Passive laser gyro based on optical force induced transparency effect and measuring method thereof

Abstract

The application provides a passive laser gyroscope based on an optical force-induced transparent effect and a measuring method thereof, and the passive laser gyroscope comprises a frequency stabilization laser light source, a signal modulation input device, a balanced homodyne detection device, a ring-shaped optical resonant cavity and a signal detection and feedback device, wherein a reflective cavity mirror with optical mechanical resonant structure characteristics is integrated in the ring-shaped optical resonant cavity; the passive laser gyroscope utilizes the optical force-induced transparent effect and optical-mechanical coupling to generate a narrow transparent window modulated by a mechanical damping rate on the ring-shaped optical resonant cavity of the passive laser gyroscope, so as to improve the quality factor of the ring-shaped optical resonant cavity and enhance the measuring sensitivity of the passive laser gyroscope.

Description

Technical Field

[0001] This invention relates to the field of laser gyroscopes, and more specifically to a passive laser gyroscope based on the photodynamic transparency effect and its measurement method. Background Technology

[0002] A laser gyroscope is an inertial device that uses laser technology to measure the angular velocity of an object's rotation. It features high resolution, good stability, and a wide dynamic range, and has broad application prospects and significant strategic importance in aerospace, marine, defense, industrial production lines, physics experiments, and astronomical observation. Laser gyroscopes measure rotational angular velocity based on the Sagnac effect; the resulting frequency difference is directly proportional to the area of ​​the ring cavity and the rotational angular velocity, and inversely proportional to the wavelength and circumference of the light. Based on the presence or absence of a gain medium within the cavity, laser gyroscopes can be classified into active and passive types. Active gyroscopes have a gain medium inside the cavity; passive gyroscopes do not have a gain medium and the laser is injected externally. Passive laser gyroscopes, lacking a gain medium, effectively avoid latch-up effects and spontaneous emission noise from the gain medium, thus theoretically exhibiting superior performance compared to active gyroscopes.

[0003] Traditional passive laser gyroscopes determine angular velocity by measuring the frequency difference between clockwise and counterclockwise propagating light in a ring cavity. While eliminating noise sources such as latch-up, current passive gyroscopes still face bottlenecks in stability and sensitivity. As disclosed in patent CN103047979A, for the "laser-locked cavity" mode, the large-area ring cavity is easily affected by environmental disturbances, leading to reduced system stability; while the "cavity-locked laser" mode requires the laser to have extremely narrow linewidth and high stability, otherwise high-precision measurement remains difficult. Furthermore, traditional methods to enhance sensitivity (such as increasing the ring cavity area and shortening the wavelength) are limited by technology and size, making it difficult to significantly improve sensitivity further. In summary, a new detection method and system solution are urgently needed to overcome the sensitivity bottleneck of existing passive laser gyroscopes caused by the intrinsic linewidth limitation of the optical cavity. Summary of the Invention

[0004] Based on this, the present invention provides a passive laser gyroscope and its measurement method based on the photomechanical induced transparency effect. By introducing optical-mechanical coupling and photomechanical induced transparency interference mechanism, the equivalent linewidth of the measurement system is reduced from the optical linewidth of the resonant cavity to the linewidth of the mechanical vibration mode, thereby improving the angular velocity detection sensitivity of the gyroscope.

[0005] In a first aspect, the present invention provides a passive laser gyroscope based on the photodynamic transparency effect, comprising: a frequency-stabilized laser source, a signal modulation input device, a balanced zero-difference detection device, a ring optical resonant cavity, and a signal detection and feedback device;

[0006] The frequency-stabilized laser source is used to output a frequency-adjustable laser to the signal modulation input device;

[0007] The signal modulation input device is used to adjust the frequency of the received laser to obtain a modulated laser signal, and input the modulated laser signal to the balanced zero-difference detection device and the ring optical resonant cavity.

[0008] The balanced zero-difference detection device is used to generate a reference laser signal based on the received modulated laser signal, and to obtain a zero-difference interference signal based on the reference laser signal and the test signal output by the ring optical resonator.

[0009] The annular optical resonant cavity integrates a reflective cavity mirror with photomechanical resonance structure characteristics. The annular optical resonant cavity is used to inject two modulated laser signals in the clockwise and counterclockwise directions, respectively. The control light frequency components of the two modulated laser signals, as driving light fields, interact with the reflective cavity mirror with photomechanical resonance structure characteristics through coupling to generate anti-Stokes sidebands. The probe light frequency components of the two modulated laser signals resonate with the annular cavity and interfere with the anti-Stokes sidebands of the control light within the cavity. Then, they are output from the annular cavity as the signal to be measured to the balanced zero-difference detection device.

[0010] The signal detection and feedback device is used to detect the frequency, phase and transmittance of the zero-difference interference signal, and to send the feedback signal obtained in real time to the signal modulation input device based on the zero-difference interference signal, so as to ensure that the optically induced transparent windows of the two zero-difference interference signals after feedback adjustment appear simultaneously and have the same linear shape under the condition of passive laser gyroscope rotation, and then read out the modulation frequency of the signal modulation input device and calculate the rotational angular velocity.

[0011] Furthermore, the signal modulation input device includes a first acoustic-optic modulator, a second acoustic-optic modulator, a first electro-optic modulator, and a second electro-optic modulator;

[0012] The first acousto-optic modulator and the first electro-optic modulator are used to adjust the frequency of the first laser signal received by the signal modulation input device;

[0013] The second acousto-optic modulator and the second electro-optic modulator are used to adjust the frequency of the second laser signal received by the signal modulation input device.

[0014] Furthermore, the balanced zero-difference detection device includes a first beam splitter, a second beam splitter, a first balanced zero-difference detector, and a second balanced zero-difference detector.

[0015] The first beam splitter is used to split the modulated first laser signal to generate a first reference laser signal, and the second beam splitter is used to split the modulated second laser signal to generate a second reference laser signal.

[0016] The first balanced zero-difference detector is used to phase-lock the first output laser signal and the first reference laser signal to obtain the first zero-difference interference signal, and the second balanced zero-difference detector is used to phase-lock the second output laser signal and the second reference laser signal to obtain the second zero-difference interference signal.

[0017] Furthermore, the ring resonant cavity includes an input cavity mirror, a reflecting cavity mirror, a reflecting cavity mirror with optomechanical resonant structural characteristics, and an output cavity mirror;

[0018] The modulated first laser signal and the modulated second laser signal are injected into the ring resonant cavity in clockwise and counterclockwise directions, respectively, through the input cavity mirror. The modulated first laser signal and the modulated second laser signal interact with the reflective cavity mirror with the optomechanical resonant structure characteristics to generate anti-Stokes sidebands.

[0019] The first and second output laser signals, which contain information about the interference between the anti-Stokes sideband and the probe light, are emitted from the ring resonant cavity through the output cavity mirror.

[0020] Furthermore, the signal detection and feedback device includes a first network analyzer, a second network analyzer, and a differential feedback loop;

[0021] The first network analyzer and the second network analyzer are used to obtain the transmission information of the two probe lights based on the first zero-difference interference signal and the second zero-difference interference signal.

[0022] The differential feedback loop is used to generate a feedback signal based on the first zero-difference interference signal and the second zero-difference interference signal, and then sends the feedback signal to the signal modulation input device.

[0023] In a second aspect, the present invention also provides a measurement method based on a passive laser gyroscope, the measurement method being based on a passive laser gyroscope based on the photodynamic transparency effect as described in any one of the first aspects, the measurement method comprising the following steps:

[0024] The frequency-adjustable laser output from the frequency-stabilized laser source is input to the signal modulation input device;

[0025] The signal modulation input device modulates the frequency of the input adjustable laser to obtain a modulated laser signal.

[0026] The modulated laser signal is input to the beam splitter of the balanced zero-difference detection device to obtain the reference laser signal;

[0027] The modulated laser signals are injected clockwise and counterclockwise into a ring optical resonant cavity with an integrated photomechanical resonant structure. The control light frequency components of the two modulated laser signals act as driving light fields and interact with the integrated photomechanical resonant structure of the mirror through optical-mechanical coupling to generate anti-Stokes sidebands. The probe light frequency components of the two modulated laser signals resonate with the ring optical resonant cavity and interfere with the anti-Stokes sidebands of the control light in the ring cavity. Then, they are output as the signal to be measured to the balanced zero-difference detection device.

[0028] The test signal and the reference laser signal are phase-locked and zero-difference detection is performed to obtain a zero-difference interference signal;

[0029] The frequency, phase, and transmittance of the zero-difference interference signal are detected, and a feedback signal is obtained in real time based on the zero-difference interference signal and sent to the signal modulation input device. This ensures that when the optically induced transparent windows of the two zero-difference interference signals after feedback adjustment appear simultaneously and have the same linear shape under the condition of passive laser gyroscope rotation, the modulation frequency of the signal modulation input device can be read out and the rotational angular velocity can be calculated.

[0030] Furthermore, the calculated rotational angular velocity is specifically as follows:

[0031] The control light frequency in the two input signals is adjusted to have the same detuning amount relative to the reference resonant frequency of the ring optical resonator to produce the corresponding photomechanically induced transparency effect;

[0032] Adjust the detuning amount so that the anti-Stokes sideband generated by the coupling between the control optical field of the ring optical resonator and the vibration mode of the reflective cavity mirror with the photomechanical resonance structure is within the linewidth of the ring optical resonator.

[0033] The frequency difference between the anti-Stokes sideband and the peak of the ring optical resonator is obtained, and the frequency difference is recorded as the detuning of the anti-Stokes sideband. If the detuning of the control light of the two input signals is the same, then the detuning of the anti-Stokes sideband of the signal under test is also the same.

[0034] The frequency of the probe light of the input signal is adjusted so that the frequency of the probe light of the input signal is the same as the modulation frequency of the respective control light. The transmission frequency band of the ring optical resonator is scanned to obtain two transmittance spectra.

[0035] Set the difference between the two transmittance spectra to zero, adjust the control optical detuning amount using feedback, and read the control optical detuning amount while maintaining zero difference in the transmittance spectra to obtain the corresponding Sagnac frequency.

[0036] The rotational angular velocity of the passive laser gyroscope is obtained based on the Sagnac frequency.

[0037] Furthermore, the specific expression for the Sagnac frequency is as follows:

[0038] ,

[0039] in, For Sagnac frequency, The resonant frequency of the first-path ring optical resonator is . This is the resonant frequency of the second-path ring optical resonator. The intrinsic frequencies of the mechanical vibration modes of a reflective cavity mirror with an integrated photomechanical resonant structure. The first input signal controls the optical frequency. The second input signal controls the optical frequency. The anti-Stokes sideband detuning in the first signal to be measured. This represents the anti-Stokes sideband detuning in the second signal to be measured.

[0040] Furthermore, the specific expression for obtaining the rotational angular velocity of the passive laser gyroscope based on the Sagnac frequency is as follows:

[0041] ,

[0042] in, Let be the area surrounding the ring optical resonator. The input laser wavelength, Let be the perimeter of the ring optical resonator. This represents the rotational angular velocity of the passive laser gyroscope.

[0043] Furthermore, the measurement method based on a passive laser gyroscope also includes:

[0044] Set the difference between the two transmittance spectra to zero, and read the modulation frequencies of the first and second acousto-optic modulators.

[0045] The frequency difference between the first and second acousto-optic modulators is the Sagnac frequency.

[0046] The beneficial effects of adopting the above technical solution are as follows: This embodiment achieves high-precision indirect measurement of the Sagnac frequency by introducing a reflective cavity mirror with integrated optomechanical resonant structure characteristics and dual-path tunable light injection. Compared with the traditional method of directly measuring the cavity resonance peak, the narrower linewidth of the mechanical vibration mode replaces the wider optical linewidth of the annular cavity, effectively improving measurement accuracy. Furthermore, the combination of two probe beams with controllable frequency phase difference and feedback adjustment can, to a certain extent, offset detuning errors, improving system stability and consistency. In summary, this embodiment can significantly improve the measurement sensitivity and performance of the passive laser gyroscope. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0048] Figure 1 This is a schematic diagram of a passive laser gyroscope structure based on photodynamic transparency effect in one embodiment of this application;

[0049] Figure 2 This is a schematic diagram of a measurement method based on a passive laser gyroscope in one embodiment of this application;

[0050] Figure 3 This is a schematic diagram of the transmittance spectrum of the two output laser signals in one embodiment of this application. Detailed Implementation

[0051] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. To describe the present invention in more detail, the passive laser gyroscope and its measurement method based on the photodynamic transparency effect provided by the present invention will be specifically described below with reference to the accompanying drawings.

[0052] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "an," "a," or "the" do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "comprising" or "including" mean that the preceding element or object encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. The terms "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up," "down," "left," "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0053] Laser gyroscopes measure the rotation angle of an object based on the Sagnac effect. The Sagnac effect states that in a ring resonant cavity, if the system rotates in the plane of light propagation, the actual optical path lengths of light propagating clockwise and counterclockwise are not equal. If two beams of light propagating in opposite directions simultaneously resonate with the same longitudinal mode of the ring resonant cavity, their resonant frequencies will differ due to the rotation. This phenomenon satisfies the Sagnac equation:

[0054] ,

[0055] in, The Sagnac frequency represents the frequency difference between the clockwise and counterclockwise resonant laser beams entering the ring resonant cavity. Let be the area surrounding the ring optical resonator. The input laser wavelength, Let be the perimeter of the ring optical resonator. This represents the rotational angular velocity of the passive laser gyroscope.

[0056] The passive laser gyroscope emphasized in this application is categorized into active and passive laser gyroscopes based on the presence or absence of a gain medium within the cavity. Active laser gyroscopes have a gain medium within the cavity; the ring cavity itself is a laser, emitting light bidirectionally. Passive laser gyroscopes, on the other hand, lack a gain medium within the cavity. The laser is injected externally, and its frequency is locked to the cavity resonant frequency using PDH (Pround-Drever-Hall) locking technology. Any bias in the error signal during the locking process will cause a corresponding detuning between the laser and the cavity, ultimately coupling noise into the detected signal and affecting instrument performance.

[0057] The specific expression for the Sagnac frequency measurement sensitivity of a passive laser gyroscope is as follows:

[0058] ,

[0059] in, For Sagnac frequency measurement sensitivity, the quality factor of the ring optical resonator The laser power emitted from the ring optical resonator is In the above expression, Let be Planck's constant. The laser frequency injected into the ring cavity (i.e., the ring cavity resonant frequency). This represents the quantum efficiency of a photodiode.

[0060] Based on the aforementioned primary factors, to enhance the measurement sensitivity of the Sagnac frequency, methods such as improving the quality factor, increasing the laser power emitted from the ring optical resonator, and reducing the frequency of the injected laser can be employed.

[0061] In this embodiment, we consider enhancing the measurement sensitivity of the Sagnac frequency from the perspective of the quality factor of the ring optical resonator, wherein the specific expression for the quality factor of the ring optical resonator is:

[0062] ,

[0063] in, The laser frequency injected into the ring cavity (i.e., the ring cavity resonant frequency). It is the linewidth of the ring optical resonator.

[0064] The transparency window width of the photo-induced transparency effect is determined by the linewidth of the mechanical vibration mode. It is determined that, for a reflective cavity mirror integrating optomechanical resonant structural characteristics, the linewidth of its mechanical vibration mode is typically lower than that of the optical resonant cavity, i.e. By replacing the linewidth of the ring optical resonator with the linewidth of the mechanical vibration mode, the measurement sensitivity of the Sagnac frequency can be effectively enhanced. The expression for the quality factor of the ring optical resonator can be equivalent to:

[0065] ,

[0066] This is the equivalent quality factor.

[0067] It should be noted that the photomechanically induced transparency effect involved in the embodiments of this application refers to the interference phenomenon that occurs when light in the optical resonant cavity interacts with a reflective cavity mirror that integrates photomechanical resonant structural characteristics. Under the conditions of photomechanically induced transparency effect, the anti-Stokes scattering sideband modulated by the cavity mirror vibration mode will interfere with the optical mode in the cavity, causing the absorption / transmission peak that should have appeared to be destroyed, thereby creating a narrow window in the absorption / transmission spectrum. The width of this window is much smaller than the inherent optical linewidth of the optical resonant cavity, which is of great significance for narrowband precision measurement.

[0068] Based on the above introduction, and in conjunction with the appendix Figure 1 The schematic diagram of a passive laser gyroscope based on the photodynamic transparency effect is shown below. A detailed explanation of a passive laser gyroscope based on the photodynamic transparency effect is provided below:

[0069] The passive laser gyroscope based on photodynamic transparency provided in this embodiment includes a frequency-stabilized laser source, a signal modulation input device 300, a balance zero-difference detection device 200, a ring optical resonator 100, and a signal detection and feedback device 400.

[0070] A frequency-stabilized laser source is used to output a laser with an adjustable frequency to the signal modulation input device 300.

[0071] In this embodiment, the frequency-stabilized laser source is used to provide input laser to the ring optical resonator 100 with a stable frequency. After being emitted from the frequency-stabilized laser source, it is split into two laser beams and injected into the signal modulation input device 300, respectively, in a clockwise direction and a counterclockwise direction into the ring optical resonator 100.

[0072] The signal modulation input device 300 is used to adjust the frequency of the received laser to obtain a modulated laser signal, and input the modulated laser signal to the balanced zero-difference detection device and the ring optical resonator.

[0073] In this embodiment, the signal modulation input device uses a combination of an acousto-optic modulator and an electro-optic modulator to adjust the frequency of the received laser signal. The acousto-optic modulator (AOM) controls the intensity variation of the laser signal. The modulation signal acts on the transducer in the form of an electrical signal (amplitude modulation), and is then converted into a mechanical wave field that changes in the form of an electrical signal. When the light wave passes through the medium, the optical carrier is modulated due to this action, becoming an intensity-modulated wave "carrying" information. The electro-optic modulator (EOM) modulates the phase, amplitude, intensity, and polarization state of the laser signal.

[0074] The signal modulation input device includes a first acoustic-optic modulator 301, a second acoustic-optic modulator 302, a first electro-optic modulator 303, and a second electro-optic modulator 304.

[0075] The first acousto-optic modulator 301 and the first electro-optic modulator 303 are used to adjust the frequency of the first laser signal 1001 received by the signal modulation input device.

[0076] The second acousto-optic modulator 302 and the second electro-optic modulator 304 are used to adjust the frequency of the second laser signal 1002 received by the signal modulation input device.

[0077] The balanced zero-difference detection device 200 is used to generate a reference laser signal based on the received modulated laser signal, and to obtain a zero-difference interference signal based on the reference laser signal and the output laser signal of the ring optical resonator.

[0078] In this embodiment, the balanced zero-difference device 200 is used for phase-locking of the reference light and generating a zero-difference interference signal. The zero-difference interference signal refers to a laser signal that, using zero-difference detection technology, mixes the output test signal with a reference laser signal of the same frequency to eliminate frequency noise. This primarily eliminates the frequency noise of the probe light portion of the output test signal and reads phase change information. The resulting interference light field can eliminate the influence of frequency noise inherent in the electromagnetic wave itself. The balanced zero-difference detection device 200 includes a first beam splitter 201, a second beam splitter 202, a first balanced zero-difference detector 203, and a second balanced zero-difference detector 204.

[0079] The first beam splitter 201 is used to split the modulated first laser signal to generate a first reference laser signal 2001, and the second beam splitter 202 is used to split the modulated second laser signal to generate a second reference laser signal 2002.

[0080] The first balanced homodyne detector 203 is used to perform phase locking between the first output laser signal and the first reference laser signal 2001 to obtain a first homodyne interference signal. The second balanced homodyne detector is used to perform phase locking between the second output laser signal and the second reference laser signal 2002 to obtain a second homodyne interference signal. The balanced homodyne detector can be regarded as a phase compensator for the reference optical path, used to perform phase locking between the output laser signal and the reference laser signal. Specifically, both the first balanced homodyne detector 203 and the second balanced homodyne detector 204 include a phase compensation device, a signal differential unit, and two low-pass filters, used to adjust the phase locking between the ring cavity output light and the reference light, and to obtain a homodyne interference signal.

[0081] The annular optical resonant cavity 100 integrates a reflective cavity mirror 104 with photomechanical resonant structural characteristics. The reflective cavity mirror with photomechanical resonant structural characteristics can vibrate within a certain amplitude. This vibration can be regarded as simple harmonic motion. Other characteristics of the reflective cavity mirror are the same as those of other reflective cavity mirrors. The way to integrate the reflective cavity mirror in the annular optical resonant cavity includes, but is not limited to, using lightweight and flexible suspension, or thinning the structure to make the mirror body itself have readable mechanical modes (such as lightweight components such as suspension wires and silicon nanobeams), or using a high-stress film coated with a high-reflectivity coating, or integrating surface acoustic wave / bulk acoustic mode (SAW / BAW) devices on the reflective cavity mirror substrate. The annular optical resonant cavity 100 is used to inject two modulated laser signals in the clockwise and counterclockwise directions respectively. The control light frequency components of the two modulated laser signals are used as driving light fields to generate anti-Stokes sidebands through optical-mechanical coupling with the reflective cavity mirror 104, which has optomechanical resonance structure characteristics. The probe light frequency components of the two modulated laser signals resonate with the annular cavity and interfere with the anti-Stokes sidebands of the control light in the cavity. Then, they are output as the signal to be measured to the balanced zero-difference detection device.

[0082] In this embodiment, the ring optical resonant cavity 100 includes an input cavity mirror 101, a reflecting cavity mirror 102, a reflecting cavity mirror 104 with optomechanical resonant structure characteristics, and an output cavity mirror 103.

[0083] The modulated first laser signal and the modulated second laser signal are injected into the ring optical resonant cavity through the input cavity mirror 101 in clockwise and counterclockwise directions, respectively;

[0084] The carrier (i.e., control light) components in the modulated first and second laser signals partially enter the annular optical resonant cavity through the input cavity mirror 101, where they interact with the reflecting cavity mirror 104, which has photomechanical resonant structure characteristics, to generate anti-Stokes sidebands.

[0085] The first output laser signal and the second output laser signal, which contain information about the interference between the anti-Stokes sideband and the probe light, are emitted from the ring optical resonator through the output cavity mirror 103.

[0086] Optionally, in this embodiment, the input and output cavity mirrors can be replaced. For example, positions 101 and 102 in the attached figure can be set as input cavity mirrors for injecting laser signals, and positions 102 and 103 in the attached figure can be set as output cavity mirrors for outputting laser signals. Alternatively, the reflective cavity mirror with photomechanical resonant structure characteristics in the original scheme can be replaced with a transmission cavity mirror with photomechanical resonant structure characteristics, thus achieving laser input and output while retaining the photomechanical resonant structure characteristics. As long as the cavity mirror with the photomechanical resonant structure is retained in the annular optical resonant cavity, and the photomechanical coupling between the optical field and the vibration mode of the cavity mirror generates anti-Stokes sidebands, the input and output cavity mirrors in the annular optical resonant cavity can be replaced.

[0087] The signal detection and feedback device 400 is used to detect the frequency, phase and transmittance of the zero-difference interference signal, and to send the feedback signal to the signal modulation input device in real time based on the zero-difference interference signal. This ensures that, under the condition of passive laser gyroscope rotation, the optically induced transparent windows of the two zero-difference interference signals after feedback adjustment appear simultaneously and have the same linear shape. The carrier frequency (i.e., control light) of the injected laser is adjusted according to the feedback of the zero-difference interference signal, and the modulation frequency of the signal modulation input device is read out from this, and the rotational angular velocity is calculated.

[0088] In this embodiment, the signal detection and feedback device 400 includes a first network analyzer 401, a second network analyzer 402, and a differential feedback loop 403;

[0089] The first network analyzer 401 and the second network analyzer 402 are used to obtain the transmission information of the two probe lights based on the first zero-difference interference signal and the second zero-difference interference signal, namely the transmission spectrum data of the swept sidebands (i.e., probe lights) of the first laser signal and the second laser signal.

[0090] The differential feedback loop 403 is used to generate a feedback signal based on the first zero-difference interference signal and the second zero-difference interference signal, and send the feedback signal to the signal modulation input device 300.

[0091] The first network analyzer 401 and the second network analyzer 402 obtain the transmittance spectrum data of the probe light in the first and second zero-difference interference signals by calculation. Then, the transmittance spectrum data is input to the differential feedback loop, and a feedback signal is generated based on the differential result. The detuning of the control light of the first and second laser signals is adjusted according to the feedback signal to maintain the differential result at 0. At this point, the frequency of the control light is read, and thus the rotational angular velocity is obtained.

[0092] For the aforementioned passive laser gyroscope based on photomechanically induced transparency, a high-quality factor photomechanical resonant structure is integrated into a ring-shaped optical cavity resonator, forming an optical-mechanical coupling system with the intracavity optical field. The intrinsic vibration frequency of this photomechanical resonant structure... Much larger than the optical cavity linewidth This causes the control laser (carrier) frequency used to modulate the transparent window (i.e., the anti-Stokes sideband) in the photomechanically induced transparency effect to be detuned relative to the far-infrared cavity, thereby making the anti-Stokes sideband generated by the photomechanical coupling in a resolved-sideband (RSB) state.

[0093] In this embodiment, two frequency-tunable light fields are injected from the ring optical resonator in two incident directions: clockwise (CW) and counterclockwise (CCW). The reference frequencies of the two control beams are equal in detuning amount. Relative to the optical cavity reference resonant frequency Settings, i.e., configuration This ensures that the frequency difference between the two control beams relative to the cavity resonant frequency, as well as the amplitudes of the two control beams, are controllable and equal. The two control beams are coupled to the same reflective cavity mirror with an optomechanical resonant structure, and under the corresponding detuning conditions, excite a transparent window that generates a photomechanically induced transparency effect.

[0094] Because the mechanical vibration damping rate (i.e., vibration mode linewidth) of a reflecting cavity mirror with an optomechanical resonance structure is much smaller than the optical cavity attenuation rate (i.e., optical linewidth), When using a transparent window with photodynamic transparency effect for frequency difference measurement, the equivalent linewidth of the system is significantly reduced. Measurement accuracy is significantly improved, which is equivalent to overcoming the linewidth limitation of the optical cavity itself, increasing the quality factor of the optical cavity, and enhancing the sensitivity of the gyroscope.

[0095] Based on the aforementioned passive laser gyroscope based on the photodynamic transparency effect, this embodiment also provides a measurement method based on the aforementioned passive laser gyroscope, in conjunction with the appendix. Figure 2 As shown, the specific steps include:

[0096] Step S501: Input the frequency-adjustable laser output from the frequency-stabilized laser source to the signal modulation input device.

[0097] In step S502, the signal modulation input device modulates the frequency of the input adjustable laser to obtain a modulated laser signal.

[0098] Step S503: The modulated laser signal is input to the beam splitter of the balanced zero-difference detection device to obtain the reference laser signal.

[0099] In step S504, the modulated laser signals are injected into the annular optical resonant cavity with an integrated photomechanical resonant structure mirror in clockwise and counterclockwise directions, respectively. The control light frequency components of the two modulated laser signals act as driving light fields and interact with the annular optical resonant cavity mirror through coupling to generate anti-Stokes sidebands. The probe light frequency components of the two modulated laser signals resonate with the annular optical resonant cavity and interfere with the anti-Stokes sidebands of the control light frequency. Then, they are output as the signal to be measured to the balanced zero-difference detection device.

[0100] Step S505: Phase locking and zero-difference detection are performed on the signal to be tested and the reference laser signal to obtain a zero-difference interference signal.

[0101] Step S506: Detect the frequency, phase, and transmittance of the zero-difference interference signal, and obtain a feedback signal in real time based on the zero-difference interference signal and send it to the signal modulation input device. This ensures that when the optically induced transparent windows of the two zero-difference interference signals after feedback adjustment appear simultaneously and have the same linear shape under the condition of passive laser gyroscope rotation, the modulation frequency of the signal modulation input device can be read out and the rotational angular velocity can be calculated.

[0102] Specifically, step S506 above, which obtains the rotational angular velocity of the passive laser gyroscope based on the zero-difference interference signal, includes the following steps:

[0103] To avoid confusion regarding the following optical path parameters, the following explanations are provided: In this application's technical solution, taking the modulated laser signal input to a ring optical resonator as an example, the test signal, the reference laser signal emitted from the ring optical resonator, and the zero-difference interference signal obtained after phase locking of the two all contain two parts: control light and probe light. The control light part is equivalent to the carrier part of the laser signal, and the probe light part is equivalent to the modulation signal part of the laser signal. The frequency of the laser signal is modulated by recording the modulation signal on the carrier.

[0104] Step S5061: Adjust the control light of the two input signals to have the same detuning amount relative to the reference resonant frequency of the ring optical resonator. This is to produce the corresponding photo-induced transparency effect.

[0105] Step S5062: Adjust the detuning amount so that the anti-Stokes sideband generated by the coupling effect between the control optical field of the ring optical resonator and the cavity mirror with the optomechanical resonant structure is within the linewidth of the ring optical resonator.

[0106] Step S5063: Obtain the frequency difference between the anti-Stokes sideband and the reference resonant frequency of the ring optical resonator, and record the frequency difference as the detuning of the anti-Stokes sideband. If the control optical detuning of the two input signals If they are the same, then the anti-Stokes sideband detuning of the two signals under test is... Also the same, that is .

[0107] Step S5064: Adjust the probe light frequencies of the two input signals so that the detuning amounts of the probe light frequencies of the two input signals relative to the resonant frequency of the ring optical resonator are the same. Scan the transmission frequency band of the ring optical resonator to obtain the two transmittance spectra. (See attached image) Figure 3 As shown, the frequency of the probe light of the first input signal is The frequency of the detection light of the second input signal is .

[0108] Step S5065: Set the difference between the two transmittance spectra to zero, and use feedback adjustment to control the optical detuning. Read the frequency of the two input control lights while maintaining zero difference in the transmittance spectrum. This leads to the corresponding Sagnac frequency.

[0109] Among them, combined with the appendix Figure 3 The transmittance spectrum shown above, and the specific expression for the Sagnac frequency above, are as follows:

[0110] ,

[0111] in, For Sagnac frequency, The resonant frequency of the first-path ring optical resonator is . This is the resonant frequency of the second-path ring optical resonator. The intrinsic frequencies of the mechanical vibration modes of a reflective cavity mirror with an integrated photomechanical resonant structure. The first input signal controls the optical frequency. The second input signal controls the optical frequency. The anti-Stokes sideband detuning in the first signal to be measured. This represents the anti-Stokes sideband detuning in the second signal to be measured.

[0112] Step S5066: Obtain the rotational angular velocity of the passive laser gyroscope based on the Sagnac frequency.

[0113] The specific expression for the rotational angular velocity of the passive laser gyroscope obtained from the Sagnac frequency is as follows:

[0114] ,

[0115] in, Let be the area surrounding the ring optical resonator. The input laser wavelength, Let be the perimeter of the ring optical resonator. This represents the rotational angular velocity of the passive laser gyroscope.

[0116] In this embodiment, for the above-described passive laser gyroscope measurement method, the step S5065 of determining the Sagnac frequency can be replaced with:

[0117] The difference between the two transmittance spectra is set to zero, so that the detuning between the transparent window of each photodynamic effect and the cavity reference resonant frequency also approaches zero. At this time, the modulation frequency of the first acousto-optic modulator 301 and the second acousto-optic modulator 302 is read. The difference between the modulation frequencies of the first acousto-optic modulator 301 and the second acousto-optic modulator 302 is the Sagnac frequency.

[0118] Furthermore, in this embodiment, the frequency difference between the transparent window of the photodynamic induction effect and the reference resonant frequency of the ring optical resonator may lead to measurement errors, which are then introduced as noise into the Sagnac frequency. (This is in conjunction with the attached...) Figure 3 The relationships between the parameters shown are such that if the difference between the transparent window of the two-path optical force-induced transparency effect and the resonant frequency of the ring optical resonator is not consistent, i.e. The Sagnac frequency at this point can be expressed as:

[0119] .

[0120] Therefore, in this embodiment, the error of the final measured Sagnac frequency is limited by the second difference between the resonant frequencies of the transparent window of the two-way photodynamic induction effect and the annular optical resonator. Ultimately, it is limited by the readings and differential results of the two transmittance spectra.

[0121] The measurement method provided in this embodiment modulates and controls the optical frequency difference (the frequency difference between the probe light and the control light) to... The probe light is injected into the ring cavity from two light incident ports, one clockwise (CW) and the other counterclockwise (CCW), and the modulation frequency is adjusted. The free spectral range (FSR) of the cavity is scanned, and the scanning bandwidth can be appropriately reduced to the linewidth range of the ring optical resonator. During the scanning process, the frequency difference between the probe light and the control light incident in the clockwise (CW) and counterclockwise (CCW) directions is kept consistent, i.e., the frequency difference is set. The amplitude of the beams is kept consistent and much smaller than that of the control light, ensuring that the scanning process does not affect the opto-mechanical coupling between the control light and the cavity mirror of the optomechanical resonant structure. Furthermore, the output signals of the two transmitted beams in the clockwise (CW) and counterclockwise (CCW) directions are detected by an optical detection system, and the transmittance spectrum is acquired in real time. When the frequency difference between the two control beams is exactly equal to the Sagnac frequency of the ring cavity (…),… When the two beams of control light are adjusted by a feedback control mechanism, the transmittance spectra of the clockwise and counterclockwise light paths are made to have the same linearity at the window of the optically induced transparency effect. At this time, the frequency difference between the two control lights reflects the difference in the reference resonant frequency caused by the rotation of the gyroscope, i.e., the Sagnac frequency.

[0122] It should be understood that, although attached Figure 2 The steps in the flowchart are shown sequentially according to the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order requirement for the execution of these steps, and they can be executed in other orders. Furthermore, [the following is a list of steps]. Figure 2 At least some of the steps in the process may include multiple sub-steps or sub-stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0123] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A passive ring laser gyroscope based on the optical force induced transparency effect, characterized in that, include: Frequency-stabilized laser source, signal modulation input device, balanced zero-difference detection device, ring optical resonator, and signal detection and feedback device; The frequency-stabilized laser source is used to output a frequency-adjustable laser to the signal modulation input device; The signal modulation input device is used to adjust the frequency of the received laser to obtain a modulated laser signal, and input the modulated laser signal to the balanced zero-difference detection device and the ring optical resonant cavity. The balanced zero-difference detection device is used to generate a reference laser signal based on the received modulated laser signal, and to obtain a zero-difference interference signal based on the reference laser signal and the test signal output by the ring optical resonator. The annular optical resonant cavity integrates a reflective cavity mirror with photomechanical resonance structure characteristics. The annular optical resonant cavity is used to inject two modulated laser signals in the clockwise and counterclockwise directions, respectively. The control light frequency components of the two modulated laser signals, as driving light fields, interact with the reflective cavity mirror with photomechanical resonance structure characteristics through coupling to generate anti-Stokes sidebands. The probe light frequency components of the two modulated laser signals resonate with the annular cavity and interfere with the anti-Stokes sidebands of the control light in the cavity. Then, they are output as the signal to be measured to the balanced zero-difference detection device. The signal detection and feedback device is used to detect the frequency, phase and transmittance of the zero-difference interference signal, and to send the feedback signal to the signal modulation input device in real time based on the zero-difference interference signal. This ensures that under the condition of passive laser gyroscope rotation, the optically induced transparent windows of the two zero-difference interference signals after feedback adjustment appear simultaneously and have the same linear shape. The modulation frequency of the signal modulation input device can then be read out and the rotational angular velocity can be calculated. The calculated rotational angular velocity is specifically as follows: The control light that adjusts the input signal has the same detuning amount relative to the reference resonant frequency of the ring optical resonator to produce the corresponding photomechanically induced transparency effect; Adjust the detuning amount so that the anti-Stokes sideband generated by the coupling between the control optical field of the ring optical resonator and the vibration mode of the reflecting cavity mirror with the photomechanical resonance structure is within the linewidth of the ring optical resonator. The frequency difference between the anti-Stokes sideband and the peak of the ring optical resonator is obtained, and the frequency difference is recorded as the detuning of the anti-Stokes sideband. If the detuning of the control light of the two input signals is the same, then the detuning of the anti-Stokes sideband of the signal under test is also the same. The frequency of the probe light of the input signal is adjusted so that the frequency of the probe light of the input signal is the same as the modulation frequency of the respective control light. The transmission frequency band of the ring optical resonator is scanned to obtain two transmittance spectra. Set the difference between the two transmittance spectra to zero, adjust the optical detuning amount based on feedback, and read the control optical detuning amount while maintaining zero difference in the transmittance spectra to obtain the corresponding Sagnac frequency; The rotational angular velocity of the passive laser gyroscope is obtained based on the Sagnac frequency; Transparent window width of photophoretically induced transparency effect by mechanical vibration mode linewidth It is determined that the expression of the quality factor of the ring optical resonator is equivalent to: ； wherein, is the equivalent quality factor, is the laser frequency injected into the ring cavity.

2. The passive optical force-induced transparency based ring laser gyroscope of claim 1, wherein, The signal modulation input device includes a first acousto-optic modulator, a second acousto-optic modulator, a first electro-optic modulator, and a second electro-optic modulator; The first acousto-optic modulator and the first electro-optic modulator are used to adjust the frequency of the first laser signal received by the signal modulation input device; The second acousto-optic modulator and the second electro-optic modulator are used to adjust the frequency of the second laser signal received by the signal modulation input device.

3. The passive optical force-induced transparency based ring laser gyroscope of claim 2, wherein, The balanced zero-difference detection device includes a first beam splitter, a second beam splitter, a first balanced zero-difference detector, and a second balanced zero-difference detector. The first beam splitter is used to split the modulated first laser signal to generate a first reference laser signal, and the second beam splitter is used to split the modulated second laser signal to generate a second reference laser signal. The first balanced zero-difference detector is used to phase-lock the first output laser signal and the first reference laser signal to obtain the first zero-difference interference signal, and the second balanced zero-difference detector is used to phase-lock the second output laser signal and the second reference laser signal to obtain the second zero-difference interference signal.

4. The passive optical force-induced transparency based ring laser gyroscope of claim 3, wherein, The annular optical resonant cavity includes an input cavity mirror, a reflecting cavity mirror, a reflecting cavity mirror with photomechanical resonant structural characteristics, and an output cavity mirror; The modulated first laser signal and the modulated second laser signal are injected into the ring optical resonant cavity in clockwise and counterclockwise directions, respectively, through the input cavity mirror. The modulated first laser signal and the modulated second laser signal interact with the reflecting cavity mirror with the characteristics of photomechanical resonance structure to generate anti-Stokes sidebands. The first and second output laser signals, which contain information about the interference between the anti-Stokes sideband and the probe light, are emitted from the ring optical resonator through the output cavity mirror.

5. The passive optical force-induced transparency based ring laser gyroscope of claim 4, wherein, The signal detection and feedback device includes a first network analyzer, a second network analyzer, and a differential feedback loop; The first network analyzer and the second network analyzer are used to obtain the transmission information of the two probe lights based on the first zero-difference interference signal and the second zero-difference interference signal. The differential feedback loop is used to generate a feedback signal based on the first zero-difference interference signal and the second zero-difference interference signal, and then sends the feedback signal to the signal modulation input device.

6. A method of measurement based on a passive ring laser gyroscope, characterized in that, The measurement method is based on a passive laser gyroscope based on the photodynamic transparency effect as described in any one of claims 1-5, and the measurement method includes the following steps: The frequency-adjustable laser output from the frequency-stabilized laser source is input to the signal modulation input device; The signal modulation input device modulates the frequency of the input adjustable laser to obtain a modulated laser signal. The modulated laser signal is input to the beam splitter of the balanced zero-difference detection device to obtain the reference laser signal; The modulated laser signals are injected clockwise and counterclockwise into a ring optical resonant cavity with an integrated photomechanical resonant structure, respectively. The control light frequency components of the two modulated laser signals serve as the driving light field, which interacts with the integrated photomechanical resonant structure through optical-mechanical coupling to generate anti-Stokes sidebands. The probe light frequency components of the two modulated laser signals resonate with the ring optical resonant cavity and interfere with the anti-Stokes sidebands of the control light within the cavity. The signals are then output from the ring cavity as the signal to be measured to the balanced zero-difference detection device. The test signal and the reference laser signal are phase-locked and zero-difference detection is performed to obtain a zero-difference interference signal; The frequency, phase, and transmittance of the zero-difference interference signal are detected, and a feedback signal is obtained in real time based on the zero-difference interference signal and sent to the signal modulation input device. This ensures that when the optically induced transparent windows of the two zero-difference interference signals after feedback adjustment appear simultaneously and have the same linear shape under the condition of passive laser gyroscope rotation, the modulation frequency of the signal modulation input device can be read out and the rotational angular velocity can be calculated.

7. The passive ring laser gyro based measurement method of claim 6, wherein, The specific expression for the Sagnac frequency is: ， wherein, is the Sagnac frequency, is the resonance frequency of the first ring optical resonator, is the resonance frequency of the second ring optical resonator, is the mechanical vibration mode eigenfrequency of the reflective cavity mirror integrated with the optomechanical resonant structure, is the control light frequency in the first input signal, is the control light frequency in the second input signal, is the anti-Stokes sideband detuning in the first signal under test, is the anti-Stokes sideband detuning in the second signal under test.

8. The measurement method based on a passive laser gyroscope as described in claim 7, characterized in that, The specific expression for obtaining the rotational angular velocity of the passive laser gyroscope based on the Sagnac frequency is as follows: ， in, Let be the surrounding area of ​​the ring optical resonator. The input laser wavelength, Let be the perimeter of the ring optical resonator. This represents the rotational angular velocity of the passive laser gyroscope.

9. The measurement method based on a passive laser gyroscope as described in claim 6, characterized in that, Also includes: Set the difference between the two transmittance spectra to zero, and read the modulation frequencies of the first and second acousto-optic modulators. The frequency difference between the first and second acousto-optic modulators is the Sagnac frequency.

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