Lithium niobate dispersion compensation method, system, device and storage medium

Abstract

Embodiments of the present application provide a lithium niobate dispersion compensation method, system, device and storage medium, belonging to the technical field of integrated photonics. The method comprises: obtaining the mode effective refractive index of the target lithium niobate waveguide in a preset frequency spectrum range, and calculating the corresponding propagation constant based on the mode effective refractive index to construct a mode dispersion function; calculating the phase mismatch parameter corresponding to each frequency point based on the mode dispersion function, and constructing a frequency domain phase mismatch distribution function based on the phase mismatch parameter of each frequency point; generating a phase compensation amount corresponding to each frequency point based on the frequency domain phase mismatch distribution function; generating a modulation control parameter based on the phase compensation amount, and applying it to the lithium niobate waveguide to achieve dispersion compensation. The present application scheme realizes continuous compensation of phase mismatch of each frequency component in a wide frequency range, and changes the phase matching from local effectiveness to consistency in the whole frequency domain.

Description

Technical Field

[0001] This invention relates to the field of integrated photonics technology, and more specifically to a method, system, device, and storage medium for lithium niobate dispersion compensation. Background Technology

[0002] Lithium niobate (LNiO) is widely used in integrated photonic devices for parametric down-conversion, frequency conversion, and quantum light source construction due to its high second-order nonlinear coefficient and excellent electro-optic modulation characteristics. With increasing on-chip integration, broadband nonlinear processes based on LNiO waveguides are gradually becoming a core research direction. However, in practical engineering implementation, the mode dispersion characteristics of the waveguide significantly affect the frequency conversion process. The propagation constants corresponding to different frequency components differ, making it difficult to simultaneously satisfy the phase matching condition over a wide frequency range. Especially in bilayer thin-film LNiO waveguide structures, the mode distribution is complex, and the dispersion exhibits nonlinear characteristics with frequency, leading to significant fluctuations in phase mismatch in the frequency domain. This, in turn, causes inconsistent or even drastically reduced conversion efficiency across different frequency bands.

[0003] Existing methods typically improve dispersion characteristics by adjusting waveguide cross-sectional dimensions, altering material structure, or optimizing coupling conditions. These methods essentially involve a one-time design optimization of device structural parameters, achieving only optimal phase matching within a limited frequency band. Once the operating frequency range expands, or if there are manufacturing deviations, the original design becomes ill-suited to actual operating conditions, resulting in significant phase mismatches. Furthermore, these methods lack fine-tuning techniques for frequency distribution characteristics, failing to provide targeted compensation for phase deviations at different frequency points, thus limiting overall performance.

[0004] Therefore, given that the phase mismatch in lithium niobate waveguides exhibits a nonlinear distribution with frequency and existing methods struggle to achieve consistent compensation over a wide frequency range, there is an urgent need to propose a new dispersion compensation method to refine the phase mismatch of each frequency component and provide targeted compensation over a wide frequency range, thereby improving the phase matching consistency across the overall frequency domain. Summary of the Invention

[0005] The purpose of this invention is to provide a lithium niobate dispersion compensation method, system, device, and storage medium to at least solve the problem of difficulty in achieving consistent compensation for phase mismatch over a wide frequency range.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for dispersive compensation of lithium niobate, the method comprising: obtaining the effective refractive index of a target lithium niobate waveguide within a preset frequency range, and calculating the corresponding propagation constant based on the effective refractive index of the mode to construct a mode dispersion function; calculating phase mismatch parameters at each frequency point based on the mode dispersion function, and constructing a frequency domain phase mismatch distribution function based on the phase mismatch parameters at each frequency point; generating a phase compensation amount at each frequency point based on the frequency domain phase mismatch distribution function; generating modulation control parameters based on the phase compensation amount, and applying them to the lithium niobate waveguide to achieve dispersion compensation.

[0007] Optionally, the effective refractive index of the target lithium niobate waveguide within a preset spectral range is obtained, and the corresponding propagation constant is calculated based on the effective refractive index to construct a mode dispersion function. This includes: generating multiple discrete frequency points within the preset spectral range according to a preset frequency sampling interval; performing electromagnetic mode solving on each discrete frequency point based on the structural and material parameters of the target lithium niobate waveguide to obtain the effective refractive index of the mode at each discrete frequency point; calculating the propagation constant of each discrete frequency point based on the effective refractive index and the corresponding frequency value to generate a propagation constant sequence; and performing continuous processing on the propagation constant sequence according to a preset function fitting rule to construct a mode dispersion function characterizing the frequency response characteristics of the target lithium niobate waveguide.

[0008] Optionally, calculating the phase mismatch parameters for each frequency point based on the mode dispersion function includes: obtaining the propagation constants corresponding to the preset pump frequency, signal frequency, and idler frequency based on the mode dispersion function; wherein the propagation constants are calculated from the effective refractive index of the mode at the corresponding frequency and the frequency value, and the frequency correspondence between the pump frequency, signal frequency, and idler frequency is determined according to the energy conservation relationship; based on the propagation constants corresponding to the pump frequency, signal frequency, and idler frequency, calculating the phase mismatch value for each frequency combination according to the difference between the pump propagation constant and the signal propagation constant and the idler frequency propagation constant, generating discrete phase mismatch data; based on the discrete phase mismatch data, performing phase mismatch value completion on the unsampled frequency points according to the preset interpolation function, and mapping the completed phase mismatch value to the corresponding frequency one by one, generating phase mismatch parameters for each frequency point covering the preset spectrum range.

[0009] Optionally, constructing a frequency domain phase mismatch distribution function based on the phase mismatch parameters at each frequency point includes: establishing a one-to-one mapping relationship between frequency and phase mismatch value according to the corresponding frequency value based on the phase mismatch parameters at each frequency point; and constructing a frequency domain phase mismatch distribution function with frequency as the independent variable and phase mismatch value as the dependent variable based on the one-to-one mapping relationship between frequency and phase mismatch value, so as to characterize the phase mismatch variation characteristics within the preset frequency range.

[0010] Optionally, generating the phase compensation amount corresponding to each frequency point based on the frequency domain phase mismatch distribution function includes: extracting the phase mismatch value corresponding to each frequency point based on the frequency domain phase mismatch distribution function, and segmenting the frequency according to the phase mismatch value to generate phase mismatch change intervals corresponding to different frequency intervals; calculating the phase error accumulation amount of the corresponding frequency interval based on the phase mismatch value in each of the phase mismatch change intervals, and determining the target compensation phase change trend of each frequency point based on the phase error accumulation amount; and performing reverse compensation calculation on the phase mismatch value of each frequency point based on the target compensation phase change trend to generate the phase compensation amount corresponding to each frequency point; wherein, the phase compensation amount is used to offset the phase mismatch value of the corresponding frequency point.

[0011] Optionally, calculating the cumulative phase error of the corresponding frequency interval based on the phase mismatch value within each phase mismatch variation interval includes: extracting the phase mismatch value of each frequency point located between the frequency boundaries within each phase mismatch variation interval, and generating a phase mismatch subsequence for the corresponding frequency interval; calculating the phase error increment for each frequency point based on the phase mismatch value of each frequency point in the phase mismatch subsequence and the frequency interval between adjacent frequency points, and generating a phase error increment sequence; and accumulating the phase error within the corresponding frequency interval point by point based on the phase error increment sequence to generate the cumulative phase error of the corresponding frequency interval.

[0012] Optionally, generating modulation control parameters based on the phase compensation amount and applying them to the lithium niobate waveguide to achieve dispersion compensation includes: converting the phase compensation amount into a target phase distribution along the propagation direction of the lithium niobate waveguide based on the one-to-one mapping relationship between the phase compensation amount at each frequency point and the corresponding frequency, generating a phase modulation sequence at the corresponding position; calculating the equivalent refractive index change at each corresponding position based on the phase modulation sequence according to a preset optical path modulation relationship, and generating a corresponding refractive index modulation sequence; determining the modulation control parameters at each corresponding position based on the refractive index modulation sequence, and mapping the modulation control parameters into a driving signal to control the refractive index change at the corresponding position of the lithium niobate waveguide; and performing spatially distributed modulation on the lithium niobate waveguide based on the driving signal so that the phase compensation amount at each frequency point acts on the corresponding propagation path to achieve dispersion compensation within the preset frequency range.

[0013] A second aspect of the present invention provides a lithium niobate dispersion compensation system, the system comprising: a data acquisition unit, configured to acquire the effective refractive index of a target lithium niobate waveguide within a preset frequency range, and calculate the corresponding propagation constant based on the effective refractive index of the mode to construct a mode dispersion function; a function construction unit, configured to calculate the phase mismatch parameters corresponding to each frequency point based on the mode dispersion function, and construct a frequency domain phase mismatch distribution function based on the phase mismatch parameters of each frequency point; a compensation amount determination unit, configured to generate a phase compensation amount corresponding to each frequency point based on the frequency domain phase mismatch distribution function; and an execution unit, configured to generate modulation control parameters based on the phase compensation amount and apply them to the lithium niobate waveguide to achieve dispersion compensation.

[0014] 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 lithium niobate dispersion compensation method as described above.

[0015] 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 lithium niobate dispersion compensation method.

[0016] Through the above technical solution, this invention achieves quantitative characterization of the frequency-dependent propagation characteristics in lithium niobate waveguides by obtaining the effective refractive index of the mode and constructing the mode dispersion function. Based on this, the phase mismatch parameters at each frequency point are calculated, forming a frequency-domain phase mismatch distribution, transforming phase mismatch from discrete analysis to continuous frequency-domain description. Furthermore, based on this distribution, phase compensation amounts corresponding to each frequency point are generated and converted into modulation control parameters applied to the waveguide, achieving targeted phase compensation for different frequency components. This process transforms phase mismatch over a wide frequency range from an uncontrollable state to a calculable and adjustable state, thereby improving the consistency of phase matching and the overall frequency-domain conversion efficiency.

[0017] 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

[0018] 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 lithium niobate dispersion compensation method provided in one embodiment of the present invention; Figure 2(a) is a phase mismatch distribution curve of a lithium niobate waveguide provided in one embodiment of the present invention in the wavelength range of 1500 nm to 1600 nm; Figure 2 (b) is a frequency domain phase error cumulative curve obtained based on phase mismatch distribution calculation according to one embodiment of the present invention; Figure 2 (c) is a schematic diagram of the phase deviation distribution result after applying phase compensation according to one embodiment of the present invention; Figure 3 This is a system structure diagram of a lithium niobate dispersion compensation 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

[0019] 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.

[0020] like Figure 1 As shown, an embodiment of the present invention provides a method for lithium niobate dispersion compensation, the method comprising: Step S10: Obtain the effective refractive index of the target lithium niobate waveguide within a preset frequency range, and calculate the corresponding propagation constant based on the effective refractive index of the mode to construct the mode dispersion function.

[0021] Specifically, multiple discrete frequency points are generated within the preset frequency spectrum range according to a preset frequency sampling interval. Based on the structural and material parameters of the target lithium niobate waveguide, electromagnetic mode solving is performed on each discrete frequency point to obtain the effective refractive index of the mode at each discrete frequency point. Based on the effective refractive index of the mode and the corresponding frequency value of each discrete frequency point, the propagation constant of each discrete frequency point is calculated to generate a propagation constant sequence. Based on the propagation constant sequence, continuous processing is performed according to a preset function fitting rule to construct a mode dispersion function to characterize the frequency response characteristics of the target lithium niobate waveguide.

[0022] In this embodiment of the invention, the preset spectrum range is set according to the actual application scenario. For example, the communication band commonly used by quantum light sources can be selected from the range of 1500nm to 1600nm. To ensure the stability and accuracy of subsequent calculations, a frequency sampling grid needs to be constructed within this spectrum range. The sampling interval is not arbitrarily set, but is determined in conjunction with the waveguide dispersion change rate. When the dispersion changes rapidly, the sampling density needs to be increased to avoid the accumulation of subsequent fitting errors.

[0023] After establishing the frequency sampling grid, electromagnetic mode solving is performed for each discrete frequency point. This solution essentially involves eigenmode analysis of the waveguide cross-sectional structure, with input parameters including waveguide geometry, material refractive index distribution, and boundary conditions. This solution process yields the effective refractive index of the mode at the corresponding frequency. This refractive index is not an abstract quantity but directly reflects the propagation speed and spatial distribution characteristics of light in the waveguide, forming the basis for subsequent propagation constant calculations.

[0024] After obtaining the effective refractive index of the mode at each frequency point, it needs to be converted into the propagation constant. The calculation of the propagation constant is a deterministic mapping relationship, and the result reflects the phase accumulation rate of the light field in the propagation direction at different frequencies. Through this mapping, a set of data sequences with frequency as the independent variable and propagation constant as the dependent variable can be obtained. This sequence is still in discrete form and cannot be directly used for continuous frequency domain analysis.

[0025] To enable this data to participate in the subsequent construction of the phase mismatch function, the propagation constant sequence needs to be made continuous. This process can be understood as reconstructing discrete points into a continuous curve, which can be achieved using polynomial fitting, spline interpolation, or other continuous function approximation methods. The key here is not the specific algorithm used, but ensuring that the reconstructed function has good smoothness and differentiability in the frequency domain, thus providing a stable input for subsequent phase calculations.

[0026] Through the above processing, the mode dispersion function can be obtained, which establishes a continuous correspondence between frequency and propagation constant. Once this function is determined, all subsequent phase correlation calculations can be performed directly based on it, thereby avoiding repeated electromagnetic solutions and improving overall computational efficiency.

[0027] In a specific embodiment, let the angular frequency range be... Construct a set of discrete frequency points within this interval. Adjacent frequency points satisfy For each frequency point The corresponding effective refractive index of the mode is obtained by solving the electromagnetic mode. .

[0028] Based on the above results, the propagation constant is calculated: ; in, It is the speed of light in a vacuum.

[0029] This yields the discrete propagation constant sequence: ; A function fit is performed on the sequence to construct a continuous functional expression of the propagation constant with respect to frequency. In this embodiment, a polynomial fitting form is used: ; Among them, coefficient It is obtained by solving discrete data using the least squares method.

[0030] Through the above processing, the mode dispersion function is formed. This function directly participates in the calculation of phase mismatch parameters in subsequent steps. Specifically, it is called under different frequency combinations to obtain the propagation constant, thereby achieving a unified calculation of phase relationships. This completes the entire process from solving discrete modes to constructing a continuous dispersion function, enabling the waveguide's frequency domain propagation characteristics to have a computable and callable functional expression, and providing fundamental support for subsequent dispersion compensation.

[0031] Step S20: Calculate the phase mismatch parameters for each frequency point based on the mode dispersion function, and construct a frequency domain phase mismatch distribution function based on the phase mismatch parameters for each frequency point.

[0032] Specifically, the calculation of phase mismatch parameters for each frequency point based on the mode dispersion function includes: obtaining the propagation constants corresponding to the preset pump frequency, signal frequency, and idler frequency based on the mode dispersion function; wherein the propagation constants are calculated from the effective refractive index of the mode at the corresponding frequency and the frequency value, and the frequency correspondence between the pump frequency, signal frequency, and idler frequency is determined according to the energy conservation relationship; based on the propagation constants corresponding to the pump frequency, signal frequency, and idler frequency, the phase mismatch value for each frequency combination is calculated according to the difference between the pump propagation constant and the signal propagation constant and the idler frequency propagation constant, generating discrete phase mismatch data; based on the discrete phase mismatch data, the phase mismatch value is completed for the unsampled frequency points according to the preset interpolation function, and the completed phase mismatch value is mapped one-to-one with the corresponding frequency to generate phase mismatch parameters for each frequency point covering the preset spectrum range.

[0033] Furthermore, a frequency domain phase mismatch distribution function is constructed based on the phase mismatch parameters at each frequency point, including: establishing a one-to-one mapping relationship between frequency and phase mismatch value according to the corresponding frequency value based on the phase mismatch parameters at each frequency point; and constructing a frequency domain phase mismatch distribution function with frequency as the independent variable and phase mismatch value as the dependent variable based on the one-to-one mapping relationship between frequency and phase mismatch value, so as to characterize the phase mismatch variation characteristics within the preset frequency range.

[0034] In this embodiment of the invention, the mode dispersion function obtained in step S10 is... By directly incorporating frequency combination relationships, a unified calculation of the phase matching state in the nonlinear interaction process is performed. Furthermore, the discrete calculation results are transformed into a parameter set covering the entire spectrum range, providing a clear input basis for the subsequent compensation process.

[0035] The entire processing chain maintains a continuous and unidirectional data flow. The mode dispersion function, as input, is mapped to a propagation constant via frequency combination relationships. The phase mismatch value is then calculated using the phase difference, ultimately forming a set of phase mismatch parameters indexed by frequency. Based on this, the parameter set is transformed into a frequency domain function expression to describe the overall variation of the phase mismatch within the spectral range.

[0036] Specifically, the frequency combination relationship involved in the nonlinear process is determined. In this embodiment, the pump frequency is set as... The signal frequency is , idle frequency The three elements satisfy the law of conservation of energy: ; This relationship holds true across the entire spectrum and is used to construct a set of frequency combinations. For any signal frequency within a preset spectrum range... The corresponding idle frequency can be determined based on the above relationships: ; After the frequency combination is determined, the mode dispersion function is called. Obtain the propagation constants for the corresponding frequencies: ; ; ; The propagation constants mentioned above are all derived from the mode dispersion function constructed in the previous stage, and their values ​​reflect the rate of change of the propagation phase of the light field at the corresponding frequency.

[0037] Based on the propagation constant, the phase mismatch value is calculated. Phase mismatch is defined as the difference between the pump propagation constant and the signal and idler propagation constants, and its expression is: ; This expression can be calculated for every frequency combination, thus forming a discrete phase mismatch dataset: ; The aforementioned dataset uses signal frequency as an index to record the degree of phase mismatch for corresponding frequency combinations. In actual calculations, the signal frequency... The sampling is performed at a preset frequency interval to obtain complete discrete phase mismatch data across the entire preset frequency spectrum.

[0038] Due to the existence of discrete sampling intervals, some frequency points are not directly involved in electromagnetic mode solving and phase mismatch calculation. To ensure that subsequent processing covers the entire spectrum, a completion process is performed on the unsampled frequency points. The completion process performs interpolation calculations based on existing discrete data to obtain the corresponding phase mismatch values ​​for the unsampled frequency points. After the interpolation process is completed, the completed data and the original discrete data are organized together to form a set of phase mismatch parameters for each frequency point covering a preset spectrum range.

[0039] Through the above steps, a set of phase mismatch parameters indexed by frequency is obtained: ; This set is continuously distributed across the frequency spectrum, with each frequency point corresponding to a unique phase mismatch value, thus providing a complete data foundation for subsequent frequency domain modeling.

[0040] After obtaining the phase mismatch parameters at each frequency point, a function is performed on them to construct a frequency domain phase mismatch distribution function. This function describes the overall trend of phase mismatch variation with frequency and serves as the input for subsequent phase compensation calculations.

[0041] During the construction process, the phase mismatch parameters at each frequency point are first sorted according to their frequency values ​​to ensure that the data has a monotonic order in the frequency domain. The sorted data forms a one-to-one mapping relationship between frequency and phase mismatch value, and this mapping relationship itself already has the basic form of functional expression.

[0042] Based on this, the mapping relationship is transformed into an explicit function expression. In this embodiment, the frequency domain phase mismatch distribution function is defined as follows: The independent variable is frequency. The dependent variable is the corresponding phase mismatch value. This function is continuously defined over the entire preset frequency spectrum, and its value is determined by the aforementioned discrete data and the completion result.

[0043] To ensure the stability of the function in numerical calculations, the function maintains continuity and first derivative continuity during construction, which makes the phase mismatch change smooth during frequency variation, thereby avoiding the introduction of numerical oscillations in subsequent compensation calculations.

[0044] In one specific embodiment, the pump wavelength is set to 775nm, corresponding to an angular frequency of This is a constant. Within the communication band, the signal wavelength range is selected as 1500nm to 1600nm, and converted into an angular frequency range. For each signal frequency within this range... Calculate the corresponding idle frequency And the propagation constant is obtained based on the mode dispersion function.

[0045] Taking a certain frequency point as an example, let... The corresponding idle frequency is Calculated using the mode dispersion function: ; ; And further calculate the phase mismatch: ; Performing the above calculations across the entire frequency spectrum yields the complete phase mismatch data distribution. In the actual calculation results, it can be observed that the phase mismatch value exhibits a nonlinear variation characteristic in the frequency domain, approaching zero near the center frequency and gradually increasing at the spectral edges. This trend directly reflects the influence of waveguide dispersion on nonlinear interactions.

[0046] By transforming discrete calculation results into function form This function provides a continuous frequency domain description of phase mismatch. It can be used not only for qualitative analysis of phase matching within a spectral range but also as a direct input for subsequent phase compensation calculations, giving the compensation process a clear frequency dependence. In engineering implementation, this frequency domain phase mismatch distribution function further serves as the basis for generating control variables. By analyzing the function's variation characteristics in the frequency domain, the intensity of compensation demand in different frequency intervals can be determined, thereby achieving fine-grained control of phase mismatch.

[0047] Step S30: Generate the phase compensation amount for each frequency point based on the frequency domain phase mismatch distribution function.

[0048] Specifically, the phase mismatch value for each frequency point is extracted based on the frequency domain phase mismatch distribution function, and the frequency is segmented according to the phase mismatch value to generate phase mismatch variation intervals corresponding to different frequency ranges; the cumulative phase error of the corresponding frequency range is calculated based on the phase mismatch value within each of the phase mismatch variation intervals, and the target compensation phase change trend for each frequency point is determined based on the cumulative phase error; based on the target compensation phase change trend, reverse compensation calculation is performed on the phase mismatch value of each frequency point to generate the phase compensation amount for each frequency point; wherein, the phase compensation amount is used to offset the phase mismatch value of the corresponding frequency point.

[0049] Furthermore, calculating the cumulative phase error of the corresponding frequency interval based on the phase mismatch values ​​within each of the phase mismatch variation intervals includes: extracting the phase mismatch values ​​of each frequency point located between the frequency boundaries within each of the phase mismatch variation intervals, and generating a phase mismatch subsequence for the corresponding frequency interval; calculating the phase error increment for each frequency point based on the phase mismatch value of each frequency point in the phase mismatch subsequence and the frequency interval between adjacent frequency points, and generating a phase error increment sequence; and accumulating the phase error within the corresponding frequency interval point by point based on the phase error increment sequence to generate the cumulative phase error for the corresponding frequency interval.

[0050] In this embodiment of the invention, the frequency domain phase mismatch distribution function is discretely sampled to obtain a frequency sequence. ,in, Indicates the first Each sampling frequency point, , This represents the total number of sampling points. The interval between adjacent frequency points is defined as: ; in, Indicates the first The frequency interval of each frequency range is determined by a preset frequency sampling interval.

[0051] For each frequency point Extract the phase mismatch value from the frequency domain phase mismatch distribution function. To form a discrete phase mismatch sequence Since phase mismatch exhibits a non-linear variation in the frequency domain, directly performing independent compensation at each frequency point would result in discontinuities in the compensation results in the frequency domain. Therefore, in this embodiment, the frequency axis is segmented. Specifically, the changing trend of the phase mismatch value is detected in the frequency sequence, and when... When the frequency range remains monotonically varied across multiple consecutive points, it is divided into a phase mismatch variation range. ,in: ; and They represent the first The starting and ending frequencies of each frequency range.

[0052] In each frequency range Within, extract the corresponding phase mismatch subsequence: ; The cumulative phase error is calculated based on this subsequence. First, the phase error increment is defined. Its expression is: ; in, Indicates the first The contribution of each frequency point to the phase error, and its unit is the dimensionless phase quantity (radians rad). This represents the phase mismatch value at that frequency point; This represents the frequency interval corresponding to that frequency point.

[0053] For frequency range The phase error increments at all frequency points within the interval are summed to obtain the cumulative phase error for that interval: ; in, Indicates the first The total phase deviation within a frequency range is physically defined as the degree of overall phase shift caused by dispersion within that range.

[0054] After obtaining the accumulated phase error, a target compensation phase distribution is constructed based on this accumulated error. The target compensation phase function is then defined. Its expression is: ; in, Let be the integral variable, representing the value at the current frequency. All previous frequency points; the negative sign indicates that the compensation direction is opposite to the phase mismatch direction, used to achieve phase cancellation.

[0055] In the discrete implementation, the above integral is expressed in a cumulative form as follows: ; in, Indicates the first The target compensation phase value corresponding to each frequency point.

[0056] This yields the phase compensation amount at each frequency point. Its definition is: ; in, Indicates frequency The phase compensation amount to be applied, in radians, is used to compensate for the phase mismatch at the corresponding frequency point. Ultimately, this forms a complete set of phase compensation parameters: ; In one specific embodiment, a preset spectral range corresponds to a wavelength of 1500nm to 1600nm. After converting this range into an angular frequency interval, discrete sampling is performed to obtain the number of frequency points. The phase mismatch distribution was calculated. Then, the spectrum was divided into three intervals: the central interval, the transition interval, and the edge interval.

[0057] Within the central section, Approaching zero, corresponding The changes are relatively small; within the marginal intervals, As the value increases, it is obtained through cumulative calculation. It exhibits a monotonic variation trend. The phase compensation amount generated in the above manner remains continuously varied throughout the entire frequency domain, ensuring that there are no abrupt changes in the compensation process between different frequency ranges, thereby guaranteeing the stability of subsequent modulation control.

[0058] In one specific implementation, such as Figure 2 As shown, the phase mismatch and compensation process within the preset frequency range is calculated and demonstrated.

[0059] Figure 2 Figure (a) shows the phase mismatch distribution curve of the lithium niobate waveguide in the wavelength range of 1500 nm to 1600 nm. It can be seen that the phase mismatch exhibits a minimum near the center of the spectrum, gradually increasing at both ends, showing an overall asymmetric trend. This reflects the influence of higher-order dispersion and material inhomogeneity in the waveguide structure on the phase matching conditions. Based on the phase mismatch distribution, error accumulation calculation is performed in the frequency domain, yielding the following results: Figure 2 The phase error accumulation curve is shown in (b) above. As the wavelength changes, the phase error gradually accumulates in the frequency domain, and a region of decreasing change appears in some intervals, indicating that the contribution of phase mismatch differs in different frequency intervals. Further, based on the phase error accumulation result, a corresponding phase compensation amount is generated and applied to the original phase mismatch distribution to obtain the compensated result, as shown below. Figure 2 As shown in (c), after compensation, the overall amplitude of the phase deviation is significantly reduced, but there is still a certain residual error, reflecting the actual adjustment accuracy limitation in the modulation control process. Through the above process, effective suppression of phase mismatch in a wide frequency range is achieved, making the phase deviation of each frequency component tend to be consistent, thereby improving the phase matching performance in the overall frequency domain.

[0060] Step S40: Generate modulation control parameters based on the phase compensation amount and apply them to the lithium niobate waveguide to achieve dispersion compensation.

[0061] Specifically, based on the one-to-one mapping relationship between the phase compensation amount at each frequency point and the corresponding frequency, the phase compensation amount is converted into a target phase distribution along the propagation direction of the lithium niobate waveguide, generating a phase modulation sequence at the corresponding position; based on the phase modulation sequence, the equivalent refractive index change at each corresponding position is calculated according to a preset optical path modulation relationship, and a corresponding refractive index modulation sequence is generated; based on the refractive index modulation sequence, the modulation control parameters at each corresponding position are determined, and the modulation control parameters are mapped into a driving signal to control the refractive index change at the corresponding position of the lithium niobate waveguide; based on the driving signal, spatially distributed modulation is performed on the lithium niobate waveguide so that the phase compensation amount at each frequency point acts on the corresponding propagation path to achieve dispersion compensation within the preset frequency range.

[0062] In this embodiment of the invention, the phase compensation amount needs to be converted into spatial modulation parameters along the propagation direction of the lithium niobate waveguide. This conversion process is based on the propagation characteristics of light in the waveguide, mapping the phase compensation requirement in the frequency domain to the phase distribution along the propagation path, thereby enabling different frequency components to obtain corresponding phase corrections during propagation.

[0063] In lithium niobate waveguides, the propagation velocities of different frequency components differ, and this difference is determined by the group velocity. For a frequency of... The group velocity of an optical signal is defined as: ; in, For the aforementioned mode dispersion function, its derivative It represents the rate of change of the propagation constant with respect to frequency.

[0064] Based on group velocity, a relationship between frequency and propagation time can be established. Let the propagation time of light in the waveguide be... Then the corresponding frequency component satisfies the following during propagation: ; Under steady-state propagation conditions, the spatial distribution of frequency components propagating along a waveguide can be characterized by the group delay. The group delay is defined as: ; in, Represents frequency The corresponding propagation delay time, This represents the total length of the waveguide.

[0065] Based on the group delay distribution, the effective locations of frequency components in the waveguide are expanded. By normalizing the group delay, a mapping relationship between frequency and spatial location is established. ; in, and These are the minimum group delay and maximum group delay within the preset spectrum range, respectively.

[0066] Through the above mapping, each frequency point in the frequency domain... Each corresponds to a unique position in the waveguide This established a frequency-space mapping relationship with a physical basis.

[0067] Based on this mapping relationship, the frequency domain phase compensation amount Converted to spatial phase distribution: ; in, It represents the inverse frequency function corresponding to a spatial location.

[0068] After obtaining the spatial phase distribution, the phase change needs to be converted into an equivalent optical path change. The phase and optical path satisfy the following relationship: ; in, Indicates the location The equivalent optical path change that needs to be introduced at this point. The wavelength corresponds to the frequency.

[0069] The change in optical path length is further converted into a change in refractive index. Let the length of the modulation segment in the waveguide be... Then we have: ; in, Indicates the location The amount of refractive index change that needs to be applied at that location.

[0070] Therefore, we can conclude that: ; Based on the above relationships, the refractive index modulation sequence distributed along the waveguide is obtained. This sequence is used to guide the actual modulation process.

[0071] In lithium niobate materials, refractive index modulation is achieved through the electro-optic effect. The applied electric field of the facility is... Then the change in refractive index satisfies: ; in, The intrinsic refractive index of the material, is the electro-optic coefficient.

[0072] From this, the distribution of the driving electric field can be deduced: ; Mapping the electric field distribution to a driving voltage signal It is then loaded onto the waveguide via electrodes to achieve spatially distributed modulation.

[0073] In one specific embodiment, let the waveguide length be... The spectral range corresponds to a group delay variation of 0.8 ps to 1.6 ps. Using the above normalization relationship, the frequency components are mapped to the waveguide length range. After calculating the phase compensation distribution, the corresponding refractive index variation is within 10... -4 The magnitude is achieved through electro-optic modulation. This process realizes a complete mapping from the frequency domain phase compensation to the spatial refractive index modulation parameters. Each variable has a clear physical meaning and calculation path, allowing the compensation to act gradually along the propagation path in the waveguide, thereby achieving dispersion compensation over a wide frequency range.

[0074] like Figure 3 As shown, this invention provides a lithium niobate dispersion compensation system. The system includes: a data acquisition unit, used to acquire the effective refractive index of the target lithium niobate waveguide within a preset frequency range, and calculate the corresponding propagation constant based on the effective refractive index of the mode to construct a mode dispersion function; a function construction unit, used to calculate the phase mismatch parameters corresponding to each frequency point based on the mode dispersion function, and construct a frequency domain phase mismatch distribution function based on the phase mismatch parameters of each frequency point; a compensation amount determination unit, used to generate a phase compensation amount corresponding to each frequency point based on the frequency domain phase mismatch distribution function; and an execution unit, used to generate modulation control parameters based on the phase compensation amount and apply them to the lithium niobate waveguide to achieve dispersion compensation.

[0075] 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 lithium niobate dispersion compensation method.

[0076] 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 lithium niobate dispersion compensation method as described above.

[0077] 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 lithium niobate dispersion compensation method.

[0078] 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.

[0079] 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.

[0080] 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 lithium niobate dispersion compensation, characterized in that, The method includes: The effective refractive index of the target lithium niobate waveguide in the preset frequency range is obtained, and the corresponding propagation constant is calculated based on the effective refractive index of the mode in order to construct the mode dispersion function. The phase mismatch parameters at each frequency point are calculated based on the mode dispersion function, and a frequency domain phase mismatch distribution function is constructed based on the phase mismatch parameters at each frequency point. The phase compensation amount for each frequency point is generated based on the frequency domain phase mismatch distribution function. Modulation control parameters are generated based on the phase compensation amount and applied to the lithium niobate waveguide to achieve dispersion compensation.

2. The lithium niobate dispersion compensation method according to claim 1, characterized in that, Obtain the effective refractive index of the target lithium niobate waveguide within a preset spectral range, and calculate the corresponding propagation constant based on the effective refractive index to construct the mode dispersion function, including: Multiple discrete frequency points are generated within the preset frequency range according to a preset frequency sampling interval. Based on the structural and material parameters of the target lithium niobate waveguide, electromagnetic mode solving is performed on each discrete frequency point to obtain the effective refractive index of the mode for each discrete frequency point. Based on the effective refractive index of the mode at each discrete frequency point and the corresponding frequency value, the propagation constant at each discrete frequency point is calculated, and a propagation constant sequence is generated. Based on the propagation constant sequence, a mode dispersion function is constructed to characterize the frequency response characteristics of the target lithium niobate waveguide by performing continuous processing according to a preset function fitting rule.

3. The lithium niobate dispersion compensation method according to claim 1, characterized in that, The phase mismatch parameters at each frequency point are calculated based on the mode dispersion function, including: Based on the mode dispersion function, the propagation constants corresponding to the preset pump frequency, signal frequency, and idle frequency are obtained; wherein... The propagation constant is calculated from the effective refractive index of the mode at the corresponding frequency and the frequency value, and the frequency correspondence between the pump frequency, signal frequency and idle frequency is determined according to the energy conservation relationship. Based on the propagation constants corresponding to the pump frequency, signal frequency, and idle frequency, the phase mismatch value of each frequency combination is calculated according to the difference between the pump propagation constant and the signal propagation constant and the idle frequency propagation constant, thereby generating discrete phase mismatch data; Based on the discrete phase mismatch data, the phase mismatch values ​​of the unsampled frequency points are filled in according to the preset interpolation function, and the filled phase mismatch values ​​are mapped one by one with the corresponding frequencies to generate phase mismatch parameters for each frequency point covering the preset spectrum range.

4. The lithium niobate dispersion compensation method according to claim 3, characterized in that, A frequency domain phase mismatch distribution function is constructed based on the phase mismatch parameters at each frequency point, including: Based on the phase mismatch parameters at each frequency point, a one-to-one mapping relationship between frequency and phase mismatch value is established according to the corresponding frequency value. Based on the one-to-one mapping relationship between frequency and phase mismatch value, a frequency domain phase mismatch distribution function is constructed with frequency as the independent variable and phase mismatch value as the dependent variable, in order to characterize the phase mismatch variation characteristics within the preset frequency range.

5. The lithium niobate dispersion compensation method according to claim 1, characterized in that, Based on the frequency domain phase mismatch distribution function, the phase compensation amount corresponding to each frequency point is generated, including: Based on the frequency domain phase mismatch distribution function, the phase mismatch value corresponding to each frequency point is extracted, and the frequency is segmented according to the phase mismatch value to generate the phase mismatch variation range corresponding to different frequency ranges. The phase error accumulation in the corresponding frequency range is calculated based on the phase mismatch value in each phase mismatch variation range, and the target compensation phase change trend at each frequency point is determined based on the phase error accumulation. Based on the target compensation phase change trend, reverse compensation calculation is performed on the phase mismatch value at each frequency point to generate the corresponding phase compensation amount at each frequency point; wherein, the phase compensation amount is used to offset the phase mismatch value at the corresponding frequency point.

6. The lithium niobate dispersion compensation method according to claim 5, characterized in that, The cumulative phase error in the corresponding frequency range is calculated based on the phase mismatch value within each of the aforementioned phase mismatch variation ranges, including: Based on the frequency boundaries corresponding to each phase mismatch variation interval, the phase mismatch values ​​of each frequency point located between the frequency boundaries are extracted to generate a phase mismatch subsequence for the corresponding frequency interval. Based on the phase mismatch value at each frequency point in the phase mismatch subsequence and the frequency interval between adjacent frequency points, the phase error increment at each corresponding frequency point is calculated, and a phase error increment sequence is generated. Based on the phase error increment sequence, the phase error within the corresponding frequency range is accumulated point by point to generate the phase error accumulation amount for the corresponding frequency range.

7. The lithium niobate dispersion compensation method according to claim 1, characterized in that, Based on the phase compensation amount, modulation control parameters are generated and applied to the lithium niobate waveguide to achieve dispersion compensation, including: Based on the one-to-one mapping relationship between the phase compensation amount at each frequency point and the corresponding frequency, the phase compensation amount is converted into a target phase distribution along the propagation direction of the lithium niobate waveguide, and a phase modulation sequence at the corresponding position is generated. Based on the phase modulation sequence, the equivalent refractive index change at each position is calculated according to the preset optical path modulation relationship, and the corresponding refractive index modulation sequence is generated. Based on the refractive index modulation sequence, the modulation control parameters corresponding to each position are determined, and the modulation control parameters are mapped to driving signals to control the refractive index change at the corresponding position of the lithium niobate waveguide. Based on the driving signal, spatial distributed modulation is performed on the lithium niobate waveguide so that the phase compensation at each frequency point acts on the corresponding propagation path to achieve dispersion compensation within the preset frequency range.

8. A lithium niobate dispersion compensation system, characterized in that, The system includes: The data acquisition unit is used to acquire the effective refractive index of the target lithium niobate waveguide in a preset frequency range, and to calculate the corresponding propagation constant based on the effective refractive index of the mode in order to construct the mode dispersion function. The function construction unit is used to calculate the phase mismatch parameters at each frequency point based on the mode dispersion function, and to construct the frequency domain phase mismatch distribution function based on the phase mismatch parameters at each frequency point. The compensation amount determination unit is used to generate the phase compensation amount corresponding to each frequency point based on the frequency domain phase mismatch distribution function. An execution unit is used to generate modulation control parameters based on the phase compensation amount and apply them to the lithium niobate waveguide to achieve dispersion compensation.

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 lithium niobate dispersion compensation 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 lithium niobate dispersion compensation method as described in any one of claims 1-7.

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