Single-beam injection microcavity angular velocity measurement device and method

Abstract

The application provides a single-beam injection microcavity angular velocity measuring device and method, and relates to the technical field of microcavity angular velocity measurement.The application takes a coupling cavity structure formed by an optical microcavity and a U-shaped waveguide as a core chip, and adopts a single-beam injection mode.The feedback phase introduced by the U-shaped waveguide is used to modulate the extinction ratio of a transmission spectrum resonance valley of the microcavity.The application fundamentally eliminates the backscattering noise of a traditional resonant microcavity gyroscope caused by bidirectional injection through single-beam injection, and improves the measurement sensitivity through the feedback mechanism of the U-shaped waveguide, thereby significantly reducing the drift and angular random walk of the gyroscope, providing a new scheme for developing a high-precision microcavity gyroscope, and having wide application prospects in the fields of intelligent driving and unmanned aerial vehicles.

Description

Technical Field

[0001] This invention relates to the field of microcavity angular velocity measurement technology, and in particular to a single-beam injection microcavity angular velocity measurement device and method. Background Technology

[0002] Resonant optical gyroscopes (ROGs) are a type of high-sensitivity inertial sensor that utilizes the Sagnac effect (also known as the optical path difference proportional to the rotational angular velocity) combined with an optical resonant cavity to measure angular velocity. Among them, resonant microcavity gyroscopes based on ultra-high quality factor (Q-value) optical microcavities exhibit significant application potential in miniaturized, low-power navigation systems due to their outstanding advantages such as small size, low power consumption, high sensitivity, and ease of on-chip integration. Their Q-value typically needs to reach 10. 6 The order of magnitude is even higher. A high Q value means that the photon has a longer lifetime in the cavity and a narrower resonant linewidth, thus enabling a more sensitive response to the small frequency shifts caused by the Sagnac effect.

[0003] Currently, high-performance resonant microcavity gyroscopes generally employ a bidirectional beam injection mechanism. Specifically, such as... Figure 1 and Figure 5 As shown, a laser beam is split into two beams and coupled into the same optical microcavity from opposite directions, forming two resonant beams propagating clockwise (CW) and counterclockwise (CCW). When the system rotates about an axis perpendicular to the cavity plane, the Sagnac effect causes the resonant frequencies of the two beams to shift by equal magnitude but opposite signs. By locking the laser frequency to the resonant peak of one beam, the transmitted light intensity of the other beam changes approximately linearly with the angular velocity. By detecting this intensity change, the angular velocity can be calculated.

[0004] However, this classic bidirectional resonant structure has an inherent and insurmountable fundamental flaw: due to the unavoidable surface roughness, defects, or impurities present during the fabrication of the microcavity, strong backscattering occurs. This backscattering generates strong reciprocal coupling between the clockwise and counterclockwise resonant beams, introducing significant noise and performance degradation, specifically manifested as follows:

[0005] Lock-in effect: At low speeds, backscatter coupling can "lock in" the frequencies of the two opposing modes, causing the Sagnac frequency difference to fail to be generated or detected, thus rendering the gyroscope ineffective in the low-speed region.

[0006] Deterioration of noise levels: Backscattering coupling significantly increases the angular random walk and zero-bias instability of the gyroscope, both of which are core indicators for measuring the accuracy and long-term stability of the gyroscope. Increased noise directly limits the improvement of the gyroscope's detection limit and overall performance.

[0007] System complexity: In order to partially suppress the effects of backscattering, it is usually necessary to introduce complex active or passive noise reduction techniques (such as phase modulation, bidirectional control loops, etc.), which not only increases the complexity, cost and power consumption of the system, but also introduces new instability factors.

[0008] In summary, backscatter noise has become the most significant technical bottleneck restricting further breakthroughs in the performance of resonant microcavity gyroscopes. Therefore, developing a novel microcavity gyroscope solution that can fundamentally suppress or eliminate backscatter noise from its working principle or system structure is a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention proposes a microcavity angular velocity measurement device and method with single-beam injection.

[0010] The first aspect of this invention discloses a single-beam injection microcavity angular velocity measurement device, the microcavity angular velocity measurement device comprising:

[0011] The U-shaped waveguide feedback microcavity chip includes an optical microcavity and a U-shaped waveguide coupled to the optical microcavity, forming a coupled cavity structure; wherein, the quality factor of the optical microcavity is a preset order of magnitude;

[0012] The laser generation and modulation unit is used to generate a frequency-stable continuous laser and to modulate and adjust its power.

[0013] A frequency-locking loop unit is used to lock the output frequency of the continuous laser at a resonant peak of the U-shaped waveguide feedback microcavity chip.

[0014] The first beam splitter is used to split the power-adjusted continuous laser beam into a signal beam and a reference beam; wherein the signal beam is coupled into the U-shaped waveguide feedback microcavity chip in a single propagation direction.

[0015] An angular velocity demodulation unit includes a balanced detector configured to receive the reference light and a first emitted signal light from the U-shaped waveguide feedback microcavity chip, and output an electrical signal related to the power difference between the two optical paths; and

[0016] The signal processing unit is used to process the electrical signal output by the angular velocity demodulation unit to obtain the angular velocity information of the microcavity angular velocity measuring device;

[0017] The microcavity angular velocity measuring device uses the feedback phase introduced by the U-shaped waveguide to modulate the extinction ratio of the transmission spectrum resonance valley of the optical microcavity. When the microcavity angular velocity measuring device rotates, the Sagnac effect causes the optical path length of the U-shaped waveguide and the optical microcavity to change in different proportions, thereby causing a change in the extinction ratio of the resonance valley. The angular velocity information is obtained by detecting the change in the extinction ratio.

[0018] Optionally, the laser generation and modulation unit includes: a continuous narrow linewidth laser, a signal generator, and an electro-optic modulator;

[0019] The continuous narrow linewidth laser is used to generate a frequency-stable continuous laser.

[0020] The signal generator is used to generate a low-frequency modulation signal to drive the electro-optic modulator to perform phase or frequency modulation on the continuous laser to provide the local oscillator signal required by the frequency-locked loop unit.

[0021] Optionally, the laser generation and modulation unit further includes: a first tunable optical attenuator;

[0022] The first tunable optical attenuator is disposed between the continuous narrow linewidth laser and the electro-optic modulator to adjust the optical power injected into the U-shaped waveguide feedback microcavity chip in order to suppress optical nonlinear effects.

[0023] Optionally, the angular velocity demodulation unit further includes a second adjustable optical attenuator and a second lock-in amplifier;

[0024] The second adjustable optical attenuator is disposed between the first beam splitter and the balanced detector to adjust the reference optical power so that it is equal to the signal optical power from the U-shaped waveguide feedback microcavity chip when the microcavity angular velocity measuring device is stationary.

[0025] The second lock-in amplifier is used to amplify and filter the electrical signal output by the balanced detector.

[0026] Optionally, the signal processing unit includes a data acquisition card for acquiring the amplified and filtered electrical signal and converting it into a digital quantity for calculation to obtain the angular velocity information of the microcavity angular velocity measuring device.

[0027] Optionally, the angular velocity demodulation unit further includes a second beam splitter for splitting the emitted light from the U-shaped waveguide feedback microcavity chip into a first emitted signal light and a second emitted signal light.

[0028] Optionally, the frequency locking loop unit includes:

[0029] A photodetector is used to receive the second outgoing signal light from the U-shaped waveguide feedback microcavity chip and convert it into an electrical signal.

[0030] The first lock-in amplifier is used to demodulate the electrical signal output by the photodetector to obtain an error signal that is proportional to the laser frequency detuning.

[0031] A proportional-integral-derivative (PI-DE) controller is used to process the error signal and output a control signal; and

[0032] A piezoelectric ceramic is connected to the continuous narrow linewidth laser for adjusting the output frequency of the laser according to the control signal.

[0033] Optionally, the ratio of the length of the U-shaped waveguide to the perimeter of the optical microcavity is configured such that when the microcavity angular velocity measuring device rotates, the relative optical path changes between the two due to the Sagnac effect are different, causing the feedback phase to change in proportion to the angular velocity.

[0034] A second aspect of the present invention discloses a method for measuring the angular velocity of a microcavity with single-beam injection, the method being implemented using the single-beam injection microcavity angular velocity measuring device described in any one of the preceding claims, the method comprising:

[0035] The generated continuous laser is modulated and its power adjusted;

[0036] The power-adjusted continuous laser beam is split into a signal beam and a reference beam; the signal beam is coupled into the U-shaped waveguide feedback microcavity chip in a single propagation direction.

[0037] The output frequency of the continuous laser is locked to a resonant peak of the U-shaped waveguide feedback microcavity chip by a frequency-locking loop unit.

[0038] The first outgoing signal light and the reference light from the U-shaped waveguide feedback microcavity chip are input to the balanced detector;

[0039] When the microcavity angular velocity measuring device rotates, the extinction ratio of the resonant valley of the transmission spectrum of the U-shaped waveguide feedback microcavity chip changes due to the Sagnac effect and feedback phase change, resulting in an imbalance of the two input optical power of the balanced detector and outputting an electrical signal related to the angular velocity.

[0040] The electrical signal is processed to obtain the angular velocity information of the microcavity angular velocity measuring device.

[0041] Optionally, before measurement, the method further includes a calibration step: placing the device on a standard rate turntable, recording the output value of the signal processing unit at different known angular velocities, establishing the scaling factor between the output voltage and the angular velocity through linear fitting, and determining the correspondence between the direction of the angular velocity and the polarity of the output voltage.

[0042] In summary, the solution proposed in this invention has the following technical effects:

[0043] Because of the single-beam injection, only a single-direction resonant light exists within the microcavity, fundamentally eliminating the coupling and noise caused by backscattering between bidirectional resonant light beams. This provides a completely new technical approach to solving the core pain points of microcavity gyroscopes.

[0044] The detection target is transformed from the frequency shift of the resonance peak to the extinction ratio change of the resonance valley. This is achieved by increasing the length of the U-shaped waveguide. This can effectively amplify the change in the feedback phase, thereby improving the device's sensitivity to the Sagnac effect.

[0045] This invention eliminates one reverse injection optical path and its corresponding control unit, simplifying the system structure, reducing calibration complexity, and improving the long-term stability of the system.

[0046] This invention is expected to achieve orders-of-magnitude improvements in key performance indicators such as zero-bias stability and angular random walk, laying a solid foundation for realizing high-performance miniaturized gyroscopes. Attached Figure Description

[0047] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0048] Figure 1 A schematic diagram of a resonant microcavity gyroscope system with conventional bidirectional beam injection;

[0049] Figure 2 A structural block diagram of a single-beam injected laser angular velocity measuring device provided in an embodiment of the present invention;

[0050] Figure 3 A schematic diagram of a coupled cavity structure consisting of an ultra-high Q-value microcavity and a U-shaped feedback waveguide, provided in an embodiment of the present invention;

[0051] Figure 4 This is a schematic diagram illustrating the variation of the extinction ratio of the microcavity transmission spectrum resonance valley under different angular velocities, as provided in an embodiment of the present invention.

[0052] Figure 5 This is a schematic diagram showing the optical path propagation direction of a traditional gyroscope within a microcavity.

[0053] Figure 6 This is a schematic diagram comparing the optical path propagation direction of the gyroscope in the microcavity with that of the present invention, provided for an embodiment of the present invention.

[0054] Explanation of icon numbers:

[0055] 1-Integrator-differentiator controller; 2-Piezoelectric ceramic; 3-Continuous narrow linewidth laser; 4-First tunable optical attenuator; 5-First lock-in amplifier; 6-Signal generator; 7-Electro-optic modulator; 8-Data acquisition card; 9-Photodetector; 10-First beam splitter; 11-Second tunable optical attenuator; 12-Second lock-in amplifier; 13-U-shaped waveguide feedback microcavity chip; 14-Balanced detector; 15-Second beam splitter. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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.

[0057] The first aspect of this invention discloses a single-beam injection microcavity angular velocity measurement device, the microcavity angular velocity measurement device comprising:

[0058] The U-shaped waveguide feedback microcavity chip 13 includes an optical microcavity and a U-shaped waveguide coupled to the optical microcavity, forming a coupled cavity structure; wherein, the quality factor of the optical microcavity needs to reach a preset level;

[0059] The laser generation and modulation unit is used to generate a frequency-stable continuous laser and to modulate and adjust its power.

[0060] The frequency-locking loop unit is used to lock the output frequency of the continuous laser at a resonant peak of the U-shaped waveguide feedback microcavity chip 13.

[0061] The first beam splitter 10 is used to split the power-adjusted continuous laser beam into a signal beam and a reference beam; wherein the signal beam is coupled into the U-shaped waveguide feedback microcavity chip 13 in a single propagation direction.

[0062] An angular velocity demodulation unit includes a balanced detector 14 configured to receive the reference light and the first emitted signal light from the U-shaped waveguide feedback microcavity chip 13, and output an electrical signal related to the power difference between the two optical paths; and

[0063] The signal processing unit is used to process the electrical signal output by the angular velocity demodulation unit to obtain the angular velocity information of the microcavity angular velocity measuring device;

[0064] The microcavity angular velocity measuring device uses the feedback phase introduced by the U-shaped waveguide to modulate the extinction ratio of the transmission spectrum resonance valley of the optical microcavity. When the microcavity angular velocity measuring device rotates, the Sagnac effect causes the optical path length of the U-shaped waveguide and the optical microcavity to change in different proportions, thereby causing a change in the extinction ratio of the resonance valley. The angular velocity information is obtained by detecting the change in the extinction ratio.

[0065] Optionally, the laser generation and modulation unit includes: a continuous narrow linewidth laser 3, a signal generator 6, and an electro-optic modulator 7;

[0066] The continuous narrow linewidth laser 3 is used to generate a frequency-stable continuous laser.

[0067] The signal generator 6 generates a low-frequency modulation signal to drive the electro-optic modulator 7 to perform phase or frequency modulation on the continuous laser to provide the local oscillator signal required by the frequency-locked loop unit.

[0068] Optionally, the laser generation and modulation unit further includes a first tunable optical attenuator 4. The first tunable optical attenuator 4 is disposed between the continuous narrow linewidth laser 3 and the electro-optic modulator 7, and is used to adjust the optical power injected into the U-shaped waveguide feedback microcavity chip 13 to suppress optical nonlinear effects.

[0069] Optionally, the angular velocity demodulation unit further includes a second adjustable optical attenuator 11 and a second lock-in amplifier 12;

[0070] The second adjustable optical attenuator 11 is disposed between the first beam splitter 10 and the balanced detector 14, and is used to adjust the reference optical power so that it is equal to the signal optical power from the U-shaped waveguide feedback microcavity chip 13 when the microcavity angular velocity measuring device is stationary.

[0071] The second lock-in amplifier 12 is used to amplify and filter the electrical signal output by the balanced detector 14.

[0072] Optionally, the signal processing unit includes a data acquisition card 8, which is used to acquire the amplified and filtered electrical signal and convert it into a digital quantity for calculation to obtain the angular velocity information of the microcavity angular velocity measuring device.

[0073] Optionally, the angular velocity demodulation unit further includes a second beam splitter 15, used to split the emitted light from the U-shaped waveguide feedback microcavity chip 13 into a first emitted signal light and a second emitted signal light.

[0074] Optionally, the frequency locking loop unit includes:

[0075] Photodetector 9 is used to receive the second outgoing signal light from the U-shaped waveguide feedback microcavity chip 13 and convert it into an electrical signal;

[0076] The first lock-in amplifier 5 is used to demodulate the electrical signal output by the photodetector 9 to obtain an error signal that is proportional to the laser frequency detuning.

[0077] A proportional-integral-derivative controller 1 is used to process the error signal and output a control signal; and

[0078] The piezoelectric ceramic 2 is connected to the continuous narrow linewidth laser 3 and is used to adjust the output frequency of the laser according to the control signal.

[0079] Optionally, the ratio of the length of the U-shaped waveguide to the perimeter of the optical microcavity is configured such that when the microcavity angular velocity measuring device rotates, the relative optical path changes between the two due to the Sagnac effect are different, causing the feedback phase to change in proportion to the angular velocity.

[0080] refer to Figure 2 The single-beam injection microcavity angular velocity measurement device provided in this embodiment mainly includes the following components:

[0081] Laser generation and modulation unit: 3. Continuous narrow linewidth laser, 4. First tunable optical attenuator, 7. Electro-optic modulator, 6. Signal generator.

[0082] Frequency-locked loop unit: first beam splitter 10, photodetector 9, first phase-locked amplifier 5, proportional-integral-differential controller 1, piezoelectric ceramic 2.

[0083] The core sensing unit is a U-shaped waveguide feedback microcavity chip 13.

[0084] Angular velocity demodulation unit: second beam splitter 15, second adjustable optical attenuator 11, balanced detector 14, second lock-in amplifier 12;

[0085] The signal processing unit may optionally be a data acquisition card 8.

[0086] The entire device uses a single-beam injection method, and all optical path components are connected sequentially according to the direction of light transmission to form a complete angular velocity measurement link.

[0087] The continuous narrow-linewidth laser 3 outputs a continuous laser with a stable frequency and extremely narrow linewidth. This laser first passes through a first adjustable optical attenuator 4, which adjusts its optical power to a suitable level to avoid exciting optical nonlinear effects (such as the Kerr effect) in the subsequent high-Q microcavity, ensuring that the device operates in the linear range.

[0088] Subsequently, the laser enters the electro-optic modulator 7. The signal generator 6 generates a low-frequency (typically several kilohertz to several hundred kilohertz) sinusoidal signal, driving the electro-optic modulator 7 to perform small-amplitude phase modulation (or frequency modulation) on the laser carrier. The modulated laser contains the carrier and sidebands, which are used for demodulation of error signals in subsequent frequency-locked loop units.

[0089] The modulated laser beam is split into two beams (signal beam and reference beam) by the first beam splitter 10 at a certain ratio (e.g., 1:1); among them,

[0090] Signal light (i.e.) Figure 2 Beam 1 in the middle): enters the sensing core unit for angular velocity sensing.

[0091] Reference light (i.e.) Figure 2 Beam 2 in the middle): As a reference for angular velocity demodulation, it is sent to the subsequent balancing detector.

[0092] The purpose of the frequency-locking loop unit is to precisely and stably lock the laser frequency at a specific resonant peak of the U-shaped waveguide feedback microcavity chip 13, ensuring that the sensing optical path operates at its optimal operating point. This loop constitutes a closed-loop negative feedback device, and the specific process is as follows:

[0093] Signal Extraction: After the signal light enters the U-shaped waveguide feedback microcavity chip 13, its transmitted light is split again by the second beam splitter 15. A small portion of the light (e.g., 10%) is then extracted. Figure 2 The light beam 1-1 in the photodetector is used as a frequency-locked probe light and is received by the photodetector 9 and converted into an electrical signal.

[0094] Error signal demodulation: The electrical signal output by photodetector 9 contains information about the light intensity change caused by the slight variation in laser frequency near the microcavity resonant peak. This signal is sent to the first lock-in amplifier 5 and mixed with the local oscillator reference signal provided by signal generator 6, and then low-pass filtered. Through lock-in amplification technology, an error signal proportional to the detuning between the laser frequency and the microcavity resonant peak is demodulated.

[0095] Feedback control: The demodulated error signal is input to proportional-integral-derivative controller 1 (i.e., PID controller 1). PID controller 1 performs proportional, integral, and derivative operations based on the magnitude and trend of the error signal, and outputs the corresponding control voltage.

[0096] Frequency fine-tuning: A control voltage is applied to the piezoelectric ceramic 2 mounted on the continuous narrow linewidth laser 3. The piezoelectric ceramic 2 deforms under the voltage, thereby finely adjusting the physical length of the external cavity or internal components of the laser, achieving rapid and precise fine-tuning of the laser output frequency.

[0097] Closed-loop locking: The above process constitutes a closed loop. When the laser frequency deviates from the resonant peak, the frequency-locking loop unit generates an error signal and drives the piezoelectric ceramic 2 to pull the frequency back. Ultimately, the laser frequency is dynamically stabilized within the full width at half maximum (FWHM) of the resonant peak, achieving high-stability frequency locking.

[0098] Angular velocity information is extracted using the equilibrium detection method, with the following specific steps:

[0099] Signal and reference light preparation:

[0100] Signal light: The main beam emitted from the U-shaped waveguide feedback microcavity chip 13 and split by the second beam splitter 15 (e.g., 90%) Figure 2 The light beams 1-2 in the middle are used as signal light carrying angular velocity modulation information and are input to one input terminal of the balance detector 14.

[0101] Reference light: Another beam (beam 2) split from the first beam splitter 10 passes through the second adjustable optical attenuator 11. When the device is stationary (angular velocity is zero), the attenuator is adjusted so that the optical power of the reference light is equal to the optical power of the signal light at this time. The adjusted reference light is then input to another input terminal of the balanced detector 14.

[0102] Balance detection:

[0103] The balanced detector 14 measures and outputs the current or voltage signal corresponding to the difference in optical power between its two input lights in real time.

[0104] In a static state: the power of the two optical paths is equal, and the output of the balanced detector is a zero-point signal (or a fixed bias voltage).

[0105] Rotation state: Due to the change in the microcavity transmission extinction ratio caused by the angular velocity, the power of beam 1-2 changes accordingly, while the reference light power remains unchanged. Therefore, the balanced detector 14 outputs a differential electrical signal that is proportional to the magnitude of the angular velocity and related to the rotation direction (corresponding to an increase or decrease in the extinction ratio).

[0106] Signal processing and output:

[0107] The weak differential signal output by the balanced detector is sent to the second lock-in amplifier 12 for amplification and filtering to suppress noise and improve the signal-to-noise ratio.

[0108] The processed analog signal is acquired by data acquisition card 8 and converted into a digital quantity.

[0109] Finally, by processing the digital signal through a host computer or embedded processor, the real-time angular velocity magnitude and direction of the device can be calculated.

[0110] The sensing core of this invention is a U-shaped waveguide feedback microcavity chip 13, the structural schematic of which is shown in the figure below. Figure 3 As shown. The chip consists of two parts:

[0111] Optical microcavities: Typically whispering-gallery style optical microcavities with extremely high quality factors (Q values), usually not less than 1×10⁻⁶. 6 Preferably not less than 1×10 7 More preferably, it reaches 1×10 8 The above enables long-term storage and enhancement of the optical field. The high-Q microcavity was chosen for the following reasons: First, a high Q value implies an extremely narrow resonant linewidth Δu (Δu = u0 / Q, where u0 is the resonant frequency), making the microcavity highly sensitive to changes in interference conditions caused by the U-shaped waveguide feedback phase, thus significantly amplifying the modulation depth of the extinction ratio. Second, the long photon lifetime resulting from the high Q value enhances the interaction between light and matter, increasing the equivalent action length of the Sagnac effect. However, unlike traditional methods, this invention successfully avoids the typically more severe backscattering coupling problem in high-Q microcavities through a single-beam injection mechanism, allowing the advantages of the high Q value to be fully utilized.

[0112] U-shaped waveguide: A section of optical waveguide bent into a "U" shape, with its two ends (i.e., the upper and lower coupling regions) coupled to an optical microcavity through evanescent field coupling, thus forming a coupled cavity structure.

[0113] The core working principle of this structure lies in feedback phase modulation:

[0114] The U-shaped waveguide guides a portion of the light emitted from one coupling region of the microcavity to another coupling region and re-injects it into the microcavity, forming optical feedback. This feedback light interferes with the light directly propagating in the microcavity.

[0115] The interference condition is determined by the phase experienced by the feedback light, which is related to the length of the U-shaped waveguide. Directly related.

[0116] When the entire chip is in a static state, the length of the microcavity perimeter Lc and the length of the U-shaped waveguide are designed. A specific proportional relationship allows the transmission spectrum of the coupled cavity to form a resonant valley with adjustable depth near the resonant peak, whose extinction ratio is controlled by the feedback phase. For example, Figure 3 As shown, Lc= + , This indicates the length of the right half of the microcavity (from the lower coupling cavity clockwise to the upper coupling region). This indicates the left half of the microcavity (from the upper coupling region clockwise to the lower coupling region).

[0117] When the microcavity angular velocity measuring device rotates, the Sagnac effect acts simultaneously on the microcavity loop and the U-shaped waveguide. However, due to the different geometric paths and optical propagation directions of the two, the relative optical path change (ΔL) caused by the rotation is different. This difference directly leads to a change in the feedback phase introduced by the U-shaped waveguide that is proportional to the rotational angular velocity Ω. The rotation refers to the rotation of the U-shaped waveguide feedback microcavity chip (13) about an axis perpendicular to its cavity plane.

[0118] The change in feedback phase modulates the interference conditions of the coupled cavity, ultimately manifesting as a linear change in the extinction ratio of the resonance valleys in the transmission spectrum. This process is as follows: Figure 4 As shown: The laser frequency is locked at the center of the resonance valley (frequency) When angular velocity From 0 to , At that time, a significant, linear change can be observed in the depth (extinction ratio) of the resonance valley, while the position of the valley center only shifts slightly (compensated in real time by the frequency-locked system). Therefore, by detecting the transmitted light power at the locking point (i.e., the manifestation of the extinction ratio), the angular velocity can be linearly inverted.

[0119] The single-beam injection method used in this invention is the key to achieving a performance breakthrough, distinguishing it from traditional solutions. Figure 5 This demonstrates the intracavity optical field state of a traditional resonant microcavity gyroscope: two laser beams, one clockwise and one counterclockwise, must be injected simultaneously to detect the relative shift in the two resonant frequencies caused by the Sagnac effect. However, due to the inherent backscattering of the microcavity (caused by defects, roughness, etc.), these two counter-propagating optical fields undergo strong reciprocal coupling. This coupling is the fundamental noise source leading to the "lock-in effect," increased angular random walk, and zero-bias instability.

[0120] Figure 6 This clearly demonstrates the optical field state of the present invention: only a single-direction resonant light exists (e.g., clockwise). Although backscattering of the microcavity still exists, due to the absence of a reverse-propagating resonant light field, the backscattered light cannot interfere with or effectively couple with another strong resonant mode, thus preventing the formation of destructive noise. In other words, single-beam injection physically removes the necessary condition for noise generation, thereby fundamentally eliminating backscattering coupling noise. This is the core mechanism by which the present invention significantly improves the performance of gyroscopes at low speeds and reduces background noise.

[0121] Before practical application, the device needs to be calibrated to determine the correspondence between the scale factor and the direction:

[0122] The entire device is mounted on a standard rate turntable that provides accurate angular velocity values.

[0123] The turntable is controlled to rotate at a series of known angular velocities (Ω1, Ω2, ...) of different magnitudes and directions.

[0124] Record the average voltage values ​​(V1, V2, ...) output from data acquisition card 8 at each angular velocity.

[0125] For these data points (Ω) i V i A linear fit is performed, and the slope of the fitted line is the scaling factor of the gyroscope (unit: V / (° / s) or V / (rad / s)).

[0126] The positive and negative polarities of the output voltage correspond to the rotation direction of the turntable (e.g., clockwise is positive, counterclockwise is negative), thus completing the direction calibration.

[0127] The above description is a preferred embodiment of the present invention. Based on the core concept of the present invention—single-beam injection and U-shaped waveguide feedback extinction ratio modulation—those skilled in the art can make various modifications and improvements, such as:

[0128] Optical microcavities can take different shapes such as spherical, annular, and disk-shaped.

[0129] U-shaped waveguides can be integrated with microcavities on the same planar substrate, or they can be achieved through three-dimensional packaging.

[0130] Other modulation and demodulation techniques (such as Pound-Drever-Hall technology) can be used for the frequency-locked loop unit.

[0131] Angular velocity demodulation can be achieved using a combination of single-end detection and digital processing, but balanced detection can better suppress common-mode noise.

[0132] The signal processing unit can be integrated into a field-programmable gate array or an application-specific integrated circuit.

[0133] A second aspect of the present invention discloses a method for measuring the angular velocity of a microcavity with single-beam injection, the method being implemented using the single-beam injection microcavity angular velocity measuring device described in any one of the preceding claims, the method comprising:

[0134] The generated continuous laser is modulated and its power adjusted;

[0135] The power-adjusted continuous laser beam is split into a signal beam and a reference beam; the signal beam is coupled into the U-shaped waveguide feedback microcavity chip 13 in a single propagation direction;

[0136] The output frequency of the continuous laser is locked to a resonant peak of the U-shaped waveguide feedback microcavity chip 13 by a frequency-locking loop unit.

[0137] The first outgoing signal light and the reference light from the U-shaped waveguide feedback microcavity chip 13 are input to the balanced detector 14;

[0138] When the microcavity angular velocity measuring device rotates, the resonant valley extinction ratio of the transmission spectrum of the U-shaped waveguide feedback microcavity chip 13 changes due to the Sagnac effect and feedback phase change, causing the two input optical power of the balance detector 14 to become unbalanced and output an electrical signal related to angular velocity.

[0139] The electrical signal is processed to obtain the angular velocity information of the microcavity angular velocity measuring device.

[0140] Optionally, before measurement, a calibration step is also included: placing the device on a standard rate turntable, recording the output value of the signal processing unit at different known angular velocities, establishing the scaling factor between the output voltage and the angular velocity through linear fitting, and determining the correspondence between the direction of the angular velocity and the polarity of the output voltage.

[0141] 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 or all of the technical features therein, and such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A microcavity angular velocity measuring device with single-beam injection, characterized in that, The microcavity angular velocity measuring device includes: The U-shaped waveguide feedback microcavity chip (13) includes an optical microcavity and a U-shaped waveguide coupled to the optical microcavity, forming a coupled cavity structure; wherein, the quality factor of the optical microcavity is a preset order of magnitude; The laser generation and modulation unit is used to generate a frequency-stable continuous laser and to modulate and adjust its power. The frequency-locking loop unit is used to lock the output frequency of the continuous laser at one of the resonant peaks of the U-shaped waveguide feedback microcavity chip (13); The first beam splitter (10) is used to split the power-adjusted continuous laser beam into a signal beam and a reference beam; wherein the signal beam is coupled into the U-shaped waveguide feedback microcavity chip (13) in a single propagation direction. An angular velocity demodulation unit, including a balanced detector (14), is configured to receive the reference light and the first emitted signal light from the U-shaped waveguide feedback microcavity chip (13), and output an electrical signal related to the power difference between the two optical paths; and The signal processing unit is used to process the electrical signal output by the angular velocity demodulation unit to obtain the angular velocity information of the microcavity angular velocity measuring device; The microcavity angular velocity measuring device uses the feedback phase introduced by the U-shaped waveguide to modulate the extinction ratio of the transmission spectrum resonance valley of the optical microcavity. When the microcavity angular velocity measuring device rotates, the Sagnac effect causes the optical path length of the U-shaped waveguide and the optical microcavity to change in different proportions, thereby causing a change in the extinction ratio of the resonance valley. The angular velocity information is obtained by detecting the change in the extinction ratio.

2. The single-beam injection microcavity angular velocity measuring device according to claim 1, characterized in that, The laser generation and modulation unit includes: a continuous narrow linewidth laser (3), a signal generator (6), and an electro-optic modulator (7). The continuous narrow linewidth laser (3) is used to generate a frequency-stable continuous laser. The signal generator (6) is used to generate a low-frequency modulation signal to drive the electro-optic modulator (7) to perform phase or frequency modulation on the continuous laser to provide the local oscillator signal required by the frequency-locked loop unit.

3. The single-beam injection microcavity angular velocity measuring device according to claim 2, characterized in that, The laser generation and modulation unit also includes: a first tunable optical attenuator (4); The first tunable optical attenuator (4) is disposed between the continuous narrow linewidth laser (3) and the electro-optic modulator (7) to adjust the optical power injected into the U-shaped waveguide feedback microcavity chip (13) in order to suppress optical nonlinear effects.

4. The single-beam injection microcavity angular velocity measuring device according to claim 2, characterized in that, The angular velocity demodulation unit also includes a second adjustable optical attenuator (11) and a second lock-in amplifier (12). The second adjustable optical attenuator (11) is disposed between the first beam splitter (10) and the balanced detector (14) to adjust the reference optical power so that it is equal to the signal optical power from the U-shaped waveguide feedback microcavity chip (13) when the microcavity angular velocity measuring device is stationary; The second lock-in amplifier (12) is used to amplify and filter the electrical signal output by the balance detector (14).

5. The single-beam injection microcavity angular velocity measuring device according to claim 4, characterized in that, The signal processing unit includes a data acquisition card (8) for acquiring the amplified and filtered electrical signal and converting it into a digital quantity for calculation to obtain the angular velocity information of the microcavity angular velocity measuring device.

6. The single-beam injection microcavity angular velocity measuring device according to claim 4, characterized in that, The angular velocity demodulation unit also includes a second beam splitter (15) for splitting the emitted light from the U-shaped waveguide feedback microcavity chip (13) into a first emitted signal light and a second emitted signal light.

7. The single-beam injection microcavity angular velocity measuring device according to claim 6, characterized in that, The frequency locking loop unit includes: A photodetector (9) is used to receive the second outgoing signal light from the U-shaped waveguide feedback microcavity chip (13) and convert it into an electrical signal; The first lock-in amplifier (5) is used to demodulate the electrical signal output by the photodetector (9) to obtain an error signal that is proportional to the laser frequency detuning. A proportional-integral-derivative controller (1) is used to process the error signal and output a control signal; and A piezoelectric ceramic (2) is connected to the continuous narrow linewidth laser (3) for adjusting the output frequency of the laser according to the control signal.

8. The single-beam injection microcavity angular velocity measuring device according to claim 1, characterized in that, The ratio of the length of the U-shaped waveguide to the perimeter of the optical microcavity is configured such that when the microcavity angular velocity measuring device rotates, the relative optical path changes between the two due to the Sagnac effect are different, causing the feedback phase to change in proportion to the angular velocity.

9. A method for measuring the angular velocity of a microcavity with single-beam injection, characterized in that, The method is implemented using the single-beam injection microcavity angular velocity measurement device according to any one of claims 1-8, and the method includes: The generated continuous laser is modulated and its power adjusted; The power-adjusted continuous laser beam is split into a signal beam and a reference beam; the signal beam is coupled into the U-shaped waveguide feedback microcavity chip (13) in a single propagation direction. The output frequency of the continuous laser is locked to one of the resonant peaks of the U-shaped waveguide feedback microcavity chip (13) by the frequency locking loop unit; The first outgoing signal light and the reference light from the U-shaped waveguide feedback microcavity chip (13) are input to the balanced detector (14). When the microcavity angular velocity measuring device rotates, the resonant valley extinction ratio of the transmission spectrum of the U-shaped waveguide feedback microcavity chip (13) changes due to the Sagnac effect and feedback phase change, causing the two input optical power of the balance detector (14) to become unbalanced and output an electrical signal related to angular velocity. The electrical signal is processed to obtain the angular velocity information of the microcavity angular velocity measuring device.

10. The method according to claim 9, characterized in that, Before measurement, the method further includes a calibration step: placing the device on a standard rate turntable, recording the output voltage of the signal processing unit at different known angular velocities, establishing the scaling factor between the output voltage and the angular velocity through linear fitting, and determining the correspondence between the direction of the angular velocity and the polarity of the output voltage.

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