WO2013042345A1 - Optical signal processing device, polarization processing device, and optical signal processing method - Google Patents

Optical signal processing device, polarization processing device, and optical signal processing method Download PDF

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Publication number
WO2013042345A1
WO2013042345A1 PCT/JP2012/005909 JP2012005909W WO2013042345A1 WO 2013042345 A1 WO2013042345 A1 WO 2013042345A1 JP 2012005909 W JP2012005909 W JP 2012005909W WO 2013042345 A1 WO2013042345 A1 WO 2013042345A1
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signal
phase
light
quadrature
polarized light
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PCT/JP2012/005909
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French (fr)
Japanese (ja)
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一臣 遠藤
陽一 橋本
清 福知
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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
    • H04B10/60—Receivers
    • H04B10/61—Coherent receivers
    • H04B10/616—Details of the electronic signal processing in coherent optical receivers
    • H04B10/6165—Estimation of the phase of the received optical signal, phase error estimation or phase error correction

Definitions

  • the present invention relates to an optical signal processing device, a polarization processing device, and an optical signal processing method for processing an optical signal.
  • WDM wavelength division multiplexing
  • Patent Document 1 discloses a technique for compensating IQ skew of a digital signal input to a digital signal processor in a digital coherent communication receiver. This technology performs various compensations on the digital signal output from the phase control unit, detects the IQ skew of the digital signal, and calculates the shift amount of the digital signal transfer from the detected IQ skew value To do.
  • Non-Patent Document 1 discloses a polarization diversity reception system.
  • the reception sensitivity does not depend on the polarization state.
  • the polarization beam splitter separates the multilevel modulated optical signal into two orthogonally polarized optical signals.
  • the hybrid element mixes each separated optical signal with local light and outputs an optical signal corresponding to the in-phase component and the quadrature component.
  • the photodiode converts the output optical signal of the hybrid element into an electric signal.
  • Non-Patent Document 1 the maximum ratio combining method (Maximal-Ratio-Combining, MRC) is used as digital signal processing for correcting a change in reception sensitivity due to the polarization state of an input signal.
  • Maximum ratio combining method Maximal-Ratio-Combining, MRC
  • An object of the present invention is to provide an optical signal processing device, a polarization processing device, and an optical signal processing method that are used digitally coherently and can be reduced in cost and size.
  • the first polarized light generated from the external signal light received from the outside corresponds to the first in-phase light corresponding to the in-phase component of the first polarized light and the orthogonal component of the first polarized light.
  • First light separating means for separating into first orthogonal light, Second polarized light generated from the external signal light and having a polarization direction orthogonal to the first polarized light is converted to second in-phase light corresponding to the in-phase component of the second polarized light, and the second polarized light.
  • Second light separating means for separating into second orthogonal light corresponding to the orthogonal component of the wave light;
  • First photoelectric conversion means for photoelectrically converting the first in-phase light to generate a first in-phase signal;
  • Second photoelectric conversion means for photoelectrically converting the first orthogonal light to generate a first orthogonal signal;
  • Third photoelectric conversion means for photoelectrically converting the second in-phase light to generate a second in-phase signal;
  • Fourth photoelectric conversion means for photoelectrically converting the second orthogonal light to generate a second orthogonal signal;
  • Polarization processing means for processing the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal to generate an in-phase baseband signal and a quadrature baseband signal;
  • Generating and demodulating means for demodulating the in-phase baseband signal and the quadrature baseband signal to generate a transmission signal;
  • the polarization processing means includes A phase difference for calculating a phase difference
  • a calculation means The phase difference between the first in-phase signal and the first quadrature signal, and the second in-phase signal and the second quadrature signal is corrected using the phase difference ⁇ calculated by the phase difference calculation unit.
  • Phase difference correction means for Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, an intensity ratio calculation that calculates an intensity ratio between the first polarized light and the second polarized light Means, Signal synthesizing means for generating the in-phase baseband signal and the quadrature baseband signal using the phase difference ⁇ calculated by the phase difference calculating means and the intensity ratio calculated by the intensity ratio calculating means;
  • An optical signal processing device is provided.
  • the first polarized light generated from the external signal light received from the outside corresponds to the first in-phase light corresponding to the in-phase component of the first polarized light and the orthogonal component of the first polarized light.
  • First light separating means for separating into first orthogonal light, Second polarized light generated from the external signal light and having a polarization direction orthogonal to the first polarized light is converted to second in-phase light corresponding to the in-phase component of the second polarized light, and the second polarized light.
  • Second light separating means for separating into second orthogonal light corresponding to the orthogonal component of the wave light;
  • First photoelectric conversion means for photoelectrically converting the first in-phase light to generate a first in-phase signal;
  • Second photoelectric conversion means for photoelectrically converting the first orthogonal light to generate a first orthogonal signal;
  • Third photoelectric conversion means for photoelectrically converting the second in-phase light to generate a second in-phase signal;
  • Fourth photoelectric conversion means for photoelectrically converting the second orthogonal light to generate a second orthogonal signal;
  • Polarization processing means for processing the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal to generate an in-phase baseband signal and a quadrature baseband signal;
  • Demodulation means for demodulating the in-phase baseband signal and the quadrature baseband signal to generate a transmission signal;
  • the polarization processing means includes A phase difference for calculating a phase difference ⁇ between the first
  • a calculation means An intensity ratio for calculating an intensity ratio ⁇ of the first polarized light and the second polarized light using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal.
  • a calculation means Signal synthesizing means for generating the in-phase baseband signal and the quadrature baseband signal using the phase difference ⁇ calculated by the phase difference calculating means and the intensity ratio ⁇ calculated by the intensity ratio calculating means;
  • a synthesized signal obtained by synthesizing the in-phase baseband signal and the quadrature baseband signal is generated, and using the intensity of the synthesized signal, the first in-phase signal and the first quadrature signal, the second in-phase signal, Phase difference correction means for correcting a phase difference between the second quadrature signal and the second orthogonal signal;
  • An optical signal processing device is provided.
  • the first in-phase light is an in-phase component of the first polarized light separated from the external signal light
  • the first orthogonal light is an orthogonal component of the first polarized light
  • the second in-phase light is separated from the external signal light and is the in-phase component of the second polarized light whose polarization direction is orthogonal to the first polarized light
  • the second orthogonal light is an orthogonal component of the second polarized light
  • a calculation means The phase difference between the first in-phase signal and the first quadrature signal, and the second in-phase signal and the second quadrature signal is corrected using the phase difference ⁇ calculated by the phase difference calculation unit.
  • Phase difference correction means for Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, an intensity ratio calculation that calculates an intensity ratio between the first polarized light and the second polarized light Means,
  • Signal combining means for generating an in-phase baseband signal and a quadrature baseband signal using the phase difference ⁇ calculated by the phase difference calculating means and the intensity ratio calculated by the intensity ratio calculating means;
  • a polarization processing device is provided.
  • the first in-phase light is an in-phase component of the first polarized light separated from the external signal light
  • the first orthogonal light is an orthogonal component of the first polarized light
  • the second in-phase light is separated from the external signal light and is the in-phase component of the second polarized light whose polarization direction is orthogonal to the first polarized light
  • the second orthogonal light is an orthogonal component of the second polarized light
  • a calculation means Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, an intensity ratio calculation that calculates an intensity ratio between the first polarized light and the second polarized light Means, Signal combining means for generating an in-phase baseband signal and a quadrature baseband signal using the phase difference ⁇ calculated by the phase difference calculating means and the intensity ratio calculated by the intensity ratio calculating means; A synthesized signal obtained by synthesizing the in-phase baseband signal and the quadrature baseband signal is generated, and using the intensity of the synthesized signal, the first in-phase signal and the first quadrature signal, the second in-phase signal, Phase difference correction means for correcting a phase difference between the second quadrature signal and the second orthogonal signal; A polarization processing device is provided.
  • the first polarized light generated from the external signal light received from the outside corresponds to the first in-phase light corresponding to the in-phase component of the first polarized light and the orthogonal component of the first polarized light. Separating the first orthogonal light into Second polarized light generated from the external signal light and having a polarization direction orthogonal to the first polarized light is converted to second in-phase light corresponding to the in-phase component of the second polarized light, and the second polarized light.
  • the first polarized light generated from the external signal light received from the outside corresponds to the first in-phase light corresponding to the in-phase component of the first polarized light and the orthogonal component of the first polarized light. Separating the first orthogonal light into Second polarized light generated from the external signal light and having a polarization direction orthogonal to the first polarized light is converted to second in-phase light corresponding to the in-phase component of the second polarized light, and the second polarized light.
  • FIG. 1 is a block diagram illustrating a configuration of an optical receiving device 20 according to the first embodiment.
  • the optical receiver 20 is a digital coherent optical receiver, and includes a polarization beam splitter 100, a local light generator 200, and an optical signal receiver 300.
  • the polarization beam splitter 100 receives external signal light oscillated by an external device via an optical transmission line.
  • the external signal light includes a signal (also referred to as a single polarization multilevel phase optical signal) modulated by the multilevel modulation method.
  • the polarization beam splitter 100 separates the received external signal light into the first polarized light X and the second polarized light Y.
  • the polarization directions of the first polarized light and the second polarized light are orthogonal to each other.
  • the local light generation unit 200 generates local light.
  • the local light is used when the optical signal receiving unit 300 demodulates the signal.
  • the local light generation unit 200 is, for example, a distributed feedback laser diode, and outputs continuous light as local light.
  • the optical signal receiving unit 300 uses the local light generated by the local light generation unit 200 to perform coherent detection (for example, homodyne detection or heterodyne detection) on the first polarized light X and the second polarized light Y, and thereby provides an in-phase baseband.
  • coherent detection for example, homodyne detection or heterodyne detection
  • the signal E I and the orthogonal baseband signal EQ are converted.
  • the optical signal receiving unit 300 reproduces the transmitted multi-level modulated optical signal from the in-phase baseband signal E I and the quadrature baseband signal E Q , and demodulates the multi-level modulated optical signal.
  • FIG. 2 is a block diagram illustrating an example of the configuration of the optical signal receiving unit 300.
  • the optical signal receiver 300 includes an optical hybrid 320 (first optical separator), an optical hybrid 322 (first optical separator), photoelectric converters 332, 334, 336, 338, a polarization processor 340, and a demodulator 360. It has.
  • the optical hybrid 320 receives the first polarized light X and the local light and causes these two lights to interfere with each other, whereby the first in-phase light that is the in-phase component of the first polarized light X and the first polarized light X are orthogonal to each other.
  • the first orthogonal light that is a component is output.
  • the optical hybrid 322 receives the second polarized light Y and the local light and causes the two lights to interfere with each other, whereby the second in-phase light that is the in-phase component of the second polarized light Y and the second polarized light Y are orthogonal to each other.
  • the component 2nd orthogonal light is output.
  • the photoelectric conversion unit 332 generates the first-phase signal X I the first phase light by photoelectric conversion.
  • the photoelectric conversion unit 334 generates the first orthogonal signal X Q a first orthogonal light by photoelectric conversion.
  • the photoelectric conversion unit 336 generates a second phase signal Y I a second phase light by photoelectric conversion.
  • the photoelectric conversion unit 338 photoelectrically converts the second orthogonal light to generate a second orthogonal signal YQ .
  • Each of the photoelectric conversion units 332, 334, 336, and 338 includes a photoelectric conversion element such as a balanced photodiode, a transimpedance amplifier (TIA), and an analog-digital conversion unit.
  • TIA transimpedance amplifier
  • the polarization processing unit 340 processes the first in-phase signal X I , the first quadrature signal X Q , the second in-phase signal Y I , and the second quadrature signal Y Q to process the in-phase baseband signal E I and the quadrature base.
  • a band signal EQ is generated.
  • the polarization processing unit 340 obtains the power ratio ⁇ between the first polarized light X and the second polarized light Y and the phase difference ⁇ between the first polarized light X and the second polarized light Y.
  • the demodulation unit 360 demodulates the in-phase baseband signal E I and the quadrature baseband signal E Q generated by the polarization processing unit 340, and extracts transmission information.
  • FIG. 3 is a block diagram illustrating an example of the configuration of the polarization processing unit 340.
  • the polarization processing unit 340 includes a phase difference correction unit 341, a phase difference correction unit 342, a phase difference / intensity ratio calculation unit 344, a signal synthesis unit 345, a phase reproduction unit 346, and a correction amount generation unit 347.
  • Phase difference correcting unit 341 corrects the phase difference between the first phase signal X I and the first quadrature signal X Q a (skew).
  • Phase difference correcting unit 342 corrects the phase difference between the second-phase signal Y I and the second orthogonal signal Y Q a (skew).
  • Correction amounts by the phase difference correction units 341 and 342 are given by a correction amount generation unit 347.
  • One of the causes of these skews is an individual difference in signal paths (each photoelectric conversion unit and cable) from the output ends of optical hybrids 320 and 322 described later to the input end of the polarization processing unit 340. it is conceivable that.
  • the phase difference / intensity ratio calculation unit 344 processes the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, and the power of the first polarized light X and the second polarized light Y
  • the ratio ⁇ and the phase difference ⁇ between the first polarized light X and the second polarized light Y are calculated. Details of the processing performed by the phase difference / intensity ratio calculation unit 344 will be described later using a flowchart.
  • the signal synthesis unit 345 calculates the in-phase baseband signal E I and the quadrature baseband signal E Q using the power ratio ⁇ and the phase difference ⁇ calculated by the phase difference / intensity ratio calculation unit 344. Details of processing performed by the signal synthesis unit 345 will be described later with reference to flowcharts.
  • Phase recovery unit 346 corrects the phase difference of the phase baseband signals E I and quadrature baseband signals E Q. This phase difference is caused by mixing signal light and local light, for example.
  • the correction amount generation unit 347 calculates the correction amounts in the phase difference correction units 341 and 342 using the power ratio ⁇ and the phase difference ⁇ calculated by the phase difference / intensity ratio calculation unit 344. Details of the processing performed by the correction amount generation unit 347 will be described later using a flowchart.
  • FIG. 4 is a block diagram showing a functional configuration of the phase difference correction unit 341. Note that the phase difference correction unit 342 has the same configuration as the phase difference correction unit 341 shown in FIG.
  • the phase difference correction unit 341 includes an upsampling unit 402, a variable delay unit 404, and a downsampling unit 406.
  • the upsampling unit 402 has an upsampler and an interpolator.
  • the upsampler increases the sampling rate of the signal by L times by inserting L ⁇ 1 zero values between the signals.
  • Polyphase decomposition is used for the interpolator.
  • the variable delay unit 404 can apply a delay up to the maximum N ⁇ L sampling based on the correction amount input from the correction amount generation unit 347.
  • N is a delay amount. That is, the variable delay unit 404 delays the sampling data by N ⁇ T s / L (T s is the sampling time and is the reciprocal of the sampling rate).
  • the down-sampling unit 406 has a down sampler and a digital meter.
  • the downsampler reduces the sampling rate to 1 / L by thinning out L-1 samples from the signal. Polyphase decomposition is used for the digimeter.
  • L indicates the rate of increase in the sampling rate for upsampling and the rate of decrease in the sampling rate for downsampling
  • N indicates the delay amount (correction amount) of the signal.
  • FIG. 5 is a flowchart showing an operation example of the polarization processing unit 340 shown in FIG.
  • Phase difference-intensity ratio calculating unit 344 first calculates the E x and E y (step S10), and the complex amplitude ratio r, the ir, determined in each using the following (Equation 1) and (Formula 2) ( Step S20).
  • r E x / E y (Formula 1)
  • ir E y / E x (Formula 2)
  • E x is a complex number represented by X I + jX Q.
  • E y is a complex number represented by Y I + jY Q.
  • j represents a pure imaginary number.
  • the phase difference / intensity ratio calculation unit 344 calculates the average of the complex amplitude ratios r and ir (step S30).
  • the phase difference / intensity ratio calculator 344 calculates, for example, an additive average or a multiplicative average of the complex amplitude ratios r and ir.
  • the phase difference / intensity ratio calculator 344 compares the magnitude relationship between the absolute value
  • the complex amplitude ratios r and ir can be expressed as the following (Equation 3) and (Equation 4) by the power ratio ⁇ and the phase difference ⁇ , respectively. (Formula 3) (Formula 4)
  • step S40 If
  • (step S40: Yes), the phase difference / intensity ratio calculation unit 344 calculates the power ratio ⁇ and the phase difference ⁇ using the above (formula 4) (step S50). Specifically, the phase difference / intensity ratio calculation unit 344 sets ⁇
  • 2 +1) and ⁇ arg (r).
  • 2 +1) and ⁇ ⁇ arg (ir).
  • the correction amount generation unit 347 calculates correction amounts to be corrected by the phase difference correction units 341 and 342 using the power ratio ⁇ and the phase difference ⁇ calculated in step S50 or step S60. And it outputs to the phase difference correction
  • the signal synthesizer 345 calculates a complex signal E s (synthesized signal) using a maximum ratio combining method (MRC). Specifically, the signal synthesizing unit 345, a complex signal E s, the phase difference-intensity ratio calculating unit 344 power ratio ⁇ and the phase difference ⁇ obtained by substituting into the following equation (5), obtaining (Step S80). (Formula 5)
  • the signal synthesizing unit 345 outputs the real and imaginary parts of the complex signal E s, as an in-phase baseband signals E I and quadrature baseband signals E Q each.
  • the complex signal E S includes a phase shift. This phase shift is caused by the phase difference between the signal light and the local oscillation light.
  • Phase recovery unit 346 a complex signal E S including the phase shift is corrected by the carrier phase estimation method such as Feed Forward M-th Power Algorithm and Decision-Directed Phase-Locked Loop (step S90).
  • the phase difference / intensity ratio calculation unit 344 may calculate the power ratio ⁇ and the phase difference ⁇ without using the complex amplitude ratios r and ir.
  • the phase difference / intensity ratio calculation unit 344 measures the actual values of the power ratio ⁇ and the phase difference ⁇ , and outputs the average (additive average or multiplicative average) to the signal synthesis unit 345 and the correction amount generation unit 347. May be.
  • FIG. 6 is a flowchart illustrating processing performed by the correction amount generation unit 347.
  • the correction amount generation unit 347 initializes the delay amount n 1 of the phase difference correction unit 341 and the phase delay amount n 2 of the phase difference correction unit 342 by putting zero values (step S100).
  • the correction amount generation unit 347 increases the delay amount n 1 of the phase difference correction unit 341 by one step (step S102).
  • the correction amount generation unit 347 substitutes the phase difference ⁇ calculated by the phase difference / intensity ratio calculation unit 344 into, for example, the following equation (6), thereby generating an error signal ⁇ indicating the amount of change in the phase difference ⁇ . Calculate and store in a memory or the like (step S104).
  • ⁇
  • ⁇ [k] indicates the k-th ⁇ value. Therefore, when the value in parentheses attached to ⁇ is k ⁇ 1, it corresponds to one tap before k.
  • the correction amount generating unit 347, the delay amount n 2 of the phase difference correcting unit 342 is increased one step (step S110). Then, the correction amount generation unit 347 calculates the error signal ⁇ indicating the amount of change in the phase difference ⁇ by substituting the phase difference ⁇ calculated by the phase difference / intensity ratio calculation unit 344 into, for example, the above equation (6). And stored in a memory or the like (step S112).
  • FIG. 7 shows a signal X composed of a first in-phase signal XI and a first quadrature signal X Q and a signal Y composed of a second in-phase signal Y I and a second quadrature signal Y Q inputted to the signal synthesizer 345.
  • FIG. 6 is a diagram for explaining that a skew between the two (XY skew) may affect the quality of reproduced data.
  • the signal synthesizer 345 can add the X signal and the Y signal in a state where the directions of the vectors on the constellation of the X signal and the Y signal match. As a result, as shown by the circled signal points in FIG. 7C, signal points can be obtained at appropriate positions where the S / N is maximum.
  • the IQ constellation mapping is performed.
  • the signal point is obtained at the position of the square mark shown in FIG.
  • the phase difference ⁇ calculated by the phase difference / intensity ratio calculation unit 344 does not match the phase difference between the X signal and the Y signal.
  • the signal synthesis unit 345 adds the X signal and the Y signal in a state where the directions of the vectors on the constellation of the X signal and the Y signal do not match at all. In this case, the position of the signal point is greatly deviated from the proper position, and there is a possibility that an error occurs in the signal.
  • the correction amount generation unit 347 sets the correction amounts by the phase difference correction units 341 and 342 to appropriate values, the skew between the signal X and the signal Y can be suppressed.
  • FIG. 8 is a graph showing the relationship between the skew generated between the signal X and the signal Y and the variance of the error signal ⁇ calculated by Equation 6 in 50 Gbps-SP-QPSK.
  • the sampling rate of the analog-digital converter used in the photoelectric conversion units 332, 334, 336, 338 is set to 50 GS / s.
  • the error signal ⁇ calculated by Equation 6 has high sensitivity to the skew between the signal X and the signal Y. Accordingly, when the correction amounts of the phase difference correction units 341 and 342 are set so that the error signal ⁇ becomes a minimum value, the skew between the signal X and the signal Y becomes a very small value.
  • FIG. 9 is a block diagram illustrating a configuration of the polarization processing unit 340 used in the optical signal processing device 10 according to the second embodiment.
  • FIG. 10 is a flowchart showing the operation of the correction amount generation unit 347 in the present embodiment.
  • the correction amount generation unit 347 enters zero values into the delay amount n 1 of the phase difference correction unit 341 and the delay amount n 2 of the phase difference correction unit 342, and initializes these delay amounts (step S202).
  • the correction amount generation unit 347 increases the delay amount n 1 of the phase difference correction unit 341 by one step (step S204).
  • Equation 7 E s [k] indicates the k-th E s value.
  • E s [k] indicates the k-th E s value.
  • the correction amount generating unit 347, the delay amount n 2 of the phase difference correcting unit 342 is increased one step (step S212). Then, the correction amount generation unit 347 calculates the error signal ⁇ indicating the amount of change in the phase difference ⁇ by substituting the phase difference ⁇ calculated by the phase difference / intensity ratio calculation unit 344 into, for example, the above equation (7). And stored in a memory or the like (step S214).
  • the delay amount n 2 * of the phase difference correction unit 342 is determined as an actual correction amount (step S218), and the determined correction amounts n 1 * and n 2 * are output to the phase difference correction units 341 and 342, respectively (step S218). S220).
  • FIG. 11 is a graph showing the relationship between the skew between the signal X and the signal Y and the variance of the error signal ⁇ calculated by Expression (7) in 50 Gbps-SP-QPSK.
  • the sampling rate of the analog-digital converter used in the photoelectric conversion units 332, 334, 336, 338 is set to 50 GS / s.
  • the error signal ⁇ calculated by Expression (7) has high sensitivity to the skew between the signal X and the signal Y. Accordingly, when the correction amounts of the phase difference correction units 341 and 342 are set so that the error signal ⁇ becomes a minimum value, the skew between the signal X and the signal Y becomes a very small value.
  • FIG. 12 is a block diagram illustrating a functional configuration of the optical signal processing device 10 according to the third embodiment.
  • the optical signal processing device 10 according to the present embodiment includes an optical reception device 20 and an optical transmission device 40.
  • the optical receiver 20 has the configuration shown in the first embodiment or the second embodiment.
  • the optical transmission device 40 converts a transmission signal, which is an electrical signal, into an optical signal (output signal light) and outputs it to the outside.
  • the optical transmitter 40 generates a digital coherent transmission signal.
  • each of the above-described embodiments can be embodied as predetermined hardware, for example, a circuit.
  • the above-described embodiment can also be realized by causing a control program to be executed by a computer circuit (not shown) (for example, a CPU (Central Processing Unit)).
  • a computer circuit for example, a CPU (Central Processing Unit)
  • the above-described control program is stored in advance in, for example, a storage medium inside the optical receiver or an external storage medium.
  • the control program is read and executed by the computer circuit.
  • the internal storage medium include a ROM (Read Only Memory) and a hard disk.
  • examples of the external storage medium include a removable medium and a removable disk.

Abstract

The present invention is provided with the following: a separation means for separating a signal, which is a photoelectrically converted multi-value modulation optical signal, into a first signal and a second signal the polarization directions of which are orthogonal to each other; a phase difference calculation means for calculating the phase difference between the first signal and the second signal; a phase difference correction means for correcting the phase difference between the first signal and the second signal using the phase difference calculated by the phase difference calculation means; an intensity ratio calculation means for calculating the intensity ratio of the first signal and the second signal; and a synthesized signal generating means that uses the phase difference calculated by the phase difference calculation means and the intensity ratio calculated by the intensity ratio calculation means to generate a synthesized signal which is a synthesis of the first signal and the second signal.

Description

光信号処理装置、偏波処理装置、及び光信号処理方法Optical signal processing device, polarization processing device, and optical signal processing method
　本発明は、光信号を処理する光信号処理装置、偏波処理装置、及び光信号処理方法に関する。 The present invention relates to an optical signal processing device, a polarization processing device, and an optical signal processing method for processing an optical signal.
　光通信において、通信容量を増大させる方式として、波長分割多重（ＷＤＭ：Wavelength Division Multiplexing）方式が普及している。しかし、近年は通信トラフィックが増大しており、ＷＤＭ方式のみでは通信トラフィックを十分に確保できなくなる、と考えられている。これに対し、デジタルコヒーレント通信は、通信トラフィックの増大に対応するための技術である、と期待されている。 In optical communication, a wavelength division multiplexing (WDM) method is widely used as a method for increasing communication capacity. However, communication traffic has increased in recent years, and it is considered that communication traffic cannot be sufficiently secured only by the WDM system. On the other hand, digital coherent communication is expected to be a technique for dealing with an increase in communication traffic.
　特許文献１には、デジタルコヒーレント通信の受信機において、デジタルシグナルプロセッサに入力されるデジタル信号のＩＱスキューを補償する技術が開示されている。この技術は、位相制御部から出力されたデジタル信号に対して様々な補償を行った後にそのデジタル信号のＩＱスキューを検出し、検出したＩＱスキューの値から、デジタル信号の移送のシフト量を算出するものである。 Patent Document 1 discloses a technique for compensating IQ skew of a digital signal input to a digital signal processor in a digital coherent communication receiver. This technology performs various compensations on the digital signal output from the phase control unit, detects the IQ skew of the digital signal, and calculates the shift amount of the digital signal transfer from the detected IQ skew value To do.
　なお、非特許文献１には、偏波ダイバーシティ受信方式が開示されている。偏波ダイバーシティ受信方式では、受信感度は偏波状態に依存しない。偏波ダイバーシティ受信方式において、偏波ビームスプリッタは、多値変調光信号を、直交する２つの偏波の光信号に分離する。ハイブリッド素子は、分離された各光信号を局発光と混合して、同相成分及び直交成分に対応する光信号を出力する。フォトダイオードは、ハイブリッド素子の出力光信号を電気信号に変換する。 Note that Non-Patent Document 1 discloses a polarization diversity reception system. In the polarization diversity reception system, the reception sensitivity does not depend on the polarization state. In the polarization diversity reception system, the polarization beam splitter separates the multilevel modulated optical signal into two orthogonally polarized optical signals. The hybrid element mixes each separated optical signal with local light and outputs an optical signal corresponding to the in-phase component and the quadrature component. The photodiode converts the output optical signal of the hybrid element into an electric signal.
　また、非特許文献１では、入力信号の偏波状態による受信感度の変化を補正するデジタル信号処理として、最大比合成法（Ｍａｘｉｍａｌ－Ｒａｔｉｏ－Ｃｏｍｂｉｎｉｎｇ、ＭＲＣ）を用いている。 In Non-Patent Document 1, the maximum ratio combining method (Maximal-Ratio-Combining, MRC) is used as digital signal processing for correcting a change in reception sensitivity due to the polarization state of an input signal.
特開２０１０－１９３２０４号公報JP 2010-193204 A
　デジタルコヒーレントの受信技術においても、スキューを低減させる必要がある。一方で、この受信技術を用いた光信号処理装置においても、低コスト化及び小型化が求められている。 It is necessary to reduce skew even in digital coherent reception technology. On the other hand, also in the optical signal processing apparatus using this reception technique, cost reduction and size reduction are required.
　本発明は、デジタルコヒーレントに用いられ、かつ低コスト化及び小型化を図ることができる光信号処理装置、偏波処理装置、及び光信号処理方法を提供することを目的とする。 An object of the present invention is to provide an optical signal processing device, a polarization processing device, and an optical signal processing method that are used digitally coherently and can be reduced in cost and size.
　本発明によれば、外部から受信した外部信号光から生成された第１偏波光を、前記第１偏波光の同相成分に対応する第１同相光と、前記第１偏波光の直交成分に対応する第１直交光に分離する第１光分離手段と、
　前記外部信号光から生成されており前記第１偏波光とは偏波の方向が直交する第２偏波光を、前記第２偏波光の同相成分に対応する第２同相光と、前記第２偏波光の直交成分に対応する第２直交光に分離する第２光分離手段と、
　前記第１同相光を光電変換して第１同相信号を生成する第１光電変換手段と、
　前記第１直交光を光電変換して第１直交信号を生成する第２光電変換手段と、
　前記第２同相光を光電変換して第２同相信号を生成する第３光電変換手段と、
　前記第２直交光を光電変換して第２直交信号を生成する第４光電変換手段と、
　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を処理して同相ベースバンド信号及び直交ベースバンド信号を生成する偏波処理手段と、
　前記同相ベースバンド信号及び前記直交ベースバンド信号を復調処理して、送信信号を生成する生成復調手段と、
を備え、
　前記偏波処理手段は、
　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の位相差δを算出する位相差算出手段と、
　　前記位相差算出手段が算出した位相差δを用いて、前記第１同相信号及び前記第１直交信号と、前記第２同相信号及び前記第２直交信号と、の間の位相差を補正する位相差補正手段と、
　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の強度比を算出する強度比算出手段と、
　　前記位相差算出手段が算出した位相差δ、及び前記強度比算出手段が算出した強度比を用いて、前記同相ベースバンド信号及び前記直交ベースバンド信号を生成する信号合成手段と、
を備える光信号処理装置が提供される。 According to the present invention, the first polarized light generated from the external signal light received from the outside corresponds to the first in-phase light corresponding to the in-phase component of the first polarized light and the orthogonal component of the first polarized light. First light separating means for separating into first orthogonal light,
Second polarized light generated from the external signal light and having a polarization direction orthogonal to the first polarized light is converted to second in-phase light corresponding to the in-phase component of the second polarized light, and the second polarized light. Second light separating means for separating into second orthogonal light corresponding to the orthogonal component of the wave light;
First photoelectric conversion means for photoelectrically converting the first in-phase light to generate a first in-phase signal;
Second photoelectric conversion means for photoelectrically converting the first orthogonal light to generate a first orthogonal signal;
Third photoelectric conversion means for photoelectrically converting the second in-phase light to generate a second in-phase signal;
Fourth photoelectric conversion means for photoelectrically converting the second orthogonal light to generate a second orthogonal signal;
Polarization processing means for processing the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal to generate an in-phase baseband signal and a quadrature baseband signal;
Generating and demodulating means for demodulating the in-phase baseband signal and the quadrature baseband signal to generate a transmission signal;
With
The polarization processing means includes
A phase difference for calculating a phase difference δ between the first polarized light and the second polarized light using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal. A calculation means;
The phase difference between the first in-phase signal and the first quadrature signal, and the second in-phase signal and the second quadrature signal is corrected using the phase difference δ calculated by the phase difference calculation unit. Phase difference correction means for
Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, an intensity ratio calculation that calculates an intensity ratio between the first polarized light and the second polarized light Means,
Signal synthesizing means for generating the in-phase baseband signal and the quadrature baseband signal using the phase difference δ calculated by the phase difference calculating means and the intensity ratio calculated by the intensity ratio calculating means;
An optical signal processing device is provided.
　本発明によれば、外部から受信した外部信号光から生成された第１偏波光を、前記第１偏波光の同相成分に対応する第１同相光と、前記第１偏波光の直交成分に対応する第１直交光に分離する第１光分離手段と、
　前記外部信号光から生成されており前記第１偏波光とは偏波の方向が直交する第２偏波光を、前記第２偏波光の同相成分に対応する第２同相光と、前記第２偏波光の直交成分に対応する第２直交光に分離する第２光分離手段と、
　前記第１同相光を光電変換して第１同相信号を生成する第１光電変換手段と、
　前記第１直交光を光電変換して第１直交信号を生成する第２光電変換手段と、
　前記第２同相光を光電変換して第２同相信号を生成する第３光電変換手段と、
　前記第２直交光を光電変換して第２直交信号を生成する第４光電変換手段と、
　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を処理して同相ベースバンド信号及び直交ベースバンド信号を生成する偏波処理手段と、
　前記同相ベースバンド信号及び前記直交ベースバンド信号を復調処理して、送信信号を生成する復調手段と、
を備え、
　前記偏波処理手段は、
　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の位相差δを算出する位相差算出手段と、
　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の強度比αを算出する強度比算出手段と、
　　前記位相差算出手段が算出した位相差δ、及び前記強度比算出手段が算出した強度比αを用いて、前記同相ベースバンド信号及び前記直交ベースバンド信号を生成する信号合成手段と、
　　前記同相ベースバンド信号及び前記直交ベースバンド信号を合成した合成信号を生成し、当該合成信号の強度を用いて、前記第１同相信号及び前記第１直交信号と、前記第２同相信号及び前記第２直交信号と、の間の位相差を補正する位相差補正手段と、
を備える光信号処理装置が提供される。 According to the present invention, the first polarized light generated from the external signal light received from the outside corresponds to the first in-phase light corresponding to the in-phase component of the first polarized light and the orthogonal component of the first polarized light. First light separating means for separating into first orthogonal light,
Second polarized light generated from the external signal light and having a polarization direction orthogonal to the first polarized light is converted to second in-phase light corresponding to the in-phase component of the second polarized light, and the second polarized light. Second light separating means for separating into second orthogonal light corresponding to the orthogonal component of the wave light;
First photoelectric conversion means for photoelectrically converting the first in-phase light to generate a first in-phase signal;
Second photoelectric conversion means for photoelectrically converting the first orthogonal light to generate a first orthogonal signal;
Third photoelectric conversion means for photoelectrically converting the second in-phase light to generate a second in-phase signal;
Fourth photoelectric conversion means for photoelectrically converting the second orthogonal light to generate a second orthogonal signal;
Polarization processing means for processing the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal to generate an in-phase baseband signal and a quadrature baseband signal;
Demodulation means for demodulating the in-phase baseband signal and the quadrature baseband signal to generate a transmission signal;
With
The polarization processing means includes
A phase difference for calculating a phase difference δ between the first polarized light and the second polarized light using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal. A calculation means;
An intensity ratio for calculating an intensity ratio α of the first polarized light and the second polarized light using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal. A calculation means;
Signal synthesizing means for generating the in-phase baseband signal and the quadrature baseband signal using the phase difference δ calculated by the phase difference calculating means and the intensity ratio α calculated by the intensity ratio calculating means;
A synthesized signal obtained by synthesizing the in-phase baseband signal and the quadrature baseband signal is generated, and using the intensity of the synthesized signal, the first in-phase signal and the first quadrature signal, the second in-phase signal, Phase difference correction means for correcting a phase difference between the second quadrature signal and the second orthogonal signal;
An optical signal processing device is provided.
　本発明によれば、第１同相光から生成された第１同相信号、第１直交光から生成された第１直交信号、第２同相光から生成された第２同相信号、及び第２直交光から生成された第２直交信号を処理する偏波処理装置であって、
　前記第１同相光は、外部信号光から分離された第１偏波光の同相成分であり、
　前記第１直交光は、前記第１偏波光の直交成分であり、
　前記第２同相光は、前記外部信号光から分離されていて前記第１偏波光とは偏波方向が直交する第２偏波光の同相成分であり、
　前記第２直交光は、前記第２偏波光の直交成分であり、
　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の位相差δを算出する位相差算出手段と、
　　前記位相差算出手段が算出した位相差δを用いて、前記第１同相信号及び前記第１直交信号と、前記第２同相信号及び前記第２直交信号と、の間の位相差を補正する位相差補正手段と、
　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の強度比を算出する強度比算出手段と、
　　前記位相差算出手段が算出した位相差δ、及び前記強度比算出手段が算出した強度比を用いて、同相ベースバンド信号及び直交ベースバンド信号を生成する信号合成手段と、
を備える偏波処理装置が提供される。 According to the present invention, the first in-phase signal generated from the first in-phase light, the first quadrature signal generated from the first quadrature light, the second in-phase signal generated from the second in-phase light, and the second A polarization processing device for processing a second orthogonal signal generated from orthogonal light,
The first in-phase light is an in-phase component of the first polarized light separated from the external signal light,
The first orthogonal light is an orthogonal component of the first polarized light,
The second in-phase light is separated from the external signal light and is the in-phase component of the second polarized light whose polarization direction is orthogonal to the first polarized light,
The second orthogonal light is an orthogonal component of the second polarized light,
A phase difference for calculating a phase difference δ between the first polarized light and the second polarized light using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal. A calculation means;
The phase difference between the first in-phase signal and the first quadrature signal, and the second in-phase signal and the second quadrature signal is corrected using the phase difference δ calculated by the phase difference calculation unit. Phase difference correction means for
Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, an intensity ratio calculation that calculates an intensity ratio between the first polarized light and the second polarized light Means,
Signal combining means for generating an in-phase baseband signal and a quadrature baseband signal using the phase difference δ calculated by the phase difference calculating means and the intensity ratio calculated by the intensity ratio calculating means;
A polarization processing device is provided.
　本発明によれば、第１同相光から生成された第１同相信号、第１直交光から生成された第１直交信号、第２同相光から生成された第２同相信号、及び第２直交光から生成された第２直交信号を処理する偏波処理装置であって、
　前記第１同相光は、外部信号光から分離された第１偏波光の同相成分であり、
　前記第１直交光は、前記第１偏波光の直交成分であり、
　前記第２同相光は、前記外部信号光から分離されていて前記第１偏波光とは偏波方向が直交する第２偏波光の同相成分であり、
　前記第２直交光は、前記第２偏波光の直交成分であり、
　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の位相差δを算出する位相差算出手段と、
　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の強度比を算出する強度比算出手段と、
　　前記位相差算出手段が算出した位相差δ、及び前記強度比算出手段が算出した強度比を用いて、同相ベースバンド信号及び直交ベースバンド信号を生成する信号合成手段と、
　　前記同相ベースバンド信号及び前記直交ベースバンド信号を合成した合成信号を生成し、当該合成信号の強度を用いて、前記第１同相信号及び前記第１直交信号と、前記第２同相信号及び前記第２直交信号と、の間の位相差を補正する位相差補正手段と、
を備える偏波処理装置が提供される。 According to the present invention, the first in-phase signal generated from the first in-phase light, the first quadrature signal generated from the first quadrature light, the second in-phase signal generated from the second in-phase light, and the second A polarization processing device for processing a second orthogonal signal generated from orthogonal light,
The first in-phase light is an in-phase component of the first polarized light separated from the external signal light,
The first orthogonal light is an orthogonal component of the first polarized light,
The second in-phase light is separated from the external signal light and is the in-phase component of the second polarized light whose polarization direction is orthogonal to the first polarized light,
The second orthogonal light is an orthogonal component of the second polarized light,
A phase difference for calculating a phase difference δ between the first polarized light and the second polarized light using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal. A calculation means;
Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, an intensity ratio calculation that calculates an intensity ratio between the first polarized light and the second polarized light Means,
Signal combining means for generating an in-phase baseband signal and a quadrature baseband signal using the phase difference δ calculated by the phase difference calculating means and the intensity ratio calculated by the intensity ratio calculating means;
A synthesized signal obtained by synthesizing the in-phase baseband signal and the quadrature baseband signal is generated, and using the intensity of the synthesized signal, the first in-phase signal and the first quadrature signal, the second in-phase signal, Phase difference correction means for correcting a phase difference between the second quadrature signal and the second orthogonal signal;
A polarization processing device is provided.
　本発明によれば、外部から受信した外部信号光から生成された第１偏波光を、前記第１偏波光の同相成分に対応する第１同相光と、前記第１偏波光の直交成分に対応する第１直交光に分離し、
　前記外部信号光から生成されており前記第１偏波光とは偏波の方向が直交する第２偏波光を、前記第２偏波光の同相成分に対応する第２同相光と、前記第２偏波光の直交成分に対応する第２直交光に分離し、
　前記第１同相光を光電変換して第１同相信号を生成し、
　前記第１直交光を光電変換して第１直交信号を生成し、
　前記第２同相光を光電変換して第２同相信号を生成し、
　前記第２直交光を光電変換して第２直交信号を生成し、
　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の位相差δを算出し、
　算出した前記位相差δを用いて、前記第１同相信号及び前記第１直交信号と、前記第２同相信号及び前記第２直交信号と、の間の位相差を補正し、
　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の強度比を算出し、
　算出した前記位相差δ及び前記強度比を用いて、同相ベースバンド信号及び直交ベースバンド信号を生成し、
　前記同相ベースバンド信号及び前記直交ベースバンド信号を用いて復調処理して、送信信号を生成する光信号処理方法が提供される。 According to the present invention, the first polarized light generated from the external signal light received from the outside corresponds to the first in-phase light corresponding to the in-phase component of the first polarized light and the orthogonal component of the first polarized light. Separating the first orthogonal light into
Second polarized light generated from the external signal light and having a polarization direction orthogonal to the first polarized light is converted to second in-phase light corresponding to the in-phase component of the second polarized light, and the second polarized light. Separating into the second orthogonal light corresponding to the orthogonal component of the wave light,
Photoelectrically converting the first in-phase light to generate a first in-phase signal;
Photoelectrically converting the first orthogonal light to generate a first orthogonal signal;
Photoelectrically converting the second in-phase light to generate a second in-phase signal;
Photoelectrically converting the second orthogonal light to generate a second orthogonal signal;
Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, a phase difference δ between the first polarization light and the second polarization light is calculated,
Using the calculated phase difference δ, the phase difference between the first in-phase signal and the first quadrature signal and the second in-phase signal and the second quadrature signal is corrected,
Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, an intensity ratio between the first polarized light and the second polarized light is calculated,
Using the calculated phase difference δ and the intensity ratio, an in-phase baseband signal and a quadrature baseband signal are generated,
An optical signal processing method for generating a transmission signal by performing demodulation processing using the in-phase baseband signal and the quadrature baseband signal is provided.
　本発明によれば、外部から受信した外部信号光から生成された第１偏波光を、前記第１偏波光の同相成分に対応する第１同相光と、前記第１偏波光の直交成分に対応する第１直交光に分離し、
　前記外部信号光から生成されており前記第１偏波光とは偏波の方向が直交する第２偏波光を、前記第２偏波光の同相成分に対応する第２同相光と、前記第２偏波光の直交成分に対応する第２直交光に分離し、
　前記第１同相光を光電変換して第１同相信号を生成し、
　前記第１直交光を光電変換して第１直交信号を生成し、
　前記第２同相光を光電変換して第２同相信号を生成し、
　前記第２直交光を光電変換して第２直交信号を生成し、
　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の位相差δを算出し、
　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の強度比を算出し、
　算出した前記位相差δ及び前記強度比を用いて、同相ベースバンド信号及び直交ベースバンド信号を生成し、
　　前記同相ベースバンド信号及び前記直交ベースバンド信号を合成した合成信号を生成し、当該合成信号の強度を用いて、前記第１同相信号及び前記第１直交信号と、前記第２同相信号及び前記第２直交信号と、の間の位相差を補正し、
　前記同相ベースバンド信号及び前記直交ベースバンド信号を用いて復調処理して、送信信号を生成する、光信号処理方法が提供される。 According to the present invention, the first polarized light generated from the external signal light received from the outside corresponds to the first in-phase light corresponding to the in-phase component of the first polarized light and the orthogonal component of the first polarized light. Separating the first orthogonal light into
Second polarized light generated from the external signal light and having a polarization direction orthogonal to the first polarized light is converted to second in-phase light corresponding to the in-phase component of the second polarized light, and the second polarized light. Separating into the second orthogonal light corresponding to the orthogonal component of the wave light,
Photoelectrically converting the first in-phase light to generate a first in-phase signal;
Photoelectrically converting the first orthogonal light to generate a first orthogonal signal;
Photoelectrically converting the second in-phase light to generate a second in-phase signal;
Photoelectrically converting the second orthogonal light to generate a second orthogonal signal;
Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, a phase difference δ between the first polarization light and the second polarization light is calculated,
Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, an intensity ratio between the first polarized light and the second polarized light is calculated,
Using the calculated phase difference δ and the intensity ratio, an in-phase baseband signal and a quadrature baseband signal are generated,
A synthesized signal obtained by synthesizing the in-phase baseband signal and the quadrature baseband signal is generated, and using the intensity of the synthesized signal, the first in-phase signal and the first quadrature signal, the second in-phase signal, Correcting the phase difference between the second quadrature signal and
There is provided an optical signal processing method for generating a transmission signal by performing demodulation processing using the in-phase baseband signal and the quadrature baseband signal.
　本発明によれば、デジタルコヒーレントに用いられる装置において、低コスト化及び小型化を図ることができる。 According to the present invention, it is possible to reduce the cost and the size of an apparatus used for digital coherent.
　上述した目的、およびその他の目的、特徴および利点は、以下に述べる好適な実施の形態、およびそれに付随する以下の図面によってさらに明らかになる。 The above-described object and other objects, features, and advantages will be further clarified by a preferred embodiment described below and the following drawings attached thereto.
第１の実施形態に係る光受信装置の構成を示すブロック図である。It is a block diagram which shows the structure of the optical receiver which concerns on 1st Embodiment. 光信号受信部の構成の一例を示すブロック図である。It is a block diagram which shows an example of a structure of an optical signal receiving part. 偏波処理部の構成の一例を示すブロック図である。It is a block diagram which shows an example of a structure of a polarization processing part. 位相差補正部の機能構成を示すブロック図である。It is a block diagram which shows the function structure of a phase difference correction part. 図３に示す偏波処理部の動作例を示すフローチャートである。It is a flowchart which shows the operation example of the polarization processing part shown in FIG. 補正量生成部３４７が行う処理を示すフローチャートである。It is a flowchart which shows the process which the correction amount production | generation part 347 performs. ＸＹスキューが、再生されるデータの品質に影響を与える場合があることを説明するための図である。It is a figure for demonstrating that an XY skew may affect the quality of the data reproduced. 信号Ｘと信号Ｙとの間に生じるスキューと、式（６）で算出したエラー信号εの分散の関係を示すグラフである。It is a graph which shows the relationship between the skew which arises between the signal X and the signal Y, and dispersion | distribution of the error signal (epsilon) calculated by Formula (6). 第２の実施形態に係る光信号処理装置に用いられる偏波処理部３４０の構成を示すブロック図である。It is a block diagram which shows the structure of the polarization processing part 340 used for the optical signal processing apparatus which concerns on 2nd Embodiment. 補正量生成部の動作を示すフローチャートである。It is a flowchart which shows operation | movement of the correction amount production | generation part. 信号Ｘと信号Ｙとの間のスキューと、式（７）で算出したエラー信号εの分散の関係を示すグラフである。It is a graph which shows the relationship between the skew between the signal X and the signal Y, and dispersion | distribution of the error signal (epsilon) calculated by Formula (7). 第３の実施形態に係る光信号処理装置の機能構成を示すブロック図である。It is a block diagram which shows the function structure of the optical signal processing apparatus which concerns on 3rd Embodiment.
　以下、本発明の実施の形態について、図面を用いて説明する。尚、すべての図面において、同様な構成要素には同様の符号を付し、適宜説明を省略する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.
（第１の実施形態）
　図１は、第１の実施形態に係る光受信装置２０の構成を示すブロック図である。光受信装置２０はデジタルコヒーレント用の光受信機であり、偏波ビームスプリッタ１００、局発光生成部２００、及び光信号受信部３００を備えている。 (First embodiment)
FIG. 1 is a block diagram illustrating a configuration of an optical receiving device 20 according to the first embodiment. The optical receiver 20 is a digital coherent optical receiver, and includes a polarization beam splitter 100, a local light generator 200, and an optical signal receiver 300.
　偏波ビームスプリッタ１００は、外部の装置が発振した外部信号光を、光伝送路を介して受信する。外部信号光は、多値変調方式により変調された信号（単一偏波多値位相光信号とも呼ばれる）を含んでいる。そして偏波ビームスプリッタ１００は、受信した外部信号光を、第１偏波光Ｘと、第２偏波光Ｙに分離する。第１偏波光と第２偏波光は、偏波の方向が互いに直交している。 The polarization beam splitter 100 receives external signal light oscillated by an external device via an optical transmission line. The external signal light includes a signal (also referred to as a single polarization multilevel phase optical signal) modulated by the multilevel modulation method. Then, the polarization beam splitter 100 separates the received external signal light into the first polarized light X and the second polarized light Y. The polarization directions of the first polarized light and the second polarized light are orthogonal to each other.
　局発光生成部２００は、局発光を生成する。局発光は、光信号受信部３００が信号を復調する際に用いられる。局発光生成部２００は、例えば、分布帰還型レーザダイオードであり、局発光として連続光を出力する。 The local light generation unit 200 generates local light. The local light is used when the optical signal receiving unit 300 demodulates the signal. The local light generation unit 200 is, for example, a distributed feedback laser diode, and outputs continuous light as local light.
　光信号受信部３００は、局発光生成部２００が生成する局発光を用いて、第１偏波光Ｘ及び第２偏波光Ｙをコヒーレント検波（例えば、ホモダイン検波もしくはヘテロダイン検波）して、同相ベースバンド信号ＥＩ及び直交ベースバンド信号ＥＱに変換する。そして光信号受信部３００は、同相ベースバンド信号ＥＩ及び直交ベースバンド信号ＥＱから、送信された多値変調光信号を再生し、この多値変調光信号の復調処理を行う。 The optical signal receiving unit 300 uses the local light generated by the local light generation unit 200 to perform coherent detection (for example, homodyne detection or heterodyne detection) on the first polarized light X and the second polarized light Y, and thereby provides an in-phase baseband. The signal E I and the orthogonal baseband signal EQ are converted. Then, the optical signal receiving unit 300 reproduces the transmitted multi-level modulated optical signal from the in-phase baseband signal E I and the quadrature baseband signal E Q , and demodulates the multi-level modulated optical signal.
　図２は、光信号受信部３００の構成の一例を示すブロック図である。光信号受信部３００は、光ハイブリッド３２０（第１光分離部）、光ハイブリッド３２２（第１光分離部）、光電変換部３３２，３３４，３３６，３３８、偏波処理部３４０、及び復調部３６０を備えている。 FIG. 2 is a block diagram illustrating an example of the configuration of the optical signal receiving unit 300. The optical signal receiver 300 includes an optical hybrid 320 (first optical separator), an optical hybrid 322 (first optical separator), photoelectric converters 332, 334, 336, 338, a polarization processor 340, and a demodulator 360. It has.
　光ハイブリッド３２０は、第１偏波光Ｘ及び局発光を受信してこれら２つの光を干渉させることにより、第１偏波光Ｘの同相成分である第１同相光と、第１偏波光Ｘの直交成分である第１直交光を出力する。光ハイブリッド３２２は、第２偏波光Ｙ及び局発光を受信してこれら２つの光を干渉させることにより、第２偏波光Ｙの同相成分である第２同相光と、第２偏波光Ｙの直交成分である第２直交光を出力する。 The optical hybrid 320 receives the first polarized light X and the local light and causes these two lights to interfere with each other, whereby the first in-phase light that is the in-phase component of the first polarized light X and the first polarized light X are orthogonal to each other. The first orthogonal light that is a component is output. The optical hybrid 322 receives the second polarized light Y and the local light and causes the two lights to interfere with each other, whereby the second in-phase light that is the in-phase component of the second polarized light Y and the second polarized light Y are orthogonal to each other. The component 2nd orthogonal light is output.
　光電変換部３３２は、第１同相光を光電変換して第１同相信号ＸＩを生成する。光電変換部３３４は、第１直交光を光電変換して第１直交信号ＸＱを生成する。光電変換部３３６は、第２同相光を光電変換して第２同相信号ＹＩを生成する。光電変換部３３８は、第２直交光を光電変換して第２直交信号ＹＱを生成する。光電変換部３３２，３３４，３３６，３３８は、いずれもバランストフォトダイオードなどの光電気変換素子、トランスインピーダンスアンプ（ＴＩＡ）、及びアナログ－デジタル変換部を具備している。 The photoelectric conversion unit 332 generates the first-phase signal X I the first phase light by photoelectric conversion. The photoelectric conversion unit 334 generates the first orthogonal signal X Q a first orthogonal light by photoelectric conversion. The photoelectric conversion unit 336 generates a second phase signal Y I a second phase light by photoelectric conversion. The photoelectric conversion unit 338 photoelectrically converts the second orthogonal light to generate a second orthogonal signal YQ . Each of the photoelectric conversion units 332, 334, 336, and 338 includes a photoelectric conversion element such as a balanced photodiode, a transimpedance amplifier (TIA), and an analog-digital conversion unit.
　偏波処理部３４０は、第１同相信号ＸＩ、第１直交信号ＸＱ、第２同相信号ＹＩ、及び第２直交信号ＹＱを処理して同相ベースバンド信号ＥＩ及び直交ベースバンド信号ＥＱを生成する。この際、偏波処理部３４０は、第１偏波光Ｘと第２偏波光Ｙのパワー比α、及び第１偏波光Ｘと第２偏波光Ｙの間の位相差δを求める。 The polarization processing unit 340 processes the first in-phase signal X I , the first quadrature signal X Q , the second in-phase signal Y I , and the second quadrature signal Y Q to process the in-phase baseband signal E I and the quadrature base. A band signal EQ is generated. At this time, the polarization processing unit 340 obtains the power ratio α between the first polarized light X and the second polarized light Y and the phase difference δ between the first polarized light X and the second polarized light Y.
　復調部３６０は、偏波処理部３４０が生成した同相ベースバンド信号ＥＩ及び直交ベースバンド信号ＥＱを復調処理して、送信情報を取り出す。 The demodulation unit 360 demodulates the in-phase baseband signal E I and the quadrature baseband signal E Q generated by the polarization processing unit 340, and extracts transmission information.
　図３は、偏波処理部３４０の構成の一例を示すブロック図である。偏波処理部３４０は、位相差補正部３４１、位相差補正部３４２、位相差・強度比算出部３４４、信号合成部３４５、位相再生部３４６、及び補正量生成部３４７を備える。 FIG. 3 is a block diagram illustrating an example of the configuration of the polarization processing unit 340. The polarization processing unit 340 includes a phase difference correction unit 341, a phase difference correction unit 342, a phase difference / intensity ratio calculation unit 344, a signal synthesis unit 345, a phase reproduction unit 346, and a correction amount generation unit 347.
　位相差補正部３４１は、第１同相信号ＸＩと第１直交信号ＸＱの間の位相差（スキュー）を補正する。位相差補正部３４２は、第２同相信号ＹＩと第２直交信号ＹＱの間の位相差（スキュー）を補正する。位相差補正部３４１，３４２による補正量は、補正量生成部３４７によって与えられる。なお、これらのスキューの発生要因の一つは、後述する光ハイブリッド３２０，３２２の出力端から偏波処理部３４０の入力端に至る信号経路（各光電変換部やケーブル）の個体差にある、と考えられる。 Phase difference correcting unit 341 corrects the phase difference between the first phase signal X I and the first quadrature signal X Q a (skew). Phase difference correcting unit 342 corrects the phase difference between the second-phase signal Y I and the second orthogonal signal Y Q a (skew). Correction amounts by the phase difference correction units 341 and 342 are given by a correction amount generation unit 347. One of the causes of these skews is an individual difference in signal paths (each photoelectric conversion unit and cable) from the output ends of optical hybrids 320 and 322 described later to the input end of the polarization processing unit 340. it is conceivable that.
　位相差・強度比算出部３４４は、第１同相信号、第１直交信号、第２同相信号、及び第２直交信号を処理して、第１偏波光Ｘと第２偏波光Ｙのパワー比α、及び第１偏波光Ｘと第２偏波光Ｙの間の位相差δを算出する。位相差・強度比算出部３４４が行う処理の詳細は、フローチャートを用いて後述する。 The phase difference / intensity ratio calculation unit 344 processes the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, and the power of the first polarized light X and the second polarized light Y The ratio α and the phase difference δ between the first polarized light X and the second polarized light Y are calculated. Details of the processing performed by the phase difference / intensity ratio calculation unit 344 will be described later using a flowchart.
　信号合成部３４５は、位相差・強度比算出部３４４が算出したパワー比αおよび位相差δを用いて、同相ベースバンド信号ＥＩおよび直交ベースバンド信号ＥＱを算出する。信号合成部３４５が行う処理の詳細は、フローチャートを用いて後述する。 The signal synthesis unit 345 calculates the in-phase baseband signal E I and the quadrature baseband signal E Q using the power ratio α and the phase difference δ calculated by the phase difference / intensity ratio calculation unit 344. Details of processing performed by the signal synthesis unit 345 will be described later with reference to flowcharts.
　位相再生部３４６は、同相ベースバンド信号ＥＩおよび直交ベースバンド信号ＥＱの位相差を補正する。この位相差は、例えば信号光と局発光の混合によって生じる。 Phase recovery unit 346 corrects the phase difference of the phase baseband signals E I and quadrature baseband signals E Q. This phase difference is caused by mixing signal light and local light, for example.
　補正量生成部３４７は、位相差・強度比算出部３４４が算出したパワー比α及び位相差δを用いて、位相差補正部３４１，３４２における補正量を算出する。補正量生成部３４７が行う処理の詳細は、フローチャートを用いて後述する。 The correction amount generation unit 347 calculates the correction amounts in the phase difference correction units 341 and 342 using the power ratio α and the phase difference δ calculated by the phase difference / intensity ratio calculation unit 344. Details of the processing performed by the correction amount generation unit 347 will be described later using a flowchart.
　図４は、位相差補正部３４１の機能構成を示すブロック図である。なお、位相差補正部３４２も、本図に示す位相差補正部３４１と同様の構成を有している。 FIG. 4 is a block diagram showing a functional configuration of the phase difference correction unit 341. Note that the phase difference correction unit 342 has the same configuration as the phase difference correction unit 341 shown in FIG.
　位相差補正部３４１は、アップサンプリング部４０２、可変遅延部４０４、及びダウンサンプリング部４０６を備えている。 The phase difference correction unit 341 includes an upsampling unit 402, a variable delay unit 404, and a downsampling unit 406.
　アップサンプリング部４０２は、アップサンプラ、及びインターポレータを有している。アップサンプラは、信号間にＬ－１個の零値を挿入することで、信号のサンプリングレートをＬ倍に上げる。インターポレータには、ポリフェーズ分解が用いられている。 The upsampling unit 402 has an upsampler and an interpolator. The upsampler increases the sampling rate of the signal by L times by inserting L−1 zero values between the signals. Polyphase decomposition is used for the interpolator.
　可変遅延部４０４は、補正量生成部３４７から入力される補正量に基づいて、最大Ｎ×Ｌサンプリングまでの遅延をかけることができる。ここで、Ｎは遅延量である。すなわち可変遅延部４０４は、サンプリングデータをＮ×Ｔｓ／Ｌ（Ｔｓはサンプリング時間であり、サンプリングレートの逆数である）だけ遅らせる。 The variable delay unit 404 can apply a delay up to the maximum N × L sampling based on the correction amount input from the correction amount generation unit 347. Here, N is a delay amount. That is, the variable delay unit 404 delays the sampling data by N × T s / L (T s is the sampling time and is the reciprocal of the sampling rate).
　ダウンサンプリング部４０６は、ダウンサンプラ及びデジメータを有している。ダウンサンプラは、信号からＬ－１個のサンプルを間引くことで、サンプリングレートを１／Ｌに下げる。デジメータには、ポリフェーズ分解が用いられている。 The down-sampling unit 406 has a down sampler and a digital meter. The downsampler reduces the sampling rate to 1 / L by thinning out L-1 samples from the signal. Polyphase decomposition is used for the digimeter.
　なお、上述のＬは、アップサンプリングのサンプリングレートの上げ率及びダウンサンプリングのサンプリングレートの下げ率を示しており、上述のＮは信号の遅延量（補正量）を示している。これらの値は、いずれも整数であり、予め任意に設定することができる。例えば、光電変換部３３２，３３４，３３６，３３８で用いられているアナログ－デジタル変換器のサンプリングレートが５０ＧＳ／ｓの時、２ｐｓステップで最大１２０ｐｓのデータ遅延を実現する場合であれば、Ｌ＝１０、Ｎ＝３とすれば良い。 Note that the above-mentioned L indicates the rate of increase in the sampling rate for upsampling and the rate of decrease in the sampling rate for downsampling, and the above-mentioned N indicates the delay amount (correction amount) of the signal. These values are all integers and can be arbitrarily set in advance. For example, when the sampling rate of the analog-digital converter used in the photoelectric conversion units 332, 334, 336, and 338 is 50 GS / s, L = 10 and N = 3.
　図５は、図３に示す偏波処理部３４０の動作例を示すフローチャートである。 FIG. 5 is a flowchart showing an operation example of the polarization processing unit 340 shown in FIG.
　まず位相差・強度比算出部３４４は、Ｅｘ及びＥｙを計算し（ステップＳ１０）、複素数振幅比ｒ、ｉｒを、以下の（式１）及び（式２）を用いて各々に求める（ステップＳ２０）。
　ｒ＝Ｅｘ／Ｅｙ　　　　（式１）
　ｉｒ＝Ｅｙ／Ｅｘ　　　（式２）
　ここで、Ｅｘは、ＸＩ＋ｊＸＱで表される複素数である。Ｅｙは、ＹＩ＋ｊＹＱで表される複素数である。ｊは、純虚数を表す。 Phase difference-intensity ratio calculating unit 344 first calculates the E x and E y (step S10), and the complex amplitude ratio r, the ir, determined in each using the following (Equation 1) and (Formula 2) ( Step S20).
r = E x / E y (Formula 1)
ir = E y / E x (Formula 2)
Here, E x is a complex number represented by X I + jX Q. E y is a complex number represented by Y I + jY Q. j represents a pure imaginary number.
　次いで位相差・強度比算出部３４４は、複素数振幅比ｒ、ｉｒの各平均を計算する（ステップＳ３０）。ここで、位相差・強度比算出部３４４は、複素数振幅比ｒ及びｉｒの、例えば加法平均又は乗法平均を算出する。 Next, the phase difference / intensity ratio calculation unit 344 calculates the average of the complex amplitude ratios r and ir (step S30). Here, the phase difference / intensity ratio calculator 344 calculates, for example, an additive average or a multiplicative average of the complex amplitude ratios r and ir.
　次いで位相差・強度比算出部３４４は、ｒの絶対値｜ｒ｜とｉｒの絶対値｜ｉｒ｜の大小関係を比較する（ステップＳ４０）。ここで、複素数振幅比ｒ、ｉｒは、パワー比αおよび位相差δによって、各々に以下の（式３）、（式４）のように表すことができる。
Figure JPOXMLDOC01-appb-I000001
　　　（式３）
Figure JPOXMLDOC01-appb-I000002
　　　（式４） Next, the phase difference / intensity ratio calculator 344 compares the magnitude relationship between the absolute value | r | of r and the absolute value | ir | of ir (step S40). Here, the complex amplitude ratios r and ir can be expressed as the following (Equation 3) and (Equation 4) by the power ratio α and the phase difference δ, respectively.
Figure JPOXMLDOC01-appb-I000001
(Formula 3)
Figure JPOXMLDOC01-appb-I000002
(Formula 4)
　｜ｒ｜＜｜ｉｒ｜の場合（ステップＳ４０：Ｙｅｓ）、位相差・強度比算出部３４４は、上記（式４）を用いて、パワー比αおよび位相差δを算出する（ステップＳ５０）。具体的には、位相差・強度比算出部３４４は、α＝｜ｒ｜２／（｜ｒ｜２＋１）、δ＝ａｒｇ（ｒ）とする。 If | r | <| ir | (step S40: Yes), the phase difference / intensity ratio calculation unit 344 calculates the power ratio α and the phase difference δ using the above (formula 4) (step S50). Specifically, the phase difference / intensity ratio calculation unit 344 sets α = | r | 2 / (| r | 2 +1) and δ = arg (r).
　一方、｜ｒ｜≧｜ｉｒ｜の場合（ステップＳ４０：Ｎｏ）、位相差・強度比算出部３４４は、上記（式５）を用いて、パワー比αおよび位相差δを算出する（ステップＳ６０）。具体的には、位相差・強度比算出部３４４は、α＝１／（｜ｉｒ｜２＋１）、δ＝－ａｒｇ（ｉｒ）とする。 On the other hand, if | r | ≧ | ir | (step S40: No), the phase difference / intensity ratio calculation unit 344 calculates the power ratio α and the phase difference δ using the above (formula 5) (step S60). ). Specifically, the phase difference / intensity ratio calculation unit 344 sets α = 1 / (| ir | 2 +1) and δ = −arg (ir).
　これらの処理と平行して、補正量生成部３４７は、ステップＳ５０又はステップＳ６０で算出されたパワー比αおよび位相差δを用いて、位相差補正部３４１，３４２が補正すべき補正量を算出し、位相差補正部３４１，３４２に出力する（ステップＳ７０）。 In parallel with these processes, the correction amount generation unit 347 calculates correction amounts to be corrected by the phase difference correction units 341 and 342 using the power ratio α and the phase difference δ calculated in step S50 or step S60. And it outputs to the phase difference correction | amendment parts 341 and 342 (step S70).
　次いで信号合成部３４５は、最大比合成法（Ｍａｘｉｍａｌ－Ｒａｔｉｏ－Ｃｏｍｂｉｎｉｎｇ：ＭＲＣ）を用いて、複素信号Ｅｓ（合成信号）を算出する。具体的には、信号合成部３４５は、複素信号Ｅｓを、位相差・強度比算出部３４４が求めたパワー比αおよび位相差δを、以下の（式５）に代入することにより、求める（ステップＳ８０）。
Figure JPOXMLDOC01-appb-I000003
　　　（式５） Next, the signal synthesizer 345 calculates a complex signal E s (synthesized signal) using a maximum ratio combining method (MRC). Specifically, the signal synthesizing unit 345, a complex signal E s, the phase difference-intensity ratio calculating unit 344 power ratio α and the phase difference δ obtained by substituting into the following equation (5), obtaining (Step S80).
Figure JPOXMLDOC01-appb-I000003
(Formula 5)
　そして信号合成部３４５は、複素信号Ｅｓの実部および虚部を、各々に同相ベースバンド信号ＥＩおよび直交ベースバンド信号ＥＱとして出力する。 The signal synthesizing unit 345 outputs the real and imaginary parts of the complex signal E s, as an in-phase baseband signals E I and quadrature baseband signals E Q each.
　複素信号ＥＳには、位相ずれが含まれている。この位相ずれは、信号光と局部発振光の位相が異なることで生じている。位相再生部３４６は、この位相ずれを含む複素信号ＥＳを、Ｆｅｅｄ　Ｆｏｒｗａｒｄ　Ｍ－ｔｈ　Ｐｏｗｅｒ　ＡｌｇｏｒｉｔｈｍやＤｅｃｉｓｉｏｎ－Ｄｉｒｅｃｔｅｄ　Ｐｈａｓｅ－Ｌｏｃｋｅｄ　Ｌｏｏｐなどの搬送波位相推定法によって補正する（ステップＳ９０）。 The complex signal E S, includes a phase shift. This phase shift is caused by the phase difference between the signal light and the local oscillation light. Phase recovery unit 346, a complex signal E S including the phase shift is corrected by the carrier phase estimation method such as Feed Forward M-th Power Algorithm and Decision-Directed Phase-Locked Loop (step S90).
　なお、図５のステップＳ３０に示した処理は、必ずしも必要ではない。また、位相差・強度比算出部３４４は、複素数振幅比ｒ、ｉｒを用いずに、パワー比αおよび位相差δを算出してもよい。例えば位相差・強度比算出部３４４は、パワー比αおよび位相差δの実際の値を測定し、これらの平均（加法平均あるいは乗法平均）を信号合成部３４５及び補正量生成部３４７に出力しても良い。 Note that the process shown in step S30 of FIG. 5 is not necessarily required. Further, the phase difference / intensity ratio calculation unit 344 may calculate the power ratio α and the phase difference δ without using the complex amplitude ratios r and ir. For example, the phase difference / intensity ratio calculation unit 344 measures the actual values of the power ratio α and the phase difference δ, and outputs the average (additive average or multiplicative average) to the signal synthesis unit 345 and the correction amount generation unit 347. May be.
　図６は、補正量生成部３４７が行う処理を示すフローチャートである。まず補正量生成部３４７は、位相差補正部３４１の遅延量ｎ１、および位相差補正部３４２の位相遅延量ｎ２に零値を入れることで初期化する（ステップＳ１００）。次いで補正量生成部３４７は、位相差補正部３４１の遅延量ｎ１を一段階増加させる（ステップＳ１０２）。そして補正量生成部３４７は、位相差・強度比算出部３４４で算出された位相差δを、例えば以下の式（６）に代入することにより、位相差δの変化量を示すエラー信号εを算出し、メモリなどに格納する（ステップＳ１０４）。 FIG. 6 is a flowchart illustrating processing performed by the correction amount generation unit 347. First, the correction amount generation unit 347 initializes the delay amount n 1 of the phase difference correction unit 341 and the phase delay amount n 2 of the phase difference correction unit 342 by putting zero values (step S100). Next, the correction amount generation unit 347 increases the delay amount n 1 of the phase difference correction unit 341 by one step (step S102). Then, the correction amount generation unit 347 substitutes the phase difference δ calculated by the phase difference / intensity ratio calculation unit 344 into, for example, the following equation (6), thereby generating an error signal ε indicating the amount of change in the phase difference δ. Calculate and store in a memory or the like (step S104).
　ε =|δ[k] － δ[k-1]| （式６）
　ここで、δ[k]はk番目のδ値を示している。従って、δに付されたカッコ内の値が、ｋ－１のときはｋよりも１タップ前に相当している。 ε = | δ [k]-δ [k-1] | (Formula 6)
Here, δ [k] indicates the k-th δ value. Therefore, when the value in parentheses attached to δ is k−1, it corresponds to one tap before k.
　次に、補正量生成部３４７は、位相差補正部３４１の遅延量ｎ１が最大遅延量ｎ１,max＝Ｎ×Ｌと一致するかどうかを判定する（ステップＳ１０６）。一致していなければ（ステップＳ１０６：Ｎｏ）、補正量生成部３４７はステップＳ１０２に戻ってｎ１を一段階増加させる。一致していれば（ステップＳ１０６：Ｙｅｓ）、補正量生成部３４７は、ｎ１に零値を入れることで初期化する（ステップＳ１０８）。 Next, the correction amount generation unit 347 determines whether or not the delay amount n 1 of the phase difference correction unit 341 matches the maximum delay amount n 1, max = N × L (step S106). If they do not match (Step S106: No), the correction amount generating unit 347 the n 1 is increased one step returns to step S102. If they match (step S106: Yes), the correction amount generating unit 347 initializes by putting zero value to n 1 (step S108).
　次に、補正量生成部３４７は、位相差補正部３４２の遅延量ｎ２を一段階増加させる（ステップＳ１１０）。そして補正量生成部３４７は、位相差・強度比算出部３４４が算出した位相差δを、例えば前述の式（６）に代入することにより、位相差δの変化量を示すエラー信号εを算出し、メモリなどに格納する（ステップＳ１１２）。 Next, the correction amount generating unit 347, the delay amount n 2 of the phase difference correcting unit 342 is increased one step (step S110). Then, the correction amount generation unit 347 calculates the error signal ε indicating the amount of change in the phase difference δ by substituting the phase difference δ calculated by the phase difference / intensity ratio calculation unit 344 into, for example, the above equation (6). And stored in a memory or the like (step S112).
　次に、補正量生成部３４７は、位相差補正部３４２の遅延量ｎ２が最大遅延量ｎ２,max＝Ｎ×Ｌと一致するかどうかを判定する（ステップＳ１１４）。一致しなければ（ステップＳ１１４：Ｎｏ）、補正量生成部３４７は、ステップＳ１１０に戻ってｎ２を一段階増加させる。一致している場合（ステップＳ１１４：Ｙｅｓ）、補正量生成部３４７は、メモリなどに格納されたエラー信号εの絶対値が最小になるときの位相差補正部３４１の遅延量ｎ１ *および位相差補正部３４２の遅延量ｎ２ *を、実際の補正量に決定し（ステップＳ１１６）、決定した補正量ｎ１ *，ｎ２ *を、それぞれ位相差補正部３４１，３４２に出力する（ステップＳ１１８）。 Next, the correction amount generating unit 347 determines whether the delay amount n 2 of the phase difference correcting unit 342 matches the maximum delay amount n 2, max = N × L ( step S114). If they do not match (Step S114: No), the correction amount generating unit 347, the n 2 increases one step returns to step S110. When the values match (step S114: Yes), the correction amount generation unit 347 determines the delay amount n 1 * and the level of the phase difference correction unit 341 when the absolute value of the error signal ε stored in the memory or the like is minimized. The delay amount n 2 * of the phase difference correction unit 342 is determined as an actual correction amount (step S116), and the determined correction amounts n 1 * and n 2 * are output to the phase difference correction units 341 and 342, respectively (step S116). S118).
　次に、本実施形態による作用及び効果を、図７及び図８を用いて説明する。 Next, operations and effects according to this embodiment will be described with reference to FIGS.
　図７は、信号合成部３４５に入力される第１同相信号ＸＩ及び第１直交信号ＸＱからなる信号Ｘと、第２同相信号ＹＩ及び第２直交信号ＹＱからなる信号Ｙとの間のスキュー（ＸＹスキュー）が、再生されるデータの品質に影響を与える場合があることを説明するための図である。 FIG. 7 shows a signal X composed of a first in-phase signal XI and a first quadrature signal X Q and a signal Y composed of a second in-phase signal Y I and a second quadrature signal Y Q inputted to the signal synthesizer 345. FIG. 6 is a diagram for explaining that a skew between the two (XY skew) may affect the quality of reproduced data.
　例えば、信号Ｘと信号Ｙとの間にスキューが発生していない場合（図７の（ａ），（ｂ）における丸印参照）、ＩＱコンスタレーションマッピング上においては、図７の（ｃ）における丸印の位置が、信号合成部３４５が算出した複素信号Ｅｓ（合成信号）の信号点となる。詳細には、位相差・強度比算出部３４４で算出される位相差δが、信号Ｘと信号Ｙとの間の位相差と一致している。このため、信号合成部３４５は、Ｘ信号とＹ信号のコンスタレーション上のベクトルの向きが一致した状態で、Ｘ信号とＹ信号の加算を行うことができる。この結果、図７（ｃ）の丸印の信号点に示すように、Ｓ／Ｎが最大となる適正な位置に信号点を得ることができる。 For example, when there is no skew between the signal X and the signal Y (see the circles in FIGS. 7A and 7B), on the IQ constellation mapping, in FIG. 7C. The position of the circle is a signal point of the complex signal E s (synthesized signal) calculated by the signal synthesis unit 345. Specifically, the phase difference δ calculated by the phase difference / intensity ratio calculation unit 344 matches the phase difference between the signal X and the signal Y. For this reason, the signal synthesizer 345 can add the X signal and the Y signal in a state where the directions of the vectors on the constellation of the X signal and the Y signal match. As a result, as shown by the circled signal points in FIG. 7C, signal points can be obtained at appropriate positions where the S / N is maximum.
　これに対し、信号Ｘと信号Ｙとの間にスキューが発生している場合には（図７（ａ）における丸印、および図７（ｂ）における四角印参照）、ＩＱコンスタレーションマッピング上においては、図７（ｄ）に示す四角印の位置に信号点が得られる。詳細には、ＸＹスキューの影響により、位相差・強度比算出部３４４で算出される位相差δが、Ｘ信号とＹ信号の間の位相差と一致しない。このため、信号合成部３４５は、Ｘ信号とＹ信号のコンスタレーション上のベクトルの向きが全く一致しない状態で、Ｘ信号とＹ信号の加算を行う。この場合、信号点の位置は適正な位置から大きくずれ、信号に誤りが発生する可能性が出てくる。 On the other hand, when there is a skew between the signal X and the signal Y (see the circle in FIG. 7A and the square in FIG. 7B), the IQ constellation mapping is performed. The signal point is obtained at the position of the square mark shown in FIG. Specifically, due to the influence of the XY skew, the phase difference δ calculated by the phase difference / intensity ratio calculation unit 344 does not match the phase difference between the X signal and the Y signal. For this reason, the signal synthesis unit 345 adds the X signal and the Y signal in a state where the directions of the vectors on the constellation of the X signal and the Y signal do not match at all. In this case, the position of the signal point is greatly deviated from the proper position, and there is a possibility that an error occurs in the signal.
　これに対し、本実施形態では、補正量生成部３４７が位相差補正部３４１，３４２による補正量を適切な値に設定しているため、信号Ｘと信号Ｙとの間のスキューを抑制できる。 On the other hand, in the present embodiment, since the correction amount generation unit 347 sets the correction amounts by the phase difference correction units 341 and 342 to appropriate values, the skew between the signal X and the signal Y can be suppressed.
　また、図８は、50Gbps-SP-QPSKにおける、信号Ｘと信号Ｙとの間に生じるスキューと、式６で算出したエラー信号εの分散の関係を示すグラフである。図８において、光電変換部３３２，３３４，３３６，３３８で用いられているアナログ－デジタル変換器のサンプリングレートを５０ＧＳ／ｓとした。また、位相差補正部３４１におけるＮ＝６，Ｌ＝１０とした。図８に示すように、式６で算出したエラー信号εは、信号Ｘと信号Ｙとの間のスキューに対して高い感度を有している。従って、エラー信号εが極小値となるように位相差補正部３４１，３４２の補正量を設定すると、信号Ｘと信号Ｙとの間のスキューは非常に小さな値になる。 FIG. 8 is a graph showing the relationship between the skew generated between the signal X and the signal Y and the variance of the error signal ε calculated by Equation 6 in 50 Gbps-SP-QPSK. In FIG. 8, the sampling rate of the analog-digital converter used in the photoelectric conversion units 332, 334, 336, 338 is set to 50 GS / s. Further, N = 6 and L = 10 in the phase difference correction unit 341 were set. As shown in FIG. 8, the error signal ε calculated by Equation 6 has high sensitivity to the skew between the signal X and the signal Y. Accordingly, when the correction amounts of the phase difference correction units 341 and 342 are set so that the error signal ε becomes a minimum value, the skew between the signal X and the signal Y becomes a very small value.
（第２の実施形態）
　図９は、第２の実施形態に係る光信号処理装置１０に用いられる偏波処理部３４０の構成を示すブロック図である。本実施形態に係る偏波処理部３４０は、補正量生成部３４７が、信号合成部３４５が出力する合成信号、すなわち信号Ｅｓ（＝ＥＩ ＋ｊ×ＥＱ、または上記（５）式）を用いて補正量を算出する点を除いて、第１の実施形態に係る偏波処理部３４０と同様である。 (Second Embodiment)
FIG. 9 is a block diagram illustrating a configuration of the polarization processing unit 340 used in the optical signal processing device 10 according to the second embodiment. In the polarization processing unit 340 according to the present embodiment, the correction amount generation unit 347 outputs the combined signal output from the signal combining unit 345, that is, the signal E s (= E I + j × E Q , or the above equation (5)). It is the same as that of the polarization processing unit 340 according to the first embodiment except that the correction amount is used to calculate the correction amount.
　図１０は、本実施形態における補正量生成部３４７の動作を示すフローチャートである。まず補正量生成部３４７は、位相差補正部３４１の遅延量ｎ１、および位相差補正部３４２の遅延量ｎ２に零値を入れ、これら遅延量を初期化する（ステップＳ２０２）。次いで補正量生成部３４７は、位相差補正部３４１の遅延量ｎ１を一段階増加させる（ステップＳ２０４）。次いで補正量生成部３４７は、偏波処理部３４０の信号合成部３４５で算出されたＥｓの振幅を、例えば式（７）に従ってエラー信号εとして計算し、メモリなどに格納する（ステップＳ２０６）。 FIG. 10 is a flowchart showing the operation of the correction amount generation unit 347 in the present embodiment. First, the correction amount generation unit 347 enters zero values into the delay amount n 1 of the phase difference correction unit 341 and the delay amount n 2 of the phase difference correction unit 342, and initializes these delay amounts (step S202). Next, the correction amount generation unit 347 increases the delay amount n 1 of the phase difference correction unit 341 by one step (step S204). Then the correction amount generating unit 347, the amplitude of the E s calculated by the signal synthesizing portion 345 of the polarization processing unit 340, for example, calculated as an error signal ε according to equation (7), and stores in a memory (step S206) .
　ε =｜Ｅｓ[k]｜ - ｜Ｅｓ[k-1]｜ （式７）
　ここで、Ｅｓ[k]はk番目のＥｓ値を示している。従って、Ｅｓに付されたカッコ内の値が、ｋ－１のときはｋよりも１タップ前に相当している。 ε = | E s [k] | - | E s [k-1] | ( Equation 7)
Here, E s [k] indicates the k-th E s value. Thus, the values in brackets attached to the E s is, when the k-1 corresponds to 1-tap before k.
　次に、補正量生成部３４７は、位相差補正部３４１の遅延量ｎ１が最大遅延量ｎ１,max＝Ｎ×Ｌと一致するかどうかを判定する（ステップＳ２０８）。一致していなければ（ステップＳ２０８：Ｎｏ）、補正量生成部３４７はステップＳ２０４に戻ってｎ１を一段階増加させる。一致していれば（ステップＳ２０８：Ｙｅｓ）、補正量生成部３４７は、ｎ１に零値を入れることで初期化する（ステップ２１０）。 Next, the correction amount generation unit 347 determines whether or not the delay amount n 1 of the phase difference correction unit 341 matches the maximum delay amount n 1, max = N × L (step S208). If they do not match (Step S208: No), the correction amount generating unit 347 the n 1 is increased one step returns to step S204. If they match (step S208: Yes), the correction amount generation unit 347 initializes the n 1 by putting a zero value (step 210).
　次に、補正量生成部３４７は、位相差補正部３４２の遅延量ｎ２を一段階増加させる（ステップＳ２１２）。そして補正量生成部３４７は、位相差・強度比算出部３４４が算出した位相差δを、例えば前述の式（７）に代入することにより、位相差δの変化量を示すエラー信号εを算出し、メモリなどに格納する（ステップＳ２１４）。 Next, the correction amount generating unit 347, the delay amount n 2 of the phase difference correcting unit 342 is increased one step (step S212). Then, the correction amount generation unit 347 calculates the error signal ε indicating the amount of change in the phase difference δ by substituting the phase difference δ calculated by the phase difference / intensity ratio calculation unit 344 into, for example, the above equation (7). And stored in a memory or the like (step S214).
　次に、補正量生成部３４７は、位相差補正部３４２の遅延量ｎ２が最大遅延量ｎ２,max＝Ｎ×Ｌと一致するかどうかを判定する（ステップＳ２１６）。一致しなければ（ステップＳ２１６：Ｎｏ）、補正量生成部３４７は、ステップＳ２１２に戻ってｎ２を一段階増加させる。一致している場合（ステップＳ２１６：Ｙｅｓ）、補正量生成部３４７は、メモリなどに格納されたエラー信号εの絶対値が最小になるときの位相差補正部３４１の遅延量ｎ１ *および位相差補正部３４２の遅延量ｎ２ *を、実際の補正量に決定し（ステップＳ２１８）、決定した補正量ｎ１ *，ｎ２ *を、それぞれ位相差補正部３４１，３４２に出力する（ステップＳ２２０）。 Next, the correction amount generating unit 347 determines whether the delay amount n 2 of the phase difference correcting unit 342 matches the maximum delay amount n 2, max = N × L ( step S216). If they do not match (Step S216: No), the correction amount generating unit 347, the n 2 increases one step returns to step S212. When the values match (step S216: Yes), the correction amount generation unit 347 determines the delay amount n 1 * and the level of the phase difference correction unit 341 when the absolute value of the error signal ε stored in the memory or the like is minimized. The delay amount n 2 * of the phase difference correction unit 342 is determined as an actual correction amount (step S218), and the determined correction amounts n 1 * and n 2 * are output to the phase difference correction units 341 and 342, respectively (step S218). S220).
　図１１は、50Gbps-SP-QPSKにおける、信号Ｘと信号Ｙとの間にスキューと、式（７）で算出したエラー信号εの分散の関係を示すグラフである。図１１において、光電変換部３３２，３３４，３３６，３３８で用いられているアナログ－デジタル変換器のサンプリングレートを５０ＧＳ／ｓとした。位相差補正部３４１におけるＮ＝６，Ｌ＝１０とした。図１１に示すように、式（７）で算出したエラー信号εは、信号Ｘと信号Ｙとの間のスキューに対して高い感度を有している。従って、エラー信号εが極小値となるように位相差補正部３４１，３４２の補正量を設定すると、信号Ｘと信号Ｙとの間のスキューは非常に小さな値になる。 FIG. 11 is a graph showing the relationship between the skew between the signal X and the signal Y and the variance of the error signal ε calculated by Expression (7) in 50 Gbps-SP-QPSK. In FIG. 11, the sampling rate of the analog-digital converter used in the photoelectric conversion units 332, 334, 336, 338 is set to 50 GS / s. In the phase difference correction unit 341, N = 6 and L = 10. As shown in FIG. 11, the error signal ε calculated by Expression (7) has high sensitivity to the skew between the signal X and the signal Y. Accordingly, when the correction amounts of the phase difference correction units 341 and 342 are set so that the error signal ε becomes a minimum value, the skew between the signal X and the signal Y becomes a very small value.
　従って、本実施形態によっても、第１の実施形態と同様の効果を得ることができる。 Therefore, according to this embodiment, the same effect as that of the first embodiment can be obtained.
（第３の実施形態）
　図１２は、第３の実施形態に係る光信号処理装置１０の機能構成を示すブロック図である。本実施形態に係る光信号処理装置１０は、光受信装置２０及び光送信装置４０を備えている。光受信装置２０は、第１の実施形態又は第２の実施形態に示した構成を有している。光送信装置４０は、電気信号である送信用信号を光信号（出力用信号光）に変換して外部に出力する。光送信装置４０は、デジタルコヒーレント方式の送信用信号を生成する。 (Third embodiment)
FIG. 12 is a block diagram illustrating a functional configuration of the optical signal processing device 10 according to the third embodiment. The optical signal processing device 10 according to the present embodiment includes an optical reception device 20 and an optical transmission device 40. The optical receiver 20 has the configuration shown in the first embodiment or the second embodiment. The optical transmission device 40 converts a transmission signal, which is an electrical signal, into an optical signal (output signal light) and outputs it to the outside. The optical transmitter 40 generates a digital coherent transmission signal.
　本実施形態によっても、第１又は第２の実施形態と同様の効果を得ることができる。 Also according to this embodiment, the same effect as the first or second embodiment can be obtained.
　なお、上記した各実施形態は、所定のハードウェア、例えば、回路として具現化することもできる。 It should be noted that each of the above-described embodiments can be embodied as predetermined hardware, for example, a circuit.
　また、上記した実施形態は、制御プログラムを図示しないコンピュータ回路（例えば、ＣＰＵ（Ｃｅｎｔｒａｌ　Ｐｒｏｃｅｓｓｉｎｇ　Ｕｎｉｔ））で実行させることによっても実現できる。この場合、上記した制御プログラムは、例えば、光受信機内部の記憶媒体、あるいは、外部の記憶媒体に予め記憶されている。そして制御プログラムは、上記コンピュータ回路によって読み出され、実行される。内部の記憶媒体としては、例えば、ＲＯＭ（Ｒｅａｄ　Ｏｎｌｙ　Ｍｅｍｏｒｙ）やハードディスク等を挙げることができる。また、外部の記憶媒体としては、例えば、リムーバブルメディアやリムーバブルディスク等を挙げることができる。 In addition, the above-described embodiment can also be realized by causing a control program to be executed by a computer circuit (not shown) (for example, a CPU (Central Processing Unit)). In this case, the above-described control program is stored in advance in, for example, a storage medium inside the optical receiver or an external storage medium. The control program is read and executed by the computer circuit. Examples of the internal storage medium include a ROM (Read Only Memory) and a hard disk. Moreover, examples of the external storage medium include a removable medium and a removable disk.
　この出願は、２０１１年９月２２日に出願された日本出願特願２０１１－２０８０８９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。 This application claims priority based on Japanese Patent Application No. 2011-208089 filed on September 22, 2011, the entire disclosure of which is incorporated herein.

Claims (14)

  1. 　外部から受信した外部信号光から生成された第１偏波光を、前記第１偏波光の同相成分に対応する第１同相光と、前記第１偏波光の直交成分に対応する第１直交光に分離する第１光分離手段と、
    　前記外部信号光から生成されており前記第１偏波光とは偏波の方向が直交する第２偏波光を、前記第２偏波光の同相成分に対応する第２同相光と、前記第２偏波光の直交成分に対応する第２直交光に分離する第２光分離手段と、
    　前記第１同相光を光電変換して第１同相信号を生成する第１光電変換手段と、
    　前記第１直交光を光電変換して第１直交信号を生成する第２光電変換手段と、
    　前記第２同相光を光電変換して第２同相信号を生成する第３光電変換手段と、
    　前記第２直交光を光電変換して第２直交信号を生成する第４光電変換手段と、
    　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を処理して同相ベースバンド信号及び直交ベースバンド信号を生成する偏波処理手段と、
    　前記同相ベースバンド信号及び前記直交ベースバンド信号を復調処理して、送信信号を生成する生成復調手段と、
    を備え、
    　前記偏波処理手段は、
    　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の位相差δを算出する位相差算出手段と、
    　　前記位相差算出手段が算出した位相差δを用いて、前記第１同相信号及び前記第１直交信号と、前記第２同相信号及び前記第２直交信号と、の間の位相差を補正する位相差補正手段と、
    　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の強度比を算出する強度比算出手段と、
    　　前記位相差算出手段が算出した位相差δ、及び前記強度比算出手段が算出した強度比を用いて、前記同相ベースバンド信号及び前記直交ベースバンド信号を生成する信号合成手段と、
    を備える光信号処理装置。     The first polarized light generated from the external signal light received from the outside is converted into first in-phase light corresponding to the in-phase component of the first polarized light and first orthogonal light corresponding to the orthogonal component of the first polarized light. First light separating means for separating;
    Second polarized light generated from the external signal light and having a polarization direction orthogonal to the first polarized light is converted to second in-phase light corresponding to the in-phase component of the second polarized light, and the second polarized light. Second light separating means for separating into second orthogonal light corresponding to the orthogonal component of the wave light;
    First photoelectric conversion means for photoelectrically converting the first in-phase light to generate a first in-phase signal;
    Second photoelectric conversion means for photoelectrically converting the first orthogonal light to generate a first orthogonal signal;
    Third photoelectric conversion means for photoelectrically converting the second in-phase light to generate a second in-phase signal;
    Fourth photoelectric conversion means for photoelectrically converting the second orthogonal light to generate a second orthogonal signal;
    Polarization processing means for processing the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal to generate an in-phase baseband signal and a quadrature baseband signal;
    Generating and demodulating means for demodulating the in-phase baseband signal and the quadrature baseband signal to generate a transmission signal;
    With
    The polarization processing means includes
    A phase difference for calculating a phase difference δ between the first polarized light and the second polarized light using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal. A calculation means;
    The phase difference between the first in-phase signal and the first quadrature signal, and the second in-phase signal and the second quadrature signal is corrected using the phase difference δ calculated by the phase difference calculation unit. Phase difference correction means for
    Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, an intensity ratio calculation that calculates an intensity ratio between the first polarized light and the second polarized light Means,
    Signal synthesizing means for generating the in-phase baseband signal and the quadrature baseband signal using the phase difference δ calculated by the phase difference calculating means and the intensity ratio calculated by the intensity ratio calculating means;
    An optical signal processing apparatus.
  2. 　請求項１に記載の光信号処理装置において、
    　前記位相差補正手段は、前記位相差の補正量を変化させながら前記位相差算出手段が算出した位相差の変化量を算出し、算出した前記変化量が最小値となるように前記補正量を設定する光信号処理装置。     The optical signal processing device according to claim 1,
    The phase difference correction unit calculates a change amount of the phase difference calculated by the phase difference calculation unit while changing the correction amount of the phase difference, and sets the correction amount so that the calculated change amount becomes a minimum value. Optical signal processing device to be set.
  3. 　請求項１または２に記載の光信号処理装置において、
    　前記位相差算出手段は、下記（１）式及び（２）式を用いて、前記位相差δを算出する光信号処理装置。
    Figure JPOXMLDOC01-appb-I000004
    ・・・（１）
    Figure JPOXMLDOC01-appb-I000005
    ・ ・・（２）
    ・ 　ただし、ｒ及びｉｒは、以下の（３）式及び（４）式のとおりである。
    　ｒ＝Ｅｘ／Ｅｙ・・・（３）
    　ｉｒ＝Ｅｙ／Ｅｘ・・・（４）
    ここで、Ｅｘ＝ＸＩ＋ｊＸＱであり、Ｅｙ＝ＹＩ＋ｊＹＱである。さらに、ＸＩは前記第１同相信号であり、ＸＱは前記第１直交信号であり、ＹＩは前記第２同相信号であり、ＹＱは前記第２直交信号である。     In the optical signal processing device according to claim 1 or 2,
    The phase difference calculation means is an optical signal processing device that calculates the phase difference δ using the following equations (1) and (2).
    Figure JPOXMLDOC01-appb-I000004
    ... (1)
    Figure JPOXMLDOC01-appb-I000005
    (2)
    -However, r and ir are as the following (3) Formula and (4) Formula.
    r = E x / E y (3)
    ir = E y / E x (4)
    Here, E x = X I + jX Q , and E y = Y I + jY Q. Furthermore, X I is the first in-phase signal, X Q is the first quadrature signal, Y I is the second in-phase signal, and Y Q is the second quadrature signal.
  4. 　請求項３に記載の光信号処理装置において、
    　前記位相差算出手段は、
    　　｜ｒ｜＜｜ｉｒ｜の場合に前記位相差δ＝ａｒｇ（ｒ）として、
    　　｜ｒ｜≧｜ｉｒ｜の場合に前記位相差δ＝－ａｒｇ（ｉｒ）とする光信号処理装置。     The optical signal processing device according to claim 3,
    The phase difference calculating means includes
    When | r | <| ir |, the phase difference δ = arg (r)
    An optical signal processing apparatus that sets the phase difference δ = −arg (ir) when | r | ≧ | ir |.
  5. 　外部から受信した外部信号光から生成された第１偏波光を、前記第１偏波光の同相成分に対応する第１同相光と、前記第１偏波光の直交成分に対応する第１直交光に分離する第１光分離手段と、
    　前記外部信号光から生成されており前記第１偏波光とは偏波の方向が直交する第２偏波光を、前記第２偏波光の同相成分に対応する第２同相光と、前記第２偏波光の直交成分に対応する第２直交光に分離する第２光分離手段と、
    　前記第１同相光を光電変換して第１同相信号を生成する第１光電変換手段と、
    　前記第１直交光を光電変換して第１直交信号を生成する第２光電変換手段と、
    　前記第２同相光を光電変換して第２同相信号を生成する第３光電変換手段と、
    　前記第２直交光を光電変換して第２直交信号を生成する第４光電変換手段と、
    　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を処理して同相ベースバンド信号及び直交ベースバンド信号を生成する偏波処理手段と、
    　前記同相ベースバンド信号及び前記直交ベースバンド信号を復調処理して、送信信号を生成する復調手段と、
    を備え、
    　前記偏波処理手段は、
    　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の位相差δを算出する位相差算出手段と、
    　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の強度比αを算出する強度比算出手段と、
    　　前記位相差算出手段が算出した位相差δ、及び前記強度比算出手段が算出した強度比αを用いて、前記同相ベースバンド信号及び前記直交ベースバンド信号を生成する信号合成手段と、
    　　前記同相ベースバンド信号及び前記直交ベースバンド信号を合成した合成信号を生成し、当該合成信号の強度を用いて、前記第１同相信号及び前記第１直交信号と、前記第２同相信号及び前記第２直交信号と、の間の位相差を補正する位相差補正手段と、
    を備える光信号処理装置。     The first polarized light generated from the external signal light received from the outside is converted into first in-phase light corresponding to the in-phase component of the first polarized light and first orthogonal light corresponding to the orthogonal component of the first polarized light. First light separating means for separating;
    Second polarized light generated from the external signal light and having a polarization direction orthogonal to the first polarized light is converted to second in-phase light corresponding to the in-phase component of the second polarized light, and the second polarized light. Second light separating means for separating into second orthogonal light corresponding to the orthogonal component of the wave light;
    First photoelectric conversion means for photoelectrically converting the first in-phase light to generate a first in-phase signal;
    Second photoelectric conversion means for photoelectrically converting the first orthogonal light to generate a first orthogonal signal;
    Third photoelectric conversion means for photoelectrically converting the second in-phase light to generate a second in-phase signal;
    Fourth photoelectric conversion means for photoelectrically converting the second orthogonal light to generate a second orthogonal signal;
    Polarization processing means for processing the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal to generate an in-phase baseband signal and a quadrature baseband signal;
    Demodulation means for demodulating the in-phase baseband signal and the quadrature baseband signal to generate a transmission signal;
    With
    The polarization processing means includes
    A phase difference for calculating a phase difference δ between the first polarized light and the second polarized light using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal. A calculation means;
    An intensity ratio for calculating an intensity ratio α of the first polarized light and the second polarized light using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal. A calculation means;
    Signal synthesizing means for generating the in-phase baseband signal and the quadrature baseband signal using the phase difference δ calculated by the phase difference calculating means and the intensity ratio α calculated by the intensity ratio calculating means;
    A synthesized signal obtained by synthesizing the in-phase baseband signal and the quadrature baseband signal is generated, and using the intensity of the synthesized signal, the first in-phase signal and the first quadrature signal, the second in-phase signal, Phase difference correction means for correcting a phase difference between the second quadrature signal and the second orthogonal signal;
    An optical signal processing apparatus.
  6. 　請求項５に記載の光信号処理装置において、
    　前記位相差補正手段は、前記位相差の補正量を変化させながら前記合成信号の強度の変化量を算出し、算出した前記変化量が最小値となるように前記補正量を設定する光信号処理装置。     The optical signal processing device according to claim 5,
    The phase difference correction unit calculates an amount of change in intensity of the combined signal while changing the amount of correction of the phase difference, and sets the correction amount so that the calculated amount of change becomes a minimum value. apparatus.
  7. 　請求項５又は６に記載の光信号処理装置において、
    　前記位相差補正手段は、以下の（５）式を用いて前記合成信号Ｅｓを生成する光信号処理装置。
    Figure JPOXMLDOC01-appb-I000006
    ・・・（５）
    ここで、Ｅｘ＝ＸＩ＋ｊＸＱであり、Ｅｙ＝ＹＩ＋ｊＹＱである。さらに、ＸＩは前記第１同相信号であり、ＸＱは前記第１直交信号であり、ＹＩは前記第２同相信号であり、ＹＱは前記第２直交信号である。     In the optical signal processing device according to claim 5 or 6,
    The phase difference correcting means, the following equation (5) the optical signal processing apparatus for generating the synthetic signal E s using.
    Figure JPOXMLDOC01-appb-I000006
    ... (5)
    Here, E x = X I + jX Q , and E y = Y I + jY Q. Furthermore, X I is the first in-phase signal, X Q is the first quadrature signal, Y I is the second in-phase signal, and Y Q is the second quadrature signal.
  8. 　請求項１～７のいずれか一項に記載の光信号処理装置において、
    　前記偏波処理手段は、最大比合成法（Ｍａｘｉｍａｌ－Ｒａｔｉｏ－Ｃｏｍｂｉｎｉｎｇ）を用いて前記同相ベースバンド信号及び前記直交ベースバンド信号を生成する光信号処理装置。     The optical signal processing device according to any one of claims 1 to 7,
    The polarization processing means is an optical signal processing device that generates the in-phase baseband signal and the quadrature baseband signal using a maximum ratio combining method (Maximal-Ratio-Combining).
  9. 　請求項１～８のいずれか一項に記載の光信号処理装置において、
    　前記外部信号光から前記第１偏波光及び第２偏波光を生成する偏波分離手段をさらに備える光信号処理装置。     The optical signal processing device according to any one of claims 1 to 8,
    An optical signal processing device further comprising polarization separation means for generating the first polarized light and the second polarized light from the external signal light.
  10. 　請求項１～９のいずれか一項に記載の光信号処理装置において、
    　外部に送信すべき信号を示す出力用信号光を生成して外部に出力する光出力手段をさらに備える光信号処理装置。     The optical signal processing device according to any one of claims 1 to 9,
    An optical signal processing apparatus further comprising optical output means for generating and outputting output signal light indicating a signal to be transmitted to the outside.
  11. 　第１同相光から生成された第１同相信号、第１直交光から生成された第１直交信号、第２同相光から生成された第２同相信号、及び第２直交光から生成された第２直交信号を処理する偏波処理装置であって、
    　前記第１同相光は、外部信号光から分離された第１偏波光の同相成分であり、
    　前記第１直交光は、前記第１偏波光の直交成分であり、
    　前記第２同相光は、前記外部信号光から分離されていて前記第１偏波光とは偏波方向が直交する第２偏波光の同相成分であり、
    　前記第２直交光は、前記第２偏波光の直交成分であり、
    　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の位相差δを算出する位相差算出手段と、
    　　前記位相差算出手段が算出した位相差δを用いて、前記第１同相信号及び前記第１直交信号と、前記第２同相信号及び前記第２直交信号と、の間の位相差を補正する位相差補正手段と、
    　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の強度比を算出する強度比算出手段と、
    　　前記位相差算出手段が算出した位相差δ、及び前記強度比算出手段が算出した強度比を用いて、同相ベースバンド信号及び直交ベースバンド信号を生成する信号合成手段と、
    を備える偏波処理装置。     The first in-phase signal generated from the first in-phase light, the first quadrature signal generated from the first quadrature light, the second in-phase signal generated from the second in-phase light, and the second quadrature light. A polarization processing device for processing a second orthogonal signal,
    The first in-phase light is an in-phase component of the first polarized light separated from the external signal light,
    The first orthogonal light is an orthogonal component of the first polarized light,
    The second in-phase light is separated from the external signal light and is the in-phase component of the second polarized light whose polarization direction is orthogonal to the first polarized light,
    The second orthogonal light is an orthogonal component of the second polarized light,
    A phase difference for calculating a phase difference δ between the first polarized light and the second polarized light using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal. A calculation means;
    The phase difference between the first in-phase signal and the first quadrature signal, and the second in-phase signal and the second quadrature signal is corrected using the phase difference δ calculated by the phase difference calculation unit. Phase difference correction means for
    Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, an intensity ratio calculation that calculates an intensity ratio between the first polarized light and the second polarized light Means,
    Signal combining means for generating an in-phase baseband signal and a quadrature baseband signal using the phase difference δ calculated by the phase difference calculating means and the intensity ratio calculated by the intensity ratio calculating means;
    A polarization processing apparatus.
  12. 　第１同相光から生成された第１同相信号、第１直交光から生成された第１直交信号、第２同相光から生成された第２同相信号、及び第２直交光から生成された第２直交信号を処理する偏波処理装置であって、
    　前記第１同相光は、外部信号光から分離された第１偏波光の同相成分であり、
    　前記第１直交光は、前記第１偏波光の直交成分であり、
    　前記第２同相光は、前記外部信号光から分離されていて前記第１偏波光とは偏波方向が直交する第２偏波光の同相成分であり、
    　前記第２直交光は、前記第２偏波光の直交成分であり、
    　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の位相差δを算出する位相差算出手段と、
    　　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の強度比を算出する強度比算出手段と、
    　　前記位相差算出手段が算出した位相差δ、及び前記強度比算出手段が算出した強度比を用いて、同相ベースバンド信号及び直交ベースバンド信号を生成する信号合成手段と、
    　　前記同相ベースバンド信号及び前記直交ベースバンド信号を合成した合成信号を生成し、当該合成信号の強度を用いて、前記第１同相信号及び前記第１直交信号と、前記第２同相信号及び前記第２直交信号と、の間の位相差を補正する位相差補正手段と、
    を備える偏波処理装置。     The first in-phase signal generated from the first in-phase light, the first quadrature signal generated from the first quadrature light, the second in-phase signal generated from the second in-phase light, and the second quadrature light. A polarization processing device for processing a second orthogonal signal,
    The first in-phase light is an in-phase component of the first polarized light separated from the external signal light,
    The first orthogonal light is an orthogonal component of the first polarized light,
    The second in-phase light is separated from the external signal light and is the in-phase component of the second polarized light whose polarization direction is orthogonal to the first polarized light,
    The second orthogonal light is an orthogonal component of the second polarized light,
    A phase difference for calculating a phase difference δ between the first polarized light and the second polarized light using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal. A calculation means;
    Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, an intensity ratio calculation that calculates an intensity ratio between the first polarized light and the second polarized light Means,
    Signal combining means for generating an in-phase baseband signal and a quadrature baseband signal using the phase difference δ calculated by the phase difference calculating means and the intensity ratio calculated by the intensity ratio calculating means;
    A synthesized signal obtained by synthesizing the in-phase baseband signal and the quadrature baseband signal is generated, and using the intensity of the synthesized signal, the first in-phase signal and the first quadrature signal, the second in-phase signal, Phase difference correction means for correcting a phase difference between the second quadrature signal and the second orthogonal signal;
    A polarization processing apparatus.
  13. 　外部から受信した外部信号光から生成された第１偏波光を、前記第１偏波光の同相成分に対応する第１同相光と、前記第１偏波光の直交成分に対応する第１直交光に分離し、
    　前記外部信号光から生成されており前記第１偏波光とは偏波の方向が直交する第２偏波光を、前記第２偏波光の同相成分に対応する第２同相光と、前記第２偏波光の直交成分に対応する第２直交光に分離し、
    　前記第１同相光を光電変換して第１同相信号を生成し、
    　前記第１直交光を光電変換して第１直交信号を生成し、
    　前記第２同相光を光電変換して第２同相信号を生成し、
    　前記第２直交光を光電変換して第２直交信号を生成し、
    　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の位相差δを算出し、
    　算出した前記位相差δを用いて、前記第１同相信号及び前記第１直交信号と、前記第２同相信号及び前記第２直交信号と、の間の位相差を補正し、
    　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の強度比を算出し、
    　算出した前記位相差δ及び前記強度比を用いて、同相ベースバンド信号及び直交ベースバンド信号を生成し、
    　前記同相ベースバンド信号及び前記直交ベースバンド信号を用いて復調処理して、送信信号を生成する光信号処理方法。     The first polarized light generated from the external signal light received from the outside is converted into first in-phase light corresponding to the in-phase component of the first polarized light and first orthogonal light corresponding to the orthogonal component of the first polarized light. Separate and
    Second polarized light generated from the external signal light and having a polarization direction orthogonal to the first polarized light is converted to second in-phase light corresponding to the in-phase component of the second polarized light, and the second polarized light. Separating into the second orthogonal light corresponding to the orthogonal component of the wave light,
    Photoelectrically converting the first in-phase light to generate a first in-phase signal;
    Photoelectrically converting the first orthogonal light to generate a first orthogonal signal;
    Photoelectrically converting the second in-phase light to generate a second in-phase signal;
    Photoelectrically converting the second orthogonal light to generate a second orthogonal signal;
    Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, a phase difference δ between the first polarization light and the second polarization light is calculated,
    Using the calculated phase difference δ, the phase difference between the first in-phase signal and the first quadrature signal and the second in-phase signal and the second quadrature signal is corrected,
    Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, an intensity ratio between the first polarized light and the second polarized light is calculated,
    Using the calculated phase difference δ and the intensity ratio, an in-phase baseband signal and a quadrature baseband signal are generated,
    An optical signal processing method for generating a transmission signal by performing demodulation processing using the in-phase baseband signal and the quadrature baseband signal.
  14. 　外部から受信した外部信号光から生成された第１偏波光を、前記第１偏波光の同相成分に対応する第１同相光と、前記第１偏波光の直交成分に対応する第１直交光に分離し、
    　前記外部信号光から生成されており前記第１偏波光とは偏波の方向が直交する第２偏波光を、前記第２偏波光の同相成分に対応する第２同相光と、前記第２偏波光の直交成分に対応する第２直交光に分離し、
    　前記第１同相光を光電変換して第１同相信号を生成し、
    　前記第１直交光を光電変換して第１直交信号を生成し、
    　前記第２同相光を光電変換して第２同相信号を生成し、
    　前記第２直交光を光電変換して第２直交信号を生成し、
    　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の位相差δを算出し、
    　前記第１同相信号、前記第１直交信号、前記第２同相信号、及び前記第２直交信号を用いて、前記第１偏波光と前記第２偏波光の強度比を算出し、
    　算出した前記位相差δ及び前記強度比を用いて、同相ベースバンド信号及び直交ベースバンド信号を生成し、
    　　前記同相ベースバンド信号及び前記直交ベースバンド信号を合成した合成信号を生成し、当該合成信号の強度を用いて、前記第１同相信号及び前記第１直交信号と、前記第２同相信号及び前記第２直交信号と、の間の位相差を補正し、
    　前記同相ベースバンド信号及び前記直交ベースバンド信号を用いて復調処理して、送信信号を生成する、光信号処理方法。     The first polarized light generated from the external signal light received from the outside is converted into first in-phase light corresponding to the in-phase component of the first polarized light and first orthogonal light corresponding to the orthogonal component of the first polarized light. Separate and
    Second polarized light generated from the external signal light and having a polarization direction orthogonal to the first polarized light is converted to second in-phase light corresponding to the in-phase component of the second polarized light, and the second polarized light. Separating into the second orthogonal light corresponding to the orthogonal component of the wave light,
    Photoelectrically converting the first in-phase light to generate a first in-phase signal;
    Photoelectrically converting the first orthogonal light to generate a first orthogonal signal;
    Photoelectrically converting the second in-phase light to generate a second in-phase signal;
    Photoelectrically converting the second orthogonal light to generate a second orthogonal signal;
    Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, a phase difference δ between the first polarization light and the second polarization light is calculated,
    Using the first in-phase signal, the first quadrature signal, the second in-phase signal, and the second quadrature signal, an intensity ratio between the first polarized light and the second polarized light is calculated,
    Using the calculated phase difference δ and the intensity ratio, an in-phase baseband signal and a quadrature baseband signal are generated,
    A synthesized signal obtained by synthesizing the in-phase baseband signal and the quadrature baseband signal is generated, and using the intensity of the synthesized signal, the first in-phase signal and the first quadrature signal, the second in-phase signal, Correcting the phase difference between the second quadrature signal and
    An optical signal processing method for generating a transmission signal by performing demodulation processing using the in-phase baseband signal and the quadrature baseband signal.
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