Method, system, device and storage medium for photorefractive effect suppression

Abstract

This invention provides a method, system, device, and storage medium for suppressing photorefractive effects, belonging to the field of optoelectronic control technology. The method includes: acquiring output spectral data, calculating phase mismatch parameters for each frequency component, and constructing a corresponding phase mismatch distribution; calculating the equivalent dispersion shift and determining the refractive index change induced by photorefractive; generating compensation control parameters including electric field compensation parameters and pump power compensation parameters, and adjusting the waveguide electric field distribution and pump light intensity distribution; after adjustment, re-acquiring output spectral data and updating the phase mismatch distribution; and repeating the dispersion shift calculation and compensation control parameter generation process based on the updated phase mismatch distribution until the phase mismatch distribution meets a preset stability condition. This invention achieves real-time inversion and dynamic compensation of mode dispersion drift caused by photorefractive, thereby stabilizing the phase matching state and improving the stability and consistency of quantum light source output.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic control technology, and more specifically to a method, system, device, and storage medium for suppressing photorefractive effects. Background Technology

[0002] In on-chip integrated quantum light source technology, nonlinear frequency conversion devices based on silicon nitride microrings or lithium niobate waveguides have been widely used in entangled photon pair generation and quantum precision measurement scenarios. These devices typically rely on precise phase-matching conditions to achieve efficient parametric down-conversion. Once mode dispersion shifts, it directly affects the frequency conversion efficiency and the stability of the photon pair output. From an engineering perspective, the devices are not in an ideal static state during actual operation, especially under continuous pumping conditions. Photorefractive effects gradually accumulate inside the waveguide, causing the refractive index distribution to change over time, which in turn leads to mode dispersion drift.

[0003] In existing technologies, the treatment of photorefractive effects mainly focuses on the material level or structural design level. For example, it involves reducing the photorefractive coefficient through doping or mitigating the light field concentration effect by optimizing the waveguide structure. These methods are effective to some extent during the device design stage, but once the device is in actual operation, they still struggle to address the dynamic changes in photorefractive intensity caused by the continuous accumulation of light intensity and exposure time. In other words, most existing solutions are optimized at design time rather than controlled during operation. Once operating conditions change, such as pump power fluctuations or changes in ambient temperature, the original phase matching conditions will still deviate.

[0004] Furthermore, from the perspective of control methods, some existing solutions attempt to compensate for the refractive index through external electric fields or temperature control. However, these generally lack a clear feedback basis and typically rely on empirical parameters or single physical quantities for adjustment. This fails to accurately reflect the actual phase matching state within the device, leading to lag or overcompensation issues in the adjustment process. In multimode quantum light source scenarios, this problem is further amplified, with inconsistent shifts in different frequency components making it difficult to guarantee overall output consistency.

[0005] Therefore, in practical engineering applications, there is an urgent need for a technical solution that can sense changes in modal dispersion in real time during operation, invert the degree of photorefractive effect based on this, and generate targeted compensation control parameters to achieve dynamic suppression of the photorefractive effect, thereby maintaining the stable output performance of the quantum light source. Summary of the Invention

[0006] The purpose of this invention is to provide a method, system, device, and storage medium for suppressing photorefractive effects, so as to at least solve the problems in the prior art where photorefractive effects cause dynamic drift of mode dispersion and lack of effective feedback control mechanisms, thereby causing phase matching shift and unstable frequency conversion efficiency.

[0007] To achieve the above objectives, a first aspect of the present invention provides a method for suppressing photorefractive effects. The method includes: acquiring output spectral data of a quantum light source in its current operating state, and calculating phase mismatch parameters for each frequency component based on the output spectral data to construct a corresponding phase mismatch distribution; calculating the equivalent dispersion shift of the current waveguide according to a preset mode dispersion inversion rule based on the phase mismatch distribution, and determining the photorefractive-induced refractive index change based on the equivalent dispersion shift; generating compensation control parameters including electric field compensation parameters and pump power compensation parameters based on the refractive index change, and adjusting the waveguide electric field distribution and pump light intensity distribution based on the compensation control parameters; after adjustment, reacquiring the output spectral data and updating the phase mismatch distribution, and repeating the dispersion shift calculation and compensation control parameter generation process based on the updated phase mismatch distribution until the phase mismatch distribution meets a preset stability condition.

[0008] Optionally, the phase mismatch parameters of each frequency component are calculated based on the output spectral data to construct the corresponding phase mismatch distribution, including: performing spectral analysis processing on the output spectral data to extract the center frequency and light intensity value corresponding to each frequency component, forming frequency-light intensity correspondence data; calculating the propagation constant corresponding to each frequency component based on the frequency-light intensity correspondence data and a preset waveguide effective refractive index function; determining the pump propagation constant, signal light propagation constant, and idler light propagation constant corresponding to each frequency component based on the propagation constant, according to the energy conservation relationship between the pump frequency, signal frequency, and idler frequency; calculating the phase mismatch parameters of each frequency component based on the pump propagation constant, the signal light propagation constant, and the idler light propagation constant to obtain a set of phase mismatch parameters; and mapping the set of phase mismatch parameters according to the frequency dimension to generate the phase mismatch distribution.

[0009] Optionally, based on the propagation constant, the pump propagation constant, signal light propagation constant, and idler light propagation constant corresponding to each frequency component are determined according to the energy conservation relationship between the pump frequency, signal frequency, and idler frequency. This includes: identifying the pump frequency component in the frequency-intensity correspondence data and taking the center frequency corresponding to the pump frequency component as the pump frequency; based on the frequency-intensity correspondence data, combining each frequency component other than the pump frequency in pairs according to a preset frequency pairing rule to obtain multiple candidate frequency pairs; performing energy conservation constraint judgment on each candidate frequency pair, and selecting candidate frequency pairs that satisfy the condition that the sum of the two corresponding frequencies is equal to the pump frequency, as matching combinations of the signal frequency and the idler frequency; based on the propagation constant values ​​corresponding to each frequency component in the propagation constant, determining the propagation constant corresponding to the pump frequency as the pump propagation constant, determining the propagation constant corresponding to the signal frequency in each matching combination as the signal light propagation constant, and determining the propagation constant corresponding to the idler frequency in each matching combination as the idler light propagation constant.

[0010] Optionally, based on the phase mismatch distribution, the equivalent dispersion offset of the current waveguide is calculated according to a preset mode dispersion inversion rule, including: sorting the phase mismatch distribution according to the frequency dimension, extracting the frequency values ​​and phase mismatch parameters corresponding to each frequency component to form a frequency-phase mismatch corresponding data sequence; based on the frequency-phase mismatch corresponding data sequence, performing numerical differentiation processing on the phase mismatch parameters with respect to frequency, calculating the first derivative of the phase mismatch parameters with respect to frequency, and calculating the first-order change of the corresponding propagation constant with respect to frequency based on the first-order derivative; further performing numerical differentiation processing on the basis of the first-order change, calculating the second derivative of the propagation constant with respect to frequency, and using the second-order derivative as the equivalent dispersion parameter of the current waveguide; determining the equivalent dispersion offset based on the difference between the equivalent dispersion parameter and the reference dispersion parameter in the initial calibration state of the system.

[0011] Optionally, determining the photorefractive-induced refractive index change based on the equivalent dispersion shift includes: determining the change in the second derivative of the propagation constant with respect to frequency based on the equivalent dispersion shift, and constructing a corresponding propagation constant change model; based on the propagation constant change model, and combining the correspondence between the propagation constant and the effective refractive index, performing an inverse calculation on the change in the effective refractive index with respect to frequency to obtain the effective refractive index change corresponding to each frequency component; weighting the effective refractive index change corresponding to each frequency component according to the frequency dimension to obtain the overall equivalent refractive index change, wherein the weighting coefficients are determined by the light intensity values ​​in the frequency-light intensity correspondence data; and determining the equivalent refractive index change as the photorefractive-induced refractive index change.

[0012] Optionally, compensation control parameters, including electric field compensation parameters and pump power compensation parameters, are generated based on the refractive index change. The waveguide field distribution and pump light intensity distribution are then adjusted based on these compensation control parameters. This includes: calculating a target electric field change to offset the refractive index change, based on the refractive index change and the correspondence between refractive index change and electric field intensity in the electro-optic effect; determining a corresponding electric field compensation parameter based on the target electric field change; calculating a corresponding target light intensity change, based on the refractive index change and the correspondence between refractive index change and light intensity in the photorefractive effect; determining a corresponding pump power compensation parameter based on the target light intensity change; applying a driving voltage to the waveguide electrodes based on the electric field compensation parameters to adjust the electric field distribution inside the waveguide, thereby changing the corresponding refractive index distribution; and adjusting the output power of the pump light source based on the pump power compensation parameters to adjust the pump light intensity distribution in the waveguide.

[0013] Optionally, after adjustment, the output spectral data is reacquired and the phase mismatch distribution is updated. Based on the updated phase mismatch distribution, the dispersion offset calculation and compensation control parameter generation process is repeated until the phase mismatch distribution meets a preset stability condition. This includes: reacquiring the output spectral data and updating the phase mismatch distribution after adjustment; calculating the phase mismatch parameter difference of each frequency component based on the updated phase mismatch distribution and the phase mismatch distribution corresponding to the previous adjustment cycle; performing statistical processing on the phase mismatch parameter difference of each frequency component, calculating the overall deviation index, and comparing the overall deviation index with a preset stability threshold; stopping the compensation control parameter update when the overall deviation index is less than the preset stability threshold, otherwise repeating the equivalent dispersion offset calculation and compensation control parameter generation process based on the updated phase mismatch distribution.

[0014] A second aspect of the present invention provides a photorefractive effect suppression system, the system comprising: a data acquisition unit, configured to acquire output spectral data of a quantum light source in its current operating state, and calculate phase mismatch parameters of each frequency component based on the output spectral data to construct a corresponding phase mismatch distribution; a refractive index determination unit, configured to calculate the equivalent dispersion shift of the current waveguide according to a preset mode dispersion inversion rule based on the phase mismatch distribution, and determine the photorefractive-induced refractive index change based on the equivalent dispersion shift; an adjustment unit, configured to generate compensation control parameters including electric field compensation parameters and pump power compensation parameters based on the refractive index change, and adjust the waveguide electric field distribution and pump light intensity distribution based on the compensation control parameters; and an iteration unit, configured to reacquire the output spectral data and update the phase mismatch distribution after adjustment, and repeat the dispersion shift calculation and compensation control parameter generation process based on the updated phase mismatch distribution until the phase mismatch distribution meets a preset stability condition.

[0015] A third aspect of the present invention provides an electronic device, comprising: one or more processors; and a storage device having stored one or more programs thereon, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the photorefractive effect suppression method as described above.

[0016] On the other hand, the present invention provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the above-described photorefractive effect suppression method.

[0017] Through the above technical solution, this invention analyzes the output spectral data of the quantum light source to construct a phase mismatch distribution, and further inverts to obtain the equivalent dispersion shift of the waveguide and the refractive index change induced by photorefractive, thus transforming the phase matching state inside the device from unobservable to quantifiable. Based on this, electric field compensation parameters and pump power compensation parameters are generated to synergistically adjust the waveguide electric field distribution and pump light intensity distribution, achieving targeted compensation for refractive index changes. Simultaneously, by introducing a closed-loop iterative mechanism based on the phase mismatch distribution, the dispersion shift and compensation parameters are continuously corrected during operation, gradually converging the phase matching condition to a stable state. This effectively suppresses mode dispersion drift caused by photorefractive effects, improves the stability of frequency conversion efficiency, and enhances the consistency and reliability of the quantum light source output.

[0018] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart of the steps of a photorefractive effect suppression method provided in one embodiment of the present invention; Figure 2 This is a phase mismatch distribution curve provided by one embodiment of the present invention; Figure 3 This is a system structure diagram of a photorefractive effect suppression system provided in one embodiment of the present invention; Figure 4 This is an internal structural diagram of a computer device provided in one embodiment of the present invention. Detailed Implementation

[0020] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0021] like Figure 1 As shown, an embodiment of the present invention provides a method for suppressing photorefractive effects, the method comprising: Step S10: Obtain the output spectral data of the quantum light source in its current operating state, and calculate the phase mismatch parameters of each frequency component based on the output spectral data to construct the corresponding phase mismatch distribution.

[0022] Specifically, the output spectral data undergoes spectral analysis to extract the center frequency and intensity value corresponding to each frequency component, forming frequency-intensity correspondence data. Based on this frequency-intensity correspondence data and a preset waveguide effective refractive index function, the propagation constant corresponding to each frequency component is calculated. Based on the propagation constant, the pump propagation constant, signal light propagation constant, and idler light propagation constant corresponding to each frequency component are determined according to the energy conservation relationship between the pump frequency, signal frequency, and idler frequency. Based on the pump propagation constant, signal light propagation constant, and idler light propagation constant, the phase mismatch parameter of each frequency component is calculated to obtain a phase mismatch parameter set. The phase mismatch parameter set is mapped and constructed according to the frequency dimension to generate a phase mismatch distribution.

[0023] Furthermore, based on the propagation constant, the pump propagation constant, signal light propagation constant, and idler light propagation constant corresponding to each frequency component are determined according to the energy conservation relationship between the pump frequency, signal frequency, and idler frequency. This includes: identifying the pump frequency component in the frequency-intensity correspondence data and taking the center frequency corresponding to the pump frequency component as the pump frequency; based on the frequency-intensity correspondence data, combining each frequency component other than the pump frequency in pairs according to a preset frequency pairing rule to obtain multiple candidate frequency pairs; performing energy conservation constraint judgment on each candidate frequency pair, and selecting candidate frequency pairs that satisfy the condition that the sum of the two corresponding frequencies is equal to the pump frequency, as matching combinations of the signal frequency and the idler frequency; based on the propagation constant values ​​corresponding to each frequency component in the propagation constant, determining the propagation constant corresponding to the pump frequency as the pump propagation constant, determining the propagation constant corresponding to the signal frequency in each matching combination as the signal light propagation constant, and determining the propagation constant corresponding to the idler frequency in each matching combination as the idler light propagation constant.

[0024] In this embodiment of the invention, the output spectral data exists in the form of light intensity varying with frequency, and its essence is a continuous function. To facilitate subsequent calculations, the spectrum is discretized along the frequency axis, and the set of discrete frequencies is defined as follows: ,in Indicates the first Each frequency sampling point corresponds to a light intensity of This results in frequency-intensity correlation data:

[0025] in, This represents the total number of sampling points. This dataset serves as the input basis for calculating the propagation constant and subsequent weighting.

[0026] Based on frequency information, a correspondence between the effective refractive index of the waveguide and the frequency is introduced. This is used to establish the relationship between frequency and propagation behavior. For each frequency component, its corresponding propagation constant is calculated:

[0027] in, Represents frequency The corresponding propagation constant, This represents the speed of light in a vacuum. Through this calculation, the frequency space is mapped to the propagation constant space, yielding the set of propagation constants:

[0028] Based on the set of propagation constants, an energy conservation constraint is introduced to combine and filter frequency components. Specifically, the pump frequency component is identified from the frequency-intensity correspondence data. The frequency points corresponding to the local or global maxima of light intensity in the spectrum are determined by... The extreme value detection was performed to obtain:

[0029] After determining the pump frequency, a set of candidate frequency pairs is constructed for the remaining frequency components. For any two different frequencies... and Construct candidate combinations And perform energy conservation constraint judgment on the combination:

[0030] in, This represents the frequency matching tolerance, used to compensate for actual spectral discrepancies. Frequency pairs that meet the above conditions constitute a set of valid matching combinations:

[0031] in, Indicates signal frequency. Indicates the idle frequency.

[0032] For each effective frequency combination, the corresponding propagation constant is extracted from the propagation constant set and denoted as follows:

[0033] Based on this, the phase mismatch parameter is calculated. The phase mismatch parameter describes the degree of mismatch in the propagation constants between the three waves, and its definition is as follows:

[0034] in, This represents the phase mismatch for the corresponding frequency combination. Performing the above calculation on all frequency combinations that satisfy the energy conservation constraint yields the set of phase mismatch parameters:

[0035] To facilitate subsequent processing, the discrete phase mismatch data needs to be organized into a continuous distribution. The phase mismatch parameters are mapped along the frequency dimension to construct a phase mismatch distribution function. If the signal frequency is taken as the independent variable, the distribution function is expressed as follows: If we consider the bivariate case, the distribution function is expressed as follows: .

[0036] During the construction process, frequency points are used as the x-axis and phase mismatch parameters as the y-axis, and a continuous distribution is generated through interpolation. Linear interpolation or spline interpolation is used to ensure that the distribution function maintains continuity and differentiability in the frequency domain, thus meeting the derivative requirements in subsequent dispersion calculations.

[0037] In the above processing, the frequency-intensity correlation data is used not only for propagation constant calculation but also for subsequent weighting. Specifically, during the construction of the phase mismatch distribution, intensity is introduced as a weighting factor to weight the phase mismatch parameters at different frequency points, making the influence of high-intensity regions on the overall distribution more significant. The weight is defined as follows:

[0038] The weighted phase mismatch distribution is expressed as:

[0039] This weighting process makes the distribution function closer to the actual energy distribution, thereby improving the stability of the subsequent inversion process.

[0040] In engineering implementation, taking a quantum light source operating in the 1550nm band as an example, the sampling frequency range is set to 1520nm to 1580nm, corresponding to an angular frequency range of... Set the number of sampling points to . For each frequency point, the propagation constant is calculated, and frequency pairing is performed. A matching tolerance is set. rad / s is used to ensure the stability of the pairing process under discrete conditions. Through the above steps, a complete phase mismatch distribution curve can be obtained, such as... Figure 2 An example of a phase mismatch distribution curve constructed based on the above steps is given.

[0041] This distribution curve directly reflects the phase matching state of the current waveguide at each frequency component, and its variation trend has a one-to-one correspondence with the refractive index change caused by photorefractive effect. In subsequent processing, this distribution is used as input for the calculation of dispersion offset. Dispersion information is obtained by performing derivative operations on it, and then the refractive index change is further inverted.

[0042] It should be noted that the effective refractive index function Derived from simulation results or calibration experimental data during the device design phase, in the form of known functions or discrete data tables. Frequency matching tolerance. The range of values ​​determined by the system resolution does not affect the basic implementation logic of the method. The selection of the frequency discretization method and interpolation method is configured according to the actual system accuracy requirements, without changing the core processing flow of the method in this application.

[0043] Step S20: Based on the phase mismatch distribution, calculate the equivalent dispersion offset of the current waveguide according to the preset mode dispersion inversion rule, and determine the photorefractive-induced refractive index change based on the equivalent dispersion offset.

[0044] Specifically, based on the phase mismatch distribution, the equivalent dispersion offset of the current waveguide is calculated according to a preset mode dispersion inversion rule, including: sorting the phase mismatch distribution according to the frequency dimension, extracting the frequency values ​​and phase mismatch parameters corresponding to each frequency component to form a frequency-phase mismatch corresponding data sequence; based on the frequency-phase mismatch corresponding data sequence, performing numerical differentiation processing on the phase mismatch parameters with respect to frequency, calculating the first derivative of the phase mismatch parameters with respect to frequency, and calculating the first-order change of the corresponding propagation constant with respect to frequency based on the first-order derivative; further performing numerical differentiation processing on the basis of the first-order change, calculating the second derivative of the propagation constant with respect to frequency, and using the second-order derivative as the equivalent dispersion parameter of the current waveguide; determining the equivalent dispersion offset based on the difference between the equivalent dispersion parameter and the reference dispersion parameter in the initial calibration state of the system.

[0045] Further, determining the photorefractive-induced refractive index change based on the equivalent dispersion shift includes: determining the change in the second derivative of the propagation constant with respect to frequency based on the equivalent dispersion shift, and constructing a corresponding propagation constant change model; based on the propagation constant change model, and combining the correspondence between the propagation constant and the effective refractive index, performing an inverse calculation on the change in the effective refractive index with respect to frequency to obtain the effective refractive index change corresponding to each frequency component; weighting the effective refractive index change corresponding to each frequency component according to the frequency dimension to obtain the overall equivalent refractive index change, wherein the weighting coefficients are determined by the light intensity values ​​in the frequency-light intensity correspondence data; and determining the equivalent refractive index change as the photorefractive-induced refractive index change.

[0046] In this embodiment of the invention, the phase mismatch distribution has already been constructed in the previous stage, and its form is a correspondence between frequency and phase mismatch parameters. To ensure the stability of subsequent derivative calculations, this distribution is first sorted according to the frequency dimension, so that the frequency sequence satisfies a monotonically increasing relationship. Let the sorted frequency sequence be... The corresponding phase mismatch parameter is This results in a frequency-phase mismatch corresponding data sequence:

[0047] This sequence serves as the basis input for subsequent numerical differentiation.

[0048] Based on this, the phase mismatch parameter is numerically differentiated with respect to frequency. The phase mismatch parameter is essentially a combination of propagation constants; therefore, its rate of change with frequency reflects the trend of the propagation constants. The first derivative is calculated using a finite difference method:

[0049] in, This represents the first derivative of the phase mismatch parameter with respect to frequency. Physically, this derivative corresponds to the first-order variation of the propagation constant with respect to frequency. Because... Under the condition of fixed pump frequency, its variation is mainly determined by the change of propagation constant between signal light and idler light. Therefore, this first derivative can be used to characterize the variation characteristics of propagation constant.

[0050] Furthermore, a second-order numerical differentiation is performed based on the first-order derivative to obtain the second derivative of the propagation constant with respect to frequency. The second derivative is calculated using the following difference form:

[0051] The second derivative reflects the curvature characteristics of the propagation constant curve and corresponds to the group velocity dispersion parameter of the waveguide. In this embodiment, the second derivative is taken as the equivalent dispersion parameter of the current waveguide, denoted as:

[0052] Since the propagation constant information is already included in the phase mismatch, the equivalent dispersion parameter can be directly obtained through the above calculation without the need for additional measurement of the propagation constant.

[0053] After obtaining the equivalent dispersion parameters, the reference dispersion parameters from the initial system calibration state are introduced. This reference parameter is derived from device calibration or design simulation results. The equivalent dispersion offset is obtained by comparing the difference between the current equivalent dispersion parameter and the reference dispersion parameter.

[0054] This offset reflects the degree of dispersion change in the current operating state relative to the initial state, and the main source of this change is the refractive index disturbance caused by the photorefractive effect.

[0055] After obtaining the equivalent dispersion shift, it is further converted into a change in refractive index. The propagation constant and the effective refractive index satisfy the following relationship:

[0056] Expanding this relationship using its second derivative, we can obtain the correspondence between the second derivative of the propagation constant and the second derivative of the effective refractive index:

[0057] Under small perturbation conditions, the change in propagation constant caused by the change in refractive index approximately follows a linear relationship. Therefore, the dispersion shift is mapped to the effective refractive index change. Let the effective refractive index change be... Then it satisfies the following relationship with the dispersion shift:

[0058] Based on this relationship, inversion calculations are performed on each frequency component to obtain the corresponding set of effective refractive index changes. After obtaining the refractive index change for each frequency component, a frequency-weighted processing is performed. The weights are derived from the frequency-intensity correspondence data constructed in the previous stage, and are specifically defined as follows:

[0059] in, Represents frequency The corresponding light intensity. Using this weight, the changes in refractive index are weighted and summed to obtain the overall equivalent change in refractive index:

[0060] The overall change in refractive index serves as a comprehensive characterization of the photorefractive effect and is used to generate subsequent compensation control parameters.

[0061] In practical implementation, taking a 2cm long lithium niobate waveguide as an example, the operating wavelength range is 1520nm to 1580nm. The output spectrum is sampled to obtain 512 frequency points, and the corresponding phase mismatch distribution is calculated. The equivalent dispersion parameter curve is obtained through numerical differentiation, and compared with the initial calibration curve to obtain the dispersion shift curve. Further inversion yields the refractive index change distribution, which is on the order of 10. -5 ~10 -4 Between these values, the overall refractive index change is obtained after intensity-weighted processing, which is used for subsequent electric field compensation and power adjustment.

[0062] The above process progressively transforms the phase mismatch distribution into a change in refractive index, realizing the mapping from observed quantities to control quantities. The steps are connected by explicit mathematical relationships, ensuring the continuity and traceability of the calculation path. Since all calculations are based on real-time data under the current operating state, they can reflect the dynamic characteristics of the photorefractive effect, providing a stable input for closed-loop control, thereby effectively suppressing mode dispersion drift in engineering applications.

[0063] Step S30: Generate compensation control parameters including electric field compensation parameters and pump power compensation parameters based on the refractive index change, and adjust the waveguide electric field distribution and pump light intensity distribution based on the compensation control parameters.

[0064] Specifically, based on the refractive index change and the correspondence between refractive index change and electric field intensity in the electro-optic effect, a target electric field change to offset the refractive index change is calculated, and a corresponding electric field compensation parameter is determined based on the target electric field change. Based on the refractive index change and the correspondence between refractive index change and light intensity in the photorefractive effect, a corresponding target light intensity change is calculated, and a corresponding pump power compensation parameter is determined based on the target light intensity change. A driving voltage is applied to the waveguide electrodes based on the electric field compensation parameter to adjust the electric field distribution inside the waveguide, thereby changing the corresponding refractive index distribution. The output power of the pump light source is adjusted based on the pump power compensation parameter to adjust the pump light intensity distribution in the waveguide.

[0065] In this embodiment of the invention, the change in refractive index is denoted as... This is the comprehensive value after equivalent treatment of the entire waveguide, corresponding to the weighted result of the refractive index variation of each frequency component. This quantity serves as an input parameter and participates in the control calculations of both the electric field compensation and optical intensity adjustment channels.

[0066] In the electric field compensation channel, an electro-optic effect is introduced, meaning that an applied electric field causes a change in the refractive index of the material. For lithium niobate, the electro-optic effect satisfies the following relationship:

[0067] in, This represents the change in refractive index caused by the electric field. This represents the effective refractive index of the waveguide in its initial state. Indicates the electro-optic coefficient. This represents the electric field strength applied to the waveguide. This relationship shows that there is a definite functional relationship between the change in refractive index and the electric field strength.

[0068] To achieve the effect of refractive index change caused by photorefraction The offsetting effect requires the following conditions to be met:

[0069] Substituting the above relationship into the electro-optic effect expression, the target electric field strength can be obtained. :

[0070] in, This represents the target electric field strength used to compensate for the current refractive index change. Based on this target electric field strength, and further combined with the waveguide electrode structure, it is converted into driving voltage parameters. Let the electrode spacing be... The corresponding driving voltage for:

[0071] This voltage value is the electric field compensation parameter, used to drive the electrodes on both sides of the waveguide, thereby creating the desired electric field distribution inside the waveguide. By applying this voltage, the electric field distribution can be adjusted spatially, correcting the refractive index variation along the waveguide direction.

[0072] In the light intensity compensation channel, the relationship between the photorefractive effect and light intensity is utilized. The photorefractive effect is generally related to light intensity and interaction time, and its basic expression is as follows:

[0073] in, This represents the change in refractive index caused by photorefraction. Indicates the photorefractive index. Indicates light intensity. This represents the duration of light exposure. On a short timescale, the change in refractive index is approximately linearly related to the light intensity; therefore, the further accumulation of refractive index changes can be suppressed by adjusting the light intensity.

[0074] Based on the current change in refractive index The required change in light intensity can be deduced from this. Let the current pump light intensity be... Then the target light intensity satisfy:

[0075] After sorting, we get:

[0076] in, This represents the compensated target light intensity. The light intensity is then further converted into the output power parameters of the pump source. Let the waveguide cross-sectional area be... Then the relationship between light intensity and power satisfies:

[0077] Therefore, the target pump power for:

[0078] This power value serves as a pump power compensation parameter, used to adjust the output of the pump light source.

[0079] During the control execution phase, electric field compensation parameters and pump power compensation parameters are applied to the corresponding execution units. For the electric field compensation parameters, a voltage is applied to the waveguide electrodes through the electrode driving module to form an electric field distributed along the waveguide, thereby adjusting the refractive index distribution in space. For the pump power compensation parameters, the output power of the pump source is adjusted through the laser driving module to change the light intensity entering the waveguide, thus suppressing the further development of the photorefractive effect in the time dimension.

[0080] In practical implementation, for example, for a segment of electrode spacing of... Lithium niobate waveguide, initial effective refractive index Electro-optic coefficient If calculated The target electric field strength is:

[0081] The corresponding driving voltage is approximately Regarding light intensity modulation, let the current pump power be... The waveguide cross-sectional area is The target power was adjusted to approximately based on the calculated value. This is to suppress further growth in refractive index.

[0082] The aforementioned dual-channel adjustment mechanism enables coordinated control of refractive index changes in both spatial and temporal dimensions. Electric field compensation is primarily used to quickly offset existing refractive index shifts, while pump power adjustment is used to suppress the accumulation of subsequent photorefractive effects, thereby ensuring that the refractive index distribution within the waveguide remains within a stable range. The entire control process uses the refractive index change as the core input, and all parameters are derived from this quantity, forming a clear causal chain, thus ensuring the computability and feasibility of the control process.

[0083] Step S40: After the adjustment is performed, the output spectral data is reacquired and the phase mismatch distribution is updated. Based on the updated phase mismatch distribution, the dispersion offset calculation and compensation control parameter generation process is repeated until the phase mismatch distribution meets the preset stability condition.

[0084] Specifically, after adjustment, the output spectral data is reacquired and the phase mismatch distribution is updated; the phase mismatch parameter difference of each frequency component is calculated based on the updated phase mismatch distribution and the phase mismatch distribution corresponding to the previous adjustment cycle; the phase mismatch parameter difference of each frequency component is statistically processed to calculate the overall deviation index, and the overall deviation index is compared with a preset stability threshold; when the overall deviation index is less than the preset stability threshold, the compensation control parameter update is stopped; otherwise, the equivalent dispersion offset calculation and compensation control parameter generation process is repeated based on the updated phase mismatch distribution.

[0085] In this embodiment of the invention, after adjustment, the output spectral data of the quantum light source under its current operating state is reacquired. This spectral data undergoes the same data processing chain as described above, including steps such as spectral analysis, propagation constant calculation, and frequency pairing, to generate an updated phase mismatch distribution. The updated phase mismatch distribution is denoted as... ,in Indicates the current adjustment cycle. Indicates the first Each frequency component. The phase mismatch distribution corresponding to the previous adjustment cycle is denoted as... .

[0086] Based on the phase mismatch distribution of the two cycles mentioned above, the phase mismatch parameter difference of each frequency component is calculated:

[0087] in, Indicates frequency The absolute value of the phase mismatch change is used to characterize the degree of change of that frequency component between the two adjustments. By calculating the above difference for all frequency components, the phase mismatch change sequence can be obtained:

[0088] To avoid the impact of abnormal fluctuations at a single frequency point on the overall judgment, statistical processing is performed on the change sequence to construct an overall deviation index. The overall deviation index is defined using a weighted average:

[0089] in, Represents frequency The corresponding weighting coefficients, derived from frequency-intensity correlation data, are defined as follows:

[0090] in, Represents frequency The corresponding light intensity value. By introducing light intensity weighting, the high-energy frequency component occupies a higher proportion in the overall deviation index, thus making the judgment result closer to the actual output state.

[0091] After obtaining the overall deviation index, it is compared with the preset stability threshold. The stability threshold is a parameter determined by the system during the calibration phase, used to define the acceptable range of phase mismatch variation. Its value is typically set based on the target frequency conversion efficiency stability requirements. For example, when the system requires phase mismatch variation to be controlled within a certain range... When the deviation is within a certain range, the corresponding overall deviation threshold is set to the same order of magnitude.

[0092] When the following conditions are met:

[0093] Once the system is determined to have entered a stable state, the update of the compensation control parameters is stopped, and the current electric field and pump power setpoints are kept unchanged, so that the system continues to operate at this operating point.

[0094] When the above conditions are not met, that is:

[0095] If the current adjustment has not yet reached a stable state, then the updated phase mismatch distribution will be used. As new input, the equivalent dispersion offset calculation and refractive index change inversion are re-executed, and new compensation control parameters are generated accordingly, before entering the next adjustment cycle.

[0096] In practical implementation, for example, for a quantum light source system operating in the 1550nm wavelength band, the number of sampling points is set to 512, and the spectral update period is 10ms. In three consecutive adjustment cycles, the overall deviation index is 2.5×10⁻⁶. -3 1.2×10 -3 and 4.8×10 -4 When the threshold is set to 5×10-4 When the system reaches a stable condition in the third cycle, the control process stops updating.

[0097] The closed-loop judgment mechanism described above transforms the adjustment process from a single calculation into a convergent iterative process. The phase mismatch distribution serves as the sole feedback variable throughout the entire control chain, ensuring consistency between system state assessment and control parameter generation, thereby guaranteeing the predictability and stability of the adjustment results. In practical engineering applications, this mechanism effectively suppresses dynamic drift caused by photorefractive effects, enabling the quantum light source output to remain in a stable operating state over the long term.

[0098] like Figure 3 As shown, this invention provides a photorefractive effect suppression system, comprising: a data acquisition unit, configured to acquire output spectral data of a quantum light source in its current operating state, and calculate phase mismatch parameters of each frequency component based on the output spectral data to construct a corresponding phase mismatch distribution; a refractive index determination unit, configured to calculate the equivalent dispersion shift of the current waveguide based on the phase mismatch distribution and according to a preset mode dispersion inversion rule, and determine the photorefractive-induced refractive index change based on the equivalent dispersion shift; an adjustment unit, configured to generate compensation control parameters including electric field compensation parameters and pump power compensation parameters based on the refractive index change, and adjust the waveguide electric field distribution and pump light intensity distribution based on the compensation control parameters; and an iteration unit, configured to reacquire the output spectral data and update the phase mismatch distribution after adjustment, and repeat the dispersion shift calculation and compensation control parameter generation process based on the updated phase mismatch distribution until the phase mismatch distribution meets a preset stability condition.

[0099] The present invention also provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the above-described photorefractive effect suppression method.

[0100] This invention also provides an electronic device, including: one or more processors; and a storage device storing one or more programs thereon, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the photorefractive effect suppression method as described above.

[0101] In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 4As shown, the computer device includes a processor A01, a network interface A02, memory (not shown), and a database (not shown) connected via a system bus. The processor A01 provides computing and control capabilities. The memory includes internal memory A03 and a non-volatile storage medium A04. The non-volatile storage medium A04 stores an operating system B01, a computer program B02, and a database (not shown). The internal memory A03 provides an environment for the operation of the operating system B01 and the computer program B02 stored in the non-volatile storage medium A04. The network interface A02 is used for communication with external terminals via a network connection. When the computer program B02 is executed by the processor A01, it implements a method for suppressing photorefractive effects.

[0102] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a microcontroller, chip, or processor to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0103] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details described above. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe the various possible combinations.

[0104] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the embodiments of the present invention, they should also be regarded as the content disclosed by the embodiments of the present invention.

Claims

1. A method for suppressing photorefractive effects, characterized in that, The method includes: The output spectral data of the quantum light source under its current operating state is obtained, and the phase mismatch parameters of each frequency component are calculated based on the output spectral data to construct the corresponding phase mismatch distribution. Based on the phase mismatch distribution, the equivalent dispersion shift of the current waveguide is calculated according to the preset mode dispersion inversion rule, and the photorefractive-induced refractive index change is determined based on the equivalent dispersion shift. Based on the refractive index change, compensation control parameters including electric field compensation parameters and pump power compensation parameters are generated, and the waveguide electric field distribution and pump light intensity distribution are adjusted based on the compensation control parameters. After adjustment, the output spectral data is reacquired and the phase mismatch distribution is updated. Based on the updated phase mismatch distribution, the dispersion offset calculation and compensation control parameter generation process is repeated until the phase mismatch distribution meets the preset stability condition.

2. The method for suppressing photorefractive effects according to claim 1, characterized in that, Based on the output spectral data, the phase mismatch parameters of each frequency component are calculated, and the corresponding phase mismatch distribution is constructed, including: The output spectral data is subjected to spectral analysis processing to extract the center frequency and light intensity value corresponding to each frequency component, forming frequency-light intensity correspondence data; Based on the frequency-light intensity correspondence data, and combined with the preset waveguide effective refractive index function, the propagation constant corresponding to each frequency component is calculated. Based on the propagation constants, the pump propagation constant, signal light propagation constant, and idler light propagation constant corresponding to each frequency component are determined according to the energy conservation relationship between the pump frequency, signal frequency, and idler frequency. Based on the pump propagation constant, the signal light propagation constant, and the idler light propagation constant, the phase mismatch parameters of each frequency component are calculated to obtain a set of phase mismatch parameters; The phase mismatch parameter set is mapped and constructed according to the frequency dimension to generate a phase mismatch distribution.

3. The method for suppressing photorefractive effects according to claim 2, characterized in that, Based on the propagation constants, the pump propagation constant, signal light propagation constant, and idler light propagation constant corresponding to each frequency component are determined according to the energy conservation relationship between the pump frequency, signal frequency, and idler frequency, including: Identify the pump frequency component in the frequency-light intensity correspondence data, and take the center frequency corresponding to the pump frequency component as the pump frequency; Based on the frequency-intensity correspondence data, each frequency component other than the pump frequency is combined in pairs according to a preset frequency pairing rule to obtain multiple candidate frequency pairs. Energy conservation constraints are applied to each candidate frequency pair, and candidate frequency pairs that satisfy the condition that the sum of the two corresponding frequencies is equal to the pump frequency are selected as the matching combination of signal frequency and idle frequency. Based on the propagation constant values ​​corresponding to each frequency component in the propagation constant, the propagation constant corresponding to the pump frequency is determined as the pump propagation constant, the propagation constant corresponding to the signal frequency in each matching combination is determined as the signal light propagation constant, and the propagation constant corresponding to the idle frequency in each matching combination is determined as the idle light propagation constant.

4. The method for suppressing photorefractive effects according to claim 2, characterized in that, Based on the phase mismatch distribution, the equivalent dispersion shift of the current waveguide is calculated according to a preset mode dispersion inversion rule, including: The phase mismatch distribution is sorted according to the frequency dimension, and the frequency value and phase mismatch parameter corresponding to each frequency component are extracted to form a frequency-phase mismatch corresponding data sequence. Based on the frequency-phase mismatch corresponding data sequence, the phase mismatch parameter is numerically differentiated with respect to frequency to calculate the first derivative of the phase mismatch parameter with respect to frequency, and the first-order change of the corresponding propagation constant with respect to frequency is calculated based on the first derivative. Based on the first-order change, further numerical differentiation is performed to calculate the second derivative of the propagation constant with respect to frequency, and the second derivative is used as the equivalent dispersion parameter of the current waveguide. The equivalent dispersion offset is determined based on the difference between the equivalent dispersion parameter and the reference dispersion parameter in the initial calibration state of the system.

5. The method for suppressing photorefractive effects according to claim 4, characterized in that, Determining the photorefractive-induced refractive index change based on the equivalent dispersion shift includes: Based on the equivalent dispersion shift, the change in the second derivative of the propagation constant with respect to frequency is determined, and the corresponding propagation constant change model is constructed. Based on the propagation constant variation model, and combined with the correspondence between the propagation constant and the effective refractive index, the change of the effective refractive index with respect to frequency is calculated by inversion to obtain the change of the effective refractive index corresponding to each frequency component. The effective refractive index change corresponding to each frequency component is weighted according to the frequency dimension to obtain the overall equivalent refractive index change, wherein the weighting coefficient is determined by the light intensity value in the frequency-light intensity correspondence data. The equivalent refractive index change is defined as the photorefractive-induced refractive index change.

6. The method for suppressing photorefractive effects according to claim 1, characterized in that, Based on the refractive index change, compensation control parameters, including electric field compensation parameters and pump power compensation parameters, are generated. The waveguide electric field distribution and pump light intensity distribution are then adjusted based on these compensation control parameters, including: Based on the refractive index change, and combined with the correspondence between the refractive index change and the electric field strength in the electro-optic effect, the target electric field change used to offset the refractive index change is calculated, and the corresponding electric field compensation parameter is determined according to the target electric field change. Based on the refractive index change, and combined with the correspondence between refractive index change and light intensity in the photorefractive effect, the corresponding target light intensity change is calculated, and the corresponding pump power compensation parameters are determined according to the target light intensity change. A driving voltage is applied to the waveguide electrode based on the electric field compensation parameters to adjust the electric field distribution inside the waveguide, thereby changing the corresponding refractive index distribution. The output power of the pump light source is adjusted based on the pump power compensation parameters to adjust the pump light intensity distribution in the waveguide.

7. The method for suppressing photorefractive effects according to claim 6, characterized in that, After adjustment, the output spectral data is reacquired and the phase mismatch distribution is updated. Based on the updated phase mismatch distribution, the dispersion shift calculation and compensation control parameter generation process is repeated until the phase mismatch distribution meets the preset stability condition, including: After performing the adjustment, the output spectral data is reacquired and the phase mismatch distribution is updated; The phase mismatch parameter difference of each frequency component is calculated based on the updated phase mismatch distribution and the phase mismatch distribution corresponding to the previous adjustment cycle. The phase mismatch parameter difference of each frequency component is statistically processed to calculate the overall deviation index, and the overall deviation index is compared with a preset stability threshold. When the overall deviation index is less than the preset stability threshold, the compensation control parameter update is stopped; otherwise, the equivalent dispersion offset calculation and compensation control parameter generation process are repeated based on the updated phase mismatch distribution.

8. A photorefractive effect suppression system, characterized in that, The system includes: The data acquisition unit is used to acquire the output spectral data of the quantum light source in its current operating state, and to calculate the phase mismatch parameters of each frequency component based on the output spectral data, and to construct the corresponding phase mismatch distribution. The refractive index determination unit is used to calculate the equivalent dispersion shift of the current waveguide based on the phase mismatch distribution and according to the preset mode dispersion inversion rule, and to determine the refractive index change induced by photorefractive based on the equivalent dispersion shift. The adjustment unit is used to generate compensation control parameters, including electric field compensation parameters and pump power compensation parameters, based on the refractive index change, and to adjust the waveguide electric field distribution and pump light intensity distribution based on the compensation control parameters. An iterative unit is used to reacquire the output spectral data after adjustment and update the phase mismatch distribution. Based on the updated phase mismatch distribution, the process of calculating the dispersion offset and generating compensation control parameters is repeated until the phase mismatch distribution meets the preset stability condition.

9. An electronic device, characterized in that, include: One or more processors; A storage device having stored one or more programs thereon, which, when executed by the one or more processors, cause the one or more processors to implement the photorefractive effect suppression method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores instructions that, when executed on a computer, cause the computer to perform the photorefractive effect suppression method according to any one of claims 1-7.

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