012-08-02 | Fujitsu Ltd | 光伝送装置およびアナログ−デジタル変換装置 |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015004828A1 (ja) * | 2013-07-11 | 2015-01-15 | 日本電気株式会社 | 光受信装置およびモニタ信号生成方法 |
JPWO2015004828A1 (ja) * | 2013-07-11 | 2017-03-02 | 日本電気株式会社 | 光受信装置およびモニタ信号生成方法 |
US9692545B2 (en) | 2013-07-11 | 2017-06-27 | Nec Corporation | Optical reception apparatus and monitor signal generating method |
US10187174B2 (en) | 2013-07-11 | 2019-01-22 | Nec Corporation | Optical reception apparatus and monitor signal generating method |
US10554323B2 (en) | 2013-07-11 | 2020-02-04 | Nec Corporation | Optical reception apparatus and monitor signal generating method |
US10826642B2 (en) | 2013-07-11 | 2020-11-03 | Nec Corporation | Optical reception apparatus and monitor signal generating method |
US11290202B2 (en) | 2013-07-11 | 2022-03-29 | Nec Corporation | Optical reception apparatus and monitor signal generating method |
CN106471757A (zh) * | 2014-06-12 | 2017-03-01 | 日本电气株式会社 | 光接收装置和光接收方法 |
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