Residual cavity mode noise suppression method of off-axis integral cavity enhancement technology

Abstract

The invention discloses a residual cavity mode noise suppression method based on an off-axis integral cavity enhancement technology, and relates to the technical field of environmental monitoring, and the method comprises the steps: constructing an optical resonant cavity model through optical design software, and carrying out the alignment of an optical element through an alignment technology; selecting a laser as a light source, optimizing modulation parameters of the laser, and obtaining optimal light source parameter configuration through a radio frequency white noise injection technology; combining the aligned optical element with the optimal optical parameter configuration to obtain an off-axis angle; and establishing a real-time monitoring system, monitoring the intra-cavity mode change of the optical resonant cavity in real time, and adjusting the optical resonant cavity model based on a monitoring result. The model is constructed through optical design software, various performance parameters of the optical resonant cavity can be simulated and optimized in advance in a virtual environment, and therefore trial and error cost and time consumption in the actual construction process are remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental monitoring. Specifically, it relates to a method for suppressing residual cavity mode noise in off-axis integrated cavity enhanced technology. Background Art

[0002] In the field of environmental monitoring, especially for the precise measurement of atmospheric greenhouse gas concentrations, traditional technologies are often limited by detection accuracy, stability, and long-term observation capabilities. Among them, as a high-sensitivity spectroscopic detection technology, off-axis integrated cavity enhanced technology shows great potential, but its core challenge lies in how to effectively cope with and overcome the interference of residual cavity mode noise. Residual cavity mode noise mainly stems from the non-ideal mode light source distribution in the cavity. These unexpected optical modes not only reduce the signal quality but also significantly hinder the accurate extraction of the target signal.

[0003] Achieving sufficient off-axis of the off-axis integrated cavity is a key step in suppressing residual cavity mode noise. However, this process is affected by various complex factors, including but not limited to the stability of the light source power, the precise design and accurate alignment of the optical resonator, and the modulation strategy of the laser. There is a direct coupling effect between the insufficient off-axis state and the residual cavity mode noise, resulting in a decline in system performance and making it difficult to meet the requirements of high-precision measurement. In addition, the task of detecting atmospheric greenhouse gases requires the equipment to have the ability to work continuously and stably for a long time, which poses strict requirements on the detection instrument's resistance to environmental noise, interference from human activities, and noise and drift caused by multiple collinearity. Environmental noise, human activity noise, and small changes in the internal components of the instrument may all introduce additional measurement errors, affecting the accuracy and reliability of the data.

[0004] In a complex application environment, signal recognition and extraction face great challenges. Multiple types of noise sources, such as equipment inherent noise, external environmental interference, and signal transmission loss, are intertwined with the signal to be measured, greatly increasing the difficulty of weak signal recognition. Especially coherent noise, the interference waves with specific main frequencies are prone to aliasing with the original signal during signal processing, further reducing the signal quality.

[0005] In response to the problems in the related art, no effective solution has been proposed yet. Summary of the Invention

[0006] In response to the problems in the related art, the present invention proposes a method for suppressing residual cavity mode noise in off-axis integrated cavity enhanced technology to overcome the above technical problems existing in the existing related technologies.

[0007] To this end, the specific technical solution adopted by the present invention is as follows:

[0008] A method for suppressing residual cavity mode noise in off-axis integrated cavity enhanced technology, the method comprising the following steps:

[0009] S1. Construct an optical resonator model using optical design software and align the optical components using alignment technology;

[0010] S2. Select a laser as the light source, optimize the modulation parameters of the laser, and obtain the optimal light source parameter configuration through radio frequency white noise injection technology;

[0011] S3. Combine the aligned optical components with the optimal optical parameter configuration to obtain the off-axis angle;

[0012] S4. Establish a real-time monitoring system to monitor the intra-cavity mode changes of the optical resonator in real time, and adjust the optical resonator model based on the monitoring results.

[0013] Further, constructing an optical resonator model using optical design software and aligning the optical components using alignment technology includes the following steps:

[0014] S11. Define the geometric parameters of the optical resonator according to the design requirements of the off-axis integral cavity;

[0015] S12. Input the geometric parameters into the optical design software to construct an optical resonator model based on the off-axis integral cavity. The optical resonator model includes optical components and corresponding position data;

[0016] S13. Conduct a simulation analysis on the constructed optical resonator model to obtain the optimal optical resonator model;

[0017] S14. Combine the optimal optical resonator model with the position data of the optical components and use alignment technology to align the optical components.

[0018] Further, the geometric parameters include shape, position, and tilt angle.

[0019] Further, conducting a simulation analysis on the constructed optical resonator model to obtain the optimal optical resonator model includes the following steps:

[0020] S131. Use the optical design software to conduct a simulation analysis on the optical resonator model, simulate the intra-cavity mode distribution under different geometric parameters of the optical components, and based on the simulation results, obtain the original mode performance indicators of the intra-cavity mode;

[0021] S132. Analyze the simulation results to identify the characteristic parameters related to the residual cavity mode;

[0022] S133. Based on the characteristic parameters, adjust the geometric parameters of the optical resonator, and re-run the simulation analysis to obtain new mode performance indicators;

[0023] S134. Compare the original mode performance metrics with the new mode performance metrics, and based on the comparison results, determine whether the preset threshold is reached. If so, obtain the optimal optical resonator model; otherwise, repeat steps S132 to S133 until the optimal optical resonator model is obtained.

[0024] Further, combining the optimal optical resonator model with the position data of the optical elements, the alignment of the optical elements using the alignment technology includes the following steps:

[0025] S141. According to the optimal optical resonator model, select a reference optical point, and based on the reference optical point, select a reference element;

[0026] S142. Centered on the reference element, randomly select several optical elements to construct a geometric shape, and use the line connecting the reference element to the reference optical point as the optimal alignment baseline;

[0027] S143. Measure the position data of each optical element relative to the optimal alignment baseline;

[0028] S144. Combining the optimal optical resonator model with the relative position data, use the geometric optimization algorithm for iterative calculation to obtain the optimal positions of all optical elements;

[0029] S145. Use the alignment technology to align all optical elements according to the optimal positions.

[0030] Further, the formula of the geometric optimization algorithm is:

[0031] P i,d t+1 =P i,d t +x1*sin(x2)*|x3Td - P i,d t |

[0032] In the formula, P i,m t+1 represents the position of the i-th optical element in the m-th dimension in the (t + 1)-th generation;

[0033] P i,m t represents the position of the i-th optical element in the m-th dimension in the t-th generation;

[0034] x1 represents a randomly selected optical element;

[0035] x2 represents a randomly selected optical element;

[0036] x3 represents a binary random number;

[0037] T dRepresents the optimal position in the d-th dimension.

[0038] Furthermore, a laser is selected as the light source, the modulation parameters of the laser are optimized, and the optimal light source parameter configuration is obtained through the radio frequency white noise injection technique, including the following steps:

[0039] S21. According to the requirements of the off-axis integrated cavity enhanced technique, a laser is selected as the light source, and the modulation parameters of the laser are initially set. The modulation parameters include the modulation frequency and the modulation depth;

[0040] S22. Build an experimental platform and perform a modulation parameter scanning experiment on the experimental platform to obtain the performance data of the off-axis integrated cavity under different modulation parameters;

[0041] S23. Adopt the radio frequency white noise injection technique and adjust the intensity of the radio frequency white noise through an adaptive algorithm to obtain the optimal noise injection intensity;

[0042] S24. Analyze the performance data, identify the optimal modulation parameters, and combine the optimal noise injection intensity to obtain the light source configuration parameters.

[0043] Furthermore, the formula of the adaptive algorithm is:

[0044] ε(t + 1) = ε(t) + ω * e(t)

[0045] In the formula, ε represents the intensity of the radio frequency white noise;

[0046] t represents the time point;

[0047] ω represents the step size factor;

[0048] e represents the performance data error.

[0049] Furthermore, obtaining the off-axis angle by combining the aligned optical elements with the optimal optical parameter configuration includes the following steps:

[0050] S31. Based on the aligned optical elements, use optical design software to calculate the free spectral range of the optical resonator;

[0051] S32. Set the initial off-axis angle according to the geometric parameters of the optical resonator and the free spectral range;

[0052] S33. Input the geometric parameters of the aligned optical elements and the set initial off-axis angle into the optical design software, perform the simulation of the mode distribution in the optical resonator, and execute the optical path simulation;

[0053] S34. Based on the optical path simulation results, calculate the propagation path of the beam at the off-axis angle and analyze the interaction between the beam and the cavity mode;

[0054] S35. Based on the interaction analysis between the light beam and the cavity mode, adjust the off-axis angle, optimize the geometric parameters, and select the off-axis angle with the minimum residual cavity mode noise.

[0055] Furthermore, based on the optical path simulation results, calculate the propagation path of the light beam at the off-axis angle, and analyze the interaction between the light beam and the cavity mode, including the following steps:

[0056] S341. Based on the optical path simulation results, obtain the propagation path of the light beam at the off-axis angle and the mode distribution in the optical resonator.

[0057] S342. Use visualization technology to visually display the propagation path of the light beam at the off-axis angle and the mode distribution in the optical resonator.

[0058] S343. Based on the visual display results, analyze the spatial overlap between the light beam propagation path and the modes in the optical resonator, and calculate the distribution ratio of the light beam in each mode.

[0059] S344. Combine the modal interference analysis algorithm with the distribution ratio to evaluate the interaction between the light beam and the cavity mode.

[0060] The beneficial effects of the present invention are as follows:

[0061] 1. By constructing a model with optical design software, the present invention can pre-simulate and optimize various performance parameters of the optical resonator in a virtual environment, thereby significantly reducing the trial-and-error cost and time consumption in the actual construction process; at the same time, through the alignment technology, it can ensure the precise alignment between optical elements, reduce scattering and energy loss in the optical path, and thus improve the overall efficiency and stability of the optical system.

[0062] 2. By optimizing the modulation parameters of the laser, the output light reaches the best state in terms of spectral purity, stability, power and other indicators. Combining with the radio frequency white noise injection technology, it can effectively simulate the complex noise conditions in the real environment, thereby comprehensively evaluating and optimizing the system's resistance to external interference, and promoting the overall improvement of the system performance and efficiency.

[0063] 3. By combining the aligned optical elements with the optimal optical parameter configuration, the present invention can accurately calculate the off-axis angle, which not only ensures the stability of the optical resonator, but also significantly improves the mode matching degree, further optimizing the overall performance of the system; in addition, the high-efficiency operation of the real-time monitoring system can instantaneously feedback the changes in the cavity mode, providing strong support for the dynamic adjustment of the system, and ensuring that the system always maintains the best working state. Description of the Drawings

[0064] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0065] Figure 1 is a flowchart of a method for suppressing residual cavity mode noise of an off-axis integrated cavity enhanced technique according to an embodiment of the present invention. Detailed implementation manners

[0066] To further illustrate the embodiments, the present invention provides drawings. These drawings are part of the disclosure of the present invention. They are mainly used to illustrate the embodiments and can be combined with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, those of ordinary skill in the art should be able to understand other possible implementation manners and the advantages of the present invention.

[0067] According to an embodiment of the present invention, a method for suppressing residual cavity mode noise of an off-axis integrated cavity enhanced technique is provided.

[0068] Now, the present invention will be further described in combination with the drawings and specific implementation manners. As Figure 1 shown, a method for suppressing residual cavity mode noise of an off-axis integrated cavity enhanced technique according to an embodiment of the present invention includes the following steps:

[0069] S1. Use optical design software to construct an optical resonator model and align the optical elements using alignment techniques.

[0070] Specifically, using optical design software to construct an optical resonator model and align the optical elements using alignment techniques includes the following steps:

[0071] S11. Define the geometric parameters of the optical resonator according to the design requirements of the off-axis integrated cavity.

[0072] Specifically, the geometric parameters include shape, position, and tilt angle.

[0073] It should be added that the shape includes the mirror shape of the optical resonator. In addition, during the detection process, to ensure the efficient propagation and stable reflection of the light beam, the surface of the cavity mirror needs to be processed. Combining the cavity mirror coating process and the ion static elimination technique can reduce the decrease in reflectivity caused by dust deposition, thereby reducing the resulting measurement drift.

[0074] The positions include relative positions and intersection positions. The relative positions between two or more mirrors determine the shape and size of the optical resonator. For example, in a parallel plane cavity, two plane mirrors are placed parallel to each other; in a plane-concave cavity, one plane mirror and one concave mirror are placed opposite to each other at a certain distance. For an optical resonator containing a concave mirror, the focal position of the concave mirror is a key parameter, which determines the focusing point and reflection path of the light beam in the cavity.

[0075] The tilt angles include adjustable tilt angles and specific angle values. During the experiment, the adjustable tilt angle can adjust the optical path as needed to achieve the best optical performance. The specific value of the tilt angle depends on the design requirements and experimental objectives of the optical resonator. For example, in some designs, it may be necessary to tilt the mirror at a certain angle to achieve off-axis propagation of light or eliminate unnecessary interference fringes.

[0076] S12. Input the geometric parameters into the optical design software to construct an optical resonator model based on the off-axis integral cavity. The optical resonator model includes optical elements and corresponding position data.

[0077] S13. Perform simulation analysis on the constructed optical resonator model to obtain the optimal optical resonator model.

[0078] Specifically, performing simulation analysis on the constructed optical resonator model to obtain the optimal optical resonator model includes the following steps:

[0079] S131. Use the optical design software to perform simulation analysis on the optical resonator model, simulate the intracavity mode distribution under different geometric parameters of optical elements, and based on the simulation results, obtain the original mode performance indicators of the intracavity mode.

[0080] It should be added that the performance indicators include mode stability, mode purity, mode matching efficiency, quality factor (Q value), mode volume, mode divergence angle, frequency stability, and mode spectral width.

[0081] S132. Analyze the simulation results to identify the characteristic parameters related to the residual cavity mode.

[0082] It should be added that the characteristic parameters include the offset between the mode frequency and the main mode frequency, the mode energy ratio, the mode spatial distribution, the mode coupling coefficient, the mode loss, and the mode Q value.

[0083] S133. Based on the characteristic parameters, adjust the geometric parameters of the optical resonator and re-run the simulation analysis to obtain new mode performance indicators.

[0084] S134. Compare the original mode performance metrics with the new mode performance metrics, and based on the comparison result, determine whether the preset threshold is reached. If so, obtain the optimal optical resonator model; otherwise, repeat steps S132 to S133 until the optimal optical resonator model is obtained.

[0085] S14. Combine the optimal optical resonator model with the position data of the optical elements, and use the alignment technology to align the optical elements.

[0086] Specifically, combining the optimal optical resonator model with the position data of the optical elements and using the alignment technology to align the optical elements includes the following steps:

[0087] S141. According to the optimal optical resonator model, select a reference optical point, and based on the reference optical point, select a reference element.

[0088] S142. Centering on the reference element, randomly select several optical elements, construct a geometric shape, and use the connection line from the reference element to the reference optical point as the optimal alignment baseline.

[0089] S143. Measure the position data of each optical element relative to the optimal alignment baseline.

[0090] S144. Combine the optimal optical resonator model with the relative position data, and use the geometric optimization algorithm for iterative calculation to obtain the optimal positions of all optical elements.

[0091] Specifically, the formula of the geometric optimization algorithm is:

[0092] P i,d t+1 =P i,d t +x1*sin(x2)*|x3Td - P i,d t

[0093] In the formula, P i,m t+1 represents the position of the i-th optical element in the m-th dimension in the (t + 1)-th generation;

[0094] P i,m t represents the position of the i-th optical element in the m-th dimension in the t-th generation;

[0095] x1 represents a randomly selected optical element;

[0096] x2 represents a randomly selected optical element;

[0097] x3 represents a binary random number;

[0098] T dIndicates the optimal position in the d-th dimension.

[0099] S145. Use alignment technology to align all optical elements according to the optimal positions.

[0100] It should be noted that using alignment technology to align all optical elements according to the optimal positions includes:

[0101] Based on the optimal positions, fix the reference element at a predetermined position; select the optical elements to be aligned one by one according to the calculation order or according to the actual situation (such as element size, weight, installation complexity, etc.); preliminarily fix each element, and use a laser aligner to measure the position deviation of the current element relative to the optimal alignment baseline; according to the measured deviation, use fine-tuning technology (such as screw fine-tuning, piezoelectric ceramic drive, etc.) to adjust the element position until its position error is within the allowable range (usually reaching micron or even sub-micron level accuracy); repeat the above steps until the position deviations in all directions meet the requirements.

[0102] After all elements are aligned, conduct an overall verification, including checking whether the relative positions between the elements conform to the optimal configuration, and whether the overall performance of the resonant cavity (such as resonant frequency, mode stability, transmission efficiency, etc.) reaches the expected goal. If significant local or overall deviations are found, return to the corresponding elements for fine-tuning until the requirements are met.

[0103] S2. Select a laser as the light source, optimize the modulation parameters of the laser, and obtain the optimal light source parameter configuration through radio frequency white noise injection technology.

[0104] Specifically, selecting a laser as the light source, optimizing the modulation parameters of the laser, and obtaining the optimal light source parameter configuration through radio frequency white noise injection technology include the following steps:

[0105] S21. According to the requirements of off-axis integrated cavity enhancement technology, select a laser as the light source and preliminarily set the modulation parameters of the laser. The modulation parameters include modulation frequency and modulation depth.

[0106] It should be noted that in the process of modulation parameters, the phase-locked amplification technology can be used. By precisely frequency modulating the incident laser and using the phase-sensitive detection technology to achieve the extraction and phase-locked amplification of the signal with the same frequency and phase as the incident laser modulation frequency, the weak signal can be effectively extracted from the noise, thereby improving the detection sensitivity of the system.

[0107] S22. Build an experimental platform and conduct a modulation parameter scanning experiment on the experimental platform to obtain the performance data of the off-axis integrated cavity under different modulation parameters.

[0108] It should be noted that constructing the experimental platform includes: selecting experimental facilities (lasers, modulation equipment, detectors, control systems, optical elements, data acquisition systems, etc.) according to the purpose of the experiment, such as studying the influence of different modulation parameters on the performance of the off-axis integrating cavity and optimizing the light source configuration, and constructing the experimental platform based on the selected experimental facilities; using the experimental platform for testing to obtain the performance data of the off-axis integrating cavity under different modulation parameters.

[0109] Performing the modulation parameter sweep experiment includes: keeping the modulation frequency constant and gradually changing the modulation depth; at each modulation depth, recording the performance data of the off-axis integrating cavity; gradually increasing the modulation depth until the set maximum value is reached. At the same time, perform a combined modulation parameter sweep, changing the modulation frequency and modulation depth to form a two-dimensional or three-dimensional parameter space; design a grid to cover the entire parameter space, scan and record data point by point; at each parameter combination, record the performance data of the off-axis integrating cavity. In addition, the performance data includes signal-to-noise ratio (SNR), mode purity, light intensity distribution, etc.

[0110] S23. Adopt the radio frequency white noise injection technology, adjust the intensity of the radio frequency white noise through an adaptive algorithm, and obtain the optimal noise injection intensity.

[0111] Specifically, the formula of the adaptive algorithm is:

[0112] ε(t + 1) = ε(t) + ω * e(t)

[0113] In the formula, ε represents the intensity of the radio frequency white noise;

[0114] t represents the time point;

[0115] ω represents the step size factor;

[0116] e represents the performance data error.

[0117] S24. Analyze the performance data, identify the optimal modulation parameters, and combine with the optimal noise injection intensity to obtain the light source configuration parameters.

[0118] It should be noted that analyzing the performance data, identifying the optimal modulation parameters, and combining with the optimal noise injection intensity to obtain the light source configuration parameters includes:

[0119] Step 1. Multi-dimensional analysis

[0120] Two-dimensional analysis: Fix the modulation depth and plot the relationship diagram between the modulation frequency and the performance index; fix the modulation frequency and plot the relationship diagram between the modulation depth and the performance index; through these two-dimensional diagrams, initially identify the range of modulation parameters with the best performance under a certain fixed parameter.

[0121] Three-dimensional analysis: Plot the three-dimensional relationship diagram of the modulation frequency, modulation depth, and performance metrics to more comprehensively understand the performance under different parameter combinations; plot the contour map of the performance metrics to find the region with the optimal performance.

[0122] Step 2: Identify the optimal modulation parameters

[0123] Based on the two-dimensional and three-dimensional analyses, identify the local performance optimal points; comprehensively consider all data to identify the global performance optimal points, which are usually the modulation parameter combinations with the highest performance metrics; considering the stability and robustness of the system, select the modulation parameters that not only have high performance but also are stable within a certain range.

[0124] Step 3: Combine the optimal noise injection intensity

[0125] The optimal noise injection intensity obtained by adjusting the radio frequency white noise intensity through an adaptive algorithm is combined with the optimal modulation parameters to evaluate the overall performance. Under the selected optimal modulation parameters and noise injection intensity, re-run the experiment to verify whether the actual performance of the system meets the expectations.

[0126] Step 4: Determine the light source configuration parameters

[0127] Based on the above analysis, determine the final laser modulation parameters (including modulation frequency and modulation depth) and the radio frequency white noise injection intensity, set these parameters as the standard operating parameters of the laser, and record them.

[0128] S3. Combine the aligned optical elements with the optimal optical parameter configuration to obtain the off-axis angle.

[0129] Specifically, combining the aligned optical elements with the optimal optical parameter configuration to obtain the off-axis angle includes the following steps:

[0130] S31. Based on the aligned optical elements, use optical design software to calculate the free spectral range of the optical resonator.

[0131] It should be added that the geometric parameters of the aligned optical elements are input into the optical design software, a three-dimensional model of the optical resonator is constructed in the software, and the basic parameters (cavity length, refractive index, temperature, and pressure) and simulation parameters (wavelength range, resolution, and light source characteristics) of the optical resonator are defined; through the simulation function in the optical design software, calculate the mode distribution of the optical resonator, and identify different longitudinal modes (i.e., standing wave modes along the cavity axis direction) in the simulation results; according to the wavelength difference between adjacent longitudinal modes, calculate the free spectral range (FSR), and the formula is:

[0132]

[0133] In the formula, FSR represents the free spectral range; c represents the speed of light; L represents the effective cavity length of the optical resonator.

[0134] S32. Set the initial off-axis angle according to the geometric parameters of the optical resonator and the free spectral range.

[0135] S33. Input the geometric parameters of the aligned optical elements and the set initial off-axis angle into the optical design software, simulate the mode distribution in the optical resonator, and perform optical path simulation.

[0136] It should be noted that in the optical design software, set the optical path simulation to ensure that it includes the propagation path of the laser beam in the optical resonator; run the optical path simulation to track the propagation path of the laser beam between different optical elements; check the optical path diagram in the simulation results to confirm whether the laser beam propagates along the expected path and observe the interaction between the beam and each optical element; analyze the simulation results of the mode distribution to confirm the main modes and their distributions, confirm the propagation path of the laser beam at the off-axis angle, and record the interaction between the beam and each optical element, and extract key performance indicators such as signal-to-noise ratio, mode purity, and light intensity distribution to provide a basis for subsequent optimization.

[0137] S34. Based on the optical path simulation results, calculate the propagation path of the beam at the off-axis angle and analyze the interaction between the beam and the cavity mode.

[0138] Specifically, based on the optical path simulation results, calculating the propagation path of the beam at the off-axis angle and analyzing the interaction between the beam and the cavity mode includes the following steps:

[0139] S341. Based on the optical path simulation results, obtain the propagation path of the beam at the off-axis angle and the mode distribution in the optical resonator.

[0140] S342. Use visualization technology to visually display the propagation path of the beam at the off-axis angle and the mode distribution in the optical resonator.

[0141] S343. Based on the visually displayed results, analyze the spatial overlap between the beam propagation path and the modes in the optical resonator, and calculate the distribution ratio of the beam in each mode.

[0142] S344. Combine the modal interference analysis algorithm and the distribution ratio to evaluate the interaction between the beam and the cavity mode.

[0143] It should be noted that according to the modal interference analysis algorithms (such as the finite-difference time-domain method, the finite-difference frequency-domain method, the modal expansion method, etc.), initial conditions are set in combination with simulation requirements, such as the output power, wavelength, phase, etc. of the laser; the interference analysis is run to simulate the interaction between the beam and each mode in the optical resonator, and the interference patterns and related data generated during the interference analysis are recorded, such as the interference intensity, phase change, etc.; the interference patterns in the interference analysis results are checked to confirm whether the expected interference phenomena exist, and key performance indicators are extracted from the interference patterns, such as the interference intensity, the interference fringe spacing, phase change, etc., and the simulation results are compared with the theoretical predictions to verify the accuracy of the simulation results; based on the interference patterns and the distribution ratio, the coupling efficiency between the beam and each cavity mode is calculated, and the coupling efficiency calculation formula is:

[0144]

[0145] In the formula, η i represents the coupling efficiency; P i represents the power of the beam in the i-th mode; P total represents the total power of the beam.

[0146] The coupling degree between the beam and the main modes, as well as the influence of the secondary modes on the system performance, are evaluated through the coupling efficiency. The higher the modal purity, the better the system performance; based on the coupling efficiency and the modal distribution ratio, the sources and influences of the residual cavity mode noise are analyzed.

[0147] S35. Based on the interaction analysis between the beam and the cavity modes, the off-axis angle is adjusted, and geometric parameters are optimized to select the off-axis angle with the minimum residual cavity mode noise.

[0148] It should be noted that based on the interaction analysis between the beam and the cavity modes, adjusting the off-axis angle and optimizing the geometric parameters to select the off-axis angle with the minimum residual cavity mode noise includes:

[0149] A group of initial combinations of off-axis angles and geometric parameters are randomly generated as the initial population; for each combination of off-axis angles and geometric parameters, the mode distribution simulation and optical path simulation are carried out using optical design software to calculate the corresponding objective function values; according to the rules of the optimization algorithm, the individuals in the population are updated; for example, in the genetic algorithm, a new population is generated through selection, crossover, and mutation operations; the above process is repeated until the stop condition is met (such as reaching the maximum number of iterations or the convergence of the objective function value), and the combination of off-axis angles and geometric parameters with the optimal objective function value is selected from the final population.

[0150] S4. A real-time monitoring system is established to monitor the changes in the intracavity modes of the optical resonator in real time, and the optical resonator model is adjusted based on the monitoring results.

[0151] It should be noted that establishing a real-time monitoring system to monitor the changes in the intracavity mode of the optical resonator in real time and adjusting the optical resonator model based on the monitoring results includes:

[0152] Select a high-sensitivity photodetector to monitor the mode changes and noise characteristics in the optical resonator; install the photodetector at the output end of the optical resonator or at a suitable light extraction port position to ensure that it can monitor the changes in the light beam in the resonator in real time; use a high-speed data acquisition card or a lock-in amplifier to collect and digitize the signals from the photodetector for subsequent analysis; perform noise spectrum analysis on the collected light intensity signals to identify the characteristics of intracavity mode changes and residual cavity mode noise. Common methods include fast Fourier transform (FFT) or time-frequency analysis; according to the signal processing results, develop a feedback control algorithm to compare the detected residual cavity mode noise data with the target noise level. When the noise exceeds the preset threshold, the feedback system automatically triggers the adjustment of the optical resonator parameters, and adjusts the angle or position of the optical element through a precision electric displacement stage or a piezoelectric ceramic regulator; continuously collect the optical signals in the resonator through the monitoring system, observe the changes in the intracavity mode, and record the real-time data of the residual cavity mode noise. When the noise exceeds the set range, the system automatically adjusts the optical element (such as the angle of the mirror or the frequency of the laser) according to the feedback mechanism.

[0153] In summary, by means of the above technical solutions of the present invention, by constructing a model with optical design software, the performance parameters of the optical resonator can be pre-simulated and optimized in a virtual environment, thus significantly reducing the trial-and-error cost and time consumption in the actual construction process; at the same time, the alignment technology can ensure the precise alignment between optical elements, reduce the scattering and energy loss in the optical path, and thus improve the overall efficiency and stability of the optical system. By optimizing the modulation parameters of the laser, the output light reaches the best state in terms of spectral purity, stability, power and other indicators. Combining with the radio frequency white noise injection technology, it can effectively simulate the complex noise conditions in the real environment, thereby comprehensively evaluating and optimizing the system's resistance to external interference, and promoting the overall improvement of the system performance and efficiency. By combining the aligned optical elements with the optimal optical parameter configuration, the off-axis angle can be accurately calculated, which not only ensures the stability of the optical resonator, but also significantly improves the mode matching degree, further optimizing the overall performance of the system; in addition, the efficient operation of the real-time monitoring system can instantly feedback the changes in the intracavity mode, providing strong support for the dynamic adjustment of the system and ensuring that the system always maintains the best working state.

[0154] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for suppressing residual cavity mode noise in off-axis integrated cavity enhanced technology, characterized in that The method includes the following steps: S1. Use optical design software to construct an optical resonator model, and align the optical elements using alignment technology; S2. Select a laser as the light source, optimize the modulation parameters of the laser, and obtain the optimal light source parameter configuration through radio frequency white noise injection technology; S3. Combine the aligned optical elements with the optimal optical parameter configuration to obtain the off-axis angle; S4. Establish a real-time monitoring system to monitor the intracavity mode changes of the optical resonator in real time, and adjust the optical resonator model based on the monitoring results.

2. The method for suppressing residual cavity mode noise of the off-axis integrated cavity enhanced technique according to claim 1, wherein The step of using optical design software to construct an optical resonator model and align the optical elements using alignment technology includes the following steps: S11. Define the geometric parameters of the optical resonator according to the design requirements of the off-axis integrating cavity; S12. Input the geometric parameters into the optical design software to construct an optical resonator model based on the off-axis integrating cavity, where the optical resonator model includes optical elements and corresponding position data; S13. Perform simulation analysis on the constructed optical resonator model to obtain the optimal optical resonator model; S14. Combine the optimal optical resonator model with the position data of the optical elements, and use alignment technology to align the optical elements.

3. The method for suppressing residual cavity mode noise of the off-axis integrated cavity enhanced technique according to claim 2, wherein The geometric parameters include shape, position, and tilt angle.

4. The method for suppressing residual cavity mode noise of the off-axis integrated cavity enhanced technique according to claim 2, wherein The step of performing simulation analysis on the constructed optical resonator model to obtain the optimal optical resonator model includes the following steps: S131. Use optical design software to perform simulation analysis on the optical resonator model, simulate the intracavity mode distribution under different geometric parameters of the optical elements, and based on the simulation results, obtain the original mode performance indicators of the intracavity mode; S132. Analyze the simulation results to identify the characteristic parameters related to the residual cavity mode; S133. Based on the characteristic parameters, adjust the geometric parameters of the optical resonator, and re-run the simulation analysis to obtain new mode performance indicators; S134. Compare the original mode performance indicators with the new mode performance indicators, and based on the comparison results, determine whether the preset threshold is reached. If so, obtain the optimal optical resonator model; otherwise, repeat steps S132 to S133 until the optimal optical resonator model is obtained.

5. The method for suppressing residual cavity mode noise of off-axis integrated cavity enhanced technology according to claim 2, wherein The step of combining the optimal optical resonator model with the position data of the optical elements and using alignment technology to align the optical elements includes the following steps: S141. According to the optimal optical resonator model, select a reference optical point, and select a reference element based on the reference optical point; S142. Centering on the reference element, randomly select several optical elements to construct a geometric shape, and use the connection line from the reference element to the reference optical point as the optimal alignment baseline; S143. Measure the position data of each optical element relative to the optimal alignment baseline; S144. Combine the optimal optical resonator model with the relative position data, and use a geometric optimization algorithm to perform iterative calculations to obtain the optimal positions of all optical elements; S145. Use alignment technology to align all optical elements according to the optimal positions.

6. The method for suppressing residual cavity mode noise of the off-axis integrated cavity enhanced technique according to claim 5, characterized in that, The formula of the geometric optimization algorithm is: P i,d t+1 = P i,d t + x1 * sin(x2) * |x3Td - P i,d t where P i,m t+1 represents the position of the i-th optical element in the m-th dimension in the (t + 1)-th generation; P i,m t represents the position of the i-th optical element in the m-th dimension in the t-th generation; x1 represents a randomly selected optical element; x2 represents a randomly selected optical element; x3 represents a binary random number; T d represents the optimal position in the d-th dimension.

7. The method for suppressing residual cavity mode noise of the off-axis integrated cavity enhanced technique according to claim 1, wherein The selected laser is used as the light source, the modulation parameters of the laser are optimized, and the optimal light source parameter configuration is obtained through the radio frequency white noise injection technology, including the following steps: S21. According to the requirements of the off-axis integrated cavity enhanced technology, select a laser as the light source and preliminarily set the modulation parameters of the laser. The modulation parameters include the modulation frequency and the modulation depth; S22. Build an experimental platform and perform a modulation parameter scanning experiment on the experimental platform to obtain the performance data of the off-axis integrated cavity under different modulation parameters; S23. Adopt the radio frequency white noise injection technology and adjust the intensity of the radio frequency white noise through an adaptive algorithm to obtain the optimal noise injection intensity; S24. Analyze the performance data, identify the optimal modulation parameters, and combine the optimal noise injection intensity to obtain the light source configuration parameters.

8. The method for suppressing the residual cavity mode noise of the off-axis integrated cavity enhanced technique according to claim 7, wherein The formula of the adaptive algorithm is: ε(t + 1) = ε(t) + ω * e(t) In the formula, ε represents the intensity of the radio frequency white noise; t represents the time point; ω represents the step factor; e represents the performance data error.

9. The method for suppressing the residual cavity mode noise of the off-axis integrated cavity enhanced technology according to claim 1, wherein The steps of obtaining the off-axis angle by combining the aligned optical elements with the optimal optical parameter configuration include the following: S31. Based on the aligned optical elements, use optical design software to calculate the free spectral range of the optical resonator; S32. Set the initial off-axis angle according to the geometric parameters of the optical resonator and the free spectral range; S33. Input the geometric parameters of the aligned optical elements and the set initial off-axis angle into the optical design software to simulate the mode distribution in the optical resonator and perform the optical path simulation; S34. Based on the optical path simulation results, calculate the propagation path of the beam at the off-axis angle and analyze the interaction between the beam and the cavity mode; S35. Based on the interaction analysis between the beam and the cavity mode, adjust the off-axis angle, optimize the geometric parameters, and select the off-axis angle with the minimum residual cavity mode noise.

10. The method for suppressing residual cavity mode noise of the off-axis integrated cavity enhanced technique according to claim 9, wherein The steps of calculating the propagation path of the beam at the off-axis angle and analyzing the interaction between the beam and the cavity mode based on the optical path simulation results include the following: S341. Based on the optical path simulation results, obtain the propagation path of the beam at the off-axis angle and the mode distribution in the optical resonator; S342. Use visualization technology to visually display the propagation path of the beam at the off-axis angle and the mode distribution in the optical resonator; S343. Based on the visual display results, analyze the spatial overlap between the beam propagation path and the modes in the optical resonator, and calculate the distribution ratio of the beam in each mode; S344. Combine the mode interference analysis algorithm and the distribution ratio to evaluate the interaction between the beam and the cavity mode.

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