A method for precise control of laser pulse time domain waveform based on DP-PID algorithm

Abstract

The present invention relates to a method for precise control of laser pulse time domain waveform based on DP-PID algorithm, which belongs to the technical field of laser pulse time domain waveform control. The steps include system initial setting, system operation and output signal acquisition, calculation of error and root mean square error, judging whether the root mean square error is less than a set threshold, and using DP-PID algorithm to calculate waveform premodulation signal. Through iterative optimization, S2 to S5 are repeated to make the waveform of the output pulse signal light converge to the pulse target waveform set in S1, and when the cycle end condition is met, the pulse time domain waveform is precisely controlled.

Description

Technical Field

[0001] The invention relates to a laser pulse time domain waveform precision control method based on a DP-PID algorithm, belonging to the technical field of laser pulse time domain waveform control. Background Art

[0002] High-power, high-energy laser systems usually use a master oscillator power amplifier structure. Due to the characteristics of the gain medium, the power amplifier has a gain saturation effect and cannot maintain a fixed gain for a continuous high input power. Therefore, when the laser pulse is amplified, the gain within the duration of a pulse continues to decrease, which is reflected in the waveform as the pulse front edge becomes steeper, the pulse trailing edge becomes slower, and the pulse time domain waveform is severely distorted.

[0003] However, in many application fields, whether the pulse time domain waveform can be controlled after the laser pulse passes through the power amplifier is of great significance. For example, in the field of laser radar, the time domain waveform will affect the detection carrier-to-noise ratio; in the field of laser processing, the time domain waveform will affect the processing accuracy; in the field of laser communication, the time domain waveform will affect the stability of signal transmission. In addition, laser pulse time domain waveform control is also one of the important technologies for large-scale laser devices to meet the needs of inertial confinement fusion experiments.

[0004] In order to obtain a laser pulse with a specific output waveform, it is necessary to pre-modulate the waveform of the laser before power amplification to offset the waveform distortion of the power amplification process. At present, there are two types of schemes for determining the pre-modulated waveform. One type of scheme is to solve it through theoretical modeling, and the other type of scheme is to perform closed-loop control on the laser system. In the first type of scheme, the optical amplification process is numerically analyzed to solve the rate equation and the transport equation group. Even if a large number of approximations are used, there is still a large amount of calculation and large errors, and it is impossible to achieve precise control of the waveform. In the second type of scheme, by analyzing the system output and optimizing the input pre-modulated waveform, precise control can be achieved in theory. As a preferred closed-loop control technology, PID control has many advantages such as simple principle, easy implementation, and high control accuracy. It is widely used in automatic control. However, PID control, like other traditional closed-loop control technologies, is not effective when directly applied to the time-domain waveform control of laser pulses. The reason needs to be analyzed from two aspects: the nonlinear time-varying characteristics of the time-domain waveform control of laser pulses and the PID control principle.

[0005] On the one hand, the laser power amplifier in the process of laser pulse time domain waveform control is a nonlinear time-varying system. The nonlinearity mentioned here does not refer to the optical nonlinearity based on the nonlinear relationship between the polarization intensity of the medium and the light field intensity, but refers to the nonlinear relationship between the amplifier gain and the input optical power in the optical amplifier. Taking an erbium-doped fiber amplifier as an example, its small signal gain and saturation gain can differ by 10dB. The time-varying characteristics of the amplifier are due to the fact that its gain is not only related to the input optical power, but also to the consumption accumulation of the current inversion particle number.

[0006] On the other hand, PID control is designed based on linear control theory. By optimizing the control coefficients of the proportional term (P), integral term (I) and differential term (D), the strength of the error proportional amplification, error integral compensation and error differential damping are changed respectively, thereby optimizing the system's response to the error and achieving the best control effect. In this process, the control quantity of each part is linearly related to each control coefficient, and the response of the controlled system to the total control quantity is also linearly related.

[0007] For the above reasons, when PID controls the waveform, the system cannot achieve optimal response for all sampling points of a pulse cycle at the same time. For example, if 10,000 sampling points of the pre-modulated waveform are controlled, these 10,000 sampling points cannot achieve optimal response at the same time if the same control coefficient is used; and for the same sampling point, the optimal response cannot be achieved using the same control coefficient. Therefore, although PID control has many advantages, it cannot be directly applied to the control of laser pulse time domain waveforms. Summary of the invention

[0008] In view of the deficiencies in the prior art, the present invention provides a method for precise control of laser pulse waveforms based on the DP-PID algorithm. The DP-PID algorithm is a dynamic control parameter PID algorithm that solves the waveform distortion problem existing in the pulse laser power amplification process and realizes precise waveform control. It should be noted that when the content of the present invention describes the control method, it is inevitable to involve the conventional structure of a closed-loop control laser system applicable to the control method. Since the content of the present invention is not intended to identify the key features or necessary features of the laser system, the description of the laser system is not intended to limit the scope of application of the control method claimed.

[0009] The technical solution of the present invention is as follows:

[0010] A laser pulse waveform precision control method based on DP-PID algorithm comprises the following steps:

[0011] S1, system initial setting; setting the target parameters of the output pulse laser through the calculation storage unit, the parameters include the pulse target waveform, pulse repetition frequency, root mean square error threshold; setting the initial waveform pre-modulation signal through the calculation storage unit.

[0012] S2, system operation and output signal acquisition; S2-1, through the signal generation unit, the waveform pre-modulation signal is converted into a corresponding electrical signal to drive the optical modulator; S2-2, the electrical signal is converted into a corresponding pre-compensated pulse signal light through the optical modulator; S2-3, the pulse signal light after optical power amplification is detected by the photodetector, and the collected analog signal contains the time domain waveform information of the optical pulse; S2-4, the analog signal is converted into digital and sampled by the data acquisition unit, and the output pulse signal is input into the calculation and storage unit;

[0013] S3, calculating the error and the root mean square error; calculating the error and the root mean square error between the pulse target waveform and the output pulse signal;

[0014] S4, determine whether the root mean square error is less than the set threshold; when the root mean square error between the output pulse signal and the pulse target waveform is less than or equal to the threshold through the calculation storage unit, end the loop, otherwise enter step S5;

[0015] S5, using the DP-PID algorithm to calculate the waveform premodulation signal; calculating the iterative waveform premodulation signal through the calculation storage unit, and controlling the signal generating unit to generate the corresponding signal, and returning to step S2.

[0016] Through iterative optimization, S2 to S5 are repeated to make the waveform of the output pulse signal light converge to the pulse target waveform set in S1. When the cycle end condition is met, precise control of the pulse time domain waveform is achieved.

[0017] Preferably, in step S1, the pulse target waveform and the waveform premodulation signal are both time domain waveform signals of one pulse period, given in the form of a one-dimensional array, respectively denoted as W g , U k-1 , subscript g is the target, subscript k is the number of cycles, k=1 in the first cycle, and the initial waveform premodulation signal is recorded as U 0 .

[0018] Preferably, in step S1, there are many methods for determining the initial waveform premodulation signal, for example: (1) in some embodiments, the pulse target waveform can be used as the initial waveform premodulation signal; (2) in some embodiments, a square wave pulse can be used as the initial waveform premodulation signal; (3) in some embodiments, a trapezoidal pulse can be used as the initial waveform premodulation signal; (4) in some embodiments, an exponential function-shaped pulse can be used as the initial waveform premodulation signal; (5) in some embodiments, an approximate function model can be selected to describe the gain, and then the element-by-element ratio of the pulse target waveform and the gain function is used as the initial waveform premodulation signal; (6) in some embodiments, the gain function is determined by a preliminary experiment, and then the pulse target waveform ratio and the element-by-element ratio of the gain function are used as the initial waveform premodulation signal. During the preliminary experiment, a standard square wave pulse, a trapezoidal wave pulse, or an exponential function-shaped pulse can be selected as the input. The error amplitude between the initial waveform premodulation signal and the ideal premodulation signal has a small impact on the realization of waveform precision control by the present method, because the control algorithm provided by the present invention has a fast modulation response and stable convergence performance. Therefore, after the waveform premodulation signal determined in this step is input into the laser system, a large error between the output pulse signal light and the pulse target waveform is allowed. The description of the above method for determining the initial waveform premodulation signal is not intended to limit the scope of application of the control method claimed.

[0019] Preferably, in step 2, the signal generating unit is an electronic circuit or device that can generate an electrical signal with specific characteristics and shape, such as a sine wave, a square wave, a triangle wave, etc.; the optical modulator refers to a device for controlling the amplitude of an optical signal and its driving device, such as an electro-optic modulator, an acousto-optic modulator, etc.; the photodetector is a device that can convert an optical signal into an electrical signal, and here specifically refers to a high-speed photodetector with a sufficiently large bandwidth, and its response speed meets the detection of the pulse waveform to be measured, such as a photodiode, an MSM photodetector; the data acquisition unit is an electronic circuit or device that has the function of converting the analog electrical signal obtained by the detector into a digital electrical signal, and performs preliminary processing or storage, such as an ADC, a data acquisition card; the computing and storage unit is a component or module used to perform computing and data storage tasks, such as an MCU, a DSP, an FPGA, etc.

[0020] Preferably, in step S2, the output pulse signal is a time domain waveform signal of a pulse period, given in the form of a one-dimensional array, denoted as W k-1 .

[0021] Preferably, in step S3, the error calculation formula is e k =W g -W k-1 , is a one-dimensional array; the formula for calculating the root mean square error is , where N is the number of sampling points.

[0022] Preferably, in step S5, the specific steps of calculating the waveform premodulation signal are as follows:

[0023] S5-1, determine whether it is an initial cycle; if it is an initial cycle, go to step S5-2, otherwise go to step S5-3;

[0024] S5-2, calculate the control parameters; when the cycle reaches this step for the first time, according to the output pulse signal W k-1 The initial waveform premodulation signal U 0 Compared with the gain characteristics, determine the control parameters of the proportional term p , the control parameters of the integral term i , the control parameters of the differential term d , when the subsequent loop reaches this step, skip the current step;

[0025] S5-3, calculate dynamic control parameters; according to k -1 cycle output pulse signal W k-1 With waveform premodulation signal U k-1 Compared with the gain characteristics, determine the control parameter dynamic factor V k Then, the control parameters of the proportional term, integral term, and differential term are multiplied by the dynamic factor to obtain the dynamic control parameter p of the proportional term. k = p ×V k , dynamic control parameter i of the integral term k = i ×V k , dynamic control parameter d of the differential term k = d ×V k ; Control parameter dynamic factor V k It is a one-dimensional array. This factor is introduced to offset the effect of the laser amplifier as a nonlinear time-varying system as much as possible. The process of action is to use the current gain function of the system as the estimated value of the gain function of the next cycle, and change the constant parameter in the traditional PID algorithm that responds to a single sampling point and is linearly related to the control amount of each part to a dynamic array that can respond to all sampling points at the same time and is nonlinearly related to the control amount of each part, so as to achieve a better response to all sampling points of a pulse cycle at the same time. This step controls the parameter dynamic factor V k The determination method is the key to whether the DP-PID algorithm can achieve precise control of the laser pulse time domain waveform.

[0026] S5-4, calculate the control amount u of the waveform premodulation signal k ;

[0027] S5-5, calculating the iterative waveform premodulation signal; k The waveform premodulation signal U of the second cycle k =U k-1 +u k , return to step S2.

[0028] Preferably, in step S5-3, the control parameter dynamic factor V k There are many ways to calculate the specific value of, including any of the following methods: (1) In some embodiments, it can be equal to k -1 cycle of waveform premodulation signal U k-1 ; (2) In some embodiments, the k -1 cycle of waveform premodulation signal U k-1 Calculation, the calculation formula is V k =U k-1 U k-1 , where the operator represents the Hadamard product operation; (3) In some embodiments, the formula Calculation; (4) In some embodiments, the formula calculate.

[0029] Preferably, in step S5-4, the control amount u k The calculation method includes any one of the following: (1) In some embodiments, the control amount calculation formula is:

[0030] (3)

[0031] (2) In some embodiments, the control amount calculation formula is:

[0032] (4)

[0033] Wherein T is the sampling period of the sampling process in step S2-4.

[0034] The beneficial effects of the present invention are:

[0035] The present invention provides a method for precise control of laser pulse waveform based on DP-PID algorithm, which is applied to nonlinear time-varying systems to simultaneously control multiple sampling points of waveform simulation signals, solve the waveform distortion problem existing in the pulse laser power amplification process, and realize precise waveform control. Specifically, the method provided by the present invention has the following beneficial effects: (1) The calculation difficulty is small, avoiding the theoretical modeling process of solving the laser amplifier rate equation and the transport equation group, and the calculation amount is small; (2) It supports non-instantaneous control and instantaneous control, which depends on the hardware unit of the closed-loop control laser system, and is suitable for laboratory verification scenarios or integrated application scenarios; (3) The precision of laser pulse time domain waveform control is high. The DP-PID algorithm provided can enable the system to achieve a better response to all sampling points of a pulse cycle at the same time, solving the problem that traditional closed-loop control technology is difficult to cope with laser pulse time domain waveform control, and realizing precise control of pulse time domain waveform. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The closed-loop controlled laser system used in Example 1;

[0037] Figure 2 This is a flowchart of the application process;

[0038] Figure 3 The waveform diagram mentioned in step S1 in Example 1, where (a) is the pulse target waveform W g Waveform diagram, (b) is the gain function G e Waveform diagram, (c) is the initial waveform premodulation signal U 0 Waveform graph;

[0039] Figure 4 The initial waveform premodulation signal is iterated to k Schematic diagram of the system input and output results for -1=10 times, where the left column (a) to (k) are the waveform premodulation signals U input to the system 0 ~ U 10 ; The right column (l) to (v) is the pulse signal W output by the system 0 ~W 10 ;

[0040] Figure 1 Among them, 10, seed light input end; 20, pulse light power amplification module, 30, back light isolation monitoring module, 40, waveform monitoring and control module, 50, pulse signal light output end;

[0041] 21. Optical circulator, 22. Optical amplifier;

[0042] 31. Optical power meter;

[0043] 41. Computing storage unit, 42. Optical beam splitter, 43. Signal generating unit, 44. Photodetector, 45. Optical modulator, 46. Data acquisition unit. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0045] Embodiment 1:

[0046] In order to facilitate understanding of the implementation process of the control method in this embodiment, the closed-loop control laser system used in this embodiment will be introduced below. Figure 1 As shown, the system includes the following parts:

[0047] (1) a seed light input terminal 10, used for inputting continuous seed light;

[0048] (2) a pulse optical power amplification module 20, used to amplify the optical power of the pre-modulated optical pulse;

[0049] (3) a backlight isolation monitoring module 30, used to isolate the backlight, or to isolate and monitor the backlight at the same time, so as to protect the optical path components during the regulation process;

[0050] (4) a waveform monitoring and control module 40, which is used to detect the output signal light, convert the optical signal into an analog signal and a digital signal, calculate a waveform premodulation signal according to the digital signal, and then convert the signal into a premodulated optical pulse;

[0051] (5) The pulse signal light output terminal 50 is used to output the pulse signal light after waveform control and optical power amplification.

[0052] The pulse optical power amplification module 20 includes: three optical circulators 21 and three optical amplifiers 22 .

[0053] The backlight isolation monitoring module 30 includes three optical power meters 31 .

[0054] The waveform monitoring and control module 40 includes: a calculation storage unit 41 , a signal generating unit 43 , an optical modulator 45 , an optical beam splitter 42 , a photodetector 44 , and a data acquisition unit 46 .

[0055] Combine the following Figure 2 , further provides a method for precise control of laser pulse time domain waveform based on DP-PID algorithm, comprising the following steps:

[0056] A method for precise control of laser pulse time domain waveform based on DP-PID algorithm, comprising the following steps:

[0057] S1, system initial setting; setting the target parameters of the output pulse laser by calculating the storage unit 41, the parameters include the pulse target waveform, pulse repetition frequency, root mean square error threshold; setting the initial waveform pre-modulation signal by calculating the storage unit.

[0058] The pulse target waveform and waveform premodulation signal are both time domain waveform signals of one pulse period, given in the form of a one-dimensional array, denoted as W g , U k-1 , subscript g is the target, subscript k is the number of cycles, k=1 in the first cycle, and the initial waveform premodulation signal is recorded as U 0 .

[0059] Pulse target waveform W g Set to Figure 3 The square wave shown in (a) uses the error function to facilitate sampling. erf ( t ) defines the rising edge and falling edge of the square wave. The square wave formula is as follows:

[0060] (1)

[0061] in, t is the time corresponding to the sampling point, t RE is the 50% rise time, t DE is the 50% falling edge time, σ is the standard deviation of the error function. The pulse repetition frequency is set to 100kHz and the RMS error threshold is set to 1%.

[0062] In order to facilitate sampling, the gain function G is estimated by the error function e ,like Figure 3 As shown in (b). The estimated gain function here has a large error with the actual gain. The estimation formula is as follows:

[0063] (2)

[0064] in, t is the time corresponding to the sampling point, t RE is the 50% rise time, t DE is the 50% falling edge time, σ is the standard deviation of the error function defining the square wave, and the value of the normalized gain is within the interval [1, A]. The initial waveform premodulation signal U is calculated and stored in the storage unit 41. 0 Set to Figure 3 The waveform shown in (c) is calculated as follows: .

[0065] S2, system operation and output signal acquisition; S2-1, through the signal generating unit 43, the waveform pre-modulated signal is converted into a corresponding electrical signal to drive the optical modulator 45; S2-2, the electrical signal is converted into a corresponding pre-compensated pulse signal light through the optical modulator 45; S2-3, the pulse signal light after optical power amplification is detected by the photodetector 44, and the collected analog signal contains the time domain waveform information of the optical pulse; S2-4, the analog signal is converted into digital form and sampled by the data acquisition unit 46, and the output pulse signal W is obtained. k-1 The output pulse signal is a time domain waveform signal of a pulse period, given in the form of a one-dimensional array, denoted as W k-1 .

[0066] A signal generating unit is an electronic circuit or device that can generate an electrical signal with specific characteristics and shapes, such as a sine wave, square wave, or triangle wave; an optical modulator refers to a device used to control the amplitude of an optical signal and its driving device, such as an electro-optic modulator, an acousto-optic modulator, etc.; a photodetector is a device that can convert an optical signal into an electrical signal, specifically a high-speed photodetector with a sufficiently large bandwidth whose response speed meets the requirements for detecting the pulse waveform to be measured, such as a photodiode or an MSM photodetector; a data acquisition unit is an electronic circuit or device that has the function of converting the analog electrical signal obtained by the detector into a digital electrical signal and performs preliminary processing or storage, such as an ADC, a data acquisition card, a computing storage unit, or a component or module used to perform computing and data storage tasks, such as an MCU, a DSP, or an FPGA.

[0067] S3, calculate the error and RMS error; calculate the pulse target waveform W g With the output pulse signal W k-1 The error and root mean square error of k =W g -W k-1 , is a one-dimensional array; the current k The calculation of the cycle k -The root mean square error of the output result of 1 cycle is calculated as follows: , where N is the number of sampling points.

[0068] S4, determine the root mean square error RMSE Is it less than the set threshold; when the root mean square error between the output pulse signal and the target pulse waveform is less than or equal to the threshold value 1% by calculating the storage unit 41, the loop ends, otherwise it goes to step S5;

[0069] S5, using the DP-PID algorithm to calculate the waveform premodulation signal; calculating the iterative waveform premodulation signal through the calculation storage unit 41, and controlling the signal generating unit 43 to generate a corresponding signal, and returning to step S2.

[0070] In step S5, the specific steps of calculating the waveform premodulation signal are as follows:

[0071] S5-1, determine whether it is an initial cycle; if it is an initial cycle, go to step S5-2, otherwise go to step S5-3.

[0072] S5-2, calculate the control parameters; when the cycle reaches this step for the first time, according to the output pulse signal W k-1 The initial waveform premodulation signal U 0 Compared with the gain characteristics, determine the control parameters of the proportional term p= 0.060, control parameters of integral term i= 0.008, control parameters of differential term d =0.020, when the subsequent cycle reaches this step, the current step is skipped.

[0073] S5-3, calculate dynamic control parameters; according to k -1 cycle output pulse signal W k-1 With waveform premodulation signal U k-1 Compared with the gain characteristics, determine the control parameter dynamic factor V k Then, the control parameters of the proportional term, integral term, and differential term are multiplied by the dynamic factor to obtain the dynamic control parameter p of the proportional term. k = p ×V k , dynamic control parameter i of the integral term k = i ×V k , dynamic control parameter d of the differential term k = d ×V k ; Control parameter dynamic factor V k It is a one-dimensional array. This factor is introduced to offset the effect of the laser amplifier as a nonlinear time-varying system as much as possible. The process of action is to use the current gain function of the system as the estimated value of the gain function of the next cycle, and change the constant parameter in the traditional PID algorithm that responds to a single sampling point and is linearly related to the control amount of each part to a dynamic array that can respond to all sampling points at the same time and is nonlinearly related to the control amount of each part, so as to achieve a better response to all sampling points of a pulse cycle at the same time. This step controls the parameter dynamic factor V k The determination method is the key to whether the DP-PID algorithm can achieve precise control of the laser pulse time domain waveform.

[0074] Control parameter dynamic factor Vk The specific value of is calculated by k -1 cycle of waveform premodulation signal U k-1 Calculation, the calculation formula is V k =U k-1 U k-1 , where the operator Represents the Hadamard product operation.

[0075] S5-4, calculate the control amount u of the waveform premodulation signal k Since the present embodiment adopts a non-real-time control method, the sampling period effect of the sampling process in step S2-4 is not considered, and the calculation formula is given by the following formula:

[0076] (3).

[0077] S5-5, calculating the iterative waveform premodulation signal; k The waveform premodulation signal U calculated by the cycle k =U k-1 +u k , return to step S2.

[0078] After iterative optimization, the waveform of the output pulse signal light converges to the pulse target waveform set in S1. k When -1=8 cycles, RMSE<1%, achieving precise control of the pulse time domain waveform.

[0079] Furthermore, in order to verify the stability of the method, this embodiment k -1=After 8 cycles, continue k -1=9,10 cycles. Figure 4 The initial waveform premodulation signal is shown as iteratively k -1=10 system input and output results, where Figure 4 (a) to Figure 4 (k) is the waveform premodulation signal U input to the system 0 ~ U 10 , Figure 4 (l) to Figure 4 (v) is the pulse signal W output by the system 0 ~W 10 It can be seen that the output pulse signal converges quickly to the pulse target waveform without obvious overshoot oscillation, which proves that the control method not only has fast adaptive speed but also has good stability. In this process, the root mean square error RMSE data between the output pulse signal and the pulse target waveform are as follows,

[0080] k-1 = 0, 0.490335320105821;

[0081] k -1 = 1, 0.177441620771463;

[0082] k -1 = 2, 0.113345993982745;

[0083] k -1 = 3, 0.0680686430192612;

[0084] k -1 = 4, 0.0247113536085493;

[0085] k -1 = 5, 0.0199016476318587;

[0086] k -1 = 6, 0.0173653121035613;

[0087] k -1 = 7, 0.0148073664034991;

[0088] k -1 = 8, 0.00823633710742102;

[0089] k -1 = 9, 0.0124779949930095;

[0090] k -1 = 10, 0.0128139536659096.

[0091] It should be pointed out that k -1=9, the tiny oscillations generated by 10 cycles can be reduced as the number of cycles increases, and eventually a smaller root mean square error can be achieved.

[0092] Embodiment 2:

[0093] A method for precise control of laser pulse time domain waveform based on DP-PID algorithm, wherein the steps are as described in Example 1, except that in step S5-3, the control parameter dynamic factor V k The specific value of is calculated as k -1 cycle of waveform premodulation signal U k-1 .

[0094] Embodiment 3:

[0095] A method for precise control of laser pulse time domain waveform based on DP-PID algorithm, wherein the steps are as described in Example 1, except that in step S5-3, the control parameter dynamic factor V k The specific value of is calculated by using the formula calculate.

[0096] Embodiment 4:

[0097] A method for precise control of laser pulse time domain waveform based on DP-PID algorithm, wherein the steps are as described in Example 1, except that in step S5-3, the control parameter dynamic factor V k The specific value of is calculated by using the formula calculate.

[0098] Embodiment 5:

[0099] A method for precise control of laser pulse time domain waveform based on DP-PID algorithm, wherein the steps are as described in Example 1, except that in step S5-4, the control amount u k The calculation method is (4), where T is the sampling period of the sampling process in step S2-4.

Claims

1. A method for precise control of laser pulse time domain waveform based on DP-PID algorithm, characterized in that: The following steps are involved: S1, system initial setting; setting the target parameters of the output pulse laser through the calculation storage unit, the parameters include the pulse target waveform, pulse repetition frequency, root mean square error threshold; setting the initial waveform pre-modulation signal through the calculation storage unit; S2, system operation and output signal acquisition; S2-1, through the signal generation unit, the waveform pre-modulation signal is converted into a corresponding electrical signal to drive the optical modulator; S2-2, the electrical signal is converted into a corresponding pre-compensated pulse signal light through the optical modulator; S2-3, the pulse signal light after optical power amplification is detected by the photodetector, and the collected analog signal contains the time domain waveform information of the optical pulse; S2-4, the analog signal is converted into digital and sampled by the data acquisition unit, and the output pulse signal is input into the calculation and storage unit; S3, calculating the error and the root mean square error; calculating the error and the root mean square error between the pulse target waveform and the output pulse signal; S4, determining whether the root mean square error is less than a set threshold; When the root mean square error between the output pulse signal and the target pulse waveform is determined by the calculation storage unit to be less than or equal to the threshold, the loop ends, otherwise it goes to step S5; S5, using the DP-PID algorithm to calculate the waveform premodulation signal; calculating the iterative waveform premodulation signal through the calculation storage unit, and controlling the signal generating unit to generate a corresponding signal, and returning to step S2; In step S5, the specific steps of calculating the waveform premodulation signal are as follows: S5-1, determine whether it is an initial cycle; if it is an initial cycle, go to step S5-2, otherwise go to step S5-3; S5-2, calculate the control parameters; when the cycle reaches this step for the first time, according to the output pulse signal W k-1 The gain characteristic compared with the initial waveform premodulation signal U0 determines the control parameter of the proportional term p , the control parameters of the integral term i , the control parameters of the differential term d , when the subsequent loop reaches this step, skip the current step; S5-3, calculate dynamic control parameters; according to k -1 cycle output pulse signal W k-1 With waveform premodulation signal U k-1 Compared with the gain characteristics, determine the control parameter dynamic factor V k Then, the control parameters of the proportional term, integral term, and differential term are multiplied by the dynamic factor to obtain the dynamic control parameter p of the proportional term. k = p ×V k , dynamic control parameter i of the integral term k = i ×V k , dynamic control parameter d of the differential term k = d ×V k ; S5-4, calculate the control amount u of the waveform premodulation signal k ; S5-5, calculating the iterative waveform premodulation signal; k The waveform premodulation signal U of the second cycle k =U k-1 +u k , return to step S2.

2. The laser pulse time domain waveform precision control method based on DP-PID algorithm according to claim 1 is characterized in that: In step S1, the pulse target waveform and the waveform premodulation signal are both time domain waveform signals of one pulse period, given in the form of a one-dimensional array, respectively denoted as W g , U k-1 , subscript g is the target, subscript k is the number of cycles, k=1 in the first cycle, and the initial waveform premodulation signal is recorded as U0.

3. The laser pulse time domain waveform precision control method based on DP-PID algorithm according to claim 1 is characterized in that: In step S1, the method for determining the initial waveform premodulation signal includes any one of the following: (1) using a pulse target waveform as the initial waveform premodulation signal; (2) using a square wave pulse as the initial waveform premodulation signal; (3) using a trapezoidal pulse as the initial waveform premodulation signal; (4) using an exponential function-shaped pulse as the initial waveform premodulation signal; (5) selecting an approximate function model to describe the gain, and then using the element-by-element ratio of the pulse target waveform and the gain function as the initial waveform premodulation signal; (6) determining the gain function through a preliminary experiment, and then using the pulse target waveform ratio and the element-by-element ratio of the gain function as the initial waveform premodulation signal, and selecting standard square wave pulses, trapezoidal wave pulses, and exponential function-shaped pulses as input during the preliminary experiment.

4. The laser pulse time domain waveform precision control method based on DP-PID algorithm according to claim 1 is characterized in that: In step 2, the signal generating unit is an electronic circuit or device that can generate an electrical signal with specific characteristics and shapes; the optical modulator refers to a device for controlling the amplitude of an optical signal and its driving device; A photodetector is a device that can convert light signals into electrical signals, and its response speed is sufficient to detect the pulse waveform to be measured; The data acquisition unit is an electronic circuit or device that has the function of converting the analog electrical signals acquired by the detector into digital electrical signals and performing preliminary processing or storage. The computing storage unit is a component or module used to perform computing and data storage tasks.

5. The laser pulse time domain waveform precision control method based on DP-PID algorithm according to claim 1 is characterized in that: In step S2, the output pulse signal is a time domain waveform signal of a pulse period, given in the form of a one-dimensional array, denoted as W k-1 .

6. The method for precise control of laser pulse time domain waveform based on DP-PID algorithm according to claim 1, characterized in that: In step S3, the error calculation formula is e k =W g -W k-1 , is a one-dimensional array; the formula for calculating the root mean square error is , where N is the number of sampling points.

7. The laser pulse time domain waveform precision control method based on DP-PID algorithm according to claim 1 is characterized in that In step S5-3, the control parameter dynamic factor V k The specific value of can be calculated by any of the following methods: (1) equal to the k -1 cycle of waveform premodulation signal U k-1 ; (2) By k -1 cycle of waveform premodulation signal U k-1 Calculation, the calculation formula is V k =U k-1 U k-1 , where the operator represents the Hadamard product operation; (3) using the formula Calculate; (4) Use the formula calculate.

8. The method for precise control of laser pulse time domain waveform based on DP-PID algorithm according to claim 7, characterized in that: In step S5-4, the control amount u k The calculation method includes any of the following: (1) The control quantity calculation formula is: (3); (2) The control quantity calculation formula is: （4） Where T is the sampling period of the sampling process in step S2-4, e k is the error, and the calculation formula is e k =W g -W k-1 .

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