CN111238464A - Detection system and method of resonant optical gyroscope based on combination of reciprocity modulation and time division switching - Google Patents
Detection system and method of resonant optical gyroscope based on combination of reciprocity modulation and time division switching Download PDFInfo
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- G—PHYSICS
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- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/58—Turn-sensitive devices without moving masses
- G01C19/64—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams
- G01C19/72—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams with counter-rotating light beams in a passive ring, e.g. fibre laser gyrometers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/58—Turn-sensitive devices without moving masses
- G01C19/64—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams
- G01C19/72—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams with counter-rotating light beams in a passive ring, e.g. fibre laser gyrometers
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- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/27—Optical coupling means with polarisation selective and adjusting means
- G02B6/2746—Optical coupling means with polarisation selective and adjusting means comprising non-reciprocal devices, e.g. isolators, FRM, circulators, quasi-isolators
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/35—Optical coupling means having switching means
- G02B6/354—Switching arrangements, i.e. number of input/output ports and interconnection types
- G02B6/3544—2D constellations, i.e. with switching elements and switched beams located in a plane
- G02B6/3546—NxM switch, i.e. a regular array of switches elements of matrix type constellation
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Abstract
The invention discloses a resonant optical gyro detection system and method based on combination of reciprocity modulation and time division switching. Firstly, carrying out reciprocity modulation on light emitted by a laser, immediately obtaining two paths of light in a clockwise direction and a counterclockwise direction (relative to the propagation direction along an optical resonant cavity) at a Y branch, and simultaneously applying modulation signals with different frequencies to modulate the two beams of light; the Y-branch output enters a 2X 2 optical switch for time division switching, and the output enters an optical resonant cavity. And performing same-frequency demodulation on the cavity-exiting signal, wherein one path of demodulated signal is fed back to a laser tuning end after signal processing, so that the frequency of the laser is locked on the resonant frequency of the path. And the other path of demodulated signal is output as a gyro rotation signal after signal processing. The detection method of the resonant optical gyroscope provided by the invention is beneficial to inhibiting the influence of nonreciprocal noise such as residual intensity modulation and the like on the basis of increasing the system carrier suppression ratio and inhibiting the back scattering noise, and improving the detection precision of the resonant optical gyroscope.
Description
Technical Field
The invention relates to the technical field of signal detection, in particular to a detection system and a detection method of a resonant optical gyroscope combining fundamental reciprocity modulation and time division switching of a 2 x 2 optical switch. The resonant gyroscope comprises a resonant fiber optic gyroscope taking a fiber ring resonant cavity as a sensitive element and a resonant integrated optical gyroscope taking an optical resonant cavity as a core sensitive element.
Background
Resonant Optical Gyros (ROGs) are high-precision inertial sensors that use the optical Sagnac effect to achieve rotational detection. The resonant optical gyroscope without vibration parts has the advantages of miniaturization, high precision, vibration resistance and the like. ROG will have a greater advantage than Micro Electro Mechanical Systems (MEMS) and Interferometric Fiber Optic Gyroscope (IFOG).
Since the Sagnac effect is a very weak effect and the optical noise of the resonant optical gyroscope is very strong, the signal modulation and detection technology must have a noise suppression function in the resonant optical gyroscope system. In the resonant optical gyro, the most serious one affecting the detection accuracy is back scattering noise, including the influence of back scattering light intensity noise and interference term noise between back scattering light and signal light. In order to suppress the back scattering noise, different frequency phase modulation and carrier suppression methods are usually adopted for clockwise and counterclockwise light waves of the resonant cavity, wherein the different frequency phase modulation techniques are used for suppressing the back scattering light intensity noise, the carrier suppression is used for suppressing the interference term noise, and the total carrier suppression ratio of the system directly affects the suppression degree of the interference term noise. The phase modulation of the laser is generally realized by adopting integrated optical phase modulation such as lithium niobate, and researches show that the non-ideal phase modulation characteristic of the phase modulator, namely that when a voltage signal is applied to the phase modulator for phase modulation, parasitic intensity modulation is often accompanied, the parasitic intensity modulation and the phase modulation signal have the same frequency characteristic and can be demodulated by a signal demodulation module at the output end of a resonant cavity, when the light waves in the clockwise direction and the anticlockwise direction of the resonant cavity are subjected to phase modulation with different frequencies, the influence of the parasitic intensity modulation in the two opposite directions is different, and the residual intensity modulation finally becomes the detection precision of the resonant optical gyroscope. Therefore, there is an urgent need to develop a signal modulation and detection method that can effectively suppress the back scattering noise and avoid the residual intensity modulation noise.
Disclosure of Invention
The invention aims at the defects of the prior art and provides a detection system and a detection method of a resonant optical gyroscope based on the combination of reciprocity phase modulation and time division switching.A laser emits light which is subjected to reciprocity modulation, two beams of light in clockwise and anticlockwise directions (for the follow-up direction along the propagation direction of an optical resonant cavity) are obtained after the light enters a Y branch after being output, and the two beams of light are subjected to phase modulation by adopting modulation signals with different frequencies respectively by the Y branch; the signal after twice modulation is input to a 2 multiplied by 2 optical switch for time division switching, and the output of the optical switch enters an optical resonant cavity. And performing same-frequency demodulation on the clockwise and anticlockwise output signals of the cavity, wherein one path of demodulated signal is fed back to the frequency tuning end of the laser after being processed by a digital signal, so that the frequency of the laser and the resonant frequency of the path of demodulated signal are locked together. And the other path of demodulated signal is output as a gyro rotation signal after being processed by a digital signal.
The purpose of the invention is realized by the following technical scheme:
a resonant optical gyro detection system based on combination of reciprocity modulation and time division switching comprises an optical system and a signal processing system, wherein the optical system is composed of a tunable laser, an optical isolator, a first phase modulator, a Y-branch phase modulator, a 2 x 2 optical switch, an optical resonant cavity and a photoelectric conversion module, and the signal processing system is composed of a signal demodulation module, a first low-pass filter, a second low-pass filter and a servo feedback controller.
Furthermore, the tunable laser, the optical isolator, the first phase modulator and the Y-branch phase modulator are sequentially connected, and the first phase modulator is connected with the demodulation module; two output ends of the Y-branch phase modulator are respectively connected with two input ends of a 2 x 2 optical switch, two output ends of the 2 x 2 optical switch are connected with the optical resonant cavity, and the optical resonant cavity, the photoelectric conversion module and the signal demodulation module are sequentially connected; the first output end of the signal demodulation module is connected with the tuning end of the tunable laser through the first low-pass filter and the servo feedback controller, and the second output end of the signal demodulation module is connected with the second low-pass filter.
The invention provides a detection method applying the resonant optical gyro detection system, which comprises the following steps:
1) light output by the tunable laser enters a first phase modulator after passing through an optical isolator, an electrical signal with a certain frequency is adopted on the first phase modulator to carry out reciprocity modulation on the optical signal, the optical signal after the reciprocity modulation enters a Y-branch phase modulator to be divided into two parts, two paths of light are respectively modulated on the Y-branch phase modulator, then enter an optical resonant cavity through a 2 x 2 optical switch to respectively form two beams of resonant light clockwise and anticlockwise, and the resonant light after exiting the cavity is converted into the electrical signal by a photoelectric conversion module; the signal demodulation module generates a common-frequency signal on the first phase modulator and demodulates the received electric signal to obtain a demodulation signal;
2) only one output port has signal output at the same time by using a 2 multiplied by 2 optical switch, so that only clockwise resonance light or anticlockwise resonance light can be output from the optical resonant cavity at the same time; taking the demodulation signal output anticlockwise as an error signal, carrying out proportional and integral operation processing on the error signal by a first low-pass filter, and then feeding back the error signal to a tuning end of the tunable laser through a servo feedback controller to lock the frequency of the tunable laser on the resonance frequency of the optical resonant cavity in the anticlockwise direction; the demodulation signal output clockwise is subjected to proportional and integral operation processing through a first low-pass filter, and a gyro rotation signal is obtained and is finally output.
The invention also aims to provide another resonant optical gyro detection system based on the combination of reciprocity modulation and time division switching, which comprises an optical system consisting of a tunable laser, an optical isolator, a first phase modulator, a Y-branch phase modulator, a 2 x 2 optical switch, an optical resonant cavity and a photoelectric conversion module, and a signal processing system consisting of a signal demodulation module, a first low-pass filter, a second low-pass filter, a servo feedback controller, a servo frequency shift module and a closed-loop feedback phase modulator.
Furthermore, the tunable laser, the optical isolator, the first phase modulator and the Y-branch phase modulator are sequentially connected, and the first phase modulator is simultaneously connected with the signal demodulation module; two output ends of the Y-branch phase modulator are respectively connected with two input ends of a 2 x 2 optical switch, two output ends of the 2 x 2 optical switch are connected with the optical resonant cavity, and the optical resonant cavity, the photoelectric conversion module and the signal demodulation module are sequentially connected; the first output end of the signal demodulation module is connected with the tuning end of the tunable laser through a first low-pass filter and a servo feedback controller, the second output end of the signal demodulation module is sequentially connected with a second low-pass filter, a servo frequency shift module and a closed-loop feedback phase modulator, and an output end signal of the closed-loop feedback phase modulator is applied to a phase modulator on a clockwise branch in the Y-branch phase modulator.
The invention provides a detection method applying the resonant optical gyro detection system, which comprises the following steps:
1) light output by the tunable laser enters a first phase modulator after passing through an optical isolator, an electrical signal with a certain frequency is adopted on the first phase modulator to carry out reciprocity modulation on an optical signal, the optical signal after the reciprocity modulation enters a Y-branch phase modulator to be divided into two parts, two paths of light are respectively modulated on the Y-branch phase modulator again, then enter an optical resonant cavity through a 2 x 2 optical switch to respectively form two beams of resonant light clockwise and anticlockwise, and the resonant light after exiting the cavity is converted into the electrical signal by a photoelectric conversion module; the signal demodulation module generates a common-frequency signal on the first phase modulator and demodulates the received electric signal to obtain a demodulation signal;
2) the 2 x 2 optical switch is controlled to work only with one output port at the same time, so that only clockwise resonance light or anticlockwise resonance light can be output from the optical resonant cavity at the same time; taking the demodulation signal output anticlockwise as an error signal, carrying out proportional and integral operation processing on the error signal by a first low-pass filter, and then feeding back the error signal to a tuning end of the tunable laser through a servo feedback controller to lock the frequency of the tunable laser on the resonance frequency of the optical resonant cavity in the anticlockwise direction;
the demodulation signal output clockwise is subjected to proportional and integral operation processing through a second low-pass filter, then is input into a servo frequency shift module to obtain a voltage signal with gyro rotation speed information, and then is fed back to a phase modulator through a closed loop to obtain frequency shift quantity; and feeding back the frequency shift quantity to the phase modulator on the clockwise branch in the Y-branch phase modulator, so that the optical signal of the clockwise branch is locked on the resonant frequency of the optical resonant cavity in the clockwise direction, and the frequency shift quantity reflects the rotation signal of the gyroscope.
The invention has the following beneficial effects:
(1) the detection method of the resonant optical gyroscope adopts a reciprocity modulation-demodulation technology, namely, a first phase modulator applies a same-frequency modulation signal to laser so as to avoid parasitic intensity modulation caused by adopting different modulation frequencies, improve the reciprocity of a system and effectively inhibit the parasitic intensity modulation;
(2) the detection method of the resonant optical gyroscope provided by the invention adopts the Y branch, modulates the divided laser signal on the Y branch again, can bring additional carrier suppression effect, can suppress the influence of interference terms in back scattering, and improves the stability of the system.
(3) The detection method of the resonant optical gyroscope provided by the invention adopts a novel time division switching method, and the 2 multiplied by 2 optical switch is introduced to ensure that the resonant cavity only has clockwise optical signals or anticlockwise optical signals at the same time, thereby being beneficial to realizing the suppression of the back scattering intensity noise and part of interference term noise.
Drawings
FIG. 1 is a schematic structural diagram of a first resonant optical gyroscope detection system based on combination of reciprocity phase modulation and time-division switching according to the present invention;
FIG. 2 is a schematic structural diagram of a second resonant optical gyroscope detection system based on combination of reciprocity phase modulation and time-division switching according to the present invention;
FIG. 3 is a graph illustrating an output after signal processing;
FIG. 4 is a schematic diagram of the relationship between the clockwise and counterclockwise resonant frequencies and the laser frequency when the resonant optical gyroscope is rotated;
fig. 5 is a schematic diagram of an embodiment of a detection system based on a 2 x 2 optical switch resonant optical gyroscope;
in the figure: 1. the system comprises a tunable laser, 2, an isolator, 3, a phase modulator, 4, a Y-branch phase modulator (hereinafter referred to as Y-branch), 5, a 2 x 2 optical switch, 6, a first circulator, 7, a second circulator, 8, an optical resonant cavity, 9, a first photoelectric detector, 10, a second photoelectric detector, 11, a signal demodulation module, 12, a first low-pass filter, 13 servo feedback controllers, 14, a second low-pass filter, 15 and a data recorder.
Detailed Description
The present invention will be described in detail below with reference to examples and drawings, but the present invention is not limited thereto.
As shown in fig. 1, a detection system of a resonant optical gyroscope based on the combination of reciprocity phase modulation and time division switching mainly includes an optical system composed of a tunable laser, an optical isolator, a first phase modulator, a Y branch, an optical resonant cavity, and a photoelectric conversion module, and a signal processing system composed of a signal modulation/demodulation module, a feedback locking module, a first signal processing module, a second signal processing module, a servo frequency shift module, and a closed-loop feedback phase modulator. The tunable laser, the optical isolator, the phase modulator and the Y branch are sequentially connected, two outputs of the Y branch are respectively connected with two inputs of a 2 x 2 optical switch, two outputs of the optical switch are respectively connected with an optical resonant cavity in sequence, the optical resonant cavity, the photoelectric conversion module and the signal demodulation module are sequentially connected, the signal demodulation module is connected with the phase modulator, the signal demodulation module, the first signal processing module and the feedback locking module are sequentially connected with the tunable laser, and the signal demodulation module and the second signal processing module are connected with the data recorder.
The detection method of the detection system comprises the following steps:
the light output by the laser firstly passes through the isolator, enters the phase modulator, then is obtained by dividing the free spectral width of the resonant cavity by 2 √ 3, and enters the Y branch as an electric signal of modulation frequency, the Y branch is divided into two paths of clockwise and anticlockwise (relative to the subsequent transmission direction along the resonant cavity) light, and meanwhile, two paths of signals with different frequencies are applied to the Y branch to respectively modulate the clockwise and anticlockwise light, so that the extra carrier suppression effect is obtained. The two outputs of the Y branch enter a 2X 2 optical switch, the effect of time division switching is realized on the optical switch, and the carrier suppression ratio of the system is further improved. Two outputs of the Y optical switch enter the optical resonant cavity to form clockwise and anticlockwise two resonant light beams, and the two beams of light respectively enter the photoelectric detector to be converted into electric signals. The signal modulation and demodulation module generates the same frequency signals to demodulate the electric signals output by the photoelectric detector respectively, and then the demodulated signals can be obtained. The schematic diagram takes the anticlockwise direction as an example, a demodulation signal output anticlockwise is used as an error signal, and the error signal is fed back to a tuning end of the laser after being processed by a digital signal, so that the frequency of the laser is locked on the resonant frequency of the resonant cavity in the anticlockwise direction; the clockwise demodulation signal is directly used as a rotation signal to be finally output as the gyroscope after being processed by a digital signal.
As shown in fig. 2, a detection apparatus for a resonant optical gyroscope based on the combination of reciprocity phase modulation and time division switching mainly includes an optical system composed of a tunable laser, an optical isolator, a Y branch, a phase modulator, an optical resonant cavity, and a photoelectric conversion module, and a signal processing system composed of a signal modulation/demodulation module, a feedback locking module, a first signal processing module, a second signal processing module, a servo frequency shift module, and a closed-loop feedback phase modulator. The tunable laser, the optical isolator, the phase modulator and the Y branch are sequentially connected, two outputs of the Y branch are respectively connected with two inputs of a 2 x 2 optical switch, two outputs of the optical switch are respectively sequentially connected with an optical resonant cavity, the photoelectric conversion module and the signal demodulation module are sequentially connected, the signal demodulation module is connected with the phase modulator, the signal demodulation module, the first signal processing module and the feedback locking module are sequentially connected with the tunable laser, and the signal demodulation module, the second signal processing module, the servo frequency shift module and the closed-loop feedback phase modulator are sequentially connected.
The detection method of the detection system comprises the following steps:
the light output by the laser firstly passes through the isolator, enters the phase modulator, then is subjected to reciprocity modulation by adopting an electric signal with a certain frequency, the signal output by the phase modulator and subjected to reciprocity modulation enters the Y branch, the Y branch is divided into clockwise and anticlockwise (relative to the subsequent transmission direction along the resonant cavity) light, and meanwhile, two paths of signals with different frequencies are applied to the Y branch to respectively modulate the clockwise and anticlockwise light, so that the extra carrier suppression effect is obtained. The two outputs of the Y branch enter a 2X 2 optical switch, the effect of time division switching is realized on the optical switch, and the carrier suppression ratio of the system is further improved. Two outputs of the Y optical switch enter the optical resonant cavity to form clockwise and anticlockwise two resonant light beams, and the two beams of light respectively enter the photoelectric detector to be converted into electric signals. The signal modulation and demodulation module generates the same frequency signals to demodulate the electric signals output by the photoelectric detector respectively, and then the demodulated signals can be obtained. The schematic diagram takes the anticlockwise direction as an example, a demodulation signal output anticlockwise is used as an error signal, and the error signal is fed back to a tuning end of the laser after being processed by a digital signal, so that the frequency of the laser is locked on the resonant frequency of the resonant cavity in the anticlockwise direction; the clockwise demodulation signal is processed by digital signal, and then generates frequency shift signal to be fed back to the closed loop feedback phase modulator, so that the clockwise optical signal is locked on the other resonance frequency of the resonant cavity, and the frequency shift quantity reflects the rotation signal of the gyroscope.
The detection method of the resonant optical gyroscope provided by the invention is beneficial to inhibiting the influence of nonreciprocal noise such as residual intensity modulation and the like on the basis of increasing the system carrier suppression ratio and inhibiting the back scattering noise, and finally improving the detection precision of the resonant optical gyroscope.
The output demodulation curve of the resonant optical gyroscope based on the combination of reciprocal phase modulation and time-division switching is shown in fig. 3.
As shown in fig. 4, the relationship between the clockwise and counterclockwise resonant frequencies and the laser frequency when the resonant optical gyroscope rotates is schematically illustrated, the laser frequency is always stabilized at the resonant frequency of the counterclockwise beam, and the resonant frequency difference between the clockwise and counterclockwise beams is the rotation signal of the resonant optical gyroscope.
As shown in fig. 5, the implementation example of the resonant optical gyroscope based on the combination of reciprocity phase modulation and time division switching uses an optical phase modulator as a modulator and a photoelectric detector as a photoelectric conversion module, codes are written on a development platform based on an FPGA to realize a signal demodulation module, a signal processing module and a feedback locking module, and a digital multimeter or a personal computer is used as a data recorder. An optical signal output by the laser 1 enters the first phase modulator for reciprocal modulation after passing through the isolator 2, then enters the Y branch 4 to divide the optical signal into two parts to obtain clockwise and counterclockwise optical signals, and simultaneously, clockwise and counterclockwise two paths of light are modulated for the second time by adopting different frequencies on the Y branch, so that the carrier rejection ratio of the system is further improved. The two outputs of the Y branch are respectively connected with two inputs of a 2 multiplied by 2 optical switch 5, then the two outputs of the optical switch respectively enter an optical resonant cavity 8 through a first circulator 6 and a second circulator 7, clockwise and anticlockwise signals output by the optical resonant cavity respectively enter a second photoelectric detector 10 and a first photoelectric detector 9 through the second circulator 7 and the first circulator 6 again, and the outputs of the two photoelectric detectors enter a demodulation module 11 for common-frequency demodulation. After passing through the first low-pass filter 12 and the servo feedback controller 13, the counterclockwise demodulation signal is fed back to the laser tuning end 1, so that the center frequency of the laser is locked on the resonant frequency of the resonant cavity in the counterclockwise direction; after the clockwise demodulated signal passes through the second low pass filter 14, the rotation information of the gyro is output and recorded on the data recorder 15.
Claims (6)
1. A resonant optical gyro detection system based on combination of reciprocity modulation and time division switching is characterized by comprising an optical system consisting of a tunable laser, an optical isolator, a first phase modulator, a Y-branch phase modulator, a 2 x 2 optical switch, an optical resonant cavity and a photoelectric conversion module, and a signal processing system consisting of a signal demodulation module, a first low-pass filter, a second low-pass filter and a servo feedback controller.
2. The resonant optical gyro detection system based on the combination of reciprocity modulation and time division switching of claim 1, wherein the tunable laser, the optical isolator, the first phase modulator, and the Y-branch phase modulator are connected in sequence, the first phase modulator is connected with the demodulation module; two output ends of the Y-branch phase modulator are respectively connected with two input ends of a 2 x 2 optical switch, two output ends of the 2 x 2 optical switch are connected with the optical resonant cavity, and the optical resonant cavity, the photoelectric conversion module and the signal demodulation module are sequentially connected; the first output end of the signal demodulation module is connected with the tuning end of the tunable laser through the first low-pass filter and the servo feedback controller, and the second output end of the signal demodulation module is connected with the second low-pass filter.
3. A detection method for applying the resonant optical gyro detection system based on the combination of reciprocity modulation and time division switching as claimed in claim 2, characterized by comprising the following steps:
1) light output by the tunable laser enters a first phase modulator after passing through an optical isolator, an electrical signal with a certain frequency is adopted on the first phase modulator to carry out reciprocity modulation on the optical signal, the optical signal after the reciprocity modulation enters a Y-branch phase modulator to be divided into two parts, two paths of light are respectively modulated on the Y-branch phase modulator, then enter an optical resonant cavity through a 2 x 2 optical switch to respectively form two beams of resonant light clockwise and anticlockwise, and the resonant light after exiting the cavity is converted into the electrical signal by a photoelectric conversion module; the signal demodulation module generates a common-frequency signal on the first phase modulator and demodulates the received electric signal to obtain a demodulation signal;
2) only one output port has signal output at the same time by using a 2 multiplied by 2 optical switch, so that only clockwise resonance light or anticlockwise resonance light can be output from the optical resonant cavity at the same time; taking the demodulation signal output anticlockwise as an error signal, carrying out proportional and integral operation processing on the error signal by a first low-pass filter, and then feeding back the error signal to a tuning end of the tunable laser through a servo feedback controller to lock the frequency of the tunable laser on the resonance frequency of the optical resonant cavity in the anticlockwise direction; the demodulation signal output clockwise is subjected to proportional and integral operation processing through a first low-pass filter, and a gyro rotation signal is obtained and is finally output.
4. A resonant optical gyro detection system based on combination of reciprocity modulation and time division switching is characterized by comprising an optical system consisting of a tunable laser, an optical isolator, a first phase modulator, a Y-branch phase modulator, a 2 x 2 optical switch, an optical resonant cavity and a photoelectric conversion module, and a signal processing system consisting of a signal demodulation module, a first low-pass filter, a second low-pass filter, a servo feedback controller, a servo frequency shift module and a closed-loop feedback phase modulator.
5. The resonant optical gyro detection system based on the combination of reciprocity modulation and time division switching of claim 4, wherein the tunable laser, the optical isolator, the first phase modulator, and the Y-branch phase modulator are connected in sequence, and the first phase modulator is connected with the signal demodulation module at the same time; two output ends of the Y-branch phase modulator are respectively connected with two input ends of a 2 x 2 optical switch, two output ends of the 2 x 2 optical switch are connected with the optical resonant cavity, and the optical resonant cavity, the photoelectric conversion module and the signal demodulation module are sequentially connected; the first output end of the signal demodulation module is connected with the tuning end of the tunable laser through a first low-pass filter and a servo feedback controller, the second output end of the signal demodulation module is sequentially connected with a second low-pass filter, a servo frequency shift module and a closed-loop feedback phase modulator, and an output end signal of the closed-loop feedback phase modulator is applied to a phase modulator on a clockwise branch in the Y-branch phase modulator.
6. A detection method for applying the resonant optical gyro detection system based on the combination of reciprocity modulation and time division switching as claimed in claim 5, characterized by comprising the following steps:
1) light output by the tunable laser enters a first phase modulator after passing through an optical isolator, an electrical signal with a certain frequency is adopted on the first phase modulator to carry out reciprocity modulation on an optical signal, the optical signal after the reciprocity modulation enters a Y-branch phase modulator to be divided into two parts, two paths of light are respectively modulated on the Y-branch phase modulator again, then enter an optical resonant cavity through a 2 x 2 optical switch to respectively form two beams of resonant light clockwise and anticlockwise, and the resonant light after exiting the cavity is converted into the electrical signal by a photoelectric conversion module; the signal demodulation module generates a common-frequency signal on the first phase modulator and demodulates the received electric signal to obtain a demodulation signal;
2) the 2 x 2 optical switch is controlled to work only with one output port at the same time, so that only clockwise resonance light or anticlockwise resonance light can be output from the optical resonant cavity at the same time; taking the demodulation signal output anticlockwise as an error signal, carrying out proportional and integral operation processing on the error signal by a first low-pass filter, and then feeding back the error signal to a tuning end of the tunable laser through a servo feedback controller to lock the frequency of the tunable laser on the resonance frequency of the optical resonant cavity in the anticlockwise direction;
the demodulation signal output clockwise is subjected to proportional and integral operation processing through a second low-pass filter, then is input into a servo frequency shift module to obtain a voltage signal with gyro rotation speed information, and then is fed back to a phase modulator through a closed loop to obtain frequency shift quantity; and feeding back the frequency shift quantity to the phase modulator on the clockwise branch in the Y-branch phase modulator, so that the optical signal of the clockwise branch is locked on the resonant frequency of the optical resonant cavity in the clockwise direction, and the frequency shift quantity reflects the rotation signal of the gyroscope.
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| CN113465630A (en) * | 2021-07-02 | 2021-10-01 | 浙江大学 | Optical resonant cavity free spectral line width online test system and method based on coherent demodulation |
| CN113587914A (en) * | 2021-07-28 | 2021-11-02 | 北京航空航天大学 | Frequency spectrum separation method for restraining back reflection error of resonant integrated optical gyroscope |
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| CN113587914B (en) * | 2021-07-28 | 2023-05-16 | 北京航空航天大学 | Spectrum separation method for inhibiting back reflection error of resonant integrated optical gyroscope |
| CN114459457A (en) * | 2022-02-10 | 2022-05-10 | 浙江大学 | Resonant fiber-optic gyroscope system and method based on reciprocal modulation secondary demodulation |
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