JP2007057251A - Optical interferometer type phase detection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical interferometer type phase detection apparatus capable of highly accurate phase detection with phase noise reduced and detecting the phase of an optical BPF etc. of an extremely narrow band which allows no reference light to pass. <P>SOLUTION: The optical interferometer type phase detection apparatus includes a photoreceiver 8 for outputting measurement interference signals; a photodetector 9 for outputting first reference interference signals; a photoreceiver 18 for outputting second reference interference signals; a phase detection means 11 for detecting the phase (measurement phase) of the measurement interference signals to the second reference interference signals; a phase detection means 12 for detecting the phase (reference phase) of the first reference interference signals to the second reference interference signals; and a signal processing means 13 for receiving a measurement mode specification signal for specifying first mode for determining phase characteristics of an object to be measured on the basis of both measuring light and reference light after their passage through the object to be measured or second mode for determining phase characteristics of the object to be measured only on the basis of the measuring light after its passage through the object to be measured, determining phase characteristics by subtracting a reference phase from a measurement phase in the first mode, and determining phase characteristics on the basis of a measurement phase in the second mode. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical interferometer-type phase detector that measures, for example, the phase characteristics of an object to be measured from the phase of interference light output from a Mach-Zehnder interferometer, and particularly uses reference light having a wavelength different from the wavelength of the measurement light. An optical interferometer type that reduces phase noise caused by relative optical path length variation between two optical paths of the interferometer (optical path to which the object to be measured is connected and optical path that is not connected) The present invention relates to a phase detection device. The optical interferometer type phase detector of the present invention includes optical component phase, group delay (GD), differential group delay (DGD), chromatic dispersion, amplitude, insertion loss, return loss, polarization It can be used for an optical component evaluation apparatus, an optical network analyzer, and the like for evaluating wave-dependent loss.

  The relative optical path length variation between the two optical paths of the Mach-Zehnder interferometer (the optical path to which the object to be measured is connected and the optical path that is not connected) depends on the temperature and vibration of the optical coupler, fiber, etc. constituting the interferometer. It occurs due to expansion and contraction due to external factors such as, and becomes a measurement error (phase noise) of phase detection. In order to reduce such phase noise, there has heretofore been an optical interferometer type phase detector that uses reference light having a wavelength different from the wavelength of the measurement light in addition to the measurement light. (For example, see Non-Patent Document 1)

A schematic configuration of this type of optical interferometer type phase detector is shown in FIG. The wavelength variable light source 1 outputs measurement light (frequency ν _s ) in a predetermined wavelength range to the optical coupler 3. The light source 2 outputs reference light (frequency ν _r ) having a wavelength different from that of the wavelength tunable light source 1 to the optical coupler 3. The optical coupler 3 combines the measurement light and the reference light, and outputs the wavelength multiplexed light obtained thereby to an acousto-optic frequency shifter (AOFS) 4a.

AOFS4a is driven by the ultrasonic (drive signal) of a frequency f ₁ input from the ultrasonic generator 4b, and demultiplexes the wavelength-multiplexed light from the optical coupler 3 into two light, the measured one of the light The other light is output to the first optical path to which the object 10 is connected and to the second optical path to which the optical delay device 5 is connected. At this time, the wavelengths (frequency) of the light output to the first optical path, that is, the measurement light and the reference light are not frequency-shifted, but the light output to the second optical path, that is, the wavelengths of the measurement light and the reference light, respectively. Is shifted by the ultrasonic frequency f ₁ . Therefore, the frequency difference between the measurement light and the reference light output from the optical demultiplexing means 4 composed of the AOFS 4a and the ultrasonic generator 4b to the two optical paths is f ₁ , which is a heterodyne detection described later. The beat frequency f ₁ is obtained.

  The optical coupler 6 multiplexes the light in the first optical path that has passed through the DUT 10 and the light in the second optical path that has passed through the optical delay device 5, and the interference light thus obtained, that is, 2 respectively. The interference light between the measurement lights (referred to as measurement interference light) and the interference light between the reference lights (referred to as reference interference light) that have passed through the two optical paths are output to the wavelength demultiplexer 7. The optical demultiplexing means 4, the device under test 10, the optical delay device 5 and the optical coupler 6 constitute a Mach-Zehnder interferometer 20 of an optical heterodyne interference system. The optical delay unit 5 matches the optical path lengths of the two optical paths of the Mach-Zehnder interferometer 20.

The wavelength demultiplexer 7 receives the interference light (measurement interference light and reference interference light) output from the optical coupler 6, demultiplexes it into each wavelength component of the measurement light and reference light, and receives the light receiver (PD) 8 and Output to a light receiver (PD) 9. The light receiver 8 receives the measurement interference light from the wavelength demultiplexer 7, performs photoelectric conversion (heterodyne detection), and outputs a measurement interference signal having a beat frequency f ₁ . Similarly, the light receiver 9 receives the reference interference light from the wavelength demultiplexer 7 and photoelectrically converts it (heterodyne detection), and outputs a reference interference signal having a beat frequency f ₁ . The phase detection means 11 detects the phase of the measurement interference signal with respect to the reference interference signal.

  In the conventional optical interferometer type phase detector configured as described above, the measurement light and the reference light having a wavelength different from the wavelength of the measurement light are simultaneously input to the Mach-Zehnder interferometer, and each of them is a Mach-Zehnder-type interferometer. The phase of the measurement interference light (measurement interference signal) with respect to the reference interference light (reference interference signal) is detected so that it passes through the same two optical paths of the Mach-Zehnder interferometer. It is possible to reduce phase detection measurement errors (phase noise) caused by relative optical path length fluctuations between an optical path including an object and an optical path not including an object.

51th Japan Federation of Reciprocal Products “Evaluation of Chromatic Dispersion Using a Two-Wavelength Heterodyne Fiber Interferometer” 28p-R-12 (2004.3): Kensuke Ogawa, Titi Ray (DNRI)

  However, in such a conventional optical interferometer type phase detector, when the object to be measured is an optical bandpass filter (optical BPF) having a very narrow band, only the measurement light passes through the object to be measured. A state occurs in which reference light having a wavelength different from that of light does not pass. As a result, since only the measurement interference light is output from the Mach-Zehnder interferometer and the reference interference light is not output, the phase detection unit cannot detect the phase of the measurement interference signal with respect to the reference interference signal, that is, the phase of the object to be measured. This causes a problem that characteristics cannot be obtained.

  The present invention is a measurement in which the phase noise based on the measurement light and the reference light after passing through the object to be measured is reduced, and the measurement in which the phase noise based on only the measurement light after passing through the object to be measured is not reduced By switching between these two measurement modes, these problems can be solved, phase detection with high accuracy can be performed, and phase detection of an object to be measured such as a very narrow-band optical BPF that does not allow passage of reference light It is an object of the present invention to provide an optical interferometer type phase detection device which can also be used.

  In order to solve the above-described problem, in the optical interferometer type phase detection device according to claim 1 of the present invention, the wavelength variable light source (1) that outputs measurement light in a predetermined wavelength range is different from the wavelength of the measurement light. A light source (2) that outputs a reference light having a wavelength, a first optical multiplexing means (3) that receives and multiplexes the measurement light and the reference light, and outputs wavelength-multiplexed light obtained thereby; Upon receiving the wavelength multiplexed light, the first light passing through the first optical path to which the device under test (10) is connected and the second light passing through the second optical path to which the device under test is not connected are demultiplexed. And the measurement light and the reference light included in the second light demultiplexed with the respective frequencies of the measurement light and the reference light included in the demultiplexed first light. The difference in frequency between the measurement beams and the difference in frequency between the reference beams are the same. First optical demultiplexing means (4) for shifting and outputting at least one of the first light and the second light by frequency shifters (4a to 4f) so as to obtain a predetermined beat frequency. ), And second optical multiplexing means (6) for combining the first light passing through the first optical path and the second light passing through the second optical path to output first interference light. And an optical heterodyne interferometer type Mach-Zehnder interferometer (30) and a first wavelength demultiplexer (7) that receives the first interference light and demultiplexes it into wavelength components of the measurement light and the reference light. ) And a first light receiver that receives the measurement interference light related to the wavelength component of the measurement light output from the first wavelength demultiplexer, photoelectrically converts it, and outputs a measurement interference signal of the predetermined beat frequency ( 8) and the wavelength component of the reference light output from the first wavelength demultiplexer. A second photoreceiver (9) that receives the first reference interference light and photoelectrically converts the first reference interference light and outputs the first reference interference signal having the predetermined beat frequency, and the measurement interference signal and the first reference In an optical interferometer type phase detector for obtaining a wavelength-phase characteristic of the device under test based on an interference signal, the first device is provided on the first optical path of the Mach-Zehnder type interferometer and before passing through the device under test. A second optical demultiplexing means (14) for demultiplexing a part of the first light, and a second optical demultiplexing means provided on the second optical path of the Mach-Zehnder interferometer; A third optical demultiplexing means (15) for wave, the light output from the second optical demultiplexing means and the third optical demultiplexing means, respectively, to multiplex the second interference light Third optical multiplexing means (16) for outputting, and receiving the second interference light and relating to the wavelength component of the reference light. A second wavelength demultiplexer (17) for outputting the second reference interference light, and photoelectrically converting the second reference interference light to output a second reference interference signal having the predetermined beat frequency. Receiving a third light receiver (18), the measurement interference signal and the second reference interference signal, detecting a phase of the measurement interference signal with respect to the second reference interference signal and outputting the phase as a measurement phase; 1 phase detecting means (11), receiving the first reference interference signal and the second reference interference signal, and detecting the phase of the first reference interference signal with respect to the second reference interference signal. First phase detecting means (12) for outputting as a reference phase, a first mode for measuring phase characteristics of the object to be measured based on the measurement light after passing through the object to be measured and the reference light, and the object to be measured The phase of the object to be measured based only on the measurement light after passing through the object When a measurement mode designating signal designating one of the second modes for determining the characteristics is received and the measurement mode designating signal designates the first mode, the reference phase is subtracted from the measurement phase. Signal processing means for obtaining the wavelength-phase characteristic of the object to be measured from the measurement phase when the wavelength-phase characteristic of the object to be measured is obtained and the measurement mode designation signal designates the second mode. (13).

  In the optical interferometer type phase detector according to claim 2 of the present invention, the wavelength variable light source (1) for outputting the measurement light in a predetermined wavelength range and the reference light having a wavelength different from the wavelength of the measurement light are output. A light source (2) for receiving, the first optical multiplexing means (3) for receiving and multiplexing the measurement light and the reference light, and outputting the wavelength multiplexed light obtained thereby, and the wavelength multiplexed light The first light passing through the first optical path to which the device under test (10) is connected and the second light passing through the second optical path to which the device under test is not connected are separated and demultiplexed. Further, the respective frequencies of the measurement light and the reference light included in the first light and the respective frequencies of the measurement light and the reference light included in the demultiplexed second light. The frequency difference between the measurement lights and the frequency difference between the reference lights are respectively predetermined beat frequencies. The optical demultiplexing means (4) for frequency-shifting and outputting at least one of the first light and the second light by frequency shifters (4a to 4f), and the first optical path Optical heterodyne interference type Mach-Zehnder type interference having second optical multiplexing means (6) for outputting the interference light by combining the first light passing through and the second light passing through the second optical path A meter (20), a wavelength demultiplexer (7) that receives the interference light and demultiplexes it into wavelength components of the measurement light and the reference light, and a wavelength of the measurement light output from the wavelength demultiplexer A first light receiver (8) that receives measurement interference light related to the component and photoelectrically converts it to output a measurement interference signal of the predetermined beat frequency; and a wavelength component of the reference light output from the wavelength demultiplexer. Receiving the reference interference light and photoelectrically converting the predetermined beat frequency An optical interferometer type phase detector for obtaining a wavelength-phase characteristic of the device under test based on the measurement interference signal and the reference interference signal, comprising: a second light receiver (9) for outputting an illumination interference signal; Phase detection reference signal generating means (4b, 4d, 4f, 19) for generating a phase detection reference signal having the same frequency as the predetermined beat frequency based on the drive signal of the frequency shifter, the measurement interference signal, and the First phase detection means (11) that receives the phase detection reference signal, detects the phase of the measurement interference signal with respect to the phase detection reference signal, and outputs it as the measurement phase; the reference interference signal; and the phase detection reference signal The second phase detection means (12) for detecting the phase of the reference interference signal with respect to the phase detection reference signal and outputting it as a reference phase; A first mode for obtaining the phase characteristic of the object to be measured based on the measurement light and the reference light, and a second mode for obtaining the phase characteristic of the object to be measured based only on the measurement light after passing through the object to be measured. When a measurement mode designation signal designating one of the modes is received and the measurement mode designation signal designates the first mode, the reference phase is subtracted from the measurement phase, and the wavelength of the object to be measured A signal processing means (13) for obtaining a phase characteristic and obtaining a wavelength-phase characteristic of an object to be measured from the measurement phase when the measurement mode designation signal designates the second mode; It was.

  In the optical interferometer type phase detector according to claim 3 of the present invention, the wavelength variable light source (1) for outputting the measurement light in a predetermined wavelength range and the reference light having a wavelength different from the wavelength of the measurement light are output. A light source (2) for receiving, the first optical multiplexing means (3) for receiving and multiplexing the measurement light and the reference light, and outputting the wavelength multiplexed light obtained thereby, and the wavelength multiplexed light The first light passing through the first optical path to which the device under test (10) is connected and the second light passing through the second optical path to which the device under test is not connected are separated and demultiplexed. Further, the respective frequencies of the measurement light and the reference light included in the first light and the respective frequencies of the measurement light and the reference light included in the demultiplexed second light. The frequency difference between the measurement lights and the frequency difference between the reference lights are respectively predetermined beat frequencies. The first optical demultiplexing means (4) for frequency-shifting and outputting at least one of the first light and the second light by frequency shifters (4a to 4f) An optical heterodyne having second optical multiplexing means (6) for combining the first light passing through one optical path and the second light passing through the second optical path to output first interference light An interference type Mach-Zehnder interferometer (30), a first wavelength demultiplexer (7) that receives the first interference light and demultiplexes it into wavelength components of the measurement light and the reference light; A first light receiver (8) that receives measurement interference light related to a wavelength component of the measurement light output from one wavelength demultiplexer, photoelectrically converts the measurement interference light, and outputs a measurement interference signal of the predetermined beat frequency; First reference interference light related to the wavelength component of the reference light output from the first wavelength demultiplexer A second light receiver (9) that receives and photoelectrically converts and outputs a first reference interference signal having the predetermined beat frequency, and based on the measurement interference signal and the first reference interference signal, In an optical interferometer type phase detector for obtaining a wavelength-phase characteristic of an object, a part of the first light before passing through the object to be measured is provided on the first optical path of the Mach-Zehnder interferometer. Second light demultiplexing means (14) for wave and third light for demultiplexing a part of the second light provided on the second optical path of the Mach-Zehnder interferometer Demultiplexing means (15), and third optical multiplexing means for combining the light respectively output from the second optical demultiplexing means and the third optical demultiplexing means to output second interference light (16) and the second reference interference light related to the wavelength component of the reference light in response to the second interference light And a third optical receiver (18) that receives the second reference interference light and photoelectrically converts it to output a second reference interference signal having the predetermined beat frequency. ) And the first mode for obtaining the phase characteristic of the object to be measured based on the measurement light and the reference light after passing through the object to be measured, and only the measurement light after passing through the object to be measured Upon receiving a measurement mode designating signal for designating one of the second modes for obtaining the phase characteristics of the device under test, the first reference interference signal and the second reference interference signal, the measurement mode designating signal is the first mode. When the mode is designated, the first reference interference signal is output, and when the measurement mode designation signal designates the second mode, the second reference interference signal is output. And a first reference interference signal from the switch. When the phase of the measurement interference signal with respect to the first reference interference signal is detected and output as the first measurement phase, and when the second reference interference signal is received from the switch A phase detection means (11) for detecting a phase of the measurement interference signal with respect to the second reference interference signal and outputting it as a second measurement phase, and the measurement mode designating signal designating the first mode If the wavelength-phase characteristic of the object to be measured is obtained from the first measurement phase, and the measurement mode designation signal designates the second mode, the measurement object is obtained from the second measurement phase. And signal processing means (23) for obtaining the wavelength-phase characteristic of the measurement object.

  In the optical interferometer type phase detector according to claim 4 of the present invention, the wavelength variable light source (1) for outputting the measurement light in a predetermined wavelength range and the reference light having a wavelength different from the wavelength of the measurement light are output. A light source (2) for receiving, the first optical multiplexing means (3) for receiving and multiplexing the measurement light and the reference light, and outputting the wavelength multiplexed light obtained thereby, and the wavelength multiplexed light The first light passing through the first optical path to which the device under test (10) is connected and the second light passing through the second optical path to which the device under test is not connected are separated and demultiplexed. Further, the respective frequencies of the measurement light and the reference light included in the first light and the respective frequencies of the measurement light and the reference light included in the demultiplexed second light. The frequency difference between the measurement lights and the frequency difference between the reference lights are respectively predetermined beat frequencies. The optical demultiplexing means (4) for frequency-shifting and outputting at least one of the first light and the second light by frequency shifters (4a to 4f), and the first optical path Optical heterodyne interference type Mach-Zehnder type interference having second optical multiplexing means (6) for outputting the interference light by combining the first light passing through and the second light passing through the second optical path A meter (20), a wavelength demultiplexer (7) that receives the interference light and demultiplexes it into wavelength components of the measurement light and the reference light, and a wavelength of the measurement light output from the wavelength demultiplexer A first light receiver (8) that receives measurement interference light related to the component and photoelectrically converts it to output a measurement interference signal of the predetermined beat frequency; and a wavelength component of the reference light output from the wavelength demultiplexer. Receiving the reference interference light and photoelectrically converting the predetermined beat frequency An optical interferometer type phase detector for obtaining a wavelength-phase characteristic of the device under test based on the measurement interference signal and the reference interference signal, comprising: a second light receiver (9) for outputting an illumination interference signal; Phase detection reference signal generation means (4b, 4d, 4f, 19) for generating a phase detection reference signal having the same frequency as the predetermined beat frequency based on the drive signal of the frequency shifter, and the object to be measured A first mode for obtaining the phase characteristic of the object to be measured based on the later measurement light and the reference light, and a first mode for obtaining the phase characteristic of the object to be measured based only on the measurement light after passing through the object to be measured. When receiving the measurement mode designating signal designating one of the two modes, the reference interference signal and the phase detection reference signal, and the measurement mode designating signal designates the first mode, the reference interference signal And a switch (22) for outputting the phase detection reference signal when the measurement mode specifying signal specifies the second mode, and receiving the reference interference signal from the switch. The phase of the measurement interference signal relative to the reference interference signal is detected and output as the first measurement phase, and when the phase detection reference signal is received from the switch, the phase detection reference signal Phase detection means (11) for detecting the phase of the measurement interference signal and outputting it as a second measurement phase; and when the measurement mode designation signal designates the first mode, the first measurement phase If the wavelength-phase characteristic of the object to be measured is obtained from the measurement mode and the measurement mode designation signal designates the second mode, the wavelength-phase characteristic of the object to be measured is obtained from the second measurement phase. Signal processing means (2 ) And with.

  Further, in the optical interferometer type phase detection device according to claim 5 of the present invention, in the optical interferometer type phase detection device according to any one of claims 1 to 4, the first optical path of the Mach-Zehnder interferometer and An optical delay device (5) for adjusting the optical path lengths of the two optical paths is provided on either one of the second optical paths.

  According to a sixth aspect of the present invention, there is provided the optical interferometer type phase detection device according to any one of the first to fifth aspects, wherein the Mach-Zehnder type interferometer is on the first optical path. Provided on the first optical path of the Mach-Zehnder interferometer, and first light intensity detecting means (24, 25) for detecting the intensity of light input to the object to be measured. Second light intensity detection means (26, 27) for detecting the intensity of light output from the measurement object is provided.

  According to a seventh aspect of the present invention, in the optical interferometer type phase detection device according to any one of the first to sixth aspects, the first optical path of the Mach-Zehnder type interferometer is provided. In addition, third light intensity detection means (24, 28) for detecting the intensity of the reflected light from the object to be measured of the light input to the object to be measured is provided.

  According to an optical interferometer type phase detector of claim 8 of the present invention, in the optical interferometer type phase detector of claim 6 described above, an object to be measured is placed on the first optical path of the Mach-Zehnder interferometer. A polarization controller (29) for changing the polarization of the light input to.

  Further, in the optical interferometer type phase detector according to claim 9 of the present invention, in the optical interferometer type phase detector of claim 7 described above, an object to be measured is placed on the first optical path of the Mach-Zehnder interferometer. A polarization controller (29) for changing the polarization of the light input to.

  The optical interferometer type phase detector according to claim 10 of the present invention is the optical interferometer type phase detector according to any one of claims 1 to 6 and 8, wherein the first interferometer of the Mach-Zehnder type interferometer is used. An object to be measured was connected to the first optical path via an optical circulator (31) provided on the optical path.

  Moreover, in the optical interferometer type phase detection device according to claim 11 of the present invention, in the optical interferometer type phase detection device according to any one of claims 1 to 6 and 8, the first of the Mach-Zehnder type interferometer is used. An object to be measured is connected to the first optical path via an optical coupler (32) provided on the optical path.

  In the optical interferometer type phase detector according to claims 1 to 4 of the present invention, the phase characteristic of the object to be measured is obtained based on the measurement light after passing through the object to be measured and the reference light by the measurement mode designation signal. Since the first mode and the second mode for obtaining the phase characteristic of the object to be measured can be switched based on only the measurement light after passing through the object to be measured, the phase noise is reduced in the first mode. In the second mode, it is possible to detect the phase of an object to be measured such as a very narrow-band optical BPF that cannot pass the reference light in the second mode.

  In the optical interferometer type phase detector according to claim 5 of the present invention, the optical path lengths of the two optical paths of the Mach-Zehnder interferometer are matched by the optical delay unit, so that the phase detection accuracy can be improved.

  In the optical interferometer type phase detector according to claim 6 of the present invention, the insertion loss of the object to be measured can be measured.

  In the optical interferometer type phase detector according to claim 7 of the present invention, the return loss of the object to be measured can be measured.

  In the optical interferometer type phase detector according to claim 8 of the present invention, it is possible to measure the polarization dependent loss of the object to be measured.

  In the optical interferometer type phase detector according to the ninth aspect of the present invention, the polarization dependent return loss of the object to be measured can be measured.

  In the optical interferometer type phase detection device according to the tenth and eleventh aspects of the present invention, the phase characteristic of the light (reflected light) reflected from the object to be measured and returned can be detected. For example, it is possible to detect the phase characteristic of an object to be measured such as an FBG (fiber Bragg grating) that reflects only light of a specific wavelength in the input light. Further, by performing Fourier transform on the obtained amplitude / phase data, the return loss distribution of the object to be measured can be measured.

  Embodiments of the present invention will be described below.

[First Embodiment]
The configuration of the optical interferometer type phase detector of the first embodiment of the present invention is shown in FIG. The same elements as those of the conventional optical interferometer type phase detector are denoted by the same reference numerals, and detailed description thereof is omitted. The wavelength tunable light source 1 is, for example, a wavelength tunable laser, and outputs measurement light (frequency ν _s ) in a predetermined wavelength range (for example, 1530 to 1560 nm) to the optical coupler 3. The light source 2 is a laser, for example, and outputs a reference light (frequency ν _r ) having a wavelength (for example, 1565 nm) different from the wavelength of the measurement light to the optical coupler 3. The optical coupler 3 combines the measurement light and the reference light, and outputs the wavelength multiplexed light obtained thereby to the optical coupler 4 g of the optical demultiplexing means 4.

The optical coupler 4g demultiplexes the input wavelength multiplexed light into two lights, and outputs one light to the AOFS 4e and the other light to the AOFS 4c. AOFS4e is driven by the ultrasonic (drive signal) of a frequency f ₁ input from the ultrasonic generator 4f, the one optical i.e. each wavelength of the measurement light and the reference light (frequency) is shifted ₁ minute frequency f outputting a first optical path that is connected to the DUT 10, also AOFS4c is driven by the ultrasonic frequency f ₂ inputted from the ultrasonic generator 4d (drive signals), the other light i.e. Te The wavelengths (frequency) of the measurement light and the reference light are shifted by the frequency f ₂ and output to the second optical path to which the device under test 10 is not connected. Accordingly, each of the measurement light and the reference light respectively output to the two optical paths from the optical demultiplexing means 4 constituted by the optical coupler 4g, AOFS 4c, AOFS 4e, the ultrasonic generator 4d and the ultrasonic generator 4f. The frequency difference is f ₁ −f ₂ , which is the beat frequency (f ₁ −f ₂ ) of heterodyne detection described later. In the optical demultiplexing means 4 having this configuration, since the AOFSs 4c and 4e are arranged in parallel, the phase characteristics (wavelength dispersion) generated by these two AOFSs can be canceled.

  The optical coupler 14 is provided on the first optical path and demultiplexes a part of the light input from the AOFS 4 e to the device under test 10 and outputs the demultiplexed light to the optical coupler 16. The optical coupler 15 is provided on the second optical path and demultiplexes part of the light input from the AOFS 4 c to the optical delay device 5 and outputs the demultiplexed light to the optical coupler 16.

  The optical coupler 6 multiplexes the light in the first optical path that has passed through the DUT 10 and the light in the second optical path that has passed through the optical delay device 5, and the interference light thus obtained, that is, 2 respectively. The interference light between the measurement lights (referred to as measurement interference light) and the interference light between the reference lights (referred to as reference interference light) that have passed through the two optical paths are output to the wavelength demultiplexer 7. The optical demultiplexing means 4, the optical coupler 14, the device under test 10, the optical coupler 15, the optical delay device 5, and the optical coupler 6 constitute a Mach-Zehnder interferometer 30 of an optical heterodyne interference system. The optical delay device 5 matches the optical path lengths of the two optical paths of the Mach-Zehnder interferometer 30.

The wavelength demultiplexer 7 receives the interference light (measurement interference light and reference interference light) output from the optical coupler 6, demultiplexes it into each wavelength component of the measurement light and reference light, and receives the light receiver (PD) 8 and Output to a light receiver (PD) 9. The light receiver 8 receives the measurement interference light from the wavelength demultiplexer 7, performs photoelectric conversion (heterodyne detection), and outputs a measurement interference signal having a beat frequency (f ₁ −f ₂ ). Similarly, the light receiver 9 receives the reference interference light from the wavelength demultiplexer 7 and photoelectrically converts (heterodyne detection), and outputs a first reference interference signal having a beat frequency (f ₁ −f ₂ ). .

The optical coupler 16 combines a part of the light of the first optical path output from the optical coupler 14 and a part of the light of the second optical path output from the optical coupler 15, and is thus obtained. The interference light (measurement interference light and reference interference light) is output to the wavelength demultiplexer 17. The wavelength demultiplexer 17 receives the interference light from the optical coupler 16 and demultiplexes only the reference interference light and outputs it to the light receiver (PD) 18. The light receiver 18 receives the reference interference light from the wavelength demultiplexer 17, performs photoelectric conversion (heterodyne detection), and outputs a second reference interference signal having a beat frequency (f ₁ −f ₂ ).

  The phase detector 11 receives the measurement interference signal output from the light receiver 8 and the second reference interference signal output from the light receiver 18 and detects the phase of the measurement interference signal with respect to the second reference interference signal. It outputs to the signal processing means 13 as a measurement phase. The phase detector 12 receives the first reference interference signal output from the light receiver 9 and the second reference interference signal output from the light receiver 18, and receives a first reference interference signal from the first reference interference signal. The phase of the reference interference signal is detected and output to the signal processing means 13 as a reference phase.

  The signal processing means 13 receives the measurement phase and the reference phase, and outputs a measurement mode designation signal (measured light and reference light after passing through the object to be measured 10) output from an operation unit (not shown). A first mode for determining the phase characteristics of the object to be measured 10 or a second mode for determining the phase characteristics of the object to be measured 10 based only on the measurement light after passing through the object to be measured 10). When the designation signal designates the first mode, the reference phase is subtracted from the measurement phase to obtain the wavelength-phase characteristic of the DUT 10, and the measurement mode designation signal designates the second mode. If it is, the wavelength-phase characteristic of the DUT 10 is obtained from the measurement phase.

  In the optical interferometer type phase detector of the first embodiment configured as described above, a part of the light in the first optical path and the part of the light in the second optical path before passing through the DUT 10 are combined. A second reference interference signal is generated from the interference light obtained by the wave, and this is used as a reference for phase detection. The measurement interference light (measurement interference signal) and the reference interference light (first interference signal) output from the Mach-Zehnder interferometer 30 are used. 1 of the reference interference signal (1 reference interference signal) to detect and set the measurement phase and the reference phase, and the measurement object 10 based on the measurement light and the reference light after passing through the measurement object 10 by the measurement mode designation signal Since the first mode for obtaining the phase characteristic of the measurement object or the second mode for obtaining the phase characteristic of the object to be measured 10 based only on the measurement light after passing through the object to be measured 10 is designated. Mode subtracts the reference phase from the measurement phase. In the second mode, the phase detection of the object 10 to be measured such as a very narrow-band optical BPF that cannot pass the reference light by using only the measurement phase is possible. Can do.

  In FIG. 1, an optical coupler 3 that combines the measurement light output from the wavelength variable light source 1 and the reference light output from the light source 2 to multiplex the wavelength, and the wavelength multiplexed light output from the optical coupler 3 The optical coupler 4g that receives the light and splits it into two lights is functionally distinguished from each other and is constituted by different optical couplers. However, it is obvious that the optical coupler 4g can also be constituted by one optical coupler. Further, the optical delay device 5 may be provided in the first optical path to which the DUT 10 is connected instead of the second optical path. However, this optical delay device 5 is effective in increasing the phase detection accuracy by combining the optical path lengths of the two optical paths of the Mach-Zehnder interferometer 30, but it is not always essential.

[Second Embodiment]
The configuration of the optical interferometer type phase detector of the second embodiment of the present invention is shown in FIG. In the first embodiment shown in FIG. 1, the phase detection reference of the two phase detection means 11 and 12 is obtained by using a part of the light in the first optical path before passing through the DUT 10 and the light in the second optical path. In the second embodiment, the second reference interference signal is generated based on the frequency shifter drive signal. Yes. It differs from FIG. 1 of 1st Embodiment only in following (1) and (2), and others are the same. Therefore, detailed description is omitted. (1) The element that generates the second reference interference signal, that is, the optical coupler 14, the optical coupler 15, the optical coupler 16, the wavelength demultiplexer 17, and the light receiver 18 are not provided. (2) Receive and mix the ultrasonic wave (driving signal) having the frequency f ₁ output from the ultrasonic generator 4f and the ultrasonic wave (driving signal) having the frequency f ₂ output from the ultrasonic generator 4d. A mixer (MIX) 19 and a low-pass filter (LPF) 33 that generate a signal having a difference frequency (f ₁ -f ₂ ) between the two drive signals and output it as a phase detection reference signal to the phase detection means 11, 12 are provided. . A band pass filter (BPF) may be used instead of the low pass filter 33.

[Third Embodiment]
The configuration of the optical interferometer type phase detector according to the third embodiment of the present invention is shown in FIG. In the first embodiment shown in FIG. 1, high-accuracy phase detection with reduced phase noise based on the measurement light and the reference light after passing through the measurement object 10 is performed, and the second reference interference signal is used as a reference for phase detection. The signal processing means 13 receiving the measurement phase and the reference phase output from the two phase detection means 11 and 12 respectively subtracted the reference phase from the measurement phase, but in the third embodiment, the measurement phase This is performed by switching the phase detection standard of the phase detection means 11 for detecting the second reference interference signal to the first reference interference signal.

  It differs from FIG. 1 of 1st Embodiment only in following (1) and (2), and others are the same. (1) The phase detection unit 12 for detecting the reference phase and the signal processing unit 13 for subtracting the reference phase from the measurement phase are not provided. (2) The switch 22 and the signal processing means 23 are provided. Therefore, mainly the phase detector 11 to which the first reference interference signal and the second reference interference signal are input from the switch 22, the signal processing unit 23, and the switch 22 will be described.

  The switch 22 receives the first reference interference signal output from the light receiver 9 and the second reference interference signal output from the light receiver 18, and specifies the measurement mode output from the operation unit (not shown). A signal (first mode in which the phase characteristic of the device under test 10 is obtained based on the measurement light and the reference light after passing through the device under test 10 or the measurement light after passing through the device under test 10 only. When the measurement mode designation signal designates the first mode, the first reference interference signal is output to the phase detector 11. If the measurement mode designation signal designates the second mode, the second reference interference signal is output to the phase detection means 11.

  When the phase detection means 11 receives the first reference interference signal from the switch 22, the phase detection means 11 detects the phase of the measurement interference signal with respect to the first reference interference signal, and outputs it to the signal processing means 23 as the first measurement phase. When the second reference interference signal is received from the switcher 22, the phase of the measurement interference signal with respect to the second reference interference signal is detected and output to the signal processing means 23 as the second measurement phase. When the measurement mode designation signal designates the first mode, the signal processing means 23 obtains the wavelength-phase characteristic of the DUT 10 from the first measurement phase output from the phase detection means 11, Further, when the measurement mode designation signal designates the second mode, the wavelength-phase characteristic of the device under test is obtained from the second measurement phase output from the phase detection means 11.

  As a result, in the first mode, by detecting the phase of the measurement interference signal (first measurement phase) with respect to the first reference interference signal, highly accurate phase detection with reduced phase noise can be performed. In this mode, by detecting the phase of the measurement interference signal (second measurement phase) with respect to the second reference interference signal, the phase detection of the object 10 to be measured such as a very narrow-band optical BPF that cannot pass the reference light Can do.

[Fourth Embodiment]
The configuration of the optical interferometer type phase detector of the fourth embodiment of the present invention is shown in FIG. In the second embodiment shown in FIG. 2, high-accuracy phase detection based on the measurement light after passing through the measurement object 10 and the reference light with reduced phase noise is used as the phase detection reference signal. The signal processing means 13 that has received the measurement phase and the reference phase respectively output from the two phase detection means 11 and 12 subtracts the reference phase from the measurement phase. In the fourth embodiment, the measurement phase is detected. This is done by switching the phase detection reference of the phase detection means 11 to the reference interference signal (output from the light receiver 9) from the phase detection reference signal.

  It differs from FIG. 2 of 2nd Embodiment only in following (1) and (2), and others are the same. (1) The phase detection unit 12 for detecting the reference phase and the signal processing unit 13 for subtracting the reference phase from the measurement phase are not provided. (2) The switch 22 and the signal processing means 23 are provided. Therefore, the phase detector 11 to which the reference interference signal and the phase detection reference signal are input from the switch 22, the signal processor 23, and the switch 22 will be mainly described.

  The switch 22 receives the reference interference signal output from the light receiver 9 and the phase detection reference signal output from the low-pass filter 33, and also outputs a measurement mode designation signal (object to be measured) output from an operation unit (not shown). The first mode in which the phase characteristic of the device under test 10 is obtained based on the measurement light after passing through 10 and the reference light, or the phase of the device under test 10 based only on the measurement light after passing through the device under test 10. When the measurement mode designation signal designates the first mode, the reference interference signal is output to the phase detection means 11 and the measurement mode designation signal is designated. Outputs the phase detection reference signal to the phase detection means 11 when the second mode is designated.

  When receiving the reference interference signal from the switch 22, the phase detection unit 11 detects the phase of the measurement interference signal with respect to the reference interference signal and outputs it to the signal processing unit 23 as the first measurement phase. When the phase detection reference signal is received from, the phase of the measurement interference signal with respect to the phase detection reference signal is detected and output to the signal processing means 23 as the second measurement phase. When the measurement mode designation signal designates the first mode, the signal processing means 23 obtains the wavelength-phase characteristic of the DUT 10 from the first measurement phase output from the phase detection means 11, Further, when the measurement mode designation signal designates the second mode, the wavelength-phase characteristic of the device under test is obtained from the second measurement phase output from the phase detection means 11.

  As a result, in the first mode, by detecting the phase of the measurement interference signal (first measurement phase) with respect to the reference interference signal, it is possible to perform highly accurate phase detection with reduced phase noise, and in the second mode, By detecting the phase of the measurement interference signal (second measurement phase) with respect to the phase detection reference signal, the phase of the DUT 10 such as a very narrow-band optical BPF that cannot pass the reference light can be detected.

[Fifth Embodiment]
The configuration of the optical interferometer type phase detector of the fifth embodiment of the present invention is shown in FIG. In the first embodiment shown in FIG. 1, the wavelength-phase characteristic of the device under test 10 is obtained. However, in the fifth embodiment, the insertion loss measurement and the return loss measurement of the device under test 10 can be performed. I have to. It differs from FIG. 1 of 1st Embodiment only in following (1) and (2), and others are the same. Therefore, detailed description is omitted. (1) An optical coupler 24 and a light receiver for detecting the intensity of light input to the device under test 10 between the optical coupler 14 on the first optical path of the Mach-Zehnder interferometer 30 and the device under test 10. (PD) 25 and an optical coupler 26 and a light receiver (PD) 27 for detecting the intensity of light output from the device under test 10 are provided between the device under test 10 and the optical coupler 6. . Thereby, the insertion loss of the DUT 10 can be measured. (2) Light input to the device under test 10 is reflected by the device under test 10 between the optical coupler 14 on the first optical path of the Mach-Zehnder interferometer 30 and the device under test 10 and returned. An optical coupler 24 and a light receiver (PD) 28 for detecting the intensity of light (reflected light) are provided. Thereby, the return loss of the DUT 10 can be measured. In the fifth embodiment, the configuration for measuring the insertion loss and the return loss of the DUT 10 is shown by taking the case of the first embodiment as an example. This configuration is the second to fourth embodiments. Needless to say, the present invention can also be applied to the form.

[Sixth Embodiment]
The configuration of the optical interferometer type phase detector according to the sixth embodiment of the present invention is shown in FIG. In the fifth embodiment shown in FIG. 5, the insertion loss measurement and the return loss measurement of the device under test 10 can be performed. However, in the sixth embodiment, the polarization dependent loss of the device under test 10 can be measured. It has a configuration. 5 of the fifth embodiment, the polarization of light input to the device under test 10 is changed between the optical coupler 24 on the first optical path of the Mach-Zehnder interferometer 30 and the device under test 10. The only difference is that a polarization controller 29 is provided. Therefore, detailed description is omitted. Note that the polarization controller 29 may be provided between the optical coupler 14 and the optical coupler 24.

[Seventh Embodiment]
The configuration of the optical interferometer type phase detector of the seventh embodiment of the present invention is shown in FIG. In the first embodiment shown in FIG. 1, the wavelength-phase characteristic of the light (transmitted light) transmitted through the device under test 10 is obtained. In the seventh embodiment, the light is reflected from the device under test 10. The wavelength-phase characteristics of the returning light (reflected light) are obtained. FIG. 1 of the first embodiment is different from FIG. 1 only in that the DUT 10 is connected to the first optical path via the optical circulator 31 provided on the first optical path of the Mach-Zehnder interferometer 30. The others are the same. Therefore, detailed description is omitted. In the seventh embodiment, the configuration for obtaining the wavelength-phase characteristic of the reflected light from the DUT 10 is shown by taking the case of the first embodiment as an example, but this configuration is the second to fourth embodiments. Needless to say, the present invention can also be applied to the form. Further, in place of the optical circulator 31 in FIG. 7, as shown in FIG.

[Eighth Embodiment]
FIG. 9 shows the configuration of an optical interferometer type phase detector according to an eighth embodiment of the present invention. In the seventh embodiment shown in FIG. 7, the wavelength-phase characteristic of the reflected light of the device under test 10 is obtained. However, in the eighth embodiment, the return loss of the device under test 10 can be measured. ing. This embodiment is the same as FIG. 7 of the seventh embodiment except for the following points. Therefore, detailed description is omitted. That is, between the optical coupler 14 and the optical circulator 31 on the first optical path of the Mach-Zehnder interferometer 30, an optical coupler 24 and a light receiver (PD) for detecting the intensity of light input to the device under test 10. ) 25, and between the optical circulator 31 and the optical coupler 6, an optical coupler 26 and a light receiver (PD) 27 for detecting the intensity of reflected light from the DUT 10. Thereby, the return loss of the DUT 10 can be measured.

[Ninth Embodiment]
The configuration of the optical interferometer type phase detector of the ninth embodiment of the present invention is shown in FIG. In the eighth embodiment shown in FIG. 9, the configuration is such that the return loss of the device under test 10 can be measured. However, in the ninth embodiment, the configuration is such that the polarization dependent return loss of the device under test 10 can be measured. ing. FIG. 9 of the eighth embodiment is for changing the polarization of light input to the device under test 10 between the optical coupler 24 and the optical circulator 31 on the first optical path of the Mach-Zehnder interferometer 30. The only difference is that the polarization controller 29 is provided. Therefore, detailed description is omitted. Note that the polarization controller 29 may be provided between the optical coupler 14 and the optical coupler 24.

[Tenth embodiment]
FIG. 11 shows the configuration of an optical interferometer type phase detector according to the tenth embodiment of the present invention. In the first embodiment shown in FIG. 1, the optical demultiplexing means 4 uses two frequency shifters, and the respective frequencies of the measurement light and the reference light that are output to the first optical path and the second optical path, respectively. Although the difference was configured to f ₁ -f _2, in the tenth embodiment, the light dividing means 4 using one frequency shifter, is output to the first optical path and second optical path of the measurement The frequency difference between the lights and the reference lights is set to f ₁ . It differs from FIG. 1 of 1st Embodiment only in the structure of the optical demultiplexing means 4 of the Mach-Zehnder interferometer 30, and others are the same. Therefore, description of the same part as FIG. 1 is omitted, and the optical demultiplexing means 4 will be described.

The optical demultiplexing unit 4 includes an optical coupler 4g, an AOFS 4e, and an ultrasonic generator 4f. The optical coupler 4g demultiplexes the wavelength multiplexed light (measurement light and reference light) input from the optical coupler 3 into two lights, outputs one light to the optical coupler 14 on the first optical path, and the other Are output to the AOFS 4e. The AOFS 4e is driven by the ultrasonic wave (driving signal) having the frequency f ₁ input from the ultrasonic generator 4f, and shifts the wavelength (frequency) of the other light, that is, the measurement light and the reference light by the frequency f _1. To the optical coupler 15 on the second optical path. Therefore, the respective frequency differences between the measurement beams and the reference beams output from the optical demultiplexing unit 4 to the two optical paths are f ₁ . The optical demultiplexing means 4 of the tenth embodiment may be the optical demultiplexing means 4 shown in FIG. 16 of the conventional example in addition to the one shown in FIG.

[Eleventh embodiment]
The configuration of the optical interferometer type phase detector of the eleventh embodiment of the present invention is shown in FIG. In the second embodiment shown in FIG. 2, the optical demultiplexing means 4 uses two frequency shifters, and the respective frequencies of the measurement light and the reference light that are output to the first optical path and the second optical path, respectively. Although the difference is set to f ₁ −f ₂ , in the eleventh embodiment, the optical demultiplexing unit 4 uses a single frequency shifter, and the measurement is output to each of the first optical path and the second optical path. The frequency difference between the lights and the reference lights is set to f ₁ . It differs from FIG. 2 of 2nd Embodiment only in following (1) and (2), and others are the same. (1) The mixer 19 is not provided. (2) The configuration of the optical demultiplexing means 4 of the Mach-Zehnder interferometer 20 is different. Therefore, description of the same part as FIG. 2 is omitted, and the optical demultiplexing means 4 will be mainly described.

The optical demultiplexing unit 4 includes an optical coupler 4g, an AOFS 4e, and an ultrasonic generator 4f. The optical coupler 4g splits the wavelength multiplexed light (measurement light and reference light) input from the optical coupler 3 into two lights, and outputs one light to the device under test 10 on the first optical path. The other light is output to the AOFS 4e. The AOFS 4e is driven by the ultrasonic wave (driving signal) having the frequency f ₁ input from the ultrasonic generator 4f, and shifts the wavelength (frequency) of the other light, that is, the measurement light and the reference light by the frequency f _1. To the optical delay device 5 on the second optical path. Therefore, the respective frequency differences between the measurement beams and the reference beams output from the optical demultiplexing unit 4 to the two optical paths are f ₁ . The ultrasonic generator 4f outputs to the phase detector 11 and the phase detector 12 ultrasonic frequency f ₁ (driving signal) as the phase detection reference signal. The optical demultiplexing means 4 of the eleventh embodiment may be the optical demultiplexing means 4 shown in FIG. 16 of the conventional example in addition to the one shown in FIG.

[Twelfth embodiment]
The configuration of the optical interferometer type phase detector of the twelfth embodiment of the present invention is shown in FIG. In the third embodiment shown in FIG. 3, the optical demultiplexing means 4 uses two frequency shifters, and the respective frequencies of the measurement light and the reference light output to the first optical path and the second optical path, respectively. Although the difference is f ₁ −f ₂ , in the twelfth embodiment, the optical demultiplexing unit 4 uses a single frequency shifter to perform measurement output to the first optical path and the second optical path, respectively. The frequency difference between the lights and the reference lights is set to f ₁ . This embodiment is the same as FIG. 3 of the third embodiment except for the configuration of the optical demultiplexing means 4 of the Mach-Zehnder interferometer 30. By the way, since this optical demultiplexing means 4 is the same as the content demonstrated in FIG. 11 of 10th Embodiment, the description is abbreviate | omitted.

The optical demultiplexing means 4 of the first to ninth embodiments described above may be those shown in FIGS. 14 and 15 in addition to those shown in FIGS. 14 and 15 indicate the frequency ν _s of the measurement light included in the wavelength multiplexed light.

That is, in FIG. 14, AOFS 4a and AOFS 4c are arranged in series. First, the AOFS 4a demultiplexes the input wavelength multiplexed light (measurement light and reference light) into two lights, outputs one light as the first light to the first optical path, and outputs the other light. The ultrasonic wave input from the ultrasonic generator 4b is shifted by the frequency f1 (giving + _1st order diffraction) and output to the AOFS 4c. Next, the AOFS 4c shifts the light from the AOFS 4a by the frequency f _{2 of the} ultrasonic wave input from the ultrasonic generator 4d (gives −1st order diffraction) and outputs it as the second light to the second optical path. To do. Therefore, the respective frequency differences between the measurement beams and the reference beams output from the optical demultiplexing unit 4 to the two optical paths are f ₁ −f ₂ .

In FIG. 15, similarly to FIG. 14, AOFS 4a and AOFS 4c are arranged in series. First, the AOFS 4a demultiplexes the input wavelength multiplexed light (measurement light and reference light) into two lights, one of which is input to the AOFS 4c and the other of which is input from the ultrasonic generator 4b. The sound wave is shifted by the frequency f ₁ and outputted as the first light to the first optical path. Next, the AOFS 4c shifts the light from the AOFS 4a by the frequency f _{2 of the} ultrasonic wave input from the ultrasonic generator 4d, and outputs it as the second light to the second optical path. Therefore, the respective frequency differences between the measurement beams and the reference beams output from the optical demultiplexing unit 4 to the two optical paths are f ₁ −f ₂ .

The figure which shows the structure of 1st Embodiment of this invention. The figure which shows the structure of 2nd Embodiment of this invention. The figure which shows the structure of 3rd Embodiment of this invention. The figure which shows the structure of 4th Embodiment of this invention. The figure which shows the structure of 5th Embodiment of this invention. The figure which shows the structure of 6th Embodiment of this invention. The figure which shows the structure of 7th Embodiment of this invention. The figure which shows another structure of 7th Embodiment of this invention. The figure which shows the structure of 8th Embodiment of this invention. The figure which shows the structure of 9th Embodiment of this invention. The figure which shows the structure of 10th Embodiment of this invention. The figure which shows the structure of 11th Embodiment of this invention. The figure which shows the structure of 12th Embodiment of this invention. The figure which shows another structure of an optical demultiplexing means The figure which shows another structure of an optical demultiplexing means The figure which shows schematic structure of a prior art example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Variable wavelength light source, 2 ... Light source, 3, 4g, 6, 14, 15, 16, 24, 26, 32 ... Optical coupler, 4 ... Optical demultiplexing means, 4a, 4c, 4e, acousto-optic frequency shifter (AOFS), 4b, 4d, 4f, ultrasonic generator, 5 ... optical delay, 7, 17 ... wavelength demultiplexer, 8, 9, 18, 25, 27, 28 ... light receiver (PD), 10 ... object to be measured, 11, 12 ... phase detection means, 13, 23 ... signal processing means, 19 ... mixer (MIX) 20, 30 ... Mach-Zehnder interferometers, 22 ... switches, 29 ... polarization controllers, 31 ... optical circulators, 33 ... low pass filters (LPF).

Claims (11)

A wavelength tunable light source (1) that outputs measurement light in a predetermined wavelength range;
A light source (2) that outputs reference light having a wavelength different from the wavelength of the measurement light;
First optical multiplexing means (3) for receiving and multiplexing the measurement light and the reference light and outputting the wavelength multiplexed light obtained thereby;
Upon receiving the wavelength-multiplexed light, the first light passing through the first optical path to which the device under test (10) is connected and the second light passing through the second optical path to which the device under test is not connected are separated. The measurement light and the reference included in the second light demultiplexed with the respective frequencies of the measurement light and the reference light included in the demultiplexed first light. The frequency of at least one of the first light and the second light is set so that the frequency difference between the measurement lights and the frequency difference between the reference lights with respect to the respective frequencies of the light each have a predetermined beat frequency. The first optical demultiplexing means (4) that outputs the frequency shifted by the shifters (4a to 4f), and the first light that passes through the first optical path and the second light that passes through the second optical path And a second optical multiplexing means (6) for outputting the first interference light. That the Mach-Zehnder interferometer optical heterodyne interferometry (30),
A first wavelength demultiplexer (7) that receives the first interference light and demultiplexes it into each wavelength component of the measurement light and the reference light;
A first light receiver (8) that receives measurement interference light related to the wavelength component of the measurement light output from the first wavelength demultiplexer, photoelectrically converts the measurement interference light, and outputs a measurement interference signal of the predetermined beat frequency; ,
Receiving a first reference interference light related to a wavelength component of the reference light output from the first wavelength demultiplexer, photoelectrically converting the second reference interference light and outputting a first reference interference signal having the predetermined beat frequency; An optical interferometer type phase detector for obtaining a wavelength-phase characteristic of the object to be measured based on the measurement interference signal and the first reference interference signal;
Second optical demultiplexing means (14) provided on the first optical path of the Mach-Zehnder interferometer, for demultiplexing a part of the first light before passing through the object to be measured;
Third optical demultiplexing means (15) provided on the second optical path of the Mach-Zehnder interferometer, for demultiplexing a part of the second light;
A third optical multiplexing means (16) for combining the light respectively output from the second optical demultiplexing means and the third optical demultiplexing means to output a second interference light;
A second wavelength demultiplexer (17) that receives the second interference light and outputs a second reference interference light related to a wavelength component of the reference light;
A third light receiver (18) that receives and photoelectrically converts the second reference interference light and outputs a second reference interference signal of the predetermined beat frequency;
First phase detection means (11) for receiving the measurement interference signal and the second reference interference signal, detecting a phase of the measurement interference signal with respect to the second reference interference signal, and outputting the phase as a measurement phase;
Second phase detection that receives the first reference interference signal and the second reference interference signal, detects the phase of the first reference interference signal with respect to the second reference interference signal, and outputs it as a reference phase Means (12);
A first mode for obtaining a phase characteristic of the measurement object based on the measurement light and the reference light after passing through the measurement object, and the measurement object based only on the measurement light after passing through the measurement object When a measurement mode designating signal designating any one of the second modes for obtaining the phase characteristics of the signal is received and the measurement mode designating signal designates the first mode, the reference phase is calculated from the measurement phase. A signal for obtaining the wavelength-phase characteristic of the object to be measured from the measurement phase when the wavelength-phase characteristic of the object to be measured is obtained by subtraction, and the measurement mode designation signal designates the second mode. An optical interferometer type phase detector comprising a processing means (13). A wavelength tunable light source (1) that outputs measurement light in a predetermined wavelength range;
A light source (2) that outputs reference light having a wavelength different from the wavelength of the measurement light;
First optical multiplexing means (3) for receiving and multiplexing the measurement light and the reference light and outputting the wavelength multiplexed light obtained thereby;
Upon receiving the wavelength-multiplexed light, the first light passing through the first optical path to which the device under test (10) is connected and the second light passing through the second optical path to which the device under test is not connected are separated. The measurement light and the reference included in the second light demultiplexed with the respective frequencies of the measurement light and the reference light included in the demultiplexed first light. The frequency of at least one of the first light and the second light is set so that the frequency difference between the measurement lights and the frequency difference between the reference lights with respect to the respective frequencies of the light each have a predetermined beat frequency. The optical demultiplexing means (4) that outputs the frequency shifted by the shifters (4a to 4f), and the first light that passes through the first optical path and the second light that passes through the second optical path are combined. Optical heterogeneity having second optical multiplexing means (6) for outputting interference light by wave generation Mach-Zehnder interferometer in-interference system (20),
A wavelength demultiplexer (7) that receives the interference light and demultiplexes it into each wavelength component of the measurement light and the reference light;
A first light receiver (8) that receives measurement interference light related to the wavelength component of the measurement light output from the wavelength demultiplexer, photoelectrically converts the measurement interference light, and outputs a measurement interference signal of the predetermined beat frequency;
A second light receiver (9) that receives reference interference light related to the wavelength component of the reference light output from the wavelength demultiplexer, photoelectrically converts the reference interference light, and outputs a reference interference signal having the predetermined beat frequency; In an optical interferometer type phase detector for obtaining a wavelength-phase characteristic of the device under test based on the measurement interference signal and the reference interference signal,
Phase detection reference signal generating means (4b, 4d, 4f, 19) for generating a phase detection reference signal having the same frequency as the predetermined beat frequency based on the drive signal of the frequency shifter;
First phase detection means (11) for receiving the measurement interference signal and the phase detection reference signal, detecting a phase of the measurement interference signal with respect to the phase detection reference signal, and outputting the phase as a measurement phase;
Second phase detection means (12) that receives the reference interference signal and the phase detection reference signal, detects a phase of the reference interference signal with respect to the phase detection reference signal, and outputs it as a reference phase;
A first mode for obtaining a phase characteristic of the measurement object based on the measurement light and the reference light after passing through the measurement object, and the measurement object based only on the measurement light after passing through the measurement object When a measurement mode designating signal designating any one of the second modes for obtaining the phase characteristics of the signal is received and the measurement mode designating signal designates the first mode, the reference phase is calculated from the measurement phase. A signal for obtaining the wavelength-phase characteristic of the object to be measured from the measurement phase when the wavelength-phase characteristic of the object to be measured is obtained by subtraction, and the measurement mode designation signal designates the second mode. An optical interferometer type phase detector comprising a processing means (13). A wavelength tunable light source (1) that outputs measurement light in a predetermined wavelength range;
A light source (2) that outputs reference light having a wavelength different from the wavelength of the measurement light;
First optical multiplexing means (3) for receiving and multiplexing the measurement light and the reference light and outputting the wavelength multiplexed light obtained thereby;
Upon receiving the wavelength-multiplexed light, the first light passing through the first optical path to which the device under test (10) is connected and the second light passing through the second optical path to which the device under test is not connected are separated. The measurement light and the reference included in the second light demultiplexed with the respective frequencies of the measurement light and the reference light included in the demultiplexed first light. The frequency of at least one of the first light and the second light is set so that the frequency difference between the measurement lights and the frequency difference between the reference lights with respect to the respective frequencies of the light each have a predetermined beat frequency. The first optical demultiplexing means (4) that outputs the frequency shifted by the shifters (4a to 4f), and the first light that passes through the first optical path and the second light that passes through the second optical path And a second optical multiplexing means (6) for outputting the first interference light. That the Mach-Zehnder interferometer optical heterodyne interferometry (30),
A first wavelength demultiplexer (7) that receives the first interference light and demultiplexes it into each wavelength component of the measurement light and the reference light;
A first light receiver (8) that receives measurement interference light related to the wavelength component of the measurement light output from the first wavelength demultiplexer, photoelectrically converts the measurement interference light, and outputs a measurement interference signal of the predetermined beat frequency; ,
Receiving a first reference interference light related to a wavelength component of the reference light output from the first wavelength demultiplexer, photoelectrically converting the second reference interference light and outputting a first reference interference signal having the predetermined beat frequency; An optical interferometer type phase detector for obtaining a wavelength-phase characteristic of the object to be measured based on the measurement interference signal and the first reference interference signal;
Second optical demultiplexing means (14) provided on the first optical path of the Mach-Zehnder interferometer, for demultiplexing a part of the first light before passing through the object to be measured;
Third optical demultiplexing means (15) provided on the second optical path of the Mach-Zehnder interferometer, for demultiplexing a part of the second light;
A third optical multiplexing means (16) for combining the light respectively output from the second optical demultiplexing means and the third optical demultiplexing means to output a second interference light;
A second wavelength demultiplexer (17) that receives the second interference light and outputs a second reference interference light related to a wavelength component of the reference light;
A third light receiver (18) that receives and photoelectrically converts the second reference interference light and outputs a second reference interference signal of the predetermined beat frequency;
A first mode for obtaining a phase characteristic of the measurement object based on the measurement light and the reference light after passing through the measurement object, and the measurement object based only on the measurement light after passing through the measurement object Receiving a measurement mode designating signal for designating any one of the second modes for obtaining the phase characteristics of the signal, the first reference interference signal, and the second reference interference signal, and the measurement mode designating signal determines the first mode. A switch that outputs the first reference interference signal when designated, and outputs the second reference interference signal when the measurement mode designation signal designates the second mode. (22)
When the first reference interference signal is received from the switch, the phase of the measurement interference signal with respect to the first reference interference signal is detected and output as a first measurement phase, and the switch Phase detection means (11) for detecting a phase of the measurement interference signal with respect to the second reference interference signal and outputting it as a second measurement phase when receiving the second reference interference signal;
When the measurement mode designation signal designates the first mode, the wavelength-phase characteristic of the object to be measured is obtained from the first measurement phase, and the measurement mode designation signal indicates the second mode. An optical interferometer type phase detection device comprising signal processing means (23) for obtaining the wavelength-phase characteristic of the object to be measured from the second measurement phase when specified. A wavelength tunable light source (1) that outputs measurement light in a predetermined wavelength range;
A light source (2) that outputs reference light having a wavelength different from the wavelength of the measurement light;
First optical multiplexing means (3) for receiving and multiplexing the measurement light and the reference light and outputting the wavelength multiplexed light obtained thereby;
Upon receiving the wavelength-multiplexed light, the first light passing through the first optical path to which the device under test (10) is connected and the second light passing through the second optical path to which the device under test is not connected are separated. The measurement light and the reference included in the second light demultiplexed with the respective frequencies of the measurement light and the reference light included in the demultiplexed first light. The frequency of at least one of the first light and the second light is set so that the frequency difference between the measurement lights and the frequency difference between the reference lights with respect to the respective frequencies of the light each have a predetermined beat frequency. The optical demultiplexing means (4) that outputs the frequency shifted by the shifters (4a to 4f), and the first light that passes through the first optical path and the second light that passes through the second optical path are combined. Optical heterogeneity having second optical multiplexing means (6) for outputting interference light by wave generation Mach-Zehnder interferometer in-interference system (20),
A wavelength demultiplexer (7) that receives the interference light and demultiplexes it into each wavelength component of the measurement light and the reference light;
A first light receiver (8) that receives measurement interference light related to the wavelength component of the measurement light output from the wavelength demultiplexer, photoelectrically converts the measurement interference light, and outputs a measurement interference signal of the predetermined beat frequency;
A second light receiver (9) that receives reference interference light related to the wavelength component of the reference light output from the wavelength demultiplexer, photoelectrically converts the reference interference light, and outputs a reference interference signal having the predetermined beat frequency; In an optical interferometer type phase detector for obtaining a wavelength-phase characteristic of the device under test based on the measurement interference signal and the reference interference signal,
Phase detection reference signal generating means (4b, 4d, 4f, 19) for generating a phase detection reference signal having the same frequency as the predetermined beat frequency based on the drive signal of the frequency shifter;
A first mode for obtaining a phase characteristic of the measurement object based on the measurement light and the reference light after passing through the measurement object, and the measurement object based only on the measurement light after passing through the measurement object Receiving a measurement mode designating signal designating one of the second modes for obtaining the phase characteristic of the signal, the reference interference signal and the phase detection reference signal, and the measurement mode designating signal designating the first mode A switch (22) that outputs the reference interference signal and outputs the phase detection reference signal when the measurement mode designation signal designates the second mode;
When the reference interference signal is received from the switch, the phase of the measurement interference signal with respect to the reference interference signal is detected and output as a first measurement phase, and the phase detection reference signal is received from the switch. A phase detection means (11) for detecting the phase of the measurement interference signal with respect to the phase detection reference signal and outputting it as a second measurement phase;
When the measurement mode designation signal designates the first mode, the wavelength-phase characteristic of the object to be measured is obtained from the first measurement phase, and the measurement mode designation signal indicates the second mode. An optical interferometer type phase detection device comprising signal processing means (23) for obtaining the wavelength-phase characteristic of the object to be measured from the second measurement phase when specified.   An optical delay device (5) for adjusting an optical path length of the two optical paths is provided on one of the first optical path and the second optical path of the Mach-Zehnder interferometer. The optical interferometer type phase detector according to any one of claims 1 to 4. First light intensity detection means (24, 25) provided on the first optical path of the Mach-Zehnder interferometer for detecting the intensity of light input to the object to be measured;
And a second light intensity detecting means (26, 27) provided on the first optical path of the Mach-Zehnder interferometer for detecting the intensity of light output from the object to be measured. An optical interferometer type phase detector according to any one of claims 1 to 5.   Third light intensity detection means (24, 28) for detecting the intensity of light reflected by the object to be measured on the first optical path of the Mach-Zehnder interferometer. An optical interferometer type phase detector according to any one of claims 1 to 6, further comprising:   The polarization controller (29) for changing the polarization of light input to the object to be measured is provided on the first optical path of the Mach-Zehnder interferometer. Optical interferometer type phase detector.   The polarization controller (29) for changing the polarization of the light input to the object to be measured is provided on the first optical path of the Mach-Zehnder interferometer. Optical interferometer type phase detector.   The object to be measured is connected to the first optical path via an optical circulator (31) provided on the first optical path of the Mach-Zehnder interferometer. The optical interferometer type phase detector according to any one of the above. The object to be measured is connected to the first optical path via an optical coupler (32) provided on the first optical path of the Mach-Zehnder interferometer. The optical interferometer type phase detector according to any one of the above.

r ₂ c ₈ c; Courier New; Wingdings;

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