JP5462086B2 - Optical coherent detector evaluation apparatus and optical coherent detector evaluation method - Google Patents

Description

  The present invention relates to an optical coherent detector evaluation apparatus and an optical coherent detector evaluation method for evaluating an optical coherent detector used for a front end of a digital optical coherent detection receiver.

  Recently, with an increase in capacity of optical communication, long-distance transmission of 100 G (bps / channel) class is required. In these long-distance transmissions, a transmission method having resistance against fiber dispersion and wavelength filtering, Attention has been focused on a multi-value modulation method with high frequency efficiency, in which a plurality of data is placed on a signal (symbol), and research on digital optical coherent detection technology has been actively conducted as one of the techniques (for example, see Patent Document 1). .

  For example, quadrature phase shift keying (QPSK) and quadrature phase shift keying (DP-QPSK), which are quadrature modulation and quadrature modulation, are signals of 25 G / symbol and 100 Gbps transmission. This is also a transmission method that uses digital optical coherent detection technology.

  In the optical coherent detector of digital optical coherent detection, polarization separation for polarization diversity of input optical coherent detection signal light, narrow line width laser used as local light, and homodyne detection or heterodyne detection of input optical coherent detection signal light. Thus, a 90 ° optical hybrid for demodulation is required. These devices integrate multiple optical elements, making it difficult to evaluate the characteristics of each part. The signal is actually passed between the transmitter and receiver, and the transmitter / receiver is evaluated comprehensively based on the bit error rate. ing.

JP 2008-153863 A

  If there is a problem in the overall evaluation between the transmitter and the receiver, it is necessary to identify the cause because of the need to find the cause, but at the present time it cannot be done easily. .

  Therefore, an object of the present invention is to provide an optical coherent detector evaluation apparatus and an optical coherent detector evaluation method that can easily evaluate an optical coherent detector.

In order to achieve the above object, the optical coherent detector evaluation apparatus according to the present invention generates a pair of combined light in which two input lights are combined to invert the phase, receives the balanced light, and performs gain adjustment. An optical coherent detector evaluation apparatus (101) for testing an optical coherent detector (41) that outputs a balanced electrical signal of the combined light and outputs an electrical signal before gain adjustment. A light source (11) for outputting light, a light branching part (15) for branching the light from the light source into two branched lights, and a first light that transmits or blocks one branched light from the light branching part An optical shutter (16), an optical delay (20) that delays one of the branched lights from the optical branching unit by an arbitrary delay amount, and light from the optical delay is input to the optical coherent detector. With one side of the light A first optical output unit (17) that outputs the light, a second optical shutter (18) that transmits or blocks the other branched light from the optical branching unit, and output light of the second optical shutter, The second optical output unit (19) that outputs the other input light of the optical coherent detector, and an optical path between the light source and the first optical output unit, and at least one of the branched lights A polarization controller (21) for changing the polarization state and a plurality of input terminals, and the gain-adjusted electrical signal and the gain-adjusted electrical signal from the optical coherent detector are a pair of the combined light. A digital signal obtained by detecting, for each input terminal, the signal power of the two-signal input section (22) input to the different input terminal for each input and the signal power of the electric signal before gain adjustment input to the two-signal input section. Output power A detection unit (23), the optical bias voltage setting unit that sets a bias voltage to be balanced received by a coherent detector (25), second signal for performing signal processing using the signal power over detected by the power detection unit A processing unit (26), a two-signal display unit (27) for displaying a signal processing result of the two-signal processing unit, the first optical shutter, the second optical shutter, the optical delay device, and the polarization A controller, a bias voltage setting section, a two-signal control section (28) for controlling operations of the two-signal processing section and the two-signal display section.

  Light source (11), optical branching unit (15), first optical output unit (17), second optical output unit (19), two-signal input unit (22), and power detection unit (23 ) And the two-signal processing unit (26), it is possible to input light to the optical coherent detector (41) and analyze the output signal from the optical coherent detector (41). In order to include the first optical shutter (16), the second optical shutter (18), the polarization controller (21), the bias voltage setting unit (25), and the two-signal control unit (28), Various evaluations can be performed on the optical coherent detector (41). Therefore, the optical coherent detector evaluation apparatus of the present invention can easily evaluate the optical coherent detector.

In the optical coherent detector evaluation apparatus according to the present invention, the two-signal control unit keeps the polarization state changed by the polarization controller constant, and supplies the branched light to the first optical shutter and the second optical shutter. In the state where the bias voltage setting unit is controlled to a bias voltage for receiving one of the pair of combined lights by the optical coherent detector, the delay amount of the optical delay device is changed, and the first delay is changed. A two-signal non-differential delay control section (28-11) for outputting one of the branched lights from an optical output section and outputting the other of the branched lights from the second optical output section; The unit includes a two-signal non-differential phase processing unit (26-11) for storing the output value of the digital signal from the power detection unit in association with the delay amount of the optical delay unit and the input terminal, signal The display unit includes a two-signal non-differential phase display unit (27-11) that displays an output value of the digital signal stored in the two-signal processing unit in a graph with respect to a delay amount of the optical delay device. Also good.
Since the two-signal non-differential delay control unit (28-11) is provided, two input lights can be input to the optical coherent detector (41) while changing the phase difference between the two input lights. Thereby, the phase difference of each output signal of an optical coherent detector (41) can be measured. Since the two-signal non-differential phase processing unit (26-11) and the two-signal non-differential phase display unit (27-11) are provided, the phase orthogonality is evaluated by comparing the phases of the output signals of the coherent detectors. can do. Therefore, the optical coherent detector evaluation apparatus of the present invention can easily evaluate the phase orthogonality of the optical coherent detector.

In the optical coherent detector evaluation apparatus according to the present invention, the two-signal control unit keeps the polarization state changed by the polarization controller constant, and supplies the branched light to the first optical shutter and the second optical shutter. In the state where the bias voltage setting unit is controlled to a bias voltage for receiving the balanced pair of combined light with the optical coherent detector, the delay amount of the optical delay device is changed. A two-signal differential delay control unit (28-12) for outputting one of the branched lights from an optical output unit and outputting the other of the branched lights from the second optical output unit; Comprises a two-signal differential phase processing unit (26-12) for storing an output value of a digital signal from the power detection unit in association with a delay amount of the optical delay unit and the input terminal, Radical 113 is the output value of the digital signal stored in said second signal processing unit may comprise a second signal differential phase display unit for displaying a graph (27-12) with respect to the delay amount of the optical delay device.
Since the two-signal differential delay control unit (28-12) is provided, the two input lights can be input to the optical coherent detector (41) while changing the phase difference between the two input lights. As a result, the optical coherent detector (41) receives balanced light by combining two input lights having an arbitrary phase difference. Since the two-signal differential phase processing unit (26-12) and the two-signal differential phase display unit (27-12) are provided, the phase orthogonality can be evaluated by comparing the phases of the balanced received signals. Therefore, the optical coherent detector evaluation apparatus of the present invention can easily evaluate the phase orthogonality of the optical coherent detector.

In the optical coherent detector evaluation apparatus according to the present invention, the optical coherent detector separates one of the two input lights in a predetermined polarization state, and combines the two input lights to invert the phase. Generates a pair of light, receives balanced light and outputs a gain-adjusted electrical signal, and also receives the combined light pair in balanced light and outputs an electrical signal before gain adjustment, the two-signal control The first optical shutter blocks one of the branched lights, the second optical shutter transmits the other branched light, and the optical coherent detector receives one of the combined light pairs. Two signals for outputting the other of the branched light from the second optical output unit while changing the polarization state of the polarization controller while the bias voltage setting unit is controlled to the bias voltage to be A wave state control unit (28-14), and the two-signal processing unit calculates a branching ratio of local light in the arbitrary polarization state using an output value of the digital signal from the power detection unit. A signal local optical branching ratio processing unit (26-14), wherein the two signal display unit displays a branching ratio of the local light in the arbitrary polarization state calculated by the two signal processing unit; A ratio display section (27-14) may be provided.
As a result, the optical coherent detector (41) receives light obtained by branching the other input light into the P-polarized component side and the S-polarized component side. Since the two-signal local optical branching ratio processing unit (26-14) and the two-signal local optical branching ratio display unit (27-14) are provided, the light on the P-polarized component side and the S-polarized light branched by the optical coherent detector (41) The intensity ratio of the component-side light can be measured to evaluate the local light branching ratio of the optical coherent detector (41). Therefore, the optical coherent detector evaluation apparatus of the present invention can easily evaluate the branching ratio of the optical coherent detector.

In the optical coherent detector evaluation apparatus of the present invention, an optical phase modulator (12) that phase-modulates light from the light source with an input phase modulation signal, and a phase modulation signal generator (13) that generates the phase modulation signal. ), A driver (14) for driving the optical phase modulator in accordance with a signal from the phase modulation signal generator, and outputting phase modulated light from the optical phase modulator, and the input to the two-signal input unit A waveform measurement unit (24) that measures the signal waveform of the electric signal after gain adjustment for each of the input terminals, and the two-signal control unit causes the optical phase modulator to output phase-modulated light, and The polarization state changed by the polarization controller is kept constant, one of the branched lights is transmitted through the first optical shutter, the other of the branched lights is transmitted through the second optical shutter, and the optical coherent In the state where the bias voltage setting unit is controlled to a bias voltage for receiving the balanced pair of the combined light with a waver, one of the branched lights is output from the first light output unit, and the second light is output. A two-signal phase modulation light control unit (28-15) for outputting the other of the branched lights from the output unit , wherein the two-signal processing unit replaces the signal power with the signal waveform measured by the waveform measurement unit. It may be used .
Since the optical phase modulator (12), the phase modulation signal generation unit (13), the driver (14), the waveform measurement unit (24), and the two-signal phase modulation light control unit (28-15) are provided, two input lights are received. Phase-modulated light can be input to the optical coherent detector (41). Thereby, the skew can be measured using the waveform of the output signal from the optical coherent detector (41). Therefore, the optical coherent detector evaluation apparatus of the present invention can easily evaluate the skew of the optical coherent detector.

In the optical coherent detector evaluation device according to the present invention, the light source has a variable output wavelength of light, and the two-signal control unit transmits the one of the branched lights to the first optical shutter, and The output wavelength of the light source is changed in a state in which the other of the branched light is transmitted through the optical shutter and the bias voltage setting unit is controlled to a bias voltage for receiving one of the combined light pairs by the optical coherent detector. A two-signal interference light wavelength control unit (28-16) that outputs one of the branched light and the other of the branched light, and the two-signal processing unit outputs an output value of the digital signal from the power detection unit. A two-signal interference light processing unit (26-16) that stores the light source in association with the output wavelength of the light source, and the two-signal display unit stores each output wavelength of the light source stored in the two-signal processing unit. Of the output value of the digital signal may comprise a second signal interference light display unit (27-16) to be displayed on each of the input terminals.
Since the two-signal interference light wavelength control unit (28-16) is provided, two input lights can be input to the optical coherent detector (41) while changing the wavelength. Thus, the optical coherent detector (41) receives the combined light obtained by combining the two input lights at an arbitrary wavelength. Since the two-signal interference light processing unit (26-16) and the two-signal interference light display unit (27-16) are provided, the light intensity of each combined light is measured for each wavelength, and the wavelength characteristic of the interference intensity is evaluated. Can do. Therefore, the optical coherent detector evaluation apparatus of the present invention can easily evaluate the wavelength characteristic of the interference intensity of the optical coherent detector.

In the optical coherent detector evaluation apparatus according to the present invention, the light source has a variable output wavelength of light, and the two-signal control unit uses a bias voltage for receiving one of the pair of combined lights by the optical coherent detector. In a state where the bias voltage setting unit is controlled, the output wavelength of the light source is changed by transmitting one of the branched lights to the first optical shutter and blocking the other of the branched lights to the second optical shutter. Output one of the branched lights, or cause the first optical shutter to block one of the branched lights and allow the second optical shutter to transmit the other of the branched lights, thereby outputting an output wavelength of the light source. A two-signal branching optical wavelength controller (28-17) that outputs the other of the branched lights while changing the wavelength, and the two-signal processing unit is maximum when the polarization state is changed by the polarization controller. The output value of each digital signal is stored in association with the output wavelength of the light source and the input terminal, and the light at each output wavelength of the light source using the output power of the light source and the output value of the digital signal. A two-signal light loss processing unit (26-17) for calculating a loss between each input / output port of the coherent detector for each input terminal, wherein the two-signal display unit calculates the light source calculated by the two-signal processing unit; A two-signal light loss display unit (27-17) for displaying the loss of the optical coherent detector at each output wavelength for each of the input terminals.
Since the two-signal branching light wavelength controller (28-17) is provided, the input light can be input to the optical coherent detector (41) while changing the wavelength. Since the two-signal light loss processing unit (26-17) and the two-signal light loss display unit (27-17) are provided, the optical coherent detector (41) is used by using the optical power of the output light from the optical coherent detector (41). ) Loss between each input / output port can be measured. Therefore, the optical coherent detector evaluation apparatus of the present invention can easily evaluate the wavelength characteristic of the loss of the optical coherent detector.

In order to achieve the above object, the optical coherent detector evaluation apparatus according to the present invention generates a pair of combined light in which two input lights are combined to invert the phase, receives the balanced light, and performs gain adjustment. Or an optical coherent detector evaluation device (102) for testing the optical coherent detector (42) that outputs the electrical signal before the gain adjustment and outputs the electrical signal before gain adjustment. An intensity-modulated light source (31) for outputting intensity-modulated light, an optical branching part (15) for branching the intensity-modulated light from the intensity-modulated light source into two branched lights, and one branch from the optical branching part A first optical shutter (16) that transmits or blocks light, an optical delay (20) that delays one of the branched lights from the optical branching unit by an arbitrary delay amount, and light from the optical delay The optical co A first optical output section (17) that outputs as one of the input lights of the -lent detector, a second optical shutter (18) that transmits or blocks the other branched light from the optical branch section, and the second The output light from the optical shutter is inserted into the optical path between the second optical output unit (19) that outputs the other light as the input light of the optical coherent detector, and the intensity-modulated light source and the first optical shutter. A polarization controller (21) that changes at least one polarization state of the branched light, and a plurality of input terminals, and the electric signal after the gain adjustment from the optical coherent detector or before the gain adjustment. One signal input section (34) in which any one of the electrical signals is input to the different input terminals for each pair of the combined light, and the intensity before gain adjustment input to the one signal input section Modulated A rectifier circuit (35) that converts an electrical signal from alternating current to direct current for each input terminal, and a power detection unit that detects the signal power of the electrical signal from the rectifier circuit for each input terminal and outputs a digital signal ( 23), a bias voltage setting unit (25) for setting a bias voltage for receiving balanced light by the optical coherent detector, and a gain adjusting circuit setting unit (39 for setting an operation of gain adjustment by the optical coherent detector) a) first signal processing unit for performing signal processing using the signal power over detected by the power detection unit (36), one signal display unit for displaying the signal processing result of the first signal processing section (37), The polarization controller, the first optical shutter, the second optical shutter, the optical delay device, the bias voltage setting unit, the gain adjustment circuit setting unit, the one signal processing unit, and the like. And a one-signal control section (38) for controlling the operation of the one-signal display section.

  Intensity modulated light source (31), optical branching unit (15), first optical output unit (17), second optical output unit (19), one signal input unit (34), and power detection unit (23) and the one signal processing unit (36), it is possible to input light to the optical coherent detector (42) and analyze the output signal from the optical coherent detector (42). Since the gain adjustment circuit setting unit (39) and the rectifier circuit (35) are provided, the electrical signal before gain adjustment can be output from the optical coherent detector (42). Since the first optical shutter (16), the second optical shutter (18), the polarization controller (21), and the bias voltage setting unit (25) are provided, the optical coherent detector (42) is provided. Various evaluations can be made. Therefore, the optical coherent detector evaluation apparatus of the present invention can easily evaluate the optical coherent detector.

In the optical coherent detector evaluation apparatus of the present invention, the one signal control unit keeps the polarization state changed by the polarization controller constant, transmits one of the branched lights to the first optical shutter, and The other of the branched lights is transmitted through a second optical shutter, the bias voltage setting unit is controlled to a bias voltage that receives the combined light pair in a balanced manner by the optical coherent detector, and gain is obtained by the optical coherent detector. While the gain adjustment circuit setting unit is controlled so that the operation of the circuit to be adjusted is stopped, one of the branched lights is output from the first optical output unit while changing the delay amount of the optical delay device. And a one-signal non-differential delay control unit (38-21) for outputting the other of the branched lights from the second optical output unit, wherein the one-signal processing unit A one-signal non-differential phase processing unit (36-21) for storing an output value of a digital signal in association with a delay amount of the optical delay device and the input terminal; and the one-signal display unit includes the one-signal processing unit A one-signal non-differential phase display unit (37-21) that displays the output value of the digital signal stored in the unit in a graph with respect to the delay amount of the optical delay unit may be provided.
Since the one-signal non-differential delay control unit (38-21) is provided, two input lights can be input to the optical coherent detector (42) while changing the phase difference between the two input lights. Thereby, the phase difference of each output signal of an optical coherent detector (42) can be measured. Since the single-signal non-differential phase processing unit (36-21) and the single-signal non-differential phase display unit (37-21) are provided, the phase orthogonality is evaluated by comparing the phases of the output signals of the coherent detectors. can do. Therefore, the optical coherent detector evaluation apparatus of the present invention can easily evaluate the phase orthogonality of the optical coherent detector.

In the optical coherent detector evaluation apparatus of the present invention, the one signal control unit keeps the polarization state changed by the polarization controller constant, transmits one of the branched lights to the first optical shutter, and A second optical shutter that transmits the other of the branched lights, and the optical coherent detector controls the bias voltage setting unit to a bias voltage that receives one of the combined light pairs; and the optical coherent detector uses the gain In the state where the gain adjustment circuit setting unit is controlled so that the operation of the circuit to be adjusted is stopped, and the bias voltage setting unit is controlled to a bias voltage for receiving one of the pair of the combined light by the optical coherent detector, While changing the delay amount of the optical delay device, one of the branched lights is output from the first optical output unit and the other of the branched light is output from the second optical output unit. A one-signal differential delay control unit (38-22) that outputs a digital signal output value from the power detection unit to a delay amount of the optical delay unit and the input terminal. And a one-signal differential phase processing unit (36-22) for storing in association with each other, wherein the one-signal display unit outputs an output value of the digital signal stored in the one-signal processing unit to a delay amount of the optical delay You may provide the 1 signal differential phase display part (37-22) displayed on a graph.
Since the one-signal differential delay control unit (38-22) is provided, the two input lights can be input to the optical coherent detector (42) while changing the phase difference between the two input lights. As a result, the optical coherent detector (42) receives balanced light by combining two input lights having an arbitrary phase difference. Since the one-signal differential phase processing unit (36-22) and the one-signal differential phase display unit (37-22) are provided, the phase orthogonality can be evaluated by comparing the signals received with balanced light reception. Therefore, the optical coherent detector evaluation apparatus of the present invention can easily evaluate the phase orthogonality of the optical coherent detector.

In the optical coherent detector evaluation device according to the present invention, the optical coherent detector separates one of the two input lights in a predetermined polarization state, and combines the two input lights to invert the phase. A pair of light is generated to receive a balanced light and the gain is adjusted, or a gain-adjusted electric signal or the combined light is balanced to receive and an electric signal before gain adjustment is output, One signal control unit causes the first optical shutter to block one of the branched lights, allows the second optical shutter to transmit the other of the branched lights, and the optical coherent detector detects the pair of the combined lights. In a state where the bias voltage setting unit is controlled to a bias voltage for receiving one side, and the gain adjustment circuit setting unit is controlled so that the operation of the circuit for gain adjustment by the optical coherent detector is stopped. A one-signal polarization state control unit (38-24) for outputting the other of the branched light from the second optical output unit while changing a polarization state of the polarization controller; A one-signal local optical branching ratio processing unit (36-24) for calculating a branching ratio of local light in the arbitrary polarization state using an output value of a digital signal from the power detection unit, The display unit may include a one-signal local light branching ratio display unit (37-24) that displays a branching ratio of local light in the arbitrary polarization state calculated by the one-signal processing unit.
Since the one-signal polarization state controller (38-24) is provided, the other input light can be input to the optical coherent detector (42). As a result, the optical coherent detector (42) branches and receives the other input light into the P-polarized component side and the S-polarized component side. Since the one-signal local optical branching ratio processing unit (36-24) and the one-signal local optical branching ratio display unit (37-24) are provided, the P-polarized component side light and the S-polarized light branched by the optical coherent detector (42) The intensity ratio of the component-side light can be measured, and the local light branching ratio of the optical coherent detector (42) can be evaluated. Therefore, the optical coherent detector evaluation apparatus of the present invention can easily evaluate the branching ratio of the optical coherent detector.

In the optical coherent detector evaluation device of the present invention, a continuous light source (30) that outputs continuous light, and an optical phase modulator (12) that phase-modulates the continuous light from the continuous light source with an input phase modulation signal; A phase modulation signal generation unit (13) for generating the phase modulation signal, and a driver for driving the optical phase modulator in accordance with a signal from the phase modulation signal generation unit and outputting phase modulation light from the optical phase modulator (14) and a waveform measurement unit (24) that measures the signal waveform of the electric signal after gain adjustment input to the one signal input unit for each input terminal, and the one signal control unit includes: The phase modulated light is output to the optical phase modulator, the polarization state changed by the polarization controller is kept constant, one of the branched lights is transmitted through the first optical shutter, and the second light is transmitted. To shutter A circuit that controls the bias voltage setting unit to a bias voltage that transmits the other of the branched light beams and that receives the balanced pair of light beams by the optical coherent detector and adjusts the gain by the optical coherent detector operates. One signal for outputting one of the branched lights from the first light output section and outputting the other of the branched lights from the second light output section in a state where the gain adjustment circuit setting section is controlled as described above A phase modulation light control unit (38-25) may be provided , and the one signal processing unit may use the signal waveform measured by the waveform measurement unit instead of the signal power .
To include a continuous light source (30), an optical phase modulator (12), a phase modulation signal generation unit (13), a driver (14), a waveform measurement unit (24), and a one-signal phase modulation light control unit (38-25) The phase-modulated light can be input to the optical coherent detector (42) from the two input lights. Since the optical coherent detector (42) receives balanced light by combining two input lights, the skew can be measured using the waveform of the output signal from the optical coherent detector (42). Therefore, the optical coherent detector evaluation apparatus of the present invention can easily evaluate the skew of the optical coherent detector.

In the optical coherent detector evaluation apparatus of the present invention, the intensity-modulated light source has a variable light output wavelength, and the one-signal control unit transmits one of the branched lights to the first optical shutter, The other of the branched lights is transmitted through a second optical shutter, the bias voltage setting unit is controlled to a bias voltage that receives the combined light pair in a balanced manner by the optical coherent detector, and gain is obtained by the optical coherent detector. While the gain adjustment circuit setting unit is controlled to stop the operation of the circuit to be adjusted, one of the branched lights is output from the first light output unit while changing the output wavelength of the intensity-modulated light source. And a one-signal interference light wavelength control unit (38-26) for outputting the other of the branched lights from the second optical output unit, wherein the one-signal processing unit is supplied from the power detection unit. A one-signal interference light processing unit (36-26) that stores an output value of a digital signal in association with an output wavelength of the intensity-modulated light source and the input terminal, and the one-signal display unit includes: You may provide the one signal interference light display part (37-26) which displays the output value of the said digital signal in each output wavelength of the said intensity | strength modulation light source to memorize | store for every said input terminal.
Since the one-signal interference light wavelength control unit (38-26) is provided, two input lights can be input to the optical coherent detector (42) while changing the wavelength. As a result, the optical coherent detector (42) receives the combined light obtained by combining the two input lights at an arbitrary wavelength. Since the single signal interference light processing unit (36-26) and the single signal interference light display unit (37-26) are provided, the light intensity of each combined light is measured for each wavelength, and the wavelength characteristics of the interference intensity are evaluated. Can do. Therefore, the optical coherent detector evaluation apparatus of the present invention can easily evaluate the wavelength characteristic of the interference intensity of the optical coherent detector.

In the optical coherent detector evaluation apparatus of the present invention, the intensity-modulated light source has a variable output wavelength of light, and the one-signal control unit receives a bias of one of the pair of combined lights by the optical coherent detector. The branch light is applied to the first optical shutter in a state where the bias voltage setting unit is controlled to a voltage and the gain adjustment circuit setting unit is controlled so that the operation of the circuit for adjusting the gain by the optical coherent detector is stopped. One of the branched light is transmitted to the second optical shutter and the other of the branched light is blocked to output one of the branched light while changing the output wavelength of the intensity-modulated light source, or the first optical shutter. One of the branched lights is shielded, the other of the branched lights is transmitted to the second optical shutter, and the other of the branched lights is output while changing the output wavelength of the intensity-modulated light source. One signal branching optical wavelength control unit (38-27), and the one signal processing unit outputs an output value of each digital signal that is maximized when a polarization state is changed by the polarization controller. Each of the optical coherent detectors at each output wavelength of the intensity-modulated light source is stored in association with the output wavelength of the intensity-modulated light source and the input terminal, and using the output power of the intensity-modulated light source and the output value of the digital signal. A one-signal light loss processing unit (36-27) for calculating a loss between the input and output ports for each input terminal, wherein the one-signal display unit is the optical coherent detector at each output wavelength of the intensity-modulated light source; One signal light loss display section (37-27) for displaying the loss of each of the input terminals may be provided.
Since the one-signal branching light wavelength control unit (38-27) is provided, the input light can be input to the optical coherent detector (42) while changing the wavelength. Since the single-signal optical loss processing unit (36-27) and the single-signal optical loss display unit (37-27) are provided, the optical coherent detector (41) is used by using the optical power of the output light from the optical coherent detector (42). ) Loss between each input / output port can be measured. Therefore, the optical coherent detector evaluation apparatus of the present invention can easily evaluate the wavelength characteristic of the loss of the optical coherent detector.

In order to achieve the above object, the optical coherent detector evaluation method of the present invention generates a pair of combined light in which two input lights are combined to invert the phase, receives balanced light, and performs gain adjustment. An optical coherent detector evaluation method for testing an optical coherent detector (41) that outputs a balanced electrical signal and outputs an electrical signal before gain adjustment, and outputs from the light source The two-signal non-differential outputs the two branched lights as the two input lights of the optical coherent detector while changing the delay amount of one branched light. Delayed light output procedure (S111), and the electric signal before gain adjustment from the optical coherent detector, which is received by the optical coherent detector and output from the two branched lights Input to the different input terminals for each pair of the combined light, detect the signal power of the electrical signal before gain adjustment for each input terminal, output a digital signal, and output the digital signal for the delay amount A two-signal non-differential phase processing procedure (S112) for displaying values in a graph.
Since the two-signal non-differential delayed optical output procedure (S111) is provided, two input lights can be input to the optical coherent detector (41) while changing the phase difference between the two input lights. Thus, the optical coherent detector (41) receives the combined light obtained by combining the two input lights having an arbitrary phase difference. Since the two-signal non-differential phase processing procedure (S112) is provided, the phase orthogonality can be evaluated by comparing the phases of the combined lights. Therefore, the optical coherent detector evaluation method of the present invention can easily evaluate the phase orthogonality of the optical coherent detector.

In order to achieve the above object, the optical coherent detector evaluation method of the present invention generates a pair of combined light in which two input lights are combined to invert the phase, receives balanced light, and performs gain adjustment. An optical coherent detector evaluation method for testing an optical coherent detector (41) that outputs a balanced electrical signal and outputs an electrical signal before gain adjustment, and outputs from the light source The two-signal differential delayed light that branches the light into two branched lights and outputs the two branched lights as the two input lights of the optical coherent detector while changing the delay amount of one of the branched lights An output procedure (S121), and the electric power before the gain adjustment from the optical coherent detector in which the two branched lights are received by the optical coherent detector in a balanced manner and output. Signal is input to each of the input terminals different for each pair of the combined light, the signal power of the electric signal before gain adjustment is detected for each input terminal, and a digital signal is output, and the digital signal corresponding to the delay amount And a two-signal differential phase processing procedure (S122) for displaying the output values in a graph.
Since the two-signal differential delay light output procedure (S121) is provided, two input lights can be input to the optical coherent detector (41) while changing the phase difference between the two input lights. As a result, the optical coherent detector (41) receives balanced light by combining two input lights having an arbitrary phase difference. Since the two-signal differential phase processing procedure (S122) is included, the phase orthogonality can be evaluated by comparing the phases of the balanced received signals. Therefore, the optical coherent detector evaluation method of the present invention can easily evaluate the phase orthogonality of the optical coherent detector.

In order to achieve the above object, the optical coherent detector evaluation method of the present invention separates one of two input lights in a predetermined polarization state, and combines the two input lights to invert the phase. An optical coherent detector that generates a combined light pair, receives a balanced light and outputs a gain-adjusted electric signal, and receives a balanced light of the combined light pair and outputs a pre-gain electric signal An optical coherent detector evaluation method for performing the test of (41), wherein the light from the light source is split into two branched lights, and the polarization state of the light from the light source is changed, and the optical coherent detector A two-signal polarization output procedure (141) for outputting the branched light as the other of the input light, and the electric power before gain adjustment in which the other of the branched light is received by the optical coherent detector and output. Is input to the input terminal that is different for each pair of the combined light, the signal power of the electric signal before gain adjustment input to the input terminal is converted into a digital signal, and the output value of the digital signal is A two-signal local optical branching ratio measurement procedure (S142) for storing in association with the input terminal and the predetermined polarization state, and calculating and displaying the other branching ratio of the input light in an arbitrary polarization state, in order Have.
Since the two-signal polarization output procedure (141) is included, the other input light can be input to the optical coherent detector (41). As a result, the optical coherent detector (41) receives light obtained by branching the other input light into the P-polarized component side and the S-polarized component side. Since it has the two-signal local optical branching ratio measurement procedure (S142), the optical coherent detector (41) measures the intensity ratio of the light on the P-polarized component side and the light on the S-polarized component side, and the optical coherent detector (41) 41) The branching ratio of local light can be evaluated. Therefore, the optical coherent detector evaluation method of the present invention can easily evaluate the branching ratio of the optical coherent detector.

In order to achieve the above object, the optical coherent detector evaluation method of the present invention generates a pair of combined light in which two input lights are combined to invert the phase, receives balanced light, and performs gain adjustment. An optical coherent detector evaluation method for testing an optical coherent detector (41) that outputs a balanced electrical signal and outputs an electrical signal before gain adjustment, and outputs from the light source A two-signal phase-modulated light output procedure (S151) for phase-modulating the light into two branched lights and outputting the branched lights as one of the input light and the other of the input lights of the optical coherent detector; The gain-adjusted electrical signal from the optical coherent detector, which is output after the two branched lights are balanced and received by the optical coherent detector, is used as the combined light. Each input to different ones of the input terminals for each pair, a second signal skew processing procedure of measuring the signal waveform of the electrical signal after the gain adjustment for each of the input terminals and (S152), in sequence.
Since the two-signal phase-modulated light output procedure (S151) is provided, the intensity-modulated light can be input to the optical coherent detector (41) from the two input lights. As a result, the optical coherent detector (41) balances the combined light obtained by combining the two input lights and adjusts the gain. Since the two-signal skew processing procedure (S152) is included, the skew can be measured using the waveform of the output signal from the optical coherent detector (41). Therefore, the optical coherent detector evaluation method of the present invention can easily evaluate the skew of the optical coherent detector.

In order to achieve the above object, the optical coherent detector evaluation method of the present invention generates a pair of combined light in which two input lights are combined to invert the phase, receives balanced light, and performs gain adjustment. An optical coherent detector evaluation method for testing an optical coherent detector (41) that outputs a balanced electrical signal and outputs an electrical signal before gain adjustment, and outputs from the light source Two-signal interference wavelength-tunable light that branches the light from the light source into two branched lights while changing the output wavelength of the light, and outputs the two branched lights as the two input lights of the optical coherent detector Output procedure (S161) and the electric signal before the gain adjustment from the optical coherent detector which is received by the optical coherent detector and output from the two branched lights Input to the input terminals that are different for each pair of the combined light, convert the signal power of the electric signal before gain adjustment input to the input terminal into a digital signal, and output the value of the digital signal to the light source Two-signal interference intensity measurement procedure (S162) for storing in association with the output wavelength and the input terminal and displaying the light intensity of the combined light at the optical coherent detector at each output wavelength of the light source for each input terminal And in order.
Since the two-signal interference wavelength variable optical output procedure (S161) is included, two input lights can be input to the optical coherent detector (41) while changing the wavelength. As a result, the optical coherent detector (41) receives the combined light obtained by combining the two input lights having arbitrary wavelengths. Since the two-signal interference intensity measurement procedure (S162) is included, the received signal can be measured for each wavelength, and the wavelength characteristic of the interference intensity can be evaluated. Therefore, the optical coherent detector evaluation method of the present invention can easily evaluate the wavelength characteristic of the interference intensity of the optical coherent detector.

In order to achieve the above object, an optical coherent detector evaluation method according to the present invention generates a pair of combined lights whose phases are inverted by combining two input lights to generate one of the combined lights constituting the pair. An optical coherent detector (41) that receives one of them and outputs a gain-adjusted electric signal, and receives either one of the combined lights constituting the pair and outputs an electric signal before gain adjustment. An optical coherent detector evaluation method for performing the above test, wherein the light from the light source is split into two branched lights while changing the output wavelength of the light from the light source, and any of the input lights of the optical coherent detector is selected. Either one of the two branched lights is output as a two-signal wavelength variable branch light output procedure (S171), and one of the branched branched lights is converted into one of the two branched lights. One of the deviations is received by the optical coherent detector and output, and the electric signal before gain adjustment is input to the different input terminal for each pair of the combined light, and the signal power of the electric signal before gain adjustment Is detected for each input terminal and converted into a digital signal, and the output value of each digital signal that becomes maximum when the polarization state is changed by the polarization controller is output to the output wavelength of the light source and the input terminal. Associating and storing, calculating the loss between each input / output port of the optical coherent detector at each output wavelength of the light source using the output power of the light source and the output value of the digital signal for each input terminal, A two-signal loss measurement procedure (S172) for displaying the loss of the optical coherent detector at each output wavelength of the light source for each of the input terminals.
Since the two-signal wavelength variable branch light output procedure (S171) is provided, the input light can be input to the optical coherent detector (41) while changing the wavelength. Thus, the optical coherent detector (41) separates and receives input light having an arbitrary wavelength. Since the two-signal loss measurement procedure (S172) is included, the loss of the optical coherent detector (41) can be measured using the optical power of the output light from the optical coherent detector (41). Therefore, the optical coherent detector evaluation method of the present invention can easily evaluate the wavelength characteristic of the loss of the optical coherent detector.

In order to achieve the above object, an optical coherent detector evaluation method according to the present invention generates a pair of combined lights whose phases are inverted by combining two input lights to generate one of the combined lights constituting the pair. An optical coherent detector (42) that receives one of them and outputs a gain-adjusted electrical signal that is gain-adjusted, and receives either one of the combined lights constituting the pair and outputs an electrical signal before gain adjustment. An optical coherent detector evaluation method for performing the test in which the two input lights of the optical coherent detector are split while splitting the intensity-modulated light into two branched lights and changing the delay amount of one of the branched lights. A one-signal non-differential delayed light output procedure (S211) for outputting the two branched lights, and the optical coherent light received and outputted by the optical coherent detector. The electrical signal before gain adjustment from the gain detector is input to the different input terminals for each pair of the combined light, and the signal power of the electrical signal before gain adjustment is detected for each input terminal to obtain a digital signal. And a one-signal non-differential phase processing procedure (S212) for displaying the output value of the digital signal with respect to the delay amount in a graph.
Since it has the one-signal non-differential delayed light output procedure (S211), it is possible to input the two input lights to the optical coherent detector (42) while changing the phase difference between the two input lights. Thus, the optical coherent detector (42) receives the combined light obtained by combining the two input lights having an arbitrary phase difference. Since the single-signal non-differential phase processing procedure (S212) is included, the phase orthogonality can be evaluated by comparing the phases of the combined lights. Therefore, the optical coherent detector evaluation method of the present invention can easily evaluate the phase orthogonality of the optical coherent detector.

In order to achieve the above object, the optical coherent detector evaluation method of the present invention generates a pair of combined light in which two input lights are combined to invert the phase, receives balanced light, and performs gain adjustment. An optical coherent detector evaluation method for testing an optical coherent detector (42) that outputs a balanced electrical signal and outputs the electrical signal before gain adjustment or outputs an electrical signal of One-signal differential delayed light that branches the modulated light into two branched lights and outputs the two branched lights as the two input lights of the optical coherent detector while changing one delay amount of the branched lights. An output procedure (S221), and the two branched lights before being gain-adjusted from the optical coherent detector output by receiving the balanced light at the optical coherent detector. A power signal is input to each of the input terminals different for each pair of the combined light, the signal power of the electrical signal before gain adjustment is detected for each input terminal, a digital signal is output, and the digital signal corresponding to the delay amount is output. A one-signal differential phase processing procedure (S222) for displaying the output value of the signal in a graph.
Since it has the one-signal differential delay light output procedure (S221), it is possible to input the two input lights to the optical coherent detector (42) while changing the phase difference between the two input lights. Thus, the optical coherent detector (42) receives the combined light obtained by combining the two input lights having an arbitrary phase difference. Since it has the one-signal differential phase processing procedure (S222), the phase orthogonality can be evaluated by comparing the phases of the combined lights. Therefore, the optical coherent detector evaluation method of the present invention can easily evaluate the phase orthogonality of the optical coherent detector.

In order to achieve the above object, the optical coherent detector evaluation method of the present invention separates one of two input lights in a predetermined polarization state, and combines the two input lights to invert the phase. Optical coherent detection that generates a pair of combined light to receive balanced light and outputs a gain-adjusted electric signal, or receives the combined light pair in balanced light and outputs an electric signal before gain adjustment An optical coherent detector evaluation method for testing the detector (42), wherein the intensity-modulated light is split into two branched lights, and the polarization state of the intensity-modulated light is changed, and the optical coherent detector A one-signal polarized light output procedure (S241) for outputting the branched light as the other of the input light, and the electric power before the gain adjustment, which is received and output by the optical coherent detector. A signal is input to each input terminal that is different for each pair of the combined light, the signal power of the electrical signal before gain adjustment input to the input terminal is converted into a digital signal, and the output value of the digital signal is converted to the digital signal. A one-signal local optical branching ratio measurement procedure (S242) for storing in association with the input terminal and the predetermined polarization state, and calculating and displaying the other branching ratio of the input light in an arbitrary polarization state, in order Have.
Since the one-signal polarization output procedure (S241) is included, the other input light can be input to the optical coherent detector (42). As a result, the optical coherent detector (41) receives light obtained by branching the other input light into the P-polarized component side and the S-polarized component side. Since it has a one-signal local optical branching ratio measurement procedure (S242), the intensity ratio of the light on the P-polarized component side and the light on the S-polarized component side branched by the optical coherent detector (42) is measured, and the optical coherent detector ( 42) The branching ratio of local light can be evaluated. Therefore, the optical coherent detector evaluation method of the present invention can easily evaluate the branching ratio of the optical coherent detector.

In order to achieve the above object, the optical coherent detector evaluation method of the present invention generates a pair of combined light in which two input lights are combined to invert the phase, receives balanced light, and performs gain adjustment. Or an optical coherent detector for testing the optical coherent detector (42) that outputs the electrical signal before the gain adjustment and outputs the electrical signal before gain adjustment. A one-signal phase-modulated light output procedure (S251) for branching the modulated light into two branched lights and outputting the branched light as one of the input light and the other of the input light of the optical coherent detector; The gain-adjusted electrical signal from the optical coherent detector, which is output after the branched light is received by the optical coherent detector in a balanced manner, is output for each pair of the combined light. Type Re in different said input terminal respectively, having first signal skew processing procedure of measuring the signal waveform of the electrical signal after the gain adjustment for each of the input terminals and (S252), in sequence.
Since it has a one-signal phase-modulated light output procedure (S251), it is possible to input intensity-modulated light from the two input lights to the optical coherent detector (42). As a result, the optical coherent detector (42) balances the combined light obtained by combining the two input lights and adjusts the gain. Since the single signal skew processing procedure (S252) is included, the skew can be measured using the waveform of the output signal from the optical coherent detector (42). Therefore, the optical coherent detector evaluation method of the present invention can easily evaluate the skew of the optical coherent detector.

In order to achieve the above object, the optical coherent detector evaluation method of the present invention generates a pair of combined light in which two input lights are combined to invert the phase, receives balanced light, and performs gain adjustment. An optical coherent detector evaluation method for testing an optical coherent detector (42) that outputs a balanced electric signal of the combined light and outputs an electric signal before gain adjustment. One-signal interference that branches the intensity-modulated light into two branched lights while changing the output wavelength of the intensity-modulated light from the modulated light source, and outputs the two branched lights as the two input lights of the optical coherent detector Wavelength tunable optical output procedure (S261), and the gain adjustment from the optical coherent detector in which the two branched lights are received and output by the optical coherent detector. The previous electrical signal is input to the input terminal that is different for each pair of the combined light, the signal power of the electrical signal before gain adjustment input to the input terminal is converted into a digital signal, and the output of the digital signal A value is stored in association with the output wavelength of the intensity modulated light source and the input terminal, and the light intensity of the combined light at the optical coherent detector at each output wavelength of the intensity modulated light source is displayed for each input terminal. A one-signal interference intensity measurement procedure (S262).
Since the single-signal interference wavelength variable optical output procedure (S261) is provided, two input lights can be input to the optical coherent detector (42) while changing the wavelength. As a result, the optical coherent detector (42) receives balanced light by combining two input lights at an arbitrary wavelength. Since it has the one-signal interference intensity measurement procedure (S262), it is possible to measure the balanced received signal for each wavelength and evaluate the wavelength characteristic of the interference intensity. Therefore, the optical coherent detector evaluation method of the present invention can easily evaluate the wavelength characteristic of the interference intensity of the optical coherent detector.

In order to achieve the above object, an optical coherent detector evaluation method according to the present invention generates a pair of combined lights whose phases are inverted by combining two input lights to generate one of the combined lights constituting the pair. An optical coherent detector (42) that receives one of the signals and outputs a gain-adjusted electric signal, or receives one of the combined lights constituting the pair and outputs an electric signal before gain adjustment. The optical coherent detector evaluation method for performing a test on the optical coherent detector, wherein the intensity modulated light is branched into two branched lights while changing the output wavelength of the intensity modulated light from the intensity modulated light source, One signal wavelength variable branch light output procedure (S271) for outputting either one of the two branched lights as one of the input lights, and one of the branched lights is One of the two branched lights is received by the optical coherent detector, and the electric signal before gain adjustment output from the optical coherent detector is input to the different input terminal for each pair of the combined lights, and the electric signal before gain adjustment is input. The signal power of the signal is detected for each input terminal and converted into a digital signal, and the output value of each digital signal that becomes maximum when the polarization state is changed by the polarization controller is output from the intensity-modulated light source. Between the input and output ports of the optical coherent detector at each output wavelength of the intensity modulated light source using the output power of the intensity modulated light source and the output value of the digital signal. One signal for calculating the loss for each input terminal and displaying the loss of the optical coherent detector at each output wavelength of the intensity-modulated light source for each input terminal Having a loss measurement procedure (S272), in sequence.
Since the one-signal wavelength variable branch light output procedure (S271) is included, the input light can be input to the optical coherent detector (42) while changing the wavelength. Thus, the optical coherent detector (41) separates and receives input light having an arbitrary wavelength. Since one signal loss measurement procedure (S272) is included, the loss of the optical coherent detector (42) can be measured using the optical power of the output light from the optical coherent detector (42). Therefore, the optical coherent detector evaluation method of the present invention can easily evaluate the wavelength characteristic of the loss of the optical coherent detector.

  The above inventions can be combined as much as possible.

  ADVANTAGE OF THE INVENTION According to this invention, the optical coherent detector evaluation apparatus and optical coherent detector evaluation method which can evaluate an optical coherent detector simply can be provided.

An example of the optical coherent detector evaluation apparatus which concerns on Embodiment 1 is shown. An example of the optical coherent detector which concerns on Embodiment 1 is shown. 1 shows a first example of an optical coherent detector evaluation method according to a first embodiment. The example of a display of a two signal non-differential phase display part is shown. 2 shows a second example of an optical coherent detector evaluation method according to the first embodiment. The example of a display of a two signal differential phase display part is shown. 3 shows a third example of the optical coherent detector evaluation method according to the first embodiment. 4 shows a fourth example of an optical coherent detector evaluation method according to the first embodiment. The example of a display of a two signal skew display part is shown. 5 shows a fifth example of an optical coherent detector evaluation method according to the first embodiment. The example of a display of a two signal interference light display part is shown. 6 shows a sixth example of the optical coherent detector evaluation method according to the first embodiment. The example of a display of a two signal light loss display part is shown. An example of the optical coherent detector evaluation apparatus which concerns on Embodiment 2 is shown. An example of the optical coherent detector which concerns on Embodiment 2 is shown. The 1st example of the optical coherent detector evaluation method which concerns on Embodiment 2 is shown. s 6 shows a second example of an optical coherent detector evaluation method according to the second embodiment. 8 shows a third example of an optical coherent detector evaluation method according to the second embodiment. 4 shows a fourth example of an optical coherent detector evaluation method according to Embodiment 2. 5 shows a fifth example of an optical coherent detector evaluation method according to Embodiment 2. 6 shows a sixth example of an optical coherent detector evaluation method according to Embodiment 2.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
FIG. 1 shows an example of an optical coherent detector evaluation apparatus according to this embodiment. The optical coherent detector evaluation apparatus 101 according to the present embodiment tests the optical coherent detector 41. The optical coherent detector evaluation apparatus 101 includes a light source 11, an optical phase modulator 12, a phase modulation signal generation unit 13, a driver 14, an optical branching unit 15, a first optical shutter 16, and an optical delay unit 20. A first optical output unit 17, a second optical shutter 18, a second optical output unit 19, a polarization controller 21, a two-signal input unit 22, a power detection unit 23, and a waveform measurement unit. 24, a bias voltage setting unit 25, a two-signal processing unit 26, a two-signal display unit 27, and a two-signal control unit 28.

FIG. 2 shows an example of an optical coherent detector. The optical coherent detector 41 synthesizes one of the input lights S and the other of the input lights L to generate a pair of combined lights whose phases are inverted, receives balanced light, and adjusts the gain-adjusted electric signal PI _{C. , PQ} C, SI C, and balanced receiving with combined light pair outputs the SQ _C and the gain adjustment before the electrical signal _{PI U, PQ U, SI U} , and outputs the SQ _U. The optical coherent detector 41 detects the signal light S by inputting one S of the input light as the signal light and the other L of the input light as the local light.

  The optical coherent detector 41 includes an input port 51, an input port 54, a PBS (Polarization Beam Splitter) 52, a BS (Beam Splitter) 55, a 90 ° optical hybrid 53-P, and a balanced PD (Photo Diode). 57-1, 57-2, 57-3, 57-4, TIA (Trans Impedance Amplifier) 58-1, 58-2, 58-3, 58-4, AGC (Automatic Gain Control Amplifier) 59-1. , 59-2, 59-3, 59-4.

  The PBS 52 separates the input light input to the input port 51 for each polarization component. For example, the P-polarized component and the S-polarized component are separated. The BS 55 branches the input light input to the input port 54. The 90 ° optical hybrid 53-P generates a pair of combined light whose phases are inverted by combining the light of the P-polarized component from the PBS 52 and the light from the BS 55. For example, the 90 ° optical hybrid 53-P includes a pair of combined light (P + L) and combined light (P-L) and a pair of combined light (P + jL) and combined light (P-jL). Generate. The 90 ° optical hybrid 53-S generates a pair of combined light whose phases are inverted by combining the light of the S-polarized component from the PBS 52 and the light from the BS 55. For example, the 90 ° optical hybrid 53-S includes a pair of combined light (S + L) and combined light (S-L) and a pair of combined light (S + jL) and combined light (S-jL). Generate.

  The balanced PDs 57-1, 57-2, 57-3, 57-4 receive a balanced reception of the combined light pair. For example, the balanced PD 57-1 receives balanced light of the combined light (P + L) and the combined light (PL). The balanced PD 57-2 receives the combined light (P + jL) and the combined light (P-jL) in a balanced manner. The balanced PD 57-3 receives the combined light (S + L) and the combined light (S-L) in a balanced manner. The balanced PD 57-4 receives the combined light (S + jL) and the combined light (S−jL) in a balanced manner.

The TIA 58-1 converts the output current of the balanced PD 57-1 into a voltage and outputs the voltage to the AGC 59-1 and the output port. Thereby, the optical coherent detector 41 outputs the electrical signal PI _U from the TIA 58-1 to the input terminal 22-2. The AGC 59-1 adjusts the gain of the output voltage from the TIA 58-1. Thus, coherent detection unit 41 outputs to the input terminal 22-1 an electrical signal PI _C from AGC59-1.

The TIA 58-2 converts the output current of the balanced PD 57-2 into a voltage and outputs it to the AGC 59-2 and the output port. Thereby, the optical coherent detector 41 outputs the electrical signal PQ _U from the TIA 58-2 to the input terminal 22-4. The AGC 59-2 adjusts the gain of the output voltage from the TIA 58-2. Thus, coherent detection unit 41 outputs to the input terminal 22-3 an electrical signal PQ _C from AGC59-2.

The TIA 58-3 converts the output current of the balanced PD 57-3 into a voltage and outputs the voltage to the AGC 59-3 and the output port. Thus, coherent detection unit 41 outputs to the input terminal 22-6 an electrical signal SI _U from TIA58-3. The AGC 59-3 adjusts the gain of the output voltage from the TIA 58-3. Thus, the optical coherent detector 41 outputs to the input terminal 22-5 an electrical signal SI _C from AGC59-3.

The TIA 58-4 converts the output current of the balanced PD 57-4 into a voltage and outputs it to the AGC 59-4 and the output port. Thus, coherent detection unit 41 outputs to the input terminal 22-8 an electrical signal SQ _U from TIA58-4. The AGC 59-4 adjusts the gain of the output voltage from the TIA 58-4. Thus, coherent detection unit 41 outputs to the input terminal 22-7 an electrical signal SQ _C from AGC59-4.

  The light source 11 shown in FIG. 1 outputs continuous light. The optical phase modulator 12 modulates the phase of the light from the light source 11 with the input phase modulation signal. The phase modulation signal generator 13 generates a phase modulation signal. The driver 14 drives the optical phase modulator 12 in accordance with the signal from the phase modulation signal generator 13, and outputs phase modulated light or continuous light from the optical phase modulator 12. The optical branching unit 15 branches the light from the optical phase modulator 12 into two branched lights.

  The optical delay device 20 delays one of the branched lights from the optical branching unit 15 by an arbitrary delay amount. The polarization controller 21 is disposed in the optical path between the optical phase modulator 12 and the first optical output unit 17 and changes at least one polarization state of the branched light.

  The first optical shutter 16 transmits or blocks one branched light from the light branching unit 15. The first optical output unit 17 outputs the light from the optical delay device 20 to the input port 51 as one of the input lights S of the optical coherent detector 41. The second optical shutter 18 transmits or blocks the other branched light from the light branching unit 15. The second light output unit 19 outputs the output light of the second optical shutter 18 to the input port 54 as the other L of the input light of the optical coherent detector 41.

Second signal input unit 22 has a plurality of input terminals 22-1 to 22-8, an electric signal after the gain adjustment from the coherent detection unit _{41 PI C, PQ C, SI} C, SQ C and the gain adjustment before Electrical signals PI _U , PQ _U , SI _U , and SQ _U are input to different input terminals 22-1 to 22-8 for each pair of combined light. For example, the electrical signal PI _C is input to the input terminal 22-1, electric signal PI _U is input to the input terminal 22-2, electric signal PQ _C is input to the input terminal 22-3, electric signal PQ _U is input is input to the terminal 22-4, electric signal SI _C is input to the input terminal 22-5, electric signal SI _U is input to the input terminal 22-6, electric signal SQ _C is input to the input terminal 22-7, electrical signal SQ _U is input to the input terminal 22-8.

The power detection unit 23 inputs the signal power of the electric signals PI _U , PQ _U , SI _U , SQ _U before gain adjustment input to the two-signal input unit 22 to the input terminals 22-2, 22-4, 22-6. It detects every 22-8 and outputs a digital signal. Waveform measuring section 24, second signal input unit electrical signals _PI C after the gain adjustment is inputted to the _22, PQ _C, SI C, the input signal waveform of the SQ _C terminal 22-1,22-3,22-5, Measure every 22-7.

  The two-signal processing unit 26 performs signal processing using the signal power detected by the power detection unit 23 and the signal waveform measured by the waveform measurement unit 24. The two-signal processing unit 26 includes a two-signal non-differential phase processing unit 26-11, a two-signal differential phase processing unit 26-12, a two-signal local optical branching ratio processing unit 26-14, and a two-signal skew processing unit. 26-15, a two-signal interference light processing unit 26-16, and a two-signal light loss processing unit 26-17.

  The display unit 27 displays the signal processing result of the two-signal processing unit 26. The two-signal display unit 27 includes a two-signal non-differential phase display unit 27-11, a two-signal differential phase display unit 27-12, a two-signal local optical branching ratio display unit 27-14, and a two-signal skew display unit. 27-15, a two-signal interference light display unit 27-16, and a two-signal light loss display unit 27-17.

  The bias voltage setting unit 25 sets the bias voltage of the balanced PDs 57-1 to 57-4 that receive the balanced light reception by the optical coherent detector 41. A voltage to be applied to each PD of the balanced PD is set to an open state or set to a voltage at which an IV conversion current does not flow, for example, 0 V, so that a PD that receives light is selected from the two PDs. . The two-signal control unit 28 includes a phase modulation signal generation unit 13, a driver 14, a first optical shutter 16, a second optical shutter 18, an optical delay device 20, a polarization controller 21, a bias voltage setting unit 25, and two-signal processing. The operations of the unit 26 and the two-signal display unit 27 are controlled. For example, the two-signal control unit 28 controls the output wavelength of the light source 11 or switches ON / OFF of the first optical shutter 16 and the second optical shutter 18 according to the evaluation contents of the optical coherent detector 41. The delay amount of the optical delay device 20 is controlled, the polarization state of the polarization controller 21 is controlled, the operation of the two-signal processing unit 26 is switched, and the display of the two-signal display unit 27 is switched. Hereinafter, a specific evaluation example of the optical coherent detector 41 will be described.

  The two-signal control unit 28 includes a two-signal non-differential delay control unit 28-11, a two-signal differential delay control unit 28-12, a two-signal polarization state control unit 28-14, and a two-signal phase modulation light control. Unit 28-15, a two-signal interference light wavelength control unit 28-16, and a two-signal branch light wavelength control unit 28-17.

FIG. 3 shows a first example of the optical coherent detector evaluation method according to the present embodiment. In the first example of the optical coherent detector evaluation method, two input lights are combined to generate a pair of combined lights whose phases are inverted, balanced reception is performed, and gain-adjusted electric signals PI _C and PQ performing _{C, SI} C, and balanced receiving with combined light pair outputs the SQ _C and the gain adjustment before the electrical signal _{PI U, PQ U, SI U} , the test of the optical coherent detector 41 which outputs the SQ _U . The first example of the optical coherent detector evaluation method includes a two-signal non-differential delayed light output procedure S111 and a two-signal non-differential phase processing procedure S112 in order, and evaluates the phase of each combined light.

  In the two-signal non-differential delayed light output procedure S111, the two input lights of the optical coherent detector 41 are branched while the light from the light source 11 is branched into two branched lights, and the delay amount of one branched light is changed. To output two branched lights. At this time, the two-signal non-differential delay control unit 28-11 outputs the continuous light to the optical phase modulator 12, keeps the polarization state changed by the polarization controller 21 constant, the first optical shutter 16 and In the state where the bias voltage setting unit 25 is controlled to a bias voltage that transmits the branched light to the second optical shutter 18 and receives one of the pair of combined light by the optical coherent detector 41, the delay amount of the optical delay device 20 is set. While changing, one of the branched lights is output from the first light output unit 17 and the other of the branched lights is output from the second light output unit 19.

  One of the branched lights is input from the first light output unit 17 to the input port 51 as one of the input lights S, and the other of the branched lights is input to the input port 54 from the second light output part 19 as the other L of the input light. Is done. The 90 ° optical hybrid 53-P outputs combined light (P + L), combined light (PL), combined light (P + jL), and combined light (P-jL). The 90 ° optical hybrid 53-S outputs combined light (S + L), combined light (S−L), combined light (S + jL), and combined light (S−jL).

  The balanced PD 57-1, the balanced PD 57-2, the balanced PD 57-3, and the balanced PD 57-4 receive one side of the combined light pair. For example, the balanced PD 57-1 receives the combined light (P + L), the balanced PD 57-2 receives the combined light (P + jL), the balanced PD 57-3 receives the combined light (S + L), and the balanced PD 57 -4 receives the combined light (S + jL). Alternatively, the balanced PD 57-1 receives the combined light (P-L), the balanced PD 57-2 receives the combined light (P-jL), and the balanced PD 57-3 receives the combined light (S-L). The balanced PD 57-4 receives the combined light (S-jL).

In the two-signal non-differential phase processing procedure S112, the electric signals PI _U , PQ _U , SI _U , before gain adjustment from the optical coherent detector 41, which are received by the optical coherent detector 41 and output from the two branched lights, are output. SQ _U is input to different input terminals 22-1 to 22-8 for each pair of combined light, and the signal power of the electrical signals PI _U , PQ _U , SI _U , SQ _U before gain adjustment is input terminal 22-1. The digital signal is output by detecting every .about.22-8, and the output value of the digital signal with respect to the delay amount is displayed in a graph.

For example, the electric signal PI _U is input to the input terminal 22-2, the electric signal PQ _U is input to the input terminal 22-4, the electric signal SI _U is input to the input terminal 22-6, and the electric signal SQ _U is input. Input to terminal 22-8. The power detection unit 23 detects the signal power of the electrical signals PI _U , PQ _U , SI _U , SQ _U for each of the input terminals 22-2, 22-4, 22-6, 22-8, and outputs a digital signal. . The two-signal non-differential phase processing unit 26-11 converts the output value of the digital signal from the power detection unit 23 into the delay amount of the optical delay device 20 and the input terminals 22-2, 22-4, 22-6, 22-. 8 is stored in association with it. The two-signal non-differential phase display unit 27-11 displays the output value of the digital signal stored in the two-signal processing unit 26 as a graph with respect to the delay amount of the optical delay device 20.

  FIG. 4 shows a display example of the two-signal non-differential phase display unit 27-11. The light intensity of the combined light (P + L), the combined light (P + jL), the combined light (S + L), and the combined light (S + jL) is displayed in a graph with respect to the delay amount of the optical delay device 20. Since the interference intensity changes by one period due to variable delay amount corresponding to the wavelength of the light source 11, the delay amount of the optical delay device 20 is changed by at least one period. Accordingly, the phase difference between the combined light (P + L), the combined light (P + jL), the combined light (S + L), and the combined light (S + jL), or the combined light (P−L), the combined light (P−jL), and the combined light (S -L) and the phase difference between the combined light (S-jL) can be evaluated. The variable step of the optical delay device 20 is preferably several nm or less.

FIG. 5 shows a second example of the optical coherent detector evaluation method according to the present embodiment. In the second example of the optical coherent detector evaluation method, two input lights are combined to generate a pair of combined lights whose phases are inverted, balanced reception is performed, and gain-adjusted electric signals PI _C and PQ performing _{C, SI} C, and balanced receiving with combined light pair outputs the SQ _C and the gain adjustment before the electrical signal _{PI U, PQ U, SI U} , the test of the optical coherent detector 41 which outputs the SQ _U . The second example of the optical coherent detector evaluation method includes a two-signal differential delay light output procedure S121 and a two-signal differential phase processing procedure S122 in order, and the output signals of the balanced PDs 57-1 to 57-4. To evaluate.

  In the two-signal differential delayed light output procedure S121, the light from the light source 11 is branched into two branched lights, and the two input lights of the optical coherent detector 41 are changed as two input lights while changing one delay amount of the branched lights. Outputs branched light. For example, the two-signal differential delay control unit 28-12 outputs continuous light to the optical phase modulator 12, keeps the polarization state changed by the polarization controller 21 constant, and maintains the first optical shutter 16 and the second optical shutter 16. In the state where the bias voltage setting unit 25 is controlled to the bias voltage that allows the branched light to pass through the optical shutter 18 and the optical coherent detector 41 receives the combined light pair in a balanced manner, the delay amount of the optical delay device 20 is changed. However, one of the branched lights is output from the first light output unit 17 and the other of the branched lights is output from the second light output unit 19.

  One of the branched lights is input from the first light output unit 17 to the input port 51 as one of the input lights S, and the other of the branched lights is input to the input port 54 from the second light output part 19 as the other L of the input light. Is done. The 90 ° optical hybrid 53-P outputs combined light (P + L), combined light (PL), combined light (P + jL), and combined light (P-jL). The 90 ° optical hybrid 53-S outputs combined light (S + L), combined light (S−L), combined light (S + jL), and combined light (S−jL).

  At this time, the balanced PD 57-1, the balanced PD 57-2, the balanced PD 57-3, and the balanced PD 57-4 receive the combined light pair in a balanced manner. For example, the balanced PD 57-1 receives the combined light (P + L) and the combined light (P−L), and the balanced PD 57-2 receives the combined light (P + jL) and the combined light (P−jL). The balanced PD 57-3 receives the combined light (S + L) and the combined light (S-L), and the balanced PD 57-4 receives the combined light (S + jL) and the combined light (S-jL). To do.

In the two-signal differential phase processing procedure S122, the electric signals PI _U , PQ _U , and SI _U before gain adjustment from the optical coherent detector 41 that are output after the two branched lights are balanced and received by the optical coherent detector 41 are output. , SQ _U are input to different input terminals 22-1 to 22-8 for each pair of combined light, and the signal power of the electrical signals PI _U , PQ _U , SI _U , SQ _U before gain adjustment is input terminal 22- Detection is performed every 1 to 22-8 to output a digital signal, and the output value of the digital signal with respect to the delay amount is displayed in a graph.

For example, the electric signal PI _U is input to the input terminal 22-2, the electric signal PQ _U is input to the input terminal 22-4, the electric signal SI _U is input to the input terminal 22-6, and the electric signal SQ _U is input. Input to terminal 22-8. The power detection unit 23 detects the signal power of the electrical signals PI _U , PQ _U , SI _U , SQ _U for each of the input terminals 22-2, 22-4, 22-6, 22-8, and outputs a digital signal. . The two-signal differential phase processing unit 26-12 converts the output value of the digital signal from the power detection unit 23 into the delay amount of the optical delay device 20 and the input terminals 22-2, 22-4, 22-6, and 22-8. Store it in association with. The two-signal differential phase display unit 27-12 displays the output value of the digital signal stored in the two-signal processing unit 26 as a graph with respect to the delay amount of the optical delay device 20.

FIG. 6 shows a display example of the two-signal differential phase display unit 27-12. The signal powers of the electrical signals PI _U , PQ _U , SI _U , and SQ _U are displayed in a graph with respect to the delay amount of the optical delay device 20. Since the signal power changes in one cycle by changing the delay amount corresponding to the wavelength of the light source 11, the delay amount of the optical delay device 20 is changed by at least one cycle. Thereby, the phase difference of the signal power of the electric signals PI _U , PQ _U , SI _U , SQ _U can be evaluated.

FIG. 7 shows a third example of the optical coherent detector evaluation method according to the present embodiment. A third example of the optical coherent detector evaluation method is a combined light in which one of two input lights is separated in a predetermined polarization state of P-polarized light and S-polarized light, and the two input lights are combined to invert the phase. electrical signal _{PI C, PQ C, SI C} , and balanced receiving with combined light pair outputs the SQ _C and the gain adjustment before the electricity to generate pairs and balanced light receiving and after gain adjustment by gain adjustment The optical coherent detector 41 that outputs the signals PI _U , PQ _U , SI _U , and SQ _U is tested. The third example of the optical coherent detector evaluation method includes a two-signal polarization output procedure S141 and a two-signal local optical branching ratio measurement procedure S142 in this order, and evaluates the branching ratio of the BS55.

  In the two-signal polarization output procedure 141, the light from the light source 11 is branched into two branched lights, and the branched light is used as the other input light L of the optical coherent detector 41 while changing the polarization state of the light from the light source 11. Is output. At this time, the two-signal polarization state control unit 28-14 causes the optical phase modulator 12 to output continuous light, causes the first optical shutter 16 to block one of the branched lights, and branches to the second optical shutter 18. While changing the polarization state of the polarization controller 21 in a state where the bias voltage setting unit 25 is controlled to a bias voltage that transmits the other of the light and receives one of the pair of combined light by the optical coherent detector 41, The other of the branched lights is output from the second light output unit 19.

  The other L of the input light is input to the input port 54. The BS 55 branches the other L of the input light. The 90 ° optical hybrid 53-P further branches the branched light from the BS 55 and outputs the branched light from four output ports. The 90 ° optical hybrid 53-S further branches the branched light from the BS 55 and outputs it from the four output ports. Two output lights from the 90 ° optical hybrid 53-P are input to the balanced PD 57-1 and the balanced PD 57-2. Two output lights from the 90 ° optical hybrid 53-S are input to the balanced PD 57-3 and the balanced PD 57-4.

  The balanced PD 57-1, the balanced PD 57-2, the balanced PD 57-3, and the balanced PD 57-4 receive one side of the combined light pair. For example, the balanced PD 57-1 and the balanced PD 57-2 receive only one of the input two branched lights. The balanced PD 57-1 and the balanced PD 57-2 receive only the other of the input two branched lights. Thereby, balanced PD57-1 and balanced PD57-2 receive the branched light branched by PBS52. Similarly to the balanced PD 57-1 and the balanced PD 57-2, the balanced PD 57-3 and the balanced PD 57-4 receive the branched light separated by the PBS 52.

In the two-signal local optical branching ratio measurement procedure S142, the other of the branched lights is received by the optical coherent detector 41 and output from the electrical signals PI _U , PQ _U , SI _U , and SQ _U before gain adjustment. Signal power of the electric signals PI _U , PQ _U , SI _U , SQ _U before gain adjustment input to the different input terminals 22-1 to 22-8 and input to the input terminals 22-1 to 22-8, respectively. Is converted into a digital signal, and the output value of the digital signal is stored in association with the input terminals 22-1 to 22-8 and a predetermined polarization state of P-polarized light and S-polarized light, and branching of local light in any polarization state Calculate and display the ratio.

  At this time, the two-signal local optical branching ratio processing unit 26-14 calculates the branching ratio of local light in an arbitrary polarization state using the output value of the digital signal from the power detection unit 23. The two-signal local light branching ratio display unit 27-14 displays the branching ratio of local light in an arbitrary polarization state calculated by the two-signal processing unit 26.

For example, the two-signal local optical branching ratio processing unit 26-14 performs digital processing of the electric signal PI _U and the electric signal PQ _U when the balanced PD 57-1 and the balanced PD 57-2 receive only one of the branched lights. All of the output value of the signal and the output value of the digital signal of the electrical signal PI _U and electrical signal PQ _U when the balanced PD 57-1 and the balanced PD 57-2 receive only the other of the branched lights. Calculate the sum of output values. Thereby, the optical power on the P polarization side is calculated. On the other hand, second signal local light branching ratio processor 26-14 is balanced PD57-3 and balanced PD57-4 the electric signal SI _U and electrical signals SQ _U when it receives the only one of the branched light All of the output value of the digital signal and the output value of the digital signal of the electric signal SI _U and electric signal SQ _U when the balanced PD 57-3 and the balanced PD 57-4 receive only the other one of the branched lights The sum of output values of is calculated. Thereby, the optical power on the S polarization side is calculated. The two-signal local optical branching ratio processing unit 26-14 calculates the ratio of the optical power on the P polarization side and the optical power on the S polarization side.

FIG. 8 shows a fourth example of the optical coherent detector evaluation method according to this embodiment. In the fourth example of the optical coherent detector evaluation method, two input lights are combined to generate a pair of combined lights whose phases are inverted, balanced received light, and gain-adjusted electric signals PI _C and PQ. performing _{C, SI} C, and balanced receiving with combined light pair outputs the SQ _C and the gain adjustment before the electrical signal _{PI U, PQ U, SI U} , the test of the optical coherent detector 41 which outputs the SQ _U . The fourth example of the optical coherent detector evaluation method, the second signal phase modulation optical output procedure S151, has a second signal skew processing procedures S152, in sequence, electrical signals _{PI C, PQ C, SI C} , skew SQ _C Evaluate.

  In the two-signal phase-modulated light output procedure S151, the light from the light source 11 is phase-modulated and branched into two branched lights, and the branched light is output as one input light S and the other input light L of the optical coherent detector 41. To do. At this time, the two-signal phase-modulated light control unit 28-15 outputs the phase-modulated light to the optical phase modulator 12, keeps the polarization state changed by the polarization controller 21 constant, and causes the first optical shutter 16 to A state in which the bias voltage setting unit 25 is controlled to a bias voltage in which one of the branched lights is transmitted, the other of the branched lights is transmitted through the second optical shutter 18, and the pair of combined light is received by the optical coherent detector 41. Thus, one of the branched lights is output from the first light output unit 17 and the other of the branched lights is output from the second light output unit 19. One S of the input light is input to the input port 51, and the other L of the input light is input to the input port 54. The balanced PDs 57-1 to 57-4 receive balanced light.

In the two-signal skew processing procedure S152, the electric signals PI _C , PQ _C , SI _C , and SQ after gain adjustment from the optical coherent detector 41 that are output after the two branched lights are balanced and received by the optical coherent detector 41 are output. the _C type for each pair of the combined light to different input terminals 22-1 to 22-8, an electric signal _PI C after the gain _adjustment, PQ _C, SI C, the input signal waveform of the SQ _C terminal 22-1～ was measured every 22-8, determining and displaying an electrical signal _PI C after the gain _adjustment, PQ _C, SI C, the delay time between SQ _C using a signal waveform of each input terminal 22-1 to 22-8 . At this time, the two-signal skew processing unit 26-15 uses the signal waveform for each of the input terminals 22-1 to 22-8 to be measured by the waveform measurement unit 24, and the electric signals PI _C , PQ _C , SI after gain adjustment. _C, obtaining a delay time between SQ _C. The two-signal skew display unit 27-15 displays the delay time required by the two-signal processing unit 26.

FIG. 9 shows a display example of the two-signal skew display section 27-15. Electrical signal PI _C, the electrical signal PQ _C, the electric signal SI _C and electric signal SQ _C, because they are phase-modulated, it is possible to detect the rising and falling of the signal. Skew is evaluated using the rising or falling time of this signal. For example, the rise time _{t PI} electrical signal PI _C to measure the delay time until the fall time _{t PQ} electrical signal PQ _C, from the rise time _{t PI} electrical signal PI _C until the rise time _{t SI} electric signal SI _C measuring the delay time of, by measuring the delay time from the rising time _{t PI} electrical signal PI _C to the fall time _{t SQ} electrical signal SQ _C, the electrical signal _{PI C, PQ C, SI C} , SQ C Skew evaluation can be performed.

FIG. 10 shows a fifth example of the optical coherent detector evaluation method according to the present embodiment. In the fifth example of the optical coherent detector evaluation method, two input lights are combined to generate a pair of combined lights whose phases are inverted, balanced reception is performed, and gain-adjusted electric signals PI _C and PQ performing _{C, SI} C, and balanced receiving with combined light pair outputs the SQ _C and the gain adjustment before the electrical signal _{PI U, PQ U, SI U} , the test of the optical coherent detector 41 which outputs the SQ _U . The fifth example of the optical coherent detector evaluation method includes a two-signal interference wavelength variable light output procedure S161 and a two-signal interference intensity measurement procedure S162 in order, and evaluates a change in the interference intensity with respect to the wavelength.

  In the two-signal interference wavelength variable light output procedure S161, the light from the light source 11 is branched into two branched lights while changing the output wavelength of the light from the light source 11, and 2 as the two input lights of the optical coherent detector 41. Outputs two split lights. At this time, the two-signal interference light wavelength control unit 28-16 causes the optical phase modulator 12 to output continuous light, causes the first optical shutter 16 to transmit one of the branched lights, and branches to the second optical shutter 18. With the bias voltage setting unit 25 controlled to a bias voltage that transmits the other of the light and receives one of the pair of combined light by the optical coherent detector 41, one of the branched light and the branched light are changed while changing the output wavelength of the light source 11. The other of the branched lights is output.

  One of the branched lights is input from the first light output unit 17 to the input port 51 as one of the input lights S, and the other of the branched lights is input to the input port 54 from the second light output part 19 as the other L of the input light. Is done. The 90 ° optical hybrid 53-P outputs combined light (P + L), combined light (PL), combined light (P + jL), and combined light (P-jL). The 90 ° optical hybrid 53-S outputs combined light (S + L), combined light (S−L), combined light (S + jL), and combined light (S−jL).

  The balanced PD 57-1, the balanced PD 57-2, the balanced PD 57-3, and the balanced PD 57-4 receive one side of the combined light pair. For example, the balanced PD 57-1 receives the combined light (P + L), the balanced PD 57-2 receives the combined light (P + jL), the balanced PD 57-3 receives the combined light (S + L), and the balanced PD 57 -4 receives the combined light (S + jL). Alternatively, the balanced PD 57-1 receives the combined light (P-L), the balanced PD 57-2 receives the combined light (P-jL), and the balanced PD 57-3 receives the combined light (S-L). The balanced PD 57-4 receives the combined light (S-jL).

In the two-signal interference intensity measurement procedure S162, the electric signals PI _U , PQ _U , SI _U , SQ _U before gain adjustment from the optical coherent detector 41, which are received and output by the optical coherent detector 41, are output. Are input to different input terminals 22-1 to 22-8 for each pair of combined light, and the electric signals PI _U , PQ _U , SI _U , before gain adjustment input to the input terminals 22-1 to 22-8, The signal power of the SQ _U is converted into a digital signal, the output value of the digital signal is stored in association with the output wavelength of the light source 11 and the input terminals 22-1 to 22-8, and optical coherent detection at each output wavelength of the light source 11 The light intensity of the interference light at the device 41 is displayed for each of the input terminals 22-1 to 22-8.

  At this time, the two-signal interference light processing unit 26-16 stores the output value of the digital signal from the power detection unit 23 in association with the output wavelength of the light source 11 and the input terminals 22-1 to 22-8. The two-signal interference light display unit 27-16 displays the output value of the digital signal at each output wavelength of the light source 11 stored in the two-signal processing unit 26 for each of the input terminals 22-1 to 22-8.

  FIG. 11 shows a display example of the two-signal interference light display unit 27-16. Synthetic light (P + L), synthetic light (PL), synthetic light (P + jL), synthetic light (P-jL), synthetic light (S + L), synthetic light (S-L), synthetic light (S + jL) or synthetic light The light intensity of (S−jL) is displayed in a graph with respect to the output wavelength of the light source 11. Thereby, the wavelength characteristic of interference intensity can be measured.

FIG. 12 shows a sixth example of the optical coherent detector evaluation method according to the present embodiment. The sixth example of the optical coherent detector evaluation method is a gain obtained by synthesizing two input lights to generate a pair of synthesized lights whose phases are inverted and receiving either one of the synthesized lights constituting the pair and adjusting the gain. electrical signal _PI C after the _adjustment, PQ _C, SI _C, receiving either the combined light to form a pair outputs the SQ _C and the gain adjustment before the electrical signal _{PI U, PQ U, SI U} , SQ _The optical coherent detector 41 that outputs _U is tested. The sixth example of the optical coherent detector evaluation method has a two-signal wavelength variable branch optical output procedure S171 and a two-signal loss measurement procedure S172 in order, and evaluates the optical loss in the optical coherent detector 41.

  In the two-signal wavelength variable branch light output procedure S171, the light from the light source 11 is branched into two branched lights while changing the output wavelength of the light from the light source 11, and is used as one of the input lights of the optical coherent detector 41. One of the two branched lights is output. At this time, the two-signal branching light wavelength control unit 28-17 causes the optical phase modulator 12 to output continuous light, and the optical coherent detector 41 uses the bias voltage setting unit 25 as a bias voltage for receiving one of the pair of combined lights. In the controlled state, one of the branched lights is blocked by the first optical shutter 16 and the other of the branched lights is transmitted to the second optical shutter 18 to change the output wavelength of the light source 11 and the other of the branched lights is changed. Output.

  The other of the branched lights is input from the second light output unit 19 to the input port 54 as the other L of the input light. The 90 ° optical hybrid 53-P outputs combined light (P + L), combined light (PL), combined light (P + jL), and combined light (P-jL). The 90 ° optical hybrid 53-S outputs combined light (S + L), combined light (S−L), combined light (S + jL), and combined light (S−jL).

  The balanced PD 57-1, the balanced PD 57-2, the balanced PD 57-3, and the balanced PD 57-4 receive one side of the combined light pair. For example, the balanced PD 57-1 receives the combined light (P + L), the balanced PD 57-2 receives the combined light (P + jL), the balanced PD 57-3 receives the combined light (S + L), and the balanced PD 57 -4 receives the combined light (S + jL). Alternatively, the balanced PD 57-1 receives the combined light (P-L), the balanced PD 57-2 receives the combined light (P-jL), and the balanced PD 57-3 receives the combined light (S-L). The balanced PD 57-4 receives the combined light (S-jL).

In the two-signal loss measurement procedure S172, one of the two branched lights is received by the optical coherent detector 41 and output from the electrical signals PI _U , PQ _U , SI _U , and SQ _U before gain adjustment. each input to different input terminals 22-1 to 22-8 for each pair, the gain adjustment before the electrical signal _{PI U, PQ U, SI U} , the signal power of SQ _U for each input terminal 22-1 to 22-8 It detects and converts into a digital signal, the output value of the digital signal is stored in association with the output wavelength of the light source 11 and the input terminals 22-1 to 22-8, and the output power of the light source 11 and the output value of the digital signal are used. The loss between each input / output port of the optical coherent detector 41 at each output wavelength of the light source 11 is calculated for each of the input terminals 22-1 to 22-8, and the optical coherent detector at each output wavelength of the light source 11 is calculated. 1 loss, is displayed for each input terminal 22-1 to 22-8.

  At this time, the two-signal light loss processing unit 26-17 determines the output value of each digital signal from the power detection unit 23 that is maximized when the polarization state is changed by the polarization controller 21 as the output wavelength of the light source 11. Between the input / output ports of the optical coherent detector 41 at each output wavelength of the light source 11 using the output power of the light source 11 and the output value of the digital signal. Is calculated for each of the input terminals 22-1 to 22-8. The two-signal light loss display unit 27-17 displays the loss of the optical coherent detector 41 at each output wavelength of the light source 11 calculated by the two-signal processing unit 26 for each of the input terminals 22-1 to 22-8.

  FIG. 13 shows a display example of the two-signal light loss display section 27-17. Synthetic light (P + L), synthetic light (PL), synthetic light (P + jL), synthetic light (P-jL), synthetic light (S + L), synthetic light (S-L), synthetic light (S + jL) or synthetic light The loss between the input / output ports of (S−jL) is displayed in a graph with respect to the output wavelength of the light source 11. Thereby, the wavelength characteristic of the loss of the optical coherent detector 41 can be measured.

  In the two-signal wavelength variable branch light output procedure S171, the two-signal branch light wavelength control unit 28-17 transmits one of the branched lights to the first optical shutter 16 and transmits the branched light to the second optical shutter 18. One of the branched lights may be output while changing the output wavelength of the light source 11 while blocking the other. Thereby, one of the input lights S is input into the input port 51, and the loss between the input port 51 and each output port can be measured.

  As described above, the optical coherent detector evaluation apparatus 101 according to the present embodiment and the optical coherent detector evaluation method according to the present embodiment can easily evaluate the optical coherent detector 41.

  In addition, in the optical coherent detector 41 of this embodiment, although the example provided with two 90 degree optical hybrids was shown, one 90 degree optical hybrid may be sufficient and three or more may be sufficient. If the number of 90 ° optical hybrids is one, the number of input terminals of the two-signal input unit 22 may be four. If the number of 90 ° optical hybrids is N, the number of input terminals of the two-signal input unit 22 may be The number may be 4 × N.

(Embodiment 2)
FIG. 14 shows an example of an optical coherent detector evaluation apparatus according to this embodiment. The optical coherent detector evaluation apparatus 102 according to the present embodiment tests the optical coherent detector 42. The optical coherent detector 42 synthesizes two input lights to generate a pair of combined lights whose phases are inverted, receives balanced light, and adjusts the gain-adjusted electric signals PI _C , PQ _C , SI _C , SQ whether or synthetic light pair outputs the _C to the balanced light receiving and gain adjustment before the electrical signal _{PI U, PQ U, SI U} , and outputs the SQ _U. The optical coherent detector 42 detects the signal light S when one of the input lights S is input as the signal light and the other L of the input light is input as the local light.

FIG. 15 shows an example of an optical coherent detector according to the present embodiment. Similar to the optical coherent detector 41 shown in FIG. 2, the optical coherent detector 42 according to the present embodiment includes an input port 51, an input port 54, a PBS 52, a BS 55, a 90 ° optical hybrid 53-P, Balanced PD57-1, 57-2, 57-3, 57-4, TIA58-1, 58-2, 58-3, 58-4, AGC59-1, 59-2, 59-3, 59- 4. Optical coherent detector 42, an electric signal _PI C when the AGC59-1～59-4 is exerting the _function, PQ _C, SI C, outputs SQ _C, AGC59-1~59-4 stops the function When this is done, electrical signals PI _U , PQ _U , SI _U , and SQ _U are output.

  The optical coherent detector evaluation apparatus 102 shown in FIG. 14 includes a continuous light source 30, an optical phase modulator 12, a phase modulation signal generation unit 13, a driver 14, an optical branching unit 15, and a first optical shutter 16. The first optical output unit 17, the second optical shutter 18, the second optical output unit 19, the optical delay device 20, the polarization controller 21, the power detection unit 23, and the waveform measurement unit 24 , Bias voltage setting unit 25, one signal processing unit 36, one signal display unit 37, intensity modulation light source 31, intensity modulation signal generation unit 32, optical switch 33, one signal input unit 34, and rectifier circuit 35, one signal control unit 38, bias voltage setting unit 25, and gain adjustment circuit setting unit 39.

  The continuous light source 30 shown in FIG. 14 outputs continuous light. The optical phase modulator 12 performs phase modulation on the continuous light from the continuous light source 30 with the input phase modulation signal. The phase modulation signal generator 13 generates a phase modulation signal. The driver 14 drives the optical phase modulator 12 in accordance with the signal from the phase modulation signal generator 13, and outputs phase modulated light or continuous light from the optical phase modulator 12. The intensity modulation signal generator 32 generates an intensity modulation signal. The intensity modulated light source 31 outputs intensity modulated light in accordance with the intensity modulated signal from the intensity modulated signal generator 32. The optical switch 33 receives the phase-modulated light or continuous light from the optical phase modulator 12 and the intensity-modulated light from the intensity-modulated light source 31, and selectively outputs phase-modulated light, continuous light, or intensity-modulated light. The polarization controller 21 changes the polarization state of the light from the optical switch 33. The optical branching unit 15 branches the light from the polarization controller 21 into two branched lights.

  The first optical shutter 16 transmits or blocks one branched light from the light branching unit 15. The optical delay device 20 delays one of the branched lights from the optical branching unit 15 by an arbitrary delay amount. The first optical output unit 17 outputs the light from the optical delay device 20 as one of the input lights S of the optical coherent detector 42. The second optical shutter 18 transmits or blocks the other branched light from the light branching unit 15. The second light output unit 19 outputs the output light of the second optical shutter 18 as the other L of the input light of the optical coherent detector 42.

First signal input unit 34 has a plurality of input terminals 34-1 to 34-4, an electric signal after the gain adjustment from the coherent detection unit _{42 PI C, PQ C, SI} C, SQ C or gain adjustment before Any one of the electrical signals PI _U , PQ _U , SI _U , and SQ _U is input to different input terminals 34-1 to 34-4 for each pair of combined lights. The rectifier circuit 35 converts the electric signals PI _U , PQ _U , SI _U , and SQ _U before gain adjustment input to the one signal input unit 34 from AC to DC for each of the input terminals 34-1 to 34-4. . The bias voltage setting unit 25 sets the bias voltage of the balanced PDs 57-1 to 57-4 that receive the balanced light reception by the optical coherent detector 42. The gain adjustment circuit setting unit 39 sets the operations of the AGCs 59-1 to 59-4 that perform gain adjustment with the optical coherent detector.

The power detector 23 detects the signal power of the electric signal obtained by detecting the intensity-modulated light of the intensity-modulated light source by the rectifier circuit 35 for each of the input terminals 34-1 to 34-4, and outputs a digital signal. Waveform measuring section 24 measures first signal input of the gain-adjusted input to the 34 electrical signals _{PI C, PQ C, SI C} , the signal waveform of the SQ _C for each input terminal 34-1 to 34-4. The one signal processing unit 36 performs signal processing using the signal power detected by the power detection unit 23 and the signal waveform measured by the waveform measurement unit 24. The one signal display unit 37 displays the signal processing result of the one signal processing unit 36.

  The one signal control unit 38 includes an intensity modulation signal generation unit 32, a phase modulation signal generation unit 13, a driver 14, an intensity modulation light source 31, a polarization controller 21, an optical switch 33, a first optical shutter 16, and a second optical shutter. 18, the operation of the optical delay device 20, the bias voltage setting unit 25, the gain adjustment circuit setting unit 39, the one signal processing unit 36, and the one signal display unit 37 are controlled.

FIG. 16 shows a first example of an optical coherent detector evaluation method according to this embodiment. In the first example of the optical coherent detector evaluation method, two input lights are combined to generate a pair of combined lights whose phases are inverted, balanced reception is performed, and gain-adjusted electric signals PI _C and PQ performing _{C, SI} C, and balanced receiving with combined light pair outputs the SQ _C and the gain adjustment before the electrical signal _{PI U, PQ U, SI U} , the test of the optical coherent detector 42 which outputs the SQ _U . The first example of the optical coherent detector evaluation method includes a one-signal non-differential delayed light output procedure S211 and a one-signal non-differential phase processing procedure S212 in order, and evaluates the phase of each combined light.

  In the one-signal non-differential delayed light output procedure S211, the intensity-modulated light from the intensity-modulated light source 31 is branched into two branched lights, and the optical coherent detector 42 changes the amount of delay of one of the branched lights. Two branched lights are output as two input lights. At this time, the one-signal non-differential delay control unit 38-21 keeps the polarization state changed by the polarization controller 21 constant, transmits one of the branched lights to the first optical shutter 16, and transmits the second light. The AGC 59-1 adjusts the gain by the optical coherent detector 42 by controlling the bias voltage setting unit 25 so that the other of the branched lights is transmitted through the shutter 18 and the optical coherent detector 42 receives the balanced light of the combined light pair. While the gain adjustment circuit setting unit 39 is controlled so that the operations of .about.59-4 are stopped, the first optical output unit 17 outputs one of the branched lights while changing the delay amount of the optical delay unit 20. At the same time, the other of the branched lights is output from the second light output unit 19.

One of the branched lights is input from the first light output unit 17 to the input port 51 as one of the input lights S, and the other of the branched lights is input to the input port 54 from the second light output part 19 as the other L of the input light. Is done. The operations of the 90 ° optical hybrid 53-P, the 90 ° optical hybrid 53-S, and the balanced PDs 57-1 to 57-4 are the same as those in the first example of the optical coherent detector evaluation method described in the first embodiment. Since the operation of AGC59-1~59-4 is stopped, the optical coherent detector 42 outputs a _{PI U, PQ U, SI U} , SQ U.

In the one-signal non-differential phase processing procedure S212, the electric signals PI _U , PQ _U , SI _U , before gain adjustment from the optical coherent detector 42, which are received by the optical coherent detector 42 and output from the two branched lights, are output. SQ _U is input to different input terminals 34-1 to 34-4 for each pair of combined light, and the signal power of the electric signals PI _U , PQ _U , SI _U , SQ _U before gain adjustment is input to the input terminal 34-1. The digital signal is output by detecting every .about.34-4, and the output value of the digital signal with respect to the delay amount is displayed in a graph.

For example, the electric signal PI _U is input to the input terminal 34-1, the electric signal PQ _U is input to the input terminal 34-2, the electric signal SI _U is input to the input terminal 34-3, and the electric signal SQ _U is input. Input to terminal 34-4. The power detector 23 detects the signal power of the electrical signals PI _U , PQ _U , SI _U , SQ _U for each of the input terminals 34-1 to 34-4 and outputs a digital signal. The one-signal non-differential phase processing unit 36-21 stores the output value of the digital signal from the power detection unit 23 in association with the delay amount of the optical delay device 20 and the input terminals 34-1 to 34-4. The one-signal non-differential phase display unit 37-21 displays the output value of the digital signal stored in the one-signal processing unit 36 as a graph with respect to the delay amount of the optical delay device 20. The display example of the one-signal non-differential phase display unit 37-21 is the same as the display example of the two-signal non-differential phase display unit 27-11 described in FIG.

FIG. 17 shows a second example of the optical coherent detector evaluation method according to this embodiment. In the second example of the optical coherent detector evaluation method, two input lights are combined to generate a pair of combined lights whose phases are inverted, balanced reception is performed, and gain-adjusted electric signals PI _C and PQ _{C, SI} C, the electrical signal _PI U before or gain adjustment for the balanced receiving a pair of combined light outputs the _{SQ C, PQ U, SI U} , the test of the optical coherent detector 42 which outputs the SQ _U Do. The second example of the optical coherent detector evaluation method includes a one-signal differential delayed light output procedure S221 and a one-signal differential phase processing procedure S222 in order, and the output signals of the balanced PDs 57-1 to 57-4. To evaluate.

  In the one-signal differential delayed light output procedure S221, the intensity modulated light from the intensity modulated light source 31 is branched into two branched lights, and the two inputs of the optical coherent detector 42 are changed while changing the delay amount of one of the branched lights. Two branched lights are output as light. At this time, the one-signal differential delay control unit 38-22 keeps the polarization state changed by the polarization controller 21 constant, transmits one of the branched lights to the first optical shutter 16, and the second optical shutter. The operation of the circuit is configured to control the bias voltage setting unit 25 to a bias voltage that allows the other of the branched light to pass through 18, receive one of the pair of combined light with the optical coherent detector 42, and adjust the gain with the optical coherent detector 42. While the gain adjustment circuit setting unit 39 is controlled to stop, the first optical output unit 17 outputs one of the branched lights and the second optical output unit while changing the delay amount of the optical delay unit 20. 19 outputs the other of the branched lights.

One of the branched lights is input from the first light output unit 17 to the input port 51 as one of the input lights S, and the other of the branched lights is input to the input port 54 from the second light output part 19 as the other L of the input light. Is done. The operations of the 90 ° optical hybrid 53-P, the 90 ° optical hybrid 53-S, and the balanced PDs 57-1 to 57-4 are the same as in the second example of the optical coherent detector evaluation method described in the first embodiment. Since the operation of AGC59-1~59-4 is stopped, the optical coherent detector 42 outputs a _{PI U, PQ U, SI U} , SQ U.

In the one-signal differential phase processing step S222, the electric signals PI _U , PQ _U , and SI _U before gain adjustment from the optical coherent detector 42 that are output after the two branched lights are balanced and received by the optical coherent detector 42 are output. , SQ _U are input to different input terminals 34-1 to 34-4 for each pair of combined light, and the signal power of the electric signals PI _U , PQ _U , SI _U , SQ _U before gain adjustment is input terminal 34- A digital signal is output by detecting every 1 to 34-4, and the output value of the digital signal with respect to the delay amount is displayed in a graph.

For example, the electric signal PI _U is input to the input terminal 34-1, the electric signal PQ _U is input to the input terminal 34-2, the electric signal SI _U is input to the input terminal 34-3, and the electric signal SQ _U is input. Input to terminal 34-4. The power detector 23 detects the signal power of the electrical signals PI _U , PQ _U , SI _U , SQ _U for each of the input terminals 34-1 to 34-4 and outputs a digital signal. The one-signal differential phase processing unit 36-22 stores the output value of the digital signal from the power detection unit 23 in association with the delay amount of the optical delay device 20 and the input terminals 34-1 to 34-4. The one-signal differential phase display unit 37-22 displays the digital signal output value stored in the one-signal processing unit 36 as a graph with respect to the delay amount of the optical delay device 20. The display example of the one-signal differential phase display unit 37-22 is the same as the display example of the two-signal differential phase display unit 27-12 described in FIG.

FIG. 18 shows a third example of the optical coherent detector evaluation method according to the present embodiment. A third example of the optical coherent detector evaluation method is a combined light in which one of two input lights is separated in a predetermined polarization state of P-polarized light and S-polarized light, and the two input lights are combined to invert the phase. electrical signal after generates a pair with balanced light and gain adjustment by gain adjustment _{PI C, PQ C, SI C} , whether or synthetic light pair outputs the SQ _C and balanced light and the gain adjustment before The optical coherent detector 42 that outputs the electrical signals PI _U , PQ _U , SI _U , and SQ _U is tested. The third example of the optical coherent detector evaluation method includes a one-signal polarization output procedure S241 and a one-signal local optical branching ratio measurement procedure S242 in this order, and evaluates the branching ratio of the BS55.

  In the one-signal polarization output procedure S241, the intensity-modulated light from the intensity-modulated light source 31 is branched into two branched lights, and the branched light is output as the other L of the input light of the optical coherent detector 42 while changing the polarization state. To do. At this time, the one-signal polarization state control unit 38-24 blocks the one of the branched lights through the first optical shutter 16 and transmits the other of the branched lights through the second optical shutter 18, and the optical coherent detector 42. The gain adjustment circuit setting unit 25 controls the bias voltage setting unit 25 to a bias voltage for receiving one of the pair of combined light and stops the operation of the AGCs 59-1 to 59-4 for adjusting the gain by the optical coherent detector 42. In the state where 39 is controlled, the second light output unit 19 outputs the other of the branched light while changing the polarization state of the polarization controller 21.

The other L of the input light is input to the input port 54. The BS 55 branches the other L of the input light. The 90 ° optical hybrid 53-P further branches the branched light from the BS 55 and outputs the branched light from four output ports. The operations of the 90 ° optical hybrid 53-P, the 90 ° optical hybrid 53-S, and the balanced PDs 57-1 to 57-4 are the same as those in the third example of the optical coherent detector evaluation method described in the first embodiment. Since the operation of AGC59-1~59-4 is stopped, the optical coherent detector 42 outputs a _{PI U, PQ U, SI U} , SQ U.

In the one-signal local optical branching ratio measurement procedure S242, the other of the branched lights is received by the optical coherent detector 42 and output from the electrical signals PI _U , PQ _U , SI _U , SQ _U before gain adjustment, and the combined light pair. The signal power of the electrical signals PI _U , PQ _U , SI _U , SQ _U before gain adjustment input to the input terminals 34-1 to 34-4, which are input to the input terminals, is converted into digital signals, The output value of the digital signal is stored in association with the input terminals 34-1 to 34-4 and the predetermined polarization state of P-polarized light and S-polarized light, and the branching ratio of the other L of the input light in an arbitrary polarization state is calculated. To display.

  At this time, the one-signal local optical branching ratio processing unit 36-24 calculates the branching ratio of the other L of the input light in an arbitrary polarization state using the output value of the digital signal from the power detection unit 23. The operation of the one-signal local optical branching ratio processing unit 36-24 is the same as that of the two-signal local optical branching ratio processing unit 26-14 described in the first embodiment. The one-signal local optical branching ratio display unit 37-24 displays the other L branching ratio of the input light in an arbitrary polarization state calculated by the one-signal processing unit 36.

FIG. 19 shows a fourth example of the optical coherent detector evaluation method according to the present embodiment. In the fourth example of the optical coherent detector evaluation method, two input lights are combined to generate a pair of combined lights whose phases are inverted, balanced received light, and gain-adjusted electric signals PI _C and PQ. _{C, SI} C, whether or synthetic light pair outputs the SQ _C and balanced light and the gain adjustment before the electrical signal _{PI U, PQ U, SI U} , the test of the optical coherent detector 42 which outputs the SQ _U Do. The fourth example of the optical coherent detector evaluation method, a first signal phase-modulated optical output procedure S251, has a first signal skew processing procedures S252, in sequence, the skew of the electrical signal _{PI C, PQ C, SI C} , SQ C Evaluate.

  In the one-signal phase-modulated light output procedure S251, the light from the continuous light source 30 is phase-modulated and branched into two branched lights, and the branched light is used as one of the input light S and the other L of the input light of the optical coherent detector 42. Output. At this time, the one-signal phase-modulated light control unit 38-25 outputs the phase-modulated light to the optical phase modulator 12, keeps the polarization state changed by the polarization controller 21 constant, and causes the first optical shutter 16 to One of the branched lights is transmitted, the other of the branched lights is transmitted through the second optical shutter 18, and the bias voltage setting unit 25 is controlled to a bias voltage for receiving the balanced pair of combined lights by the optical coherent detector 42. While the gain adjustment circuit setting unit 39 is controlled so that the AGCs 59-1 to 59-4 that perform gain adjustment with the optical coherent detector 42 operate, one of the branched lights is output from the first light output unit 17, and The other of the branched lights is output from the second light output unit 19.

One S of the input light is input to the input port 51, and the other L of the input light is input to the input port 54. The operations of the 90 ° optical hybrid 53-P, the 90 ° optical hybrid 53-S, and the balanced PDs 57-1 to 57-4 are the same as those in the fourth example of the optical coherent detector evaluation method described in the first embodiment. Since AGC59-1~59-4 is operating, coherent detection unit 42 outputs an electrical signal _{PI C, PQ C, SI C} , the SQ _C.

In the one-signal skew processing procedure S252, the electric signals PI _C , PQ _C , SI _C , and SQ after gain adjustment from the optical coherent detector 42 that are output after the two branched lights are balanced and received by the optical coherent detector 42 are output. the _C type for each pair of the combined light to different input terminals 34-1 to 34-4, an electric signal _PI C after the gain _adjustment, PQ _C, SI C, the input signal waveform of the SQ _C terminal 34-1～ was measured every 34-4, determining and displaying an electrical signal _PI C after the gain _adjustment, PQ _C, SI C, the delay time between SQ _C using a signal waveform of each input terminal 34-1 to 34-4 . At this time, the one-signal skew processing unit 36-25 uses the signal waveform for each of the input terminals 34-1 to 34-4 to be measured by the waveform measuring unit 24, and is output after adjusting the gain by the optical coherent detector 42. electrical signal _{PI C, PQ C, SI C} , obtaining a delay time between SQ _C. The one signal skew display unit 37-25 displays a delay time required by the one signal skew processing unit 36-25. The display example of the one-signal skew display section 37-25 is the same as the display example of the two-signal skew display section 27-15 shown in FIG.

FIG. 20 shows a fifth example of the optical coherent detector evaluation method according to the present embodiment. In the fifth example of the optical coherent detector evaluation method, two input lights are combined to generate a pair of combined lights whose phases are inverted, balanced reception is performed, and gain-adjusted electric signals PI _C and PQ _{C, SI} C, whether or synthetic light pair outputs the SQ _C and balanced light and the gain adjustment before the electrical signal _{PI U, PQ U, SI U} , the test of the optical coherent detector 42 which outputs the SQ _U Do. The fifth example of the optical coherent detector evaluation method includes a one-signal interference wavelength variable light output procedure S261 and a one-signal interference intensity measurement procedure S262 in order, and evaluates the change in the light intensity of the combined light with respect to the wavelength. .

  In the one-signal interference wavelength variable light output step S261, the intensity-modulated light from the intensity-modulated light source 31 is branched into two branched lights while changing the output wavelength of the intensity-modulated light from the intensity-modulated light source 31, and an optical coherent detector Two branched lights are output as the two input lights 42. At this time, the one-signal interference light wavelength control unit 38-26 causes the optical phase modulator 12 to output continuous light, allows the first optical shutter 16 to transmit one of the branched lights, and branches to the second optical shutter 18. AGC 59-1 to 59-4 that controls the bias voltage setting unit 25 to a bias voltage that allows the other of the light to pass therethrough and receives a balanced reception of the pair of combined light by the optical coherent detector 42 and adjusts the gain by the optical coherent detector 42. In the state where the gain adjustment circuit setting unit 39 is controlled so as to stop the operation of, while changing the output wavelength of the intensity-modulated light source 31, one of the branched lights is output from the first light output unit 17, and the second The other of the branched lights is output from the optical output unit 19.

One of the branched lights is input from the first light output unit 17 to the input port 51 as one of the input lights S, and the other of the branched lights is input to the input port 54 from the second light output part 19 as the other L of the input light. Is done. The operations of the 90 ° optical hybrid 53-P, the 90 ° optical hybrid 53-S, and the balanced PDs 57-1 to 57-4 are the same as in the fifth example of the optical coherent detector evaluation method described in the first embodiment. Since the operation of AGC59-1~59-4 is stopped, the optical coherent detector 42 outputs a _{PI U, PQ U, SI U} , SQ U.

In the one-signal interference intensity measurement procedure S262, electric signals PI _U , PQ _U , SI _U , before gain adjustment from the optical coherent detector 42, which are output after the two branched lights are balanced and received by the optical coherent detector 42, are output. SQ _U is input to different input terminals 34-1 to 34-4 for each pair of combined light, and electric signals PI _U , PQ _U and SI before gain adjustment input to the input terminals 34-1 to 34-4 are input. The signal power of _{U 1} and SQ _U is converted into a digital signal, the output value of the digital signal is stored in association with the output wavelength of the intensity modulation light source 31 and the input terminals 34-1 to 34-4, and each output of the intensity modulation light source 31 is stored. The light intensity of the combined light from the optical coherent detector 42 at the wavelength is displayed for each of the input terminals 34-1 to 34-4.

  At this time, the one-signal interference light processing unit 36-26 stores the output value of the digital signal from the power detection unit 23 in association with the output wavelength of the intensity modulation light source 31 and the input terminals 34-1 to 34-4. The one-signal interference light display unit 37-26 displays the output value of the digital signal at each output wavelength of the intensity modulation light source 31 stored in the one-signal processing unit 36 for each of the input terminals 34-1 to 34-4. A display example of the one-signal interference light display unit 37-26 is the same as the display example of the two-signal interference light display unit 27-16 shown in FIG.

FIG. 21 shows a sixth example of the optical coherent detector evaluation method according to the present embodiment. The sixth example of the optical coherent detector evaluation method is a gain obtained by synthesizing two input lights to generate a pair of synthesized lights whose phases are inverted and receiving either one of the synthesized lights constituting the pair and adjusting the gain. electrical signal _PI C after the _adjustment, PQ _C, SI _C, receiving either the combined light constituting or pairs to output the SQ _C and the gain adjustment before the electrical signal _{PI U, PQ U, SI U} , The optical coherent detector 42 that outputs SQ _U is tested. The sixth example of the optical coherent detector evaluation method includes a one-signal wavelength variable branch light output procedure S271 and a one-signal loss measurement procedure S272 in order, and evaluates the optical loss in the optical coherent detector 42.

  In the one-signal wavelength variable branch light output procedure S271, the intensity-modulated light from the intensity-modulated light source 31 is branched into two branched lights while changing the output wavelength of the intensity-modulated light from the intensity-modulated light source 31, and the optical coherent detector 42 is used. One of the two branched lights is output as one of the input lights. At this time, the one-signal branching light wavelength control unit 38-27 causes the optical phase modulator 12 to output continuous light, and the optical coherent detector 42 receives a bias voltage for receiving one of the pair of combined lights. In the state where the gain adjustment circuit setting unit 39 is controlled so that the operations of the AGCs 59-1 to 59-4 for adjusting the gain by the optical coherent detector 42 are stopped, one of the branched lights is supplied to the first optical shutter 16. And the second optical shutter 18 shields the other of the branched light, and outputs one of the branched light while changing the output wavelength of the intensity-modulated light source 31.

The other of the branched lights is input from the second light output unit 19 to the input port 54 as the other L of the input light. The operations of the 90 ° optical hybrid 53-P, the 90 ° optical hybrid 53-S, and the balanced PDs 57-1 to 57-4 are the same as those in the third example of the optical coherent detector evaluation method described in the first embodiment. Since the operation of AGC59-1~59-4 is stopped, the optical coherent detector 42 outputs a _{PI U, PQ U, SI U} , SQ U.

In one signal loss measurement procedure S272, one of the two branched lights is received by the optical coherent detector 42 and output from the electrical signals PI _U , PQ _U , SI _U , and SQ _U before gain adjustment. each input to different input terminals 34-1 to 34-4 for each pair, the gain adjustment before the electrical signal _{PI U, PQ U, SI U} , the signal power of SQ _U for each input terminal 34-1 to 34-4 It detects and converts into a digital signal, the output value of the digital signal is stored in association with the output wavelength of the intensity modulation light source 31 and the input terminals 34-1 to 34-4, and the output power of the intensity modulation light source 31 and the output of the digital signal The loss between each input / output port of the optical coherent detector 42 at each output wavelength of the intensity modulation light source 31 is calculated for each of the input terminals 34-1 to 34-4 using the value, and each of the intensity modulation light source 31 is calculated. The loss of the optical coherent detector 42 with a force wavelengths and displayed for each input terminal 34-1 to 34-4.

  At this time, the one-signal light loss processing unit 36-27 uses the output value of each digital signal from the power detection unit 23 that is maximized when the polarization state is changed by the polarization controller 21 to the intensity modulation light source 31. The output wavelength and the input terminals 34-1 to 34-4 are stored in association with each other, and the output power of the intensity modulation light source 31 and the output value of the digital signal are used to output the optical coherent detector 42 at each output wavelength of the intensity modulation light source 31. The loss is calculated for each of the input terminals 34-1 to 34-4. The one-signal light loss display unit 37-27 displays the loss between the input / output ports of the optical coherent detector 42 at each output wavelength of the intensity modulation light source 31 for each of the input terminals 34-1 to 34-4. The display example of the one-signal light loss display unit 37-27 is the same as the display example of the two-signal light loss display unit 27-17 shown in FIG.

  In the one-signal wavelength variable branch light output procedure S271, the one-signal branch light wavelength control unit 38-27 transmits one of the branched lights to the first optical shutter 16 and transmits the branched light to the second optical shutter 18. One of the branched lights may be output while changing the output wavelength of the intensity-modulated light source 31 while blocking the other. Thereby, one of the input lights S is input into the input port 51, and the loss between the input port 51 and each output port can be measured.

  As described above, the optical coherent detector evaluation apparatus 102 and the optical coherent detector evaluation method according to the present embodiment can easily evaluate the optical coherent detector 42.

  In addition, in the optical coherent detector 42 of this embodiment, although the example provided with two 90 degree optical hybrids was shown, one 90 degree optical hybrid may be sufficient and three or more may be sufficient. If the number of 90 ° optical hybrids is one, the number of input terminals of one signal input unit 34 may be four. If the number of 90 ° optical hybrids is N, the number of input terminals of one signal input unit 34 may be The number may be 4 × N.

  The present invention can be applied to the information communication industry.

11: light source 12: optical phase modulator 13: phase modulation signal generator 14: driver 15: optical branching unit 16: first optical shutter 17: first optical output unit 18: second optical shutter 19: second Optical output unit 20: optical delay device 21: polarization controller 22: two signal input units 22-1, 22-2, 22-3, 22-4, 22-5, 11-6, 22-7, 22-2 8: Input terminal 23: Power detection unit 24: Waveform measurement unit 25: Bias voltage setting unit 26: Two-signal signal processing unit 26-11: Two-signal non-differential phase processing unit 26-12: Two-signal differential phase processing unit 26-14: Two-signal local optical branching ratio processing unit 26-15: Two-signal skew processing unit 26-16: Two-signal interference light processing unit 26-17: Two-signal optical loss processing unit 27: Two-signal display unit 27-11 : Two-signal non-differential phase display section 27-12: Two-signal differential phase display 27-14: Two-signal local optical branching ratio display section 27-15: Two-signal skew display section 27-16: Two-signal interference light display section 27-17: Two-signal light loss display section 28: Two-signal control section 28-11 : Two-signal non-differential delay control unit 28-12: Two-signal differential delay control unit 28-14: Two-signal polarization state control unit 28-15: Two-signal phase modulation light control unit 28-16: Two-signal interference light Wavelength control unit 28-17: Two-signal branched light wavelength control unit 30: Continuous light source 31: Intensity modulation light source 32: Intensity modulation signal generation unit 33: Optical switch 34: One signal input unit 34-1, 34-2, 34- 3, 34-4, 34-5, 34-6, 34-7, 34-8: input terminal 35: rectifier circuit 36: one signal processing unit 36-21: one signal non-differential phase processing unit 36-22: One-signal differential phase processing unit 36-24: One-signal local optical branching ratio processing 36-25: One signal skew processing unit 36-26: One signal interference light processing unit 36-27: One signal light loss processing unit 37: One signal display unit 37-21: One signal non-differential phase display unit 37-22 : One-signal differential phase display section 37-24: one-signal local optical branching ratio display section 37-25: one-signal skew display section 37-26: one-signal interference light display section 37-27: one-signal light loss display section 38 : One signal control unit 38-21: One signal non-differential delay control unit 38-22: One signal differential delay control unit 38-24: One signal polarization state control unit 38-25: One signal phase modulation light control unit 38-26: one-signal interference light wavelength control unit 38-27: one-signal branching light wavelength control unit 39: gain adjustment circuit setting unit 41, 42: optical coherent detector 51 :, 54: input port 52: PBS
53-P, 53-S: 90 ° optical hybrid 55: BS
57-1, 57-2, 57-3, 57-4: Balanced PD
58-1, 58-2, 58-3, 58-4: TIA
59-1, 59-2, 59-3, 59-4: AGC
61-1, 61-2, 61-3, 61-4: LPF
62-1, 62-2, 62-3, 62-4: ADC
101, 102: Optical coherent detector evaluation device

Claims (26)

Combines two input lights to generate a pair of combined lights whose phase is inverted, receives the balanced light, outputs a gain-adjusted electrical signal, and receives the balanced light of the combined light and gain An optical coherent detector evaluation apparatus (101) for testing an optical coherent detector (41) that outputs an electric signal before adjustment,
A light source (11) for outputting light;
A light branching section (15) for branching light from the light source into two branched lights;
A first optical shutter (16) that transmits or blocks one branched light from the light branching unit;
An optical delay device (20) for delaying one of the branched lights from the optical branching unit by an arbitrary delay amount;
A first light output unit (17) for outputting light from the optical delay device as one of input light of the optical coherent detector;
A second optical shutter (18) that transmits or blocks the other branched light from the light branching unit;
A second optical output section (19) for outputting the output light of the second optical shutter as the other input light of the optical coherent detector;
A polarization controller (21) that is disposed in an optical path between the light source and the first light output unit and changes at least one polarization state of the branched light;
Two-signal input having a plurality of input terminals, wherein the electric signal after gain adjustment and the electric signal before gain adjustment from the optical coherent detector are input to different input terminals for each pair of the combined light Part (22);
A power detector (23) for detecting the signal power of the electric signal before gain adjustment input to the two-signal input unit for each input terminal and outputting a digital signal;
A bias voltage setting unit (25) for setting a bias voltage for receiving balanced light by the optical coherent detector;
Second signal processing unit for performing signal processing using the signal power over detected by the power detection unit (26),
A two-signal display unit (27) for displaying a signal processing result of the two-signal processing unit;
Two-signal control unit for controlling operations of the first optical shutter, the second optical shutter, the optical delay unit, the polarization controller, the bias voltage setting unit, the two-signal processing unit, and the two-signal display unit (28) and
An optical coherent detector evaluation apparatus. The two-signal control unit keeps the polarization state changed by the polarization controller constant, transmits the branched light to the first optical shutter and the second optical shutter, and uses the optical coherent detector to One of the branched lights is output from the first optical output unit while changing the delay amount of the optical delay unit in a state where the bias voltage setting unit is controlled to a bias voltage for receiving one of the pair of combined light. And a two-signal non-differential delay control unit (28-11) for outputting the other of the branched lights from the second optical output unit,
The two-signal processing unit includes a two-signal non-differential phase processing unit (26-11) that stores an output value of a digital signal from the power detection unit in association with a delay amount of the optical delay device and the input terminal. Prepared,
The two-signal display unit includes a two-signal non-differential phase display unit (27-11) that displays an output value of the digital signal stored in the two-signal processing unit in a graph with respect to a delay amount of the optical delay device. The optical coherent detector evaluation apparatus according to claim 1. The two-signal control unit keeps the polarization state changed by the polarization controller constant, transmits the branched light to the first optical shutter and the second optical shutter, and uses the optical coherent detector to One of the branched lights is output from the first optical output unit while changing the delay amount of the optical delay device in a state where the bias voltage setting unit is controlled to a bias voltage for receiving a balanced pair of combined light. And a two-signal differential delay control unit (28-12) for outputting the other of the branched lights from the second optical output unit,
The two-signal processing unit includes a two-signal differential phase processing unit (26-12) that stores an output value of a digital signal from the power detection unit in association with a delay amount of the optical delay unit and the input terminal. ,
The two-signal display unit includes a two-signal differential phase display unit (27-12) that displays an output value of the digital signal stored in the two-signal processing unit in a graph with respect to a delay amount of the optical delay device. The optical coherent detector evaluation apparatus according to claim 1. The optical coherent detector separates one of the two input lights in a predetermined polarization state and generates a pair of combined lights whose phases are inverted by synthesizing the two input lights to receive balanced light. And the electric signal after the gain adjustment after gain adjustment is output and the pair of the combined light is received in a balanced manner and the electric signal before the gain adjustment is output.
The two-signal control unit causes the first optical shutter to block one of the branched lights, allows the second optical shutter to transmit the other of the branched lights, and the optical coherent detector detects the pair of combined lights. Two signals for outputting the other of the branched light from the second optical output unit while changing the polarization state of the polarization controller in a state where the bias voltage setting unit is controlled to a bias voltage for receiving one of the two A polarization state controller (28-14),
The two-signal processing unit calculates a branching ratio of local light in the arbitrary polarization state using an output value of the digital signal from the power detection unit (26-14) With
The two-signal display unit includes a two-signal local light branching ratio display unit (27-14) that displays a branching ratio of local light in the arbitrary polarization state calculated by the two-signal processing unit. The optical coherent detector evaluation apparatus according to claim 1. An optical phase modulator (12) for phase-modulating light from the light source with an input phase modulation signal;
A phase modulation signal generator (13) for generating the phase modulation signal;
A driver (14) for driving the optical phase modulator in accordance with a signal from the phase modulation signal generator and outputting phase modulated light from the optical phase modulator;
A waveform measuring unit (24) for measuring the signal waveform of the electric signal after gain adjustment input to the two-signal input unit for each of the input terminals,
The two-signal control unit outputs the phase-modulated light to the optical phase modulator, keeps the polarization state changed by the polarization controller constant, and transmits one of the branched lights to the first optical shutter. In the state where the bias voltage setting unit is controlled to a bias voltage that allows the second optical shutter to transmit the other of the branched lights and the optical coherent detector receives the combined light pair in a balanced manner. A two-signal phase-modulated light control unit (28-15) that outputs one of the branched lights from the optical output unit and outputs the other of the branched lights from the second light output unit ,
The second signal processing unit in place of the signal power, optical coherent detector evaluation device according to claim 1, characterized in that Ru using the signal waveform measured by the waveform measuring section. The light source has a variable output wavelength of light,
The two-signal control unit transmits one of the branched lights to the first optical shutter, transmits the other of the branched lights to the second optical shutter, and the pair of the combined lights by the optical coherent detector. A two-signal interference light wavelength control unit that outputs one of the branched light and the other of the branched light while changing the output wavelength of the light source in a state where the bias voltage setting unit is controlled to a bias voltage for receiving one of 28-16)
The two-signal processing unit includes a two-signal interference light processing unit (26-16) that stores an output value of a digital signal from the power detection unit in association with an output wavelength of the light source and the input terminal,
The two-signal display unit includes a two-signal interference light display unit (27-16) for displaying the output value of the digital signal at each output wavelength of the light source stored in the two-signal processing unit for each input terminal. The optical coherent detector evaluation device according to claim 1, comprising: The light source has a variable output wavelength of light,
The two-signal control unit is configured to control one of the branched lights to the first optical shutter in a state where the bias voltage setting unit is controlled to a bias voltage for receiving one of the pair of combined lights by the optical coherent detector. Transmit the second optical shutter to block the other of the branched light and output one of the branched light while changing the output wavelength of the light source, or let the first optical shutter emit the branched light. A two-signal branching light wavelength control unit (28-17) that shields one of the light and transmits the other of the branched light to the second optical shutter and outputs the other of the branched light while changing the output wavelength of the light source. With
The two-signal processing unit stores an output value of each digital signal that is maximum when the polarization state is changed by the polarization controller in association with an output wavelength of the light source and the input terminal, and the light source A two-signal optical loss processing unit (26) that calculates the loss between the input and output ports of the optical coherent detector at each output wavelength of the light source for each input terminal using the output power of the digital signal and the output value of the digital signal -17)
The two-signal display unit includes a two-signal light loss display unit (27-17) for displaying the loss of the optical coherent detector at each output wavelength of the light source calculated by the two-signal processing unit for each input terminal. The optical coherent detector evaluation apparatus according to claim 1, comprising: Generates a pair of combined lights whose phases are inverted by combining two input lights and outputs a balanced light signal and outputs a gain-adjusted electric signal, or receives the balanced light of the combined light pair and An optical coherent detector evaluation device (102) for testing an optical coherent detector (42) that outputs an electrical signal before gain adjustment,
An intensity-modulated light source (31) for outputting intensity-modulated light;
A light branching section (15) for branching the intensity-modulated light from the intensity-modulated light source into two branched lights;
A first optical shutter (16) that transmits or blocks one branched light from the light branching unit;
An optical delay device (20) for delaying one of the branched lights from the optical branching unit by an arbitrary delay amount;
A first light output unit (17) for outputting light from the optical delay device as one of input light of the optical coherent detector;
A second optical shutter (18) that transmits or blocks the other branched light from the light branching unit;
A second optical output section (19) for outputting the output light of the second optical shutter as the other input light of the optical coherent detector;
A polarization controller (21) that is inserted into an optical path between the intensity-modulated light source and the first optical shutter and changes at least one polarization state of the branched light;
A plurality of input terminals, wherein either the electrical signal after gain adjustment or the electrical signal before gain adjustment from the optical coherent detector is different for each pair of the combined light; One signal input section (34) to be input;
A rectifier circuit (35) for converting the intensity-modulated electrical signal before gain adjustment input to the one signal input unit from alternating current to direct current for each input terminal;
A power detector (23) for detecting the signal power of the electrical signal from the rectifier circuit for each input terminal and outputting a digital signal;
A bias voltage setting unit (25) for setting a bias voltage for receiving balanced light by the optical coherent detector;
A gain adjustment circuit setting unit (39) for setting an operation of a circuit for gain adjustment by the optical coherent detector;
First signal processing unit for performing signal processing using the signal power over detected by the power detection unit (36),
A signal display unit (37) for displaying a signal processing result of the signal processing unit;
Operations of the polarization controller, the first optical shutter, the second optical shutter, the optical delay device, the bias voltage setting unit, the gain adjustment circuit setting unit, the one signal processing unit, and the one signal display unit One signal control unit (38) for controlling
An optical coherent detector evaluation apparatus. The one signal control unit keeps the polarization state changed by the polarization controller constant, transmits one of the branched lights to the first optical shutter, and transmits the other of the branched lights to the second optical shutter. The bias voltage setting unit is controlled to a bias voltage for receiving the balanced pair of combined light with the optical coherent detector, and the operation of the circuit for adjusting the gain with the optical coherent detector is stopped. While controlling the gain adjustment circuit setting unit, while changing the delay amount of the optical delay device, one of the branched lights is output from the first optical output unit and the branch from the second optical output unit A one-signal non-differential delay control unit (38-21) for outputting the other of the light;
The one-signal processing unit includes a one-signal non-differential phase processing unit (36-21) that stores an output value of a digital signal from the power detection unit in association with a delay amount of the optical delay device and the input terminal. Prepared,
The one-signal display unit includes a one-signal non-differential phase display unit (37-21) that displays the output value of the digital signal stored in the one-signal processing unit in a graph with respect to the delay amount of the optical delay device. The optical coherent detector evaluation apparatus according to claim 8. The one signal control unit keeps the polarization state changed by the polarization controller constant, transmits one of the branched lights to the first optical shutter, and transmits the other of the branched lights to the second optical shutter. The bias voltage setting unit is controlled to a bias voltage for receiving one of the pair of the combined light with the optical coherent detector, and the operation of the circuit for adjusting the gain with the optical coherent detector is stopped. While controlling the gain adjustment circuit setting unit and controlling the bias voltage setting unit to a bias voltage for receiving one of the pair of combined light by the optical coherent detector, changing the delay amount of the optical delay unit The one-signal differential delay control unit (38-2) outputs one of the branched lights from the first optical output unit and outputs the other of the branched lights from the second optical output unit. ) Equipped with,
The one-signal processing unit includes a one-signal differential phase processing unit (36-22) that stores an output value of a digital signal from the power detection unit in association with a delay amount of the optical delay device and the input terminal. ,
The one-signal display unit includes a one-signal differential phase display unit (37-22) that displays an output value of the digital signal stored in the one-signal processing unit in a graph with respect to a delay amount of the optical delay device. The optical coherent detector evaluation apparatus according to claim 8. The optical coherent detector separates one of the two input lights in a predetermined polarization state and generates a pair of combined lights whose phases are inverted by synthesizing the two input lights to receive balanced light. And the gain-adjusted electric signal after gain adjustment or the pair of the combined light is received in a balanced manner and the electric signal before gain adjustment is output.
The one signal control unit causes the first optical shutter to block one of the branched lights, causes the second optical shutter to transmit the other of the branched lights, and the optical coherent detector detects the pair of the combined lights. The polarization controller in a state in which the bias voltage setting unit is controlled to a bias voltage for receiving one of the signals, and the gain adjustment circuit setting unit is controlled so that the operation of the circuit for gain adjustment by the optical coherent detector is stopped. A one-signal polarization state control unit (38-24) for outputting the other of the branched light from the second light output unit while changing the polarization state of
The one-signal processing unit calculates a branching ratio of local light in the arbitrary polarization state using an output value of the digital signal from the power detection unit (36-24). With
The one-signal display unit includes a one-signal local light branching ratio display unit (37-24) that displays a branching ratio of local light in the arbitrary polarization state calculated by the one signal processing unit. The optical coherent detector evaluation apparatus according to claim 8. A continuous light source (30) for outputting continuous light;
An optical phase modulator (12) for phase-modulating continuous light from the continuous light source with an input phase modulation signal;
A phase modulation signal generator (13) for generating the phase modulation signal;
A driver (14) for driving the optical phase modulator in accordance with a signal from the phase modulation signal generator and outputting phase modulated light from the optical phase modulator;
A waveform measuring unit (24) that measures the signal waveform of the gain-adjusted electrical signal input to the one signal input unit for each input terminal; and
The one-signal control unit outputs phase-modulated light to the optical phase modulator, keeps the polarization state changed by the polarization controller constant, and transmits one of the branched lights to the first optical shutter. The bias voltage setting unit is controlled to a bias voltage that transmits the other of the branched lights to the second optical shutter and receives the combined light pair in a balanced manner by the optical coherent detector, and the optical coherent detector. In the state where the gain adjustment circuit setting unit is controlled so that the circuit for adjusting the gain in the operation, one of the branched lights is output from the first light output unit, and the branch from the second light output unit A one-signal phase modulation light control unit (38-25) for outputting the other of the light ;
The one signal processing unit in place of the signal power, optical coherent detector evaluation device according to claim 8, characterized in that Ru using the signal waveform measured by the waveform measuring section. The intensity-modulated light source has a variable output wavelength of light,
The one-signal control unit transmits one of the branched lights to the first optical shutter, transmits the other of the branched lights to the second optical shutter, and the pair of the combined lights by the optical coherent detector. The intensity-modulated light source in a state where the bias voltage setting unit is controlled to a bias voltage for receiving balanced light, and the gain adjustment circuit setting unit is controlled so that the operation of the circuit for adjusting the gain by the optical coherent detector is stopped. A one-signal interference light wavelength control unit that outputs one of the branched lights from the first light output unit and outputs the other of the branched lights from the second light output unit ( 38-26),
The one-signal processing unit includes a one-signal interference light processing unit (36-26) that stores an output value of a digital signal from the power detection unit in association with an output wavelength of the intensity-modulated light source and the input terminal,
The one-signal display unit displays the output value of the digital signal at each output wavelength of the intensity-modulated light source stored in the one-signal processing unit for each input terminal (37-26). The optical coherent detector evaluation device according to claim 8, comprising: The intensity-modulated light source has a variable output wavelength of light,
The one-signal control unit controls the bias voltage setting unit to a bias voltage for receiving one of the combined light pair by the optical coherent detector, and the operation of the circuit for adjusting the gain by the optical coherent detector stops. In the state where the gain adjustment circuit setting unit is controlled as described above, the intensity-modulated light source is configured such that one of the branched lights is transmitted through the first optical shutter and the other of the branched lights is shielded from the second optical shutter. Either one of the branched lights is output while changing the output wavelength, or one of the branched lights is shielded by the first optical shutter and the other of the branched lights is transmitted to the second optical shutter. A one-signal branched light wavelength control unit (38-27) for outputting the other of the branched light while changing the output wavelength of the intensity-modulated light source;
The one signal processing unit stores the output value of each digital signal that is maximum when the polarization state is changed by the polarization controller, in association with the output wavelength of the intensity-modulated light source and the input terminal, One signal for calculating, for each input terminal, a loss between each input / output port of the optical coherent detector at each output wavelength of the intensity modulated light source using the output power of the intensity modulated light source and the output value of the digital signal An optical loss processing unit (36-27),
The one-signal display unit includes a one-signal light loss display unit (37-27) that displays, for each input terminal, the loss of the optical coherent detector at each output wavelength of the intensity-modulated light source. The optical coherent detector evaluation apparatus according to claim 8. Combines two input lights to generate a pair of combined lights whose phase is inverted, receives the balanced light, outputs a gain-adjusted electrical signal, and receives the balanced light of the combined light and gain An optical coherent detector evaluation method for testing an optical coherent detector (41) that outputs an electric signal before adjustment,
Two signals that output the two branched lights as the two input lights of the optical coherent detector while branching the light from the light source into two branched lights and changing the delay amount of one branched light. Differential delay light output procedure (S111);
The two branched lights received by the optical coherent detector and output from the optical coherent detector before the gain adjustment from the optical coherent detector is input to the different input terminals for each pair of the combined light, and A two-signal non-differential phase processing procedure (S112) for detecting the signal power of the electric signal before gain adjustment for each of the input terminals, outputting a digital signal, and displaying the output value of the digital signal with respect to the delay amount in a graph; ,
The optical coherent detector evaluation method which has these in order. Combines two input lights to generate a pair of combined lights whose phase is inverted, receives the balanced light, outputs a gain-adjusted electrical signal, and receives the balanced light of the combined light and gain An optical coherent detector evaluation method for testing an optical coherent detector (41) that outputs an electric signal before adjustment,
Two-signal differential that branches the light from the light source into two branched lights and outputs the two branched lights as the two input lights of the optical coherent detector while changing the delay amount of one of the branched lights Delayed light output procedure (S121);
The electric signals before gain adjustment from the optical coherent detector, which are output after the two branched lights are received in a balanced manner by the optical coherent detector, are input to the different input terminals for each pair of the combined lights. The two-signal differential phase processing procedure for detecting the signal power of the electrical signal before gain adjustment for each of the input terminals and outputting a digital signal, and displaying the output value of the digital signal with respect to the delay amount in a graph (S122) When,
The optical coherent detector evaluation method which has these in order. After gain adjustment in which one of the two input lights is separated in a predetermined polarization state, and the two input lights are combined to generate a pair of combined lights whose phases are inverted to receive balanced light and adjust the gain An optical coherent detector evaluation method for testing the optical coherent detector (41) that outputs the electrical signal and outputs the electrical signal before gain adjustment and balanced reception of the pair of combined lights,
A two-signal polarization output procedure for branching light from a light source into two branched lights and outputting the branched light as the other input light of the optical coherent detector while changing the polarization state of the light from the light source ( 141),
The other of the branched lights is received by the optical coherent detector, and the electric signal before gain adjustment output from the optical coherent detector is input to the input terminal that is different for each pair of the combined light, and the input signal is input to the input terminal. The signal power of the electrical signal before gain adjustment is converted into a digital signal, the output value of the digital signal is stored in association with the input terminal and the predetermined polarization state, and the other of the input light in an arbitrary polarization state A two-signal local optical branching ratio measurement procedure (S142) for calculating and displaying the branching ratio of
The optical coherent detector evaluation method which has these in order. Combines two input lights to generate a pair of combined lights whose phase is inverted, receives the balanced light, outputs a gain-adjusted electrical signal, and receives the balanced light of the combined light and gain An optical coherent detector evaluation method for testing an optical coherent detector (41) that outputs an electric signal before adjustment,
Two-signal phase-modulated light output procedure (S151) for phase-modulating light from a light source to branch into two branched lights and outputting the branched lights as one of the input lights and the other of the input lights of the optical coherent detector )When,
The gain-adjusted electrical signals from the optical coherent detector, which are output after the two branched lights are balanced and received by the optical coherent detector, are input to the input terminals that are different for each pair of the combined light. , A two-signal skew processing procedure (S152) for measuring the signal waveform of the electric signal after the gain adjustment for each input terminal;
The optical coherent detector evaluation method which has these in order. Combines two input lights to generate a pair of combined lights whose phase is inverted, receives the balanced light, outputs a gain-adjusted electrical signal, and receives the balanced light of the combined light and gain An optical coherent detector evaluation method for testing an optical coherent detector (41) that outputs an electric signal before adjustment,
Wavelength for two-signal interference that branches the light from the light source into two branched lights while changing the output wavelength of the light from the light source, and outputs the two branched lights as the two input lights of the optical coherent detector Variable light output procedure (S161);
The two branched lights received by the optical coherent detector and output from the optical coherent detector before the gain adjustment from the optical coherent detector is input to the different input terminals for each pair of the combined light, The signal power of the electric signal before gain adjustment input to the input terminal is converted into a digital signal, the output value of the digital signal is stored in association with the output wavelength of the light source and the input terminal, and each output of the light source A two-signal interference intensity measurement procedure (S162) for displaying for each input terminal the light intensity of the combined light at the optical coherent detector at a wavelength;
The optical coherent detector evaluation method which has these in order. Combines two input lights to generate a pair of combined lights whose phases are inverted, receives either one of the combined lights constituting the pair, and outputs a gain-adjusted electrical signal that is gain-adjusted An optical coherent detector evaluation method for testing an optical coherent detector (41) that receives any one of the combined lights constituting a pair and outputs an electrical signal before gain adjustment,
While changing the output wavelength of the light from the light source, the light from the light source is branched into two branched lights, and one of the two branched lights is output as one of the input lights of the optical coherent detector Two-wavelength variable wavelength branching light output procedure (S171) and either one of the branched branched light
One of the two branched lights is received by the optical coherent detector, and the electric signal before gain adjustment output from the optical coherent detector is input to the different input terminal for each pair of the combined light, and before the gain adjustment. The signal power of the electrical signal is detected for each input terminal and converted into a digital signal, and the output value of each digital signal that becomes maximum when the polarization state is changed by the polarization controller is output from the light source. A wavelength and the input terminal are stored in association with each other, and a loss between each input / output port of the optical coherent detector at each output wavelength of the light source using the output power of the light source and the output value of the digital signal is input. A two-signal loss measurement procedure (S172) for calculating for each terminal and displaying the loss of the optical coherent detector at each output wavelength of the light source for each input terminal;
The optical coherent detector evaluation method which has these in order. Combines two input lights to generate a pair of combined lights whose phases are inverted, receives either one of the combined lights constituting the pair, and outputs a gain-adjusted electrical signal that is gain-adjusted An optical coherent detector evaluation method for testing an optical coherent detector (42) that receives any one of the combined lights constituting a pair and outputs an electrical signal before gain adjustment,
One-signal non-differential that branches the intensity-modulated light into two branched lights and outputs the two branched lights as the two input lights of the optical coherent detector while changing the delay amount of one of the branched lights Delayed light output procedure (S211);
The two branched lights received by the optical coherent detector and output from the optical coherent detector before the gain adjustment from the optical coherent detector is input to the different input terminals for each pair of the combined light, and A one-signal non-differential phase processing procedure (S212) for detecting the signal power of the electric signal before gain adjustment for each of the input terminals, outputting a digital signal, and displaying the output value of the digital signal with respect to the delay amount in a graph; ,
The optical coherent detector evaluation method which has these in order. A pair of two input lights is combined to generate a pair of combined lights whose phase is inverted to receive the balanced light and output a gain-adjusted electric signal, and the received pair of the combined light is balanced or received; An optical coherent detector evaluation method for testing an optical coherent detector (42) that outputs an electrical signal before gain adjustment,
One-signal differential delay that branches the intensity-modulated light into two branched lights and outputs the two branched lights as the two input lights of the optical coherent detector while changing one delay amount of the branched lights Optical output procedure (S221);
The electric signals before gain adjustment from the optical coherent detector, which are output after the two branched lights are received in a balanced manner by the optical coherent detector, are input to the different input terminals for each pair of the combined lights. One-signal differential phase processing procedure for detecting the signal power of the electric signal before gain adjustment for each of the input terminals, outputting a digital signal, and displaying the output value of the digital signal with respect to the delay amount in a graph (S222) When,
The optical coherent detector evaluation method which has these in order. After gain adjustment in which one of the two input lights is separated in a predetermined polarization state, and the two input lights are combined to generate a pair of combined lights whose phases are inverted to receive balanced light and adjust the gain Or an optical coherent detector evaluation method for testing an optical coherent detector (42) that receives a balanced light of the pair of combined lights and outputs an electrical signal before gain adjustment,
One-signal polarization output procedure for branching the intensity-modulated light into two branched lights and outputting the branched light as the other of the input lights of the optical coherent detector while changing the polarization state of the intensity-modulated light (S241) )When,
The other of the branched lights is received by the optical coherent detector, and the electric signal before gain adjustment output from the optical coherent detector is input to the input terminal that is different for each pair of the combined light, and the input signal is input to the input terminal The signal power of the electrical signal before gain adjustment is converted into a digital signal, the output value of the digital signal is stored in association with the input terminal and the predetermined polarization state, and the other of the input light in an arbitrary polarization state A one-signal local optical branching ratio measurement procedure (S242) for calculating and displaying the branching ratio of
The optical coherent detector evaluation method which has these in order. Generates a pair of combined lights whose phases are inverted by combining two input lights and outputs a balanced light signal and outputs a gain-adjusted electric signal, or receives the balanced light of the combined light pair and An optical coherent detector evaluation method for testing an optical coherent detector (42) that outputs an electrical signal before gain adjustment,
A one-signal phase-modulated light output procedure (S251) for branching phase-modulated light into two branched lights and outputting the branched lights as one of the input light and the other of the input light of the optical coherent detector;
The gain-adjusted electrical signals from the optical coherent detector, which are output after the two branched lights are balanced and received by the optical coherent detector, are input to the input terminals that are different for each pair of the combined light. , One signal skew processing procedure (S252) for measuring the signal waveform of the electric signal after the gain adjustment for each input terminal;
The optical coherent detector evaluation method which has these in order. Generates a pair of combined lights whose phases are inverted by combining two input lights and outputs a balanced light signal and outputs a gain-adjusted electric signal, or receives the balanced light of the combined light pair and An optical coherent detector evaluation method for testing an optical coherent detector (42) that outputs an electrical signal before gain adjustment,
One signal that branches the intensity-modulated light into two branched lights while changing the output wavelength of the intensity-modulated light from the intensity-modulated light source, and outputs the two branched lights as the two input lights of the optical coherent detector A wavelength variable optical output procedure for interference (S261);
The two branched lights received by the optical coherent detector and output from the optical coherent detector before the gain adjustment from the optical coherent detector is input to the different input terminals for each pair of the combined light, and The signal power of the electrical signal before gain adjustment input to the input terminal is converted into a digital signal, the output value of the digital signal is stored in association with the output wavelength of the intensity modulation light source and the input terminal, and the intensity modulation A one-signal interference intensity measurement procedure (S262) for displaying for each input terminal the light intensity of the combined light at the optical coherent detector at each output wavelength of the light source;
The optical coherent detector evaluation method which has these in order. A combination of two input lights to generate a pair of combined lights whose phases are inverted and either one of the combined lights constituting the pair is received and a gain-adjusted electrical signal is output; or An optical coherent detector evaluation method for testing an optical coherent detector (42) that receives any one of the combined lights constituting the pair and outputs an electrical signal before gain adjustment,
While changing the output wavelength of the intensity modulated light from the intensity modulated light source, the intensity modulated light is branched into two branched lights, and one of the two branched lights as one of the input lights of the optical coherent detector One signal wavelength variable branch light output procedure for outputting one (S271) and one of the branched light branches
One of the two branched lights is received by the optical coherent detector, and the electric signal before gain adjustment output from the optical coherent detector is input to the different input terminal for each pair of the combined light, and before the gain adjustment. The signal power of the electrical signal is detected for each input terminal, converted into a digital signal, and the output value of each digital signal that becomes maximum when the polarization state is changed by the polarization controller is the intensity-modulated light source The output wavelength and the input terminal of the optical coherent detector at each output wavelength of the intensity modulated light source using the output power of the intensity modulated light source and the output value of the digital signal. The loss of the optical coherent detector at each output wavelength of the intensity-modulated light source is displayed for each input terminal. And No. loss measurement procedure (S272),
The optical coherent detector evaluation method which has these in order.

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