A high power THz repetitive programmable pulse generation system and method embedded in a CPA system

Abstract

The application discloses a high-power THz repetitive programmable pulse generation system embedded in a CPA system and a method thereof, and belongs to the technical field of ultrafast lasers. The system comprises, along a laser transmission path, a femtosecond laser seed source, a pulse stretcher, a programmable modulation unit, a power amplifier unit and a pulse compressor in sequence. The programmable modulation unit is arranged after the pulse stretcher, and performs frequency domain modulation on a spectral phase / amplitude when the pulse is in a state of time stretching and peak power reduction, so as to generate a coded stretched pulse. After power amplification and compression, a high-power ultrafast laser pulse train with a programmable time domain waveform is output. The programmable modulation unit is arranged after stretching and before amplification in the CPA system, so that the limitation of a low damage threshold of the modulation unit is effectively avoided, and programmable output of a hundred-watt, hundred-GHz to THz repetitive pulse train is realized. The application is suitable for fields of high-power laser processing and strong field physics, and has the advantages of simple structure and strong programmability.

Description

Technical Field

[0001] This invention relates to the field of ultrafast laser technology, and in particular to a high-power, high-repetition-rate programmable pulse generation system and method using a programmable spatial light modulator. It is especially suitable for embedding a programmable modulation unit into the broadening stage of a chirped pulse amplification (CPA) system to circumvent the low damage threshold limitation of the modulation unit and achieve programmable output of equivalent repetition frequency pulse trains in the hundreds of watts, hundreds of GHz to THz ranges. Background Technology

[0002] Femtosecond lasers, with their ultrashort pulse widths and extremely high peak power, exhibit irreplaceable advantages in fields such as micro-nano fabrication, strong-field physics, and biomedicine. However, traditional femtosecond laser processing suffers from problems such as low processing efficiency, poor structural controllability, and insufficient pulse modulation flexibility in high-power scenarios. By customizing the time-domain waveform of femtosecond lasers through pulse shaping technology, the interaction process between the laser and materials can be controlled, thereby improving processing accuracy and efficiency.

[0003] Spatial light modulators (SLMs) combined with 4f pulse shaping systems are one of the mainstream technologies for realizing time-domain and frequency-domain manipulation of ultrafast lasers, offering advantages such as high resolution, programmability, and high flexibility. However, because SLMs typically use liquid crystal materials, their optical damage threshold is low, making them difficult to apply directly to high-power laser systems. Programmable metasurface elements, which have emerged in recent years, also face similar damage threshold limitations.

[0004] In existing technologies, the main methods for generating high-power programmable pulse trains are as follows:

[0005] Independent shaping scheme: This scheme places the SLM-4f system after the CPA system output to directly shape high-power pulses. However, this scheme is limited by the low damage threshold of the SLM and cannot handle average power levels above 100 watts, which can easily lead to damage to optical components.

[0006] Electro-optic / acousto-optic modulation schemes: These schemes generate pulse trains within the cavity of an oscillator or regenerative amplifier using an electro-optic modulator (EOM) or an acousto-optic modulator (AOM). These schemes have limited modulation speeds, making it difficult to achieve repetition frequencies above 100 GHz, and they also lack flexibility and programmability, failing to dynamically generate complex pulse sequences.

[0007] Frequency division superposition method: This method splits the optical path in two using a beam splitter (such as a coupler or beam splitter prism), and introduces a cascaded delay line device into one of the paths to achieve frequency multiplication. The initial pulse is boosted to a frequency of 2N times after passing through the device. However, this method has the following drawbacks: due to the difficulty in achieving strict symmetry in coupling efficiency and the difficulty in precisely controlling the optical path length, it is difficult to guarantee that the generated pulses have the same energy and equal time intervals; and the dispersion generated by the ultrashort pulses within the optical fiber is difficult to control.

[0008] One approach is to increase the modulator's own threshold, such as using a mechanical phase modulator or a special material SLM, to address the problem at the component level. However, this approach is complex, costly, and may have limitations in control accuracy.

[0009] Therefore, a new method is needed to fully utilize the flexible control capability of programmable modulation units in high-power CPA systems while overcoming their damage threshold limitations. Summary of the Invention

[0010] This invention aims to solve the technical bottleneck that existing programmable modulation units cannot be directly used in high-power scenarios, and to realize multi-dimensional programmable control of high-power femtosecond laser pulses.

[0011] To achieve the above objectives, the present invention provides a high-power THz repetition rate programmable pulse generation system embedded in a CPA system, comprising, along the laser transmission path, the following components in sequence:

[0012] A femtosecond laser seed source is used to output the initial femtosecond pulse;

[0013] A pulse stretcher is used to stretch the time of an initial femtosecond pulse and output a stretched pulse.

[0014] A programmable modulation unit, located after the pulse stretcher, is used to receive the stretched pulse and apply programmable modulation to the spectral phase and / or amplitude of the stretched pulse in the frequency domain to generate an coded stretched pulse;

[0015] The power amplification unit is used to amplify the power of the coded widened pulse and output a high-power amplified pulse;

[0016] A pulse compressor is used to compress the time of high-power amplified pulses and output a high-power ultrafast laser pulse train with a programmable time-domain waveform.

[0017] In this method, by placing the programmable modulation unit after the pulse stretcher, it can perform modulation when the pulse is in a state of time stretching and instantaneous power density reduction, thereby avoiding the limitation that the programmable modulation unit cannot directly process high-power pulses due to its low damage threshold.

[0018] Preferably, the programmable modulation unit can be a liquid crystal spatial light modulator, a digital micromirror device, a programmable metasurface, or other devices capable of applying frequency domain phase and / or amplitude modulation to the light field.

[0019] Preferably, the frequency domain phase modulation amount applied by the programmable modulation unit Large second-order dispersion introduced by pulse stretcher satisfy: ,in Angular frequency, The center frequency is used to make the modulation amount on the order of perturbation relative to the broadened phase amount, so that the risk of local peak intensity caused by multi-frequency coherent superposition is not significantly increased during the amplification process.

[0020] Preferably, the programmable modulation unit generates a coded broadened pulse through piecewise linear phase modulation in the frequency domain; the piecewise linear phase modulation in the frequency domain includes: dividing the spectrum of the broadened pulse into... Each frequency band is independently given a linear phase. ,in For the first The time delay corresponding to each frequency band (on the order of ps or fs). The center frequency of this frequency band, when the delay of the adjacent frequency bands satisfies With a fixed step relationship, sub-pulse intervals of approximately [value missing] can be formed in the time domain. The pulse train allows for programmable control of the sub-pulse interval by controlling the step value of the delay. It should be noted that frequency-domain piecewise linear phase modulation is only a preferred implementation method, and the invention is not limited thereto. Those skilled in the art can employ other phase modulation methods according to actual needs, such as phase optimization based on AI algorithms, arbitrary waveform phase modulation, etc., as long as programmable modulation is applied to the spectral phase and / or amplitude of the broadened pulse, all fall within the protection scope of this invention.

[0021] Preferably, by adjusting the number of spectral segmentation bands , broaden the spectral width of the pulse and the dispersion of the pulse stretcher At least one parameter in the parameters enables programmable control of the sub-pulse interval of a high-power ultrafast laser pulse train.

[0022] As a preferred option, the system also includes:

[0023] The feedback monitoring unit is used to collect the time-domain characteristic data of the laser pulse train output by the pulse compressor in real time.

[0024] The optimization control module is connected to the feedback monitoring unit and the programmable modulation unit respectively. It is used to adjust the phase distribution diagram loaded onto the programmable modulation unit based on the difference between the collected time-domain characteristic data and the target waveform parameters, so as to dynamically compensate for the output waveform distortion caused by the nonlinear effect of the power amplifier unit or environmental factors.

[0025] The optimization control module is also used to combine amplitude modulation strategy with phase modulation and spectral energy redistribution to achieve independent adjustment of the energy of each sub-pulse in the output pulse train and flexible control of the overall energy distribution.

[0026] Preferably, the average power of the high-power ultrafast laser pulse train can reach the level of hundreds of watts, and the equivalent repetition frequency corresponding to its time-domain sub-pulse interval is adjustable in the range of hundreds of GHz to THz.

[0027] Preferably, the pulse compressor and the pulse stretcher form a dispersion compensation link to compensate for the main dispersion introduced by the pulse stretcher, so that the target frequency domain modulation applied by the programmable modulation unit is mapped to the target time domain waveform after compression.

[0028] Preferably, the system also includes a preamplifier located between the pulse stretcher and the programmable modulation unit for pre-amplifying the stretched pulse. The preamplifier is a key intermediate stage connecting the seed source and the subsequent power amplification unit. Its core function is to amplify the weak seed pulse to an energy level that allows the subsequent amplification stage to operate efficiently with low noise and high gain, while ensuring pulse quality and improving system stability and energy extraction efficiency.

[0029] This invention also provides a method for generating high-power THz repetition rate programmable pulses embedded in a CPA system, comprising the following steps:

[0030] S1, the femtosecond laser seed source outputs the initial femtosecond pulse;

[0031] S2. The initial femtosecond pulse is time-stretched using a pulse stretcher to output a stretched pulse;

[0032] S3. Using a programmable modulation unit located after the pulse stretcher, programmable modulation is applied to the spectral phase and / or amplitude of the stretched pulse in the frequency domain to generate an coded stretched pulse.

[0033] S4. The encoded widened pulse is amplified by the power amplification unit to output a high-power amplified pulse;

[0034] S5. The high-power amplified pulse is time-compressed by a pulse compressor to output a high-power ultrafast laser pulse train with a programmable time-domain waveform.

[0035] In this method, by placing the programmable modulation unit after the pulse stretcher, it can perform modulation when the pulse is in a state of time stretching and instantaneous power density reduction, thereby avoiding the limitation that the programmable modulation unit cannot directly process high-power pulses due to its low damage threshold.

[0036] Preferably, after step S2 and before step S3, step S2a is included: pre-amplifying the broadened pulse by a pre-amplifier and outputting a pre-amplified pulse; and in step S3, the programmable modulation unit modulates the pre-amplified pulse.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. By setting the programmable modulation unit in the broadening stage of the CPA system, frequency domain modulation is performed under the state of pulse time broadening and instantaneous power density reduction. This helps to avoid the problem that the modulation unit cannot directly process high-power pulses due to the low damage threshold, and realizes the compatibility between programmable modulation and high-power output.

[0039] 2. By utilizing the segmented linear phase modulation technique in the frequency domain, and by controlling the number of frequency bands divided into spectrum and the amount of time delay, pulse trains with adjustable intervals can be accurately generated. The equivalent repetition frequency can reach the order of hundreds of GHz to THz, which can be used to realize flexible programming of high-speed pulse trains.

[0040] 3. By controlling the modulation amount to be on the order of perturbation relative to the broadened phase amount, it helps to avoid the superposition and enhancement of multi-frequency coherence and suppress the abnormal growth of local peak intensity, thereby helping to ensure the waveform fidelity of the amplified pulse.

[0041] 4. By introducing a feedback monitoring and optimization control module, the nonlinear effects of the power amplifier unit and waveform distortion caused by environmental factors can be compensated in real time, which helps the system to operate stably for a long time.

[0042] 5. This invention improves upon the existing CPA system by simply embedding a programmable modulation unit after the stretcher, without requiring large-scale modifications to the original system, resulting in low cost and easy promotion. Attached Figure Description

[0043] Figure 1 This is a system structure block diagram of the present invention.

[0044] Figure 2 This is a flowchart of the method of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0046] Terminology Explanation

[0047] In this invention, for clarity, the following terms are defined:

[0048] System fundamental repetition frequency: refers to the pulse repetition frequency of the femtosecond laser seed source, which is also the repetition frequency of the final output high-power laser pulse train (or "pulse packet").

[0049] Equivalent repetition frequency: refers to the reciprocal of the time interval between adjacent sub-pulses within a pulse train (pulse packet), used to characterize the time structure within the pulse train.

[0050] Pulse train / pulse packet: refers to the laser output structure composed of multiple sub-pulses within a system's basic repetition period.

[0051] "Stretched pulse" refers to a pulse that is in a time-spanned state after passing through a pulse stretcher, regardless of whether it has been pre-amplified. The preamplifier only increases the pulse energy and does not change the pulse's time-spanning characteristics or the state of reduced instantaneous power density. Therefore, the pre-amplified pulse still falls under the category of "stretched pulse".

[0052] "Power amplification unit" refers to an amplification stage disposed after the programmable modulation unit for amplifying the power of the coded broadened pulse. In some embodiments of the present invention, the power amplification unit is a main amplifier.

[0053] Example 1: Pulse Train Generation Based on SLM-4f System

[0054] Please see Figure 1 and Figure 2 This embodiment provides a high-power THz repetition rate programmable pulse generation system embedded in a CPA system, which includes, along the laser transmission path, the following components in sequence:

[0055] The femtosecond laser seed source (S1) uses a ytterbium-doped fiber femtosecond laser oscillator with a center wavelength of 1030 nm and a full width at half maximum (FWHM) of the spectrum. The system's base repetition frequency is 1 MHz, the single pulse energy is 400 nJ, and the average power is 400 mW.

[0056] Pulse stretcher (S2)

[0057] A fiber chirped grating was used as a stretcher to broaden the seed pulse to approximately 800 ps. The instantaneous power density of the stretched pulse was significantly reduced, providing low-power conditions for subsequent modulation.

[0058] Programmable modulation unit (S3)

[0059] This embodiment employs a 4f pulse shaping system based on a liquid crystal spatial light modulator (SLM). The system includes a diffraction grating, a cylindrical lens, an SLM, and corresponding cylindrical lenses and diffraction gratings arranged sequentially, forming a standard 4f system. A frequency domain phase distribution map is loaded onto the SLM via computer programming to achieve phase modulation of the broadened pulse spectrum.

[0060] Power amplifier unit (S4)

[0061] In this embodiment, the power amplification unit employs a single-stage main amplifier, specifically a rod-shaped fiber amplifier. It amplifies the average power of the modulated coded broadened pulse from the modulated level to over 100 watts.

[0062] Pulse compressor (S5)

[0063] A transmission grating is used in the compressor to compensate for the principal dispersion introduced by the stretcher. When the SLM is not modulated with a target phase, the pulse width after compression is restored to the femtosecond range.

[0064] Modulation Principle: In this embodiment, the goal is to generate an equally spaced pulse train with an equivalent repetition frequency of 200 GHz (sub-pulse interval of approximately 5 ps). This is achieved through piecewise linear phase modulation in the frequency domain: the spectrum of the broadened pulse is divided into... Each frequency band is given a linear phase. ,in For the first Time delay corresponding to each frequency band This is the center frequency of the frequency band. When the delay between adjacent frequency bands satisfies... With a fixed step relationship, pulse trains with intervals of approximately 5 ps are formed in the time domain. Number of spectral segmentation bands. The maximum number of sub-pulses that can be contained within a single pulse packet is determined. The actual number of sub-pulses is affected by factors such as modulation depth, for example... The number of sub-pulses is approximately 5. In this embodiment, by loading the corresponding piecewise linear phase diagram using SLM, a pulse train with a sub-pulse interval of approximately 5 ps was successfully generated.

[0065] Output results: After amplification and compression, the measured average output power is 125 W, and the sub-pulse interval within the pulse train is approximately 5 ps (equivalent repetition frequency 200 GHz). If the system's fundamental repetition frequency is 1 MHz, then the energy of each pulse packet is approximately... If the pulse packet contains The energy of each sub-pulse is determined by the total energy of the pulse packet and its energy distribution design. The autocorrelation instrument measurement results show a clear, equally spaced pulse train waveform, consistent with the target.

[0066] In this embodiment, by designing the phase and / or amplitude modulation of each frequency band, the energy distribution of the sub-pulses can also be controlled, for example, to achieve equal-energy pulse trains, energy-decreasing pulse trains, or pulse trains with specific envelopes. Parameters such as the envelope width and sidelobe suppression ratio of the pulse train can be adjusted by optimizing the phase diagram.

[0067] Phase perturbation control verification: In this embodiment, the large second-order dispersion introduced by the stretcher... Approximately The additional modulation introduced by the programmable modulation unit is small relative to the main dispersion phase of the stretcher, which satisfies the condition that the modulation amount is on the order of perturbation and avoids nonlinear distortion during the amplification process.

[0068] Dispersion compensation verification: Since the modulation unit is located in the dispersion compensation link formed by the stretcher and the compressor, the compressor compensates for the main dispersion of the stretcher, while the target modulation phase applied by the SLM is preserved and mapped to the output time domain waveform.

[0069] Example 2: System configuration with preamplifier

[0070] Based on Example 1, this embodiment adds a preamplifier (S2a) between the pulse stretcher and the programmable modulation unit.

[0071] Preamplifier configuration: This preamplifier uses a ytterbium-doped fiber amplifier with a gain of approximately 20 dB. It pre-amplifies the unmodulated broadened pulse, increasing its energy to the efficient operating range of the subsequent power amplifier unit. A bandpass filter is connected to the output of the preamplifier to suppress spontaneous emission noise generated during amplification.

[0072] Operating conditions of the modulation unit: After pre-amplification, the pulse energy is increased, but because the pulse is still in a time-spanned state, its instantaneous power density is still very low, far below the damage threshold of the liquid crystal SLM. Therefore, the introduction of the pre-amplifier does not destroy the physical basis of "safe modulation".

[0073] Beneficial effects: The preamplifier boosts the pulse energy to the efficient operating range of the power amplifier unit (main amplifier), enabling the power amplifier unit to more fully extract the energy stored in the gain medium and improve the overall energy conversion efficiency. Simultaneously, the preamplifier amplifies the seed pulse with low noise, which helps improve the signal-to-noise ratio and stability of the output pulse.

[0074] In this embodiment, the same frequency domain piecewise linear phase modulation parameters as in Embodiment 1 were used to successfully generate a pulse train with a sub-pulse interval of 5 ps, and the average output power reached 130 W (slightly higher than in Embodiment 1), verifying the positive effect of the preamplifier.

[0075] Example 3: Adaptive Compensation System with Feedback Optimization Module

[0076] Based on Example 1, this embodiment introduces a feedback optimization module to compensate for nonlinear effects and environmental drift in the amplification link, thereby achieving high-fidelity stable output.

[0077] Feedback monitoring unit: This unit can employ at least one of the following: an autocorrelation meter, a frequency-resolved optical switching measurement device, a spectral phase interferometry measurement device, or a time-domain measurement link consisting of a high-speed photodetector and a high-speed oscilloscope, to acquire the time-domain characteristics of the output laser pulse train. The monitoring data is transmitted to the optimization control module via a data interface.

[0078] Optimized control module: Employs a high-performance industrial computer with a built-in deep learning algorithm based on physical information reverse engineering. This algorithm uses the nonlinear transfer function of the power amplifier unit as a constraint and the mean square error between the target waveform and the measured waveform as a loss function. It iteratively optimizes the phase distribution map loaded onto the SLM through gradient descent.

[0079] Dynamic compensation process:

[0080] The initial phase map is generated and loaded based on the target waveform (such as a 200 GHz equivalent repetition rate pulse train).

[0081] After the system is running, the feedback monitoring unit collects the output waveform in real time and calculates the error between the output waveform and the target waveform.

[0082] The optimization control module updates the phase diagram based on the error, generates a new phase diagram, and reloads it into the SLM.

[0083] Repeat the process until the error converges.

[0084] Test results show that when the power amplifier unit operates in the saturation region, the open-loop system may exhibit significant waveform distortion after prolonged operation. However, the closed-loop system in this embodiment, after several iterations, shows a significant reduction in the waveform error vector amplitude. Furthermore, when simulating ambient temperature drift, the system can quickly and adaptively recover to the target waveform, verifying its adaptive compensation capability.

[0085] Parameter range and adjustability description

[0086] Repetition frequency adjustment: by adjusting the number of spectral segmentation bands. , broaden the spectral width of the pulse and the dispersion of the stretcher This allows for continuous adjustment of the output equivalent repetition frequency. For example, adjusting... The size can be used to quickly switch the pulse interval, combined with the spectral width. and dispersion The equivalent repetition frequency can be configured in the range of 0.1 THz to 1 THz by adjustment.

[0087] Output power: The power amplification units used in this system (such as rod fiber amplifiers and solid-state CPA amplifiers) can achieve output power from hundreds of watts to kilowatts.

[0088] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-power THz repetition rate programmable pulse generation system embedded in a CPA system, characterized in that, The laser transmission path includes, in sequence: A femtosecond laser seed source is used to output the initial femtosecond pulse; A pulse stretcher is used to stretch the initial femtosecond pulse in time and output a stretched pulse. A programmable modulation unit, disposed after the pulse stretcher, is used to receive the stretched pulse and apply programmable modulation to the spectral phase and / or amplitude of the stretched pulse in the frequency domain to generate an coded stretched pulse; A power amplification unit is used to amplify the power of the encoded stretched pulse and output a high-power amplified pulse. A pulse compressor is used to compress the high-power amplified pulse in time and output a high-power ultrafast laser pulse train with a time-domain waveform programmable. In this method, by placing the programmable modulation unit after the pulse stretcher, it can perform modulation when the pulse is in a state of time stretching and instantaneous power density reduction, thereby avoiding the limitation that the programmable modulation unit cannot directly process high-power pulses due to its low damage threshold.

2. The high-power THz repetition rate programmable pulse generation system embedded in the CPA system according to claim 1, characterized in that, The frequency-domain phase modulation amount applied by the programmable modulation unit The large second-order dispersion introduced by the pulse stretcher satisfy: ,in Angular frequency, The center frequency is set to ensure that the modulation amount is on the order of perturbation relative to the phase broadening amount, while avoiding multi-frequency coherent superposition enhancement during amplification and suppressing abnormal growth of local peak intensity.

3. The high-power THz repetition rate programmable pulse generation system embedded in the CPA system according to claim 1, characterized in that, The programmable modulation unit generates the coded broadened pulse through frequency domain piecewise linear phase modulation; The frequency-domain piecewise linear phase modulation includes: dividing the spectrum of the broadened pulse into... Each frequency band is independently given a linear phase. ,in For the first The time delay corresponding to each frequency band The center frequency of this frequency band, when the delay of the adjacent frequency bands satisfies When the fixed step relationship is established, control is used. The value of is used to achieve programmatic control of the sub-pulse interval.

4. The high-power THz repetition rate programmable pulse generation system embedded in the CPA system according to claim 3, characterized in that, By adjusting the number of frequency bands in the spectral segmentation The spectral width of the broadened pulse and the dispersion of the pulse stretcher At least one parameter in the parameters enables programmable control of the sub-pulse interval of the high-power ultrafast laser pulse train.

5. The high-power THz repetition rate programmable pulse generation system embedded in the CPA system according to claim 1, characterized in that, Also includes: The feedback monitoring unit is used to collect the time-domain characteristic data of the laser pulse train output by the pulse compressor in real time. An optimization control module is connected to the feedback monitoring unit and the programmable modulation unit respectively. It is used to adjust the phase distribution diagram loaded onto the programmable modulation unit based on the difference between the collected time-domain characteristic data and the target waveform parameters through an optimization algorithm, so as to dynamically compensate for the output waveform distortion caused by the nonlinear effect of the power amplifier unit or environmental factors. The optimization control module is also used to combine amplitude modulation strategy with phase modulation and spectral energy redistribution to achieve independent adjustment of the energy of each sub-pulse in the output pulse train and flexible control of the overall energy distribution.

6. The high-power THz repetition rate programmable pulse generation system embedded in a CPA system according to claim 1, characterized in that, The average power of the high-power ultrafast laser pulse train can reach the level of hundreds of watts, and the equivalent repetition frequency corresponding to its time-domain sub-pulse interval is adjustable in the range of hundreds of GHz to THz.

7. The high-power THz repetition rate programmable pulse generation system embedded in a CPA system according to claim 1, characterized in that, The pulse compressor and the pulse stretcher form a dispersion compensation link to compensate for the main dispersion introduced by the pulse stretcher, so that the target frequency domain modulation applied by the programmable modulation unit is mapped to the target time domain waveform after compression.

8. The high-power THz repetition rate programmable pulse generation system embedded in a CPA system according to claim 1, characterized in that, It also includes a preamplifier disposed between the pulse stretcher and the programmable modulation unit for preamplifying the stretched pulse.

9. A method for generating high-power THz repetition rate programmable pulses embedded in a CPA system, characterized in that, Includes the following steps: S1, the femtosecond laser seed source outputs the initial femtosecond pulse; S2. The initial femtosecond pulse is time-stretched using a pulse stretcher to output a stretched pulse; S3. Using a programmable modulation unit disposed after the pulse stretcher, programmable modulation is applied to the spectral phase and / or amplitude of the stretched pulse in the frequency domain to generate an coded stretched pulse; S4. The encoded broadened pulse is amplified by the power amplification unit to output a high-power amplified pulse; S5. The high-power amplified pulse is time-compressed by a pulse compressor to output a high-power ultrafast laser pulse train with a time-domain waveform programmable. In this method, by placing the programmable modulation unit after the pulse stretcher, it can perform modulation when the pulse is in a state of time stretching and instantaneous power density reduction, thereby avoiding the limitation that the programmable modulation unit cannot directly process high-power pulses due to its low damage threshold.

10. The method for generating high-power THz repetition rate programmable pulses embedded in a CPA system according to claim 9, characterized in that, The steps following step S2 and before step S3 include: S2a. The broadened pulse is pre-amplified by a pre-amplifier, and a pre-amplified pulse is output. In step S3, the programmable modulation unit modulates the pre-amplified pulse.

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