65 results about "Free spectral range" patented technology

The invention relates to the technical field of optical fiber sensors, in particular to a double-parameter optical fiber sensor based on a double interference effect and a preparation method thereof.The sensor comprises a sensing unit 5 based on a Fabry-Perot interferometer and a sensing unit 6 based on a Mach-Zehnder interferometer, and the two sensing units form a cascade structure; mutual reference probes can be realized when different parameters are measured; according to the invention, an approximate free spectral range is obtained by controlling the cavity length, a remarkable vernier effect is formed, the air pressure and temperature sensitivity can be calculated by tracking the drift of the envelope, the measurement accuracy can be effectively improved, and the device has the advantages of simple structure and small volume.

The invention discloses a micro-ring modulator with a large free spectral range and a design method of the micro-ring modulator, and belongs to the field of optoelectronic devices. A micro-ring resonant cavity corresponding to the micro-ring modulator comprises an annular waveguide, and the width of the annular waveguide is an optimized width value, so that the integral value of the group refractive index of an optical mode in the annular waveguide along a closed optical path of the annular waveguide is minimized, and meanwhile, the width is ensured to be smaller than a cut-off width supporting high-order optical mode propagation. Through the design of accurately regulating and controlling waveguide dispersion, the free spectral range of the device can be maximized on the premise of ensuring single-mode work. In addition, an asymmetric electro-optical modulation structure can be arranged on the annular waveguide so as to be matched with a distorted optical mode, and high modulation efficiency is guaranteed. The micro-ring device with ultra-large FSR, high bandwidth, high efficiency and compact size can be realized, and the micro-ring device has important application value in the field of high-density optical interconnection.

The present invention concerns a tunable Dense Wavelength Division Multiplex (DWDM) intra cavity laser device having a first optical wave guide having a first optical grating section, a second optical wave guide having a second optical grating section, an active gain section spatially separated from the second optical grating section and a phase section, and a DWDM-filter having an intra-cavity ring resonator located between the first optical wave guide and the second optical wave guide for coupling optical waves between the first and second optical wave guides. The tunable laser device is tunable in a discrete manner depending on a length of the ring resonator that is selected such that the free spectral range of the ring resonator matches a predetermined fixed wavelength spacing grid.

The application belongs to the technical field of optical communication and relates to a frequency-shift-free microwave photonic channelized receiving device, which comprises a carrier light frequency comb generating unit, a local light frequency comb generating unit, an electro-optical modulation unit, an optical phase shift unit, a channel selection and spectrum processing unit and a plurality of photoelectric conversion units. The received broadband radio frequency signal is modulated on each comb tooth of the carrier light frequency comb through the electro-optical modulation unit, and the frequency alignment between the optical local oscillator and the required receiving sub-channel can be realized based on the "vernier" effect caused by the different free spectral ranges of the carrier light frequency comb and the local light frequency comb and the inherent frequency alignment of the same pump laser. The mirror image sub-channel suppression is realized based on the opposite optical phase shifts on both sides of the pump light. The application has a simple structure, omits the frequency shift and special modulation structure required for frequency alignment, effectively suppresses the inter-channel crosstalk problem in the channelized receiving process, and can flexibly increase the channelization quantity according to actual needs.

The invention provides an F-P spectral imaging system and method, and belongs to the technical field of spectral component measurement, and the system comprises a front lens which is used for collecting light energy and converting the light energy into emergent light meeting the limitation of the clear aperture of an F-P interferometer; the annular band optical filter comprises a central area and a plurality of concentric annular areas surrounding the central area, the bandwidth of each area is the same as the free spectral range of the F-P interferometer, and the annular band optical filter is used for eliminating level aliasing in emergent light of the front lens; the F-P interferometer is used for carrying out wavelength selection on emergent light of the annular band optical filter and outputting an interference field; the imaging mirror is used for projecting the interference field to the detector; and the detector is used for converting the projected optical signal into a digital electric signal. The F-P spectral imaging system which can maintain high spectral resolution and also can realize wide spectrum coverage is constructed by introducing the annular band optical filter which is accurately matched with the FSR of the F-P interferometer.

This application provides a self-injection-locked narrow-linewidth laser with a quasi-continuous locking region, comprising: a semiconductor laser source for generating an initial linewidth laser and outputting it via end-face coupling; a photonic integrated microcavity chip including a bus waveguide and a microring resonator coupled to it via an evanescent wave, for receiving the initial linewidth laser and providing feedback light to the semiconductor laser through Rayleigh backscattering of the microring resonator to excite a self-injection-locking effect; the microring resonator is a compact folded waveguide microcavity with an ultra-low free spectral range, the free spectral range of which is less than a preset threshold, so that when the driving current of the semiconductor laser is changed for wavelength tuning, the self-injection-locking regions of adjacent resonant modes in the cavity physically overlap or are closely spliced ​​in the current tuning parameter space, so that the semiconductor laser can continuously transition between adjacent modes without experiencing permanent unlocking during continuous current tuning, forming a quasi-continuous locking region.

The present application belongs to the technical field of photonic device design, and specifically relates to a micro-ring resonator reverse design optimization method based on deep learning. The present application comprises: obtaining different micro-ring resonator structure parameters and corresponding free spectral range and quality factor, and processing and dividing the data set; building a cascade neural network model, wherein the reverse network takes the target performance index as the input to predict the structure parameter, the forward network inputs the structure parameter and outputs the performance index, and is used to constrain and correct the reverse prediction result; after training, the test set is evaluated to measure the reverse effect by the average absolute percentage error index, the weight in the loss function is changed, and multiple rounds of training are performed to determine the optimal weight configuration and final model of the reverse design. The present application has the advantages of high calculation efficiency, excellent design precision and strong physical realizability, can reduce the dependence on large-scale simulation and multiple iteration optimization, effectively shorten the device design cycle, and has high application value.

The invention discloses a method for measuring a residual birefringence difference value of a transparent ferroelectric electro-optical material based on a Fabry-Perot resonant cavity. The method comprises the following steps: constructing a Fabry-Perot resonant cavity measuring light path consisting of a broadband light source, a polarization control assembly and a sample to be measured; the polarization state of incident light is accurately controlled through a magnetic control Faraday rotating mirror, and transmission spectrums in the o-light direction and the e-light direction are obtained respectively; a high-precision spectrum acquisition module is adopted to record transmission spectrum characteristics; based on an original spectrum processing algorithm, the residual birefringence difference value of the to-be-detected material is calculated by analyzing the resonant wavelength offset and the free spectrum range change of the o-light and e-light transmission spectrums. The method solves the problem that the weak birefringence detection capability of the existing measurement technology is insufficient, has the advantages of high measurement precision, strong anti-interference capability and the like, and is suitable for performance evaluation, process optimization and device performance improvement of the transparent ferroelectric electro-optical material.

Optical transceiver architecture utilizing micro-ring modulators and micro-ring resonators configured to route resonant wavelengths of light injected into each micro-ring resonator's input port and through port to that micro-ring resonator's drop port and add port, respectively. The micro-ring resonators drop two distinct streams of data modulated onto the same optical wavelength, or two wavelengths separated by an integer number of free spectral ranges coupled into the micro-ring resonators in two different directions.

This invention discloses an alcohol detection chip and detection method based on a cascaded dual-ring resonator with dual-gradient curvature, belonging to the field of optical micro-nano sensing and integrated optics technology. This invention aims to solve the technical problems of low sensitivity, poor resolution, complex spectral analysis, and weak environmental adaptability in traditional micro-ring sensing devices, as well as the low detection accuracy of existing miniaturized equipment. The chip uses a silicon-based substrate and includes input and output waveguides, cascaded dual micro-rings, a coupling region, and two sets of miniature heating electrodes. The micro-rings employ dual-gradient waveguides with circular and Euler-circular curved structures for the inner and outer curves, respectively. The cascaded dual rings create a vernier effect, broadening the free spectral range. By adjusting the resonant wavelength through the heating electrodes, scanning detection is completed in the characteristic alcohol band around 1400nm, and high-precision alcohol measurement is achieved by combining transmission spectroscopy. This invention has a compact structure and low cost, and is suitable for rapid quantitative detection of alcohol in industrial monitoring, vehicle safety, food safety, and other scenarios.

The invention belongs to the technical field of temperature sensing, and particularly relates to an optical fiber temperature sensor based on a double-FP parallel structure, which is characterized in that the optical fiber temperature sensor is formed by connecting a reference interferometer and a sensing interferometer in parallel, the reference interferometer is composed of a first single-mode optical fiber, a hollow-core optical fiber and a second single-mode optical fiber, and the sensing interferometer is composed of a second single-mode optical fiber and a third single-mode optical fiber. The sensing interferometer is composed of a third single-mode fiber, a PDMS cavity and a fourth single-mode fiber. Wherein the optical path lengths of the PDMS cavity and the hollow-core optical fiber are controlled to be close to each other but not equal to each other, so that the free spectral range of the sensing interferometer is close to each other but not equal to the free spectral range of the reference interferometer, and the vernier effect of an output spectrum is excited to form an envelope formed by fine stripes. The optical fiber temperature sensor has the advantages of being high in sensitivity and linearity, large in detection range, good in repeatability and good in reversibility, meanwhile, the size of the optical fiber sensing probe is in the micron dimension, and the optical fiber temperature sensor is suitable for temperature detection in a narrow space.

This invention provides a traceable uncertainty assessment method for dynamic wavelength calibration. First, it performs uncertainty source analysis based on Taylor series expansion, determining that the time-frequency relationship calibration uncertainty is mainly determined by the uncertainty of the local continuous time-frequency relationship. Then, it assesses the impact of peak location on uncertainty, the uncertainty of the standard interferogram, and the uncertainty of interference intensity under complex tuning conditions, quantifying the standard interferogram uncertainty and the measurement uncertainty generated by local normalized frequency interpolation. These are then combined to obtain the combined uncertainty of the normalized time-frequency relationship. Finally, the combined uncertainty of the normalized time-frequency relationship is multiplied by the free spectral range of the F-P interferometer to obtain the absolute uncertainty of the time-frequency relationship calibration. This invention enables the quantification and propagation analysis of each error component during nonparametric point-by-point calibration, establishing a systematic uncertainty assessment framework and providing a scientific basis for the reliability of the calibration results.

The present application discloses a response waveform modulation method for an optical system, a device, a system, and a readable medium. The optical system comprises a plurality of cascaded optical elements having periodic responses and a plurality of phase modulators respectively arranged on each of the optical elements. The method comprises: acquiring an optical system response waveform target translation amount and free spectral range (FSR) lengths of respective response waveforms of the plurality of optical elements; on the basis of the optical system response waveform target translation amount, each FSR length, and a preset translation algorithm, determining respective phase modulation amounts of the plurality of optical elements; and respectively outputting the determined plurality of phase modulation amounts to the corresponding phase modulators, so that the response waveforms of the optical elements are respectively modulated by means of the plurality of phase modulators according to the plurality of phase modulation amounts, thus enabling response waveforms of the optical system to be significantly linearly translated within an extremely large range, that is, within a total FSR.

This invention discloses an optically pumped tunable vertical-cavity surface-emitting laser (VCSEL), a mirror, and their applications. The wavelength-selective mirror includes a phase-matching region and an optimization region arranged sequentially along the vertical direction. The phase-matching region is formed by periodically alternating stacks of x pairs of first high-refractive-index material layers and first low-refractive-index material layers along the vertical direction. The optimization region is formed by y pairs of second high-refractive-index material layers and z pairs of second low-refractive-index material layers, which are alternately stacked along the vertical direction, and the optical thicknesses of the second high-refractive-index material layers and the second low-refractive-index material layers are unequal. This invention breaks away from the traditional single optimization paradigm centered on lasing light in DBRs, significantly improving optical pumping efficiency while ensuring a wide tuning range and free spectral range, thereby realizing a highly efficient wide-tunable single-longitudinal-mode output MEMS-VCSEL, laying the foundation for next-generation high-performance tunable lasers.

According to the acousto-optic modulator for realizing microwave photon conversion and the preparation method thereof provided by the invention, the runway type micro-ring is constructed on the piezoelectric film layer, the acoustic resonance frequency is accurately matched with the free spectral range of the runway type micro-ring structure, the cyclic generation of an optical modulation sideband is realized, the interaction between light waves and sound waves is greatly enhanced, and the optical modulation efficiency is improved. The acousto-optic coupling efficiency is remarkably improved, the power consumption of the device is greatly reduced, microwave photon conversion is achieved, the device is compact in overall structure and small in size, high-density on-chip integration is easy to achieve, further, periodic polarization is carried out on the interdigital electrodes, a cavity is formed under the piezoelectric film layer, and the photoelectric conversion efficiency of the device is improved. And the piezoelectric film layer is suspended, so that the working bandwidth of the device is further improved, and the requirement of high-speed information processing is met.

This invention discloses a method for measuring the wavelength of low-coherence lasers using a synthetic Fizeau interferometer cavity. The method involves acquiring the interference fringes and extracting the initial phase of each actual Fizeau interferometer cavity with different free spectral ranges (FSRs) that meet the coherence length requirements of the low-coherence laser to be measured. Based on the FSRs and initial phases of each actual cavity, a synthetic Fizeau interferometer cavity with a FSR smaller than that of the physical cavities is constructed to obtain the synthetic free spectral range and synthetic initial phase. The interference order of the synthetic cavity is then determined by combining the input estimated wavelength or frequency, and wavelength refinement is performed to finally obtain the measurement wavelength. This invention does not limit the specific optical path structure or detector arrangement, and can effectively overcome the limitation of low-coherence laser coherence length on the accuracy of Fizeau wavelength measurement without increasing the optical path difference of the actual Fizeau interferometer cavity or reducing the fringe signal-to-noise ratio.

The invention discloses a miniaturized adjustment-free ultra-narrow linewidth composite filtering external cavity semiconductor laser, which belongs to the field of semiconductor lasers and is sequentially provided with a gain chip, an aspherical lens, a first FP etalon, a second FP etalon, an interference filter, a partial reflector, an optical isolator and a polarization maintaining optical fiber collimator. Wherein the first FP etalon and the second FP etalon are superposed in a non-coaxial mode to form a free spectral range difference, a longitudinal mode interval difference is generated through a Vernier effect, and a longitudinal mode interval generated by the Vernier effect is controlled by adjusting a dip angle difference between the first FP etalon and the second FP etalon. Through machining precision, optical coupling optimization and an automatic assembly technology, the problems of wide tuning bandwidth, ultra-narrow linewidth, multi-dimensional performance collaboration and environmental adaptability are synchronously solved.

The application belongs to the field of optoelectronic devices, and specifically discloses a broadband tunable laser based on heterogeneous integration, which comprises: a first resonant cavity and a first bus waveguide are coupled on one side surface, used for receiving optical signals coupled into from the first bus waveguide, and performing intracavity resonance on the light meeting the first resonant cavity resonance condition, and then coupling and reflecting; a second resonant cavity and a second bus waveguide are coupled on one side surface, used for receiving optical signals coupled into from the second bus waveguide, and performing intracavity resonance on the light meeting the second resonant cavity resonance condition, and then coupling and reflecting; a heterogeneous integration gain module is coupled on the other end of the first and second bus waveguides, used for receiving the optical signals reflected by the first resonant cavity and the second resonant cavity, and providing stimulated radiation gain, and then coupling back to the first and second bus waveguides. Through the application, large-range single-longitudinal-mode wavelength continuous tuning beyond the free spectral range limit of a single Fabry-Perot cavity is realized.

The invention belongs to the technical field of on-chip integrated sensing, and provides a chip sensing assembly and a trace gas detection device. The chip sensing assembly comprises a first mode field coupler, a power beam splitter, a non-uniform free spectral range micro-ring resonator array, a power beam combiner and a second mode field coupler which are sequentially connected in series; wherein the non-uniform free spectral range micro-ring resonator array is formed by connecting N micro-ring resonators with different resonant ring lengths in parallel, an evanescent field of an annular waveguide of each micro-ring resonator is exposed to the surface environment of the chip, and the micro-ring resonator array is used for capturing absorption information of gas molecules by using a plurality of evanescent fields; and outputting N paths of detection light carrying absorption information of gas molecules to a power beam combiner. Through a plurality of micro-ring resonators with different ring lengths, the spectrum sampling interval is greatly compressed equivalently, and the limitation of the free spectrum range of a single micro-ring is broken through, so that the on-chip system has the capability of detecting narrow line width absorption characteristics of gas molecules.

A spectral filter includes a wavelength demultiplexer having a first output and a second output, a signal channel pump rejection filter coupled to a first output, and a herald channel pump rejection filter coupled to the second output. The spectral filter also includes a first chain of asymmetric Mach-Zehnder interferometers (MZIs) coupled to the signal channel pump rejection filter. Each of the asymmetric MZIs in the first chain of asymmetric MZIs is characterized by a decreasing free spectral range. The spectral filter further includes a second chain of asymmetric MZIs coupled to the herald channel pump rejection filter. In some embodiments, each of the asymmetric MZIs in the second chain of asymmetric MZIs is characterized by a decreasing free spectral range.

The present application relates to the technical field of optical frequency compensation, and provides an optical frequency compensation method, device, equipment, medium and computer program product, the method comprising: extracting resonance frequencies of adjacent optical modes of the same mode family; determining a free spectral range value according to the resonance frequencies of the adjacent optical modes of the same mode family; analyzing the change trend of the free spectral range value to obtain a reverse structure compensation amount; and feeding back the physical structure of a target resonator based on the reverse structure compensation amount to compensate for the optical frequency drift locked to the target resonator. Through the active compensation mode, the present application obtains the optical frequency change caused by the geometric thermal expansion of the target resonator cavity, determines the reverse structure compensation amount based on the change trend of the free spectral range value, and feeds back the reverse structure compensation micro stress to the resonator to realize the dynamic compensation of the optical frequency of the target resonator, thereby solving the frequency drift of the resonator caused by thermal expansion.

The application provides a combined chip structure with a wide free spectral range, which comprises four spectral imaging chip structures, any of which comprises a pixel photosensitive unit and a narrow-band filter film, the narrow-band filter film being integrally deposited and grown on the pixel photosensitive unit, the narrow-band filter film comprising a plurality of FP cavity structures arranged in a line scanning mode, when spectral imaging is performed by using the combined chip structure, the four spectral imaging chip structures are arranged in a line along a spectral dimension, the heights of the plurality of FP cavity structures of the narrow-band filter film change along the spectral dimension, and the spectral ranges covered by the four spectral imaging chip structures are all different. The application can improve the free spectral range.

The application discloses a reflection type integrated optical resonant structure based on high-order modes, which comprises a first single-mode optical waveguide, a multimode optical waveguide, a first mode coupler, at least one optical phase shifter and a multimode conversion optical reflection module. Two single-mode ports of the first mode coupler are connected with the first single-mode optical waveguide respectively. The multimode port of the first mode coupler is connected with the optical phase shifter through the multimode optical waveguide. Or the multimode port of the first mode coupler is connected with the optical phase shifter and the multimode conversion optical reflection module through the multimode optical waveguide. The multimode conversion optical reflection module is used for changing the mode channel of the light in the incident multimode optical waveguide, so that the light is reversely propagated through another mode channel. The application does not need to bend the waveguide to form a loop, so that the design of the resonant length is more flexible, a larger free spectral range can be realized, the utilization rate of the optical field energy of the resonator is improved, and high-efficiency optical modulation of the optical resonant structure is realized.

The present application belongs to the field of communication technology, and particularly relates to a kind of on-chip multi-path broadband white noise generation method based on chaotic micro-ring optical frequency comb, the implementation of the method includes semiconductor laser, micro-ring resonator, arrayed waveguide grating, photodetector, characterized by: the above-mentioned devices are integrated in the same chip substrate;Semiconductor laser output continuous light injection micro-ring resonator will occur four-wave mixing, self-phase modulation, cross-phase modulation and dispersion combined action, and equal-interval chaotic optical frequency comb is output through the straight-through end of micro-ring resonator.Coupling together after a plurality of micro-ring resonators generate chaotic optical frequency comb of different free spectral range, demultiplexing is carried out through arrayed waveguide grating, and finally multi-path broadband noise signal is output.Compared with existing noise source, the structure is simple, and has the advantages of low power consumption, high stability, bandwidth expansion, and solves the problem of lack of multi-path broadband noise signal implementation scheme, and can be applied to the field of secure communication, random number generation, etc.

The application discloses a thickness-based refractive index gradient micro-ring resonator, comprising: a ring optical waveguide located on a substrate; an input optical waveguide configured to couple light into the ring optical waveguide; the ring optical waveguide has a feature that the thickness decreases along the radial direction, so that the refractive index decreases linearly with the micro-ring radius from small to large, under the premise of realizing a wide free spectral range and low bending loss, the resonator has a higher quality factor, the structure is simple, the resonator can be obtained through a mature photolithography technology, and is suitable for industrial application.

The invention discloses a DLC film-based EFPI acoustic sensor preparation method, device and platform and an acoustic sensor, and the method comprises the steps: controlling a DLC film deposition device through deposition parameters to adjust the type and thickness of a DLC film, and then depositing the DLC film on a silicon substrate to obtain a DLC film sample; immersing the DLC film sample into a culture dish filled with deionized water, and enabling the deionized water to permeate into an interface of a film and a silicon substrate of the DLC film sample so as to desorb the film and the silicon substrate; immersing the glass tube into deionized water, adjusting the angle to enable the end face to be parallel to the thin film, then lifting up the thin film, and standing at room temperature until water is evaporated to obtain a DLC thin film attached to the end face of the glass tube; adjusting each shaft of the displacement table, and calculating the interference cavity length through the free spectral range of the EFPI reflection spectral line; and bonding the optical fiber pigtail and the glass sleeve to obtain the EFPI acoustic sensor based on the DLC film.

The application discloses a kind of based on tunable laser sparse sampling dual-parameter simultaneous detection method and system, it is related to optical fiber sensing technical field.The method includes: based on two to be detected parameters preparation two interferometers;According to the free spectral range of interferometer, the sweep interval of tunable laser is determined;Two interferometers are inserted into the liquid to be detected, and sparse sampling is carried out using sensing device, to obtain two sparse interference spectra corresponding to two interferometers;Two sparse interference spectra are fitted respectively, to obtain two interference spectra;According to the interference spectrum, the amount of interference spectrum translation is determined, and then the change amount of two to be detected parameters relative to their respective calibration value is determined;Calibration value is added to change amount to obtain the measurement value of two to be detected parameters.The application improves the detection accuracy and sensitivity of optical fiber sensing system, and realizes dual-parameter synchronous measurement, provides a new type of sensing solution with simplified structure and excellent performance for marine environment monitoring.

The application provides a single-longitudinal-mode fiber laser which comprises a main cavity and a passive eye-shaped composite ring cavity filter module. The passive eye-shaped composite ring cavity filter module is required to select a single longitudinal mode from dense longitudinal modes of the main cavity, and the effective passband 3dB bandwidth of the eye-shaped composite ring cavity filter module must be 1-1.5 times of the longitudinal mode interval of the main cavity, and the effective free spectral range must be 0.5-1 times of the wavelength selection channel bandwidth, so that the single longitudinal mode laser output can be realized under the wavelength switching of the laser.

The invention discloses a low-phase-shift reconfigurable phase-change optical switch with an ultra-wide free spectral range, which comprises a silicon dioxide substrate layer and is characterized in that a silicon waveguide layer is arranged on the substrate layer, a heat conduction layer is arranged on the waveguide layer, and electrodes are symmetrically distributed on two sides of the silicon waveguide layer; the structure of the silicon waveguide layer is a side coupling structure of a bent waveguide and a nano-beam cavity waveguide, the two ends of the bent waveguide are respectively connected with a grating vertical coupler, a phase change material is arranged on the upper layer of a coupling area of the bent waveguide and located on the lower surface of the heat conduction layer, and the phase change material is connected with two electrodes and forms ohmic contact; a round hole array on the nano-beam cavity waveguide is designed to be of an axisymmetric structure and is divided into a gradual change area and a mirror surface area, the distance and the size of round holes in the gradual change area are the smallest in the center and gradually increased on the two sides, the distance and the size of the round holes in the mirror surface area are kept unchanged, and the round holes of the nano-beam cavity waveguide are filled with silicon dioxide. In two states of the switch, the wavelength shift is less than 2nm.

The invention discloses a PDH laser frequency locking system for generating sidebands based on a nonlinear SOA. The PDH laser frequency locking system comprises a seed laser source, a first coupler, a second coupler, a first acousto-optic frequency shifter, a second acousto-optic frequency shifter, a semiconductor optical amplifier, a circulator, a reference cavity, a photoelectric detector, a frequency mixer, a demodulation filtering module and a servo controller. A nonlinear SOA is used for replacing a traditional electro-optical modulator to efficiently generate a multi-sideband signal needed by PDH frequency locking, the system cost and complexity are remarkably reduced, and the flexibility and strength of sideband generation are improved; meanwhile, through the collaborative design of the double acousto-optic frequency shift and the SOA nonlinear effect, accurate matching of the sideband frequency interval and the free spectral range of the reference cavity is achieved, and the signal-to-noise ratio and the frequency locking stability of the PDH error signal are greatly improved.