Method and system for generating ultrafast pulse string with time-varying space-time characteristics

Abstract

The invention discloses a method and system for generating an ultrafast pulse string with time-varying space-time characteristics, and relates to the technical field of laser pulse control, and the method comprises the following steps: after an incident light pulse is reflected by a first grating and collimated by a first cylindrical lens, the spectral component of the incident light pulse is expanded along the space on the plane where a phase plate is located; realizing time domain positive Fourier transform to form two-dimensional space-spectrum distribution; modulating a phase plate, and performing complex amplitude modulation on the two-dimensional space-spectrum distribution by using the phase plate to obtain a space-spectrum; the modulated space-spectrum passes through a second lens and a second grating to realize time domain inverse Fourier transform to obtain an output pulse; the output pulse is transmitted for a certain distance on the rear surface of the grating to form an ultrafast pulse string with time-varying space-time characteristics, time and space dimensions are regulated and controlled at the same time, more complex space-time characteristics are achieved, and time and space distribution of the pulse is accurately controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of laser pulse control, and particularly to a method and system for generating an ultrafast pulse train with time-varying spatio-temporal characteristics. Background Art

[0002] An ultrafast laser pulse train refers to a series of pulses that repeat at regular time intervals. The duration of each pulse is usually very short (in the femtosecond or picosecond range), and the entire pulse train is arranged in an orderly manner in time. The frequency and interval of the pulse train can be adjusted according to specific applications.

[0003] Since the laser pulse train has lower thermal effects and an ultrafast modulation frequency compared to traditional single-pulse laser beams, in laser technology, pulse trains are commonly used in fields such as laser ablation, material processing, wireless communication, nonlinear science, and ultrafast photography. Therefore, it is particularly important to achieve the generation and arbitrary modulation of ultrafast pulse trains.

[0004] Traditional methods for generating laser pulse trains are mainly based on acousto-optic modulation and electro-optic modulation devices, but these methods have relatively low efficiency and require high-speed electronic driving. The modulation frequency (<GHz) is limited by the material properties. In addition, multiple longitudinal modes are simultaneously oscillated in the laser resonator through laser mode-locking technology to form a series of pulses with uniform time intervals. However, mode-locking technology requires precise control and stability, has high requirements for intracavity components, is easily affected by environmental factors such as temperature and vibration, and generally does not have adjustable pulse intervals.

[0005] In addition, spatio-temporal coupled wave packets or structured light with specific structures exhibit unique physical properties during propagation, focusing, and interaction with matter, and the temporal and spatial distributions of the laser beam have a non-negligible impact on their effects. Therefore, it is particularly important in the fields of laser processing and medicine. Current technical means can only achieve modulation of the laser pulse train in the time domain, cannot simultaneously control the time and space dimensions, and the temporal characteristics of the pulse train are fixed and non-adjustable.

[0006] In view of this, the present invention proposes a method and system for generating an ultrafast pulse train with time-varying spatio-temporal characteristics. Summary of the Invention

[0007] The object of the present invention is to provide a method and system for generating an ultrafast pulse train with time-varying spatio-temporal characteristics. Based on a two-dimensional ultrafast pulse shaper and a complex amplitude modulation algorithm, the sub-pulse number, time interval, and spatio-temporal shape of the output pulse train are arbitrarily controlled by modulating the two-dimensional space-spectral function of the pulse to solve the deficiencies in the background art.

[0008] According to one aspect of the present invention, there is provided a method and system for generating an ultrafast pulse train with time-varying spatio-temporal characteristics, including the following steps:

[0009] After the incident light pulse is reflected by the first grating and collimated by the first cylindrical lens, its spectral components are spread out along the space in the plane where the phase plate is located, realizing the time domain forward Fourier transform to form a two-dimensional space-spectral distribution;

[0010] Phase plate modulation, using the phase plate to perform complex amplitude modulation on the two-dimensional space-spectrum distribution to obtain a space-spectrum;

[0011] The modulated space-spectrum passes through the second lens and the second grating to achieve time domain inverse Fourier transform to obtain output pulses; the output pulses form ultrafast pulse trains with time-varying spatiotemporal characteristics after being transmitted a certain distance on the rear surface of the grating.

[0012] As a preferred technical solution of the present invention, the incident pulse is a single pulse output by a narrow linewidth ultrafast laser.

[0013] As a preferred technical solution of the present invention, the modulation function includes amplitude and phase information; the modulation function of the phase plate is adjusted to control the number of sub-pulses, time interval and space-time shape of the pulse train.

[0014] 4. The method for generating an ultrafast pulse train with time-varying spatiotemporal characteristics according to claim 3, wherein the mathematical expression of the transmittance function of the phase plate is:

[0015]

[0016] The transmittance function consists of four parts, where the first term Arg[] represents the complex angle, the second term π is the phase compensation factor, asinc[] represents the inverse Singer function, and the third term represents the linear grating, g represents the linear grating frequency, and the fourth term GDD·Ω 2 represents group delay dispersion, and GDD represents the dispersion size.

[0017] As a preferred technical solution of the present invention, the free space transmission after the second lens and the second grating can realize the two-dimensional Fourier transform of time and space, and the space-time distribution of the pulse train is expressed as:

[0018]

[0019] where u n (x,tt n ) represents the spatiotemporal distribution of the nth sub-pulse of the generated pulse train, t n =1 / f n is the time position of the sub-pulse.

[0020] As a preferred technical solution of the present invention, the distance between each element in the 4f pulse shaper is the focal length f of the cylindrical lens.

[0021] In a second aspect, the present invention provides a system for generating an ultrafast pulse train with time-varying spatiotemporal characteristics, based on the implementation of the method of the first aspect, comprising a 4f pulse shaper, wherein the 4f pulse shaper comprises two identical gratings, two identical cylindrical lenses and a phase plate;

[0022] After the incident light pulse is reflected by the first grating and collimated by the first cylindrical lens, its spectral components are spread out along the space in the plane where the phase plate is located, realizing the time domain forward Fourier transform to form a two-dimensional space-spectral distribution;

[0023] Phase plate modulation, using the phase plate to perform complex amplitude modulation on the two-dimensional space-spectrum distribution to obtain a space-spectrum;

[0024] The modulated space-spectrum passes through the second lens and the second grating to achieve time domain inverse Fourier transform to obtain output pulses; the output pulses form ultrafast pulse trains with time-varying spatiotemporal characteristics after being transmitted a certain distance on the rear surface of the grating.

[0025] In a third aspect, the present invention provides an electronic device, comprising: a processor and a memory, wherein the memory stores a computer program that can be called by the processor;

[0026] The processor executes the first aspect by calling the computer program stored in the memory.

[0027] In a fourth aspect, the present invention provides a computer-readable storage medium storing instructions, which, when executed on a computer, enable the computer to execute the method of the first aspect.

[0028] In the above technical solution, the technical effects and advantages provided by the present invention are:

[0029] The present invention controls the number of sub-pulses, time intervals and space-time shapes of the output pulse train through a complex amplitude modulation algorithm, and can flexibly generate pulse trains with customized time-varying characteristics to meet the needs of different application scenarios. It can also simultaneously regulate the time and space dimensions to achieve more complex space-time characteristics and accurately control the time and space distribution of pulses. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0031] Figure 1 A diagram of the system device for generating ultrafast pulse trains with time-varying spatiotemporal characteristics according to the present invention;

[0032] Figure 2 Four design diagrams of the transmittance function of the phase plate for generating ultrafast pulse trains with time-varying spatiotemporal characteristics according to the present invention;

[0033] Figure 3 This is an effect diagram of the space-time vortex pulse train with time-varying topological charge of the present invention;

[0034] FIG4( a ) is a three-dimensional space-time iso-intensity surface diagram of a flat-top optical pulse train with fixed energy and size over time;

[0035] FIG4( b ) is a diagram of a flat-top optical pulse train with spatial dimensions varying with time;

[0036] Figure 4(c) is a spatiotemporal intensity diagram of the pulse train;

[0037] FIG4( d ) is a diagram showing the effect that the energy of a time-varying flat-top optical pulse train increases first and then decreases with time;

[0038] FIG4( e ) is a diagram showing the effect that the energy of a time-varying flat-top optical pulse train first decreases and then increases with time. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Example 1

[0041] like Figure 1 As shown, this embodiment provides a generation system of an ultrafast pulse train with time-varying spatiotemporal characteristics, including a 4f pulse shaper, wherein the 4f pulse shaper includes two identical gratings, two identical cylindrical lenses and a phase plate; wherein:

[0042] After the incident light pulse is reflected by the first grating and collimated by the first cylindrical lens, its spectral components are spread out along the space in the plane where the phase plate is located, and a time-domain forward Fourier transform is realized to form a two-dimensional space-spectral function;

[0043] Specifically, the incident pulse is a single pulse output by a narrow-linewidth ultrafast laser; the spectral component corresponding to the incident pulse is spread out along the spatial direction on the plane where the phase plate is located, and the spatial component in the orthogonal direction forms a two-dimensional spatial-spectral distribution;

[0044] The two-dimensional space-spectral function can be expressed as:

[0045]

[0046] Where: i represents the imaginary unit, (ξ, Ω) is the rectangular coordinate of the plane where the phase plate is located; Ω = ω-ω0, ω = 2πc / λ and ω0 = 2πc / λ0 represent the simplified frequency, optical carrier frequency and center frequency respectively, where c represents the speed of light in vacuum. In addition: λ0 represents the center wavelength of the laser used, where the center wavelength of the Yb-doped fiber laser used is λ0 = 1030nm. N is the number of sub-pulses carried by the pulse train, f n Represents the slip phase, which determines the time position Δt of the nth sub-pulse n =1 / f n .

[0047] It should be noted that the spatial-spectral information described by formula (1) has amplitude and phase information, so we use a phase plate with complex amplitude modulation function to perform modulation.

[0048] Phase plate modulation, using the phase plate to perform complex amplitude modulation on the two-dimensional space-spectrum distribution to obtain a space-spectrum;

[0049] Specifically, the modulation function includes amplitude and phase information; the phase plate has a complex amplitude modulation function, which converts the pulse in the time domain into a spectral distribution in the frequency domain; the phase plate includes but is not limited to a liquid crystal spatial light modulator, a digital micromirror array, an optical diffraction element, and a metasurface modulation device; the modulation function of the phase plate is designed to control the number of sub-pulses, the time interval, and the space-time shape of the pulse train: wherein the number of pulses is determined by the parameter N in formula (1); the time interval of the sub-pulses is determined by the slip phase f n The spatiotemporal shape of the nth sub-pulse is determined by its corresponding two-dimensional spatial-spectral function in Fourier space describe.

[0050] The mathematical expression of the transmittance function of the phase plate is:

[0051]

[0052] The transmittance function consists of four parts, among which: the first term Arg[] represents the complex angle, which is used to realize pure phase modulation of two-dimensional spectrum, such as Figure 2 (a); the second term π is the phase compensation factor, which is used to calibrate the phase distortion caused by amplitude modulation, where asinc[] represents the inverse Single function, as Figure 2 (b) as shown; the third item represents a linear grating, which is used to achieve two-dimensional spectral pure amplitude modulation, such as Figure 2 (c) where g represents the linear grating frequency and the fourth term GDD·Ω 2represents the group delay dispersion, which is used to balance the coupling effect between spatial diffraction and temporal dispersion, such as Figure 2 As shown in (d), GDD represents the dispersion size.

[0053] The modulated space-spectrum passes through the second lens and the second grating to achieve time domain inverse Fourier transform to obtain output pulses; the output pulses form ultrafast pulse trains with time-varying spatiotemporal characteristics after being transmitted a certain distance on the rear surface of the grating.

[0054] Specifically, the free space transmission after the second lens and the second grating can realize the two-dimensional Fourier transform of time and space, and the space-time distribution of the pulse train is expressed as:

[0055]

[0056] where u n (x,tt n ) represents the spatiotemporal distribution of the nth sub-pulse of the generated pulse train, t n =1 / f n is the time position of the sub-pulse.

[0057] Specifically, this embodiment can achieve precise control of the temporal position and spatial distribution of the pulse train by accurately designing the modulation function of the phase plate, and expand the application potential of laser pulses in various fields, including but not limited to material processing, medical treatment, communication technology, etc. By accurately controlling the temporal and spatial characteristics of the pulse, the interaction between the laser and the material can be optimized, and the processing efficiency and quality can be improved.

[0058] Specifically, the distance between each element in the 4f pulse shaper is the focal length f of the cylindrical lens.

[0059] Specifically, the 4f pulse shaping system adapts to light beams of different wavelengths by adjusting the focal length of the cylindrical lens. When the light beam passes through the first cylindrical lens, it forms a spatial distribution of spectral components on the focal plane. The second cylindrical lens then images this distribution to complete the Fourier transform. By adjusting the focal length of the cylindrical lens, the time domain characteristics of the pulse can be compressed or broadened to adapt to different application requirements. Keeping the distance between elements equal to the focal length of the cylindrical lens helps maintain the collimation and wavefront quality of the light beam. The phase plate is placed on the focal plane of the two cylindrical lenses to optimize the modulation effect of the phase plate on the light beam with the greatest spatial expansion. By precisely controlling the distance between the elements, the focusing and diffraction characteristics of the light beam on the phase plate can be precisely controlled, thereby precisely controlling the time and spatial characteristics of the pulse and improving the modulation efficiency and the quality of pulse shaping.

[0060] Example 2

[0061] For the parts not described in detail in this embodiment, please refer to the description of Embodiment 1. This embodiment provides a method for generating an ultrafast pulse train with time-varying spatiotemporal characteristics, comprising the following steps:

[0062] After the incident light pulse is reflected by the first grating and collimated by the first cylindrical lens, its spectral components are spread out along the space in the plane where the phase plate is located, realizing the time domain forward Fourier transform to form a two-dimensional space-spectral distribution;

[0063] Specifically, the incident pulse is a single pulse output by a narrow-linewidth ultrafast laser;

[0064] Phase plate modulation, using the phase plate to perform complex amplitude modulation on the two-dimensional space-spectrum distribution to obtain a space-spectrum;

[0065] Specifically, the modulation function includes amplitude and phase information; the phase plate has a complex amplitude modulation function; the phase plate includes but is not limited to a liquid crystal spatial light modulator, a digital micromirror array, an optical diffraction element, and a metasurface modulation device; the modulation function of the phase plate is adjusted to control the number of sub-pulses, the time interval, and the space-time shape of the pulse train.

[0066] The spatial-spectral function can be expressed as:

[0067]

[0068] Where: i represents the imaginary unit, (ξ, Ω) is the rectangular coordinate of the plane where the phase plate is located; Ω = ω-ω0, ω = 2π / λ and ω0 = 2π / λ0 represent the simplified frequency, optical carrier frequency and center frequency respectively. In addition: λ0 is the center wavelength of the incident light pulse. We use an ytterbium-doped fiber laser with a center wavelength of λ0 = 1030nm. N is the number of sub-pulses carried by the pulse train, and f n Represents the slip phase, which determines the time position Δt of the nth sub-pulse n =1 / f n .

[0069] It should be noted that the spatial-spectral information described by formula (1) has amplitude and phase information, so we use a phase plate with complex amplitude modulation function to perform modulation.

[0070] The mathematical expression of the transmittance function of the phase plate is:

[0071]

[0072] The transmittance function consists of four parts, such as Figure 2 (a) is shown in the figure, where the first term Arg[] represents the complex angle, the second term π is the phase compensation factor, asinc[] represents the inverse Single function, and the third term represents the linear grating, g represents the linear grating frequency, and the fourth term GDD·Ω 2 represents group delay dispersion, and GDD represents the dispersion size.

[0073] The modulated space-spectrum passes through the second lens and the second grating to achieve time domain inverse Fourier transform to obtain output pulses; the output pulses form ultrafast pulse trains with time-varying spatiotemporal characteristics after being transmitted a certain distance on the rear surface of the grating.

[0074] Specifically, the free space transmission after the second lens and the second grating can realize the two-dimensional Fourier transform of time and space, and the space-time distribution of the pulse train is expressed as:

[0075]

[0076] where u n (x,tt n ) represents the spatiotemporal distribution of the nth sub-pulse of the generated pulse train, t n =1 / f n is the time position of the sub-pulse.

[0077] Example 3

[0078] For the parts not described in detail in this embodiment, please refer to the description of Embodiment 1. In the numerical simulation and experiment, the incident light pulse is a Gaussian pulse laser beam with a central wavelength of 1030nm and a bandwidth of 20nm, its spatial size is 2mm, the grating parameters used are 1200 lines / mm, and the focal length of the cylindrical lens is f=100mm.

[0079] Pulse trains with time-varying spatiotemporal characteristics have great advantages in light-matter interactions and multi-channel laser wireless communications. First, we simulated the pulse train formed by the spatiotemporal vortex with time-varying topological charge. The spatial-spectral representation of the sub-pulses of the pulse train is:

[0080]

[0081] in and They represent the polar diameter and polar angle in the polar coordinate system respectively, and atan() represents the inverse tangent function. represents the Laguerre polynomial with index p and l. l and w1 are the topological charge and beam waist width respectively. According to formula (1) and formula (2), we can design the transmittance function of the phase plate, which consists of four parts as follows: Figure 2 As shown in (a)-(d), the sub-pulse of the pulse train is set to p=0, there are N=6 space-time optical vortices with topological charge l ranging from -3 to +3, the time interval is set to 1ps, and the dispersion GDD=8000fs2. Figure 3is the temporal and spatial intensity distribution diagram and phase diagram of the pulse train. Figure 3 As shown in (a), the pulse train presents a space-time vortex distribution along the time dimension, with a time interval of about 1ps, and the ring size of the space-time vortex changes with time. Figure 3 (b) shows the phase distribution diagram of the space-time vortex train. It can be seen that with the change of time, its topological charge evolves from l=-3 to l=+3.

[0082] In the field of laser material processing, flat-top beams are widely used because of their more uniform spatial energy distribution. A spatiotemporal flat-top optical pulse train with time-varying energy and size has the unique advantage of softening laser energy and reducing the negative impact of thermal effects on materials. Therefore, we experimentally produced a spatiotemporal flat-top optical pulse train with time-varying energy and size. The sub-pulses of this pulse train are flat-top distributed in both time and space dimensions, and the mathematical expression of the spatiotemporal distribution of its sub-pulses is a multi-Gaussian function:

[0083]

[0084] in: represents the binomial coefficient, M is the order of the multi-Gaussian function, c n is the weight coefficient of the nth sub-pulse. We set it as M=S=25. Figure 4(a) is a three-dimensional space-time iso-intensity surface diagram of a flat-top light pulse train whose energy and size are fixed over time, where the iso-intensity value is 40%. We can see that each sub-pulse of the generated flat-top light pulse train is a flat-top light with uniform energy in both the spatial and temporal dimensions. Figure 4(c) is a space-time intensity diagram of the pulse train. Figures 4(d) and (e) are energy-varying flat-top light pulse trains, where the energy of (d) first increases and then decreases over time, and the energy of (e) first decreases and then increases over time. Figure 4(b) is a flat-top light pulse train whose spatial size varies with time, characterized in that as it evolves, the spatial width of its sub-flat-top pulses gradually decreases, but the energy is still evenly distributed in the time and space dimensions.

[0085] It can be seen that our method and system for generating ultrafast pulse trains with time-varying spatiotemporal characteristics can flexibly generate pulse trains with customized time-varying characteristics.

[0086] Example 4

[0087] For the parts not described in detail in this embodiment, please refer to the description of Embodiment 1. This embodiment provides an electronic device, including: a processor and a memory, wherein the memory stores a computer program that can be called by the processor;

[0088] The processor executes the above-mentioned method and system for generating an ultrafast pulse train with time-varying spatiotemporal characteristics by calling the computer program stored in the memory.

[0089] The electronic device may have relatively large differences due to different configurations or performances, and may include one or more processors (Central Processing Units, CPU) and one or more memories, wherein the memory stores at least one computer program, and the at least one computer program is loaded and executed by the processor to implement a method and system for generating an ultrafast pulse train with time-varying spatiotemporal characteristics provided by the above-mentioned various method embodiments. The electronic device may also include other components for realizing the functions of the device, for example, the electronic device may also have components such as a wired or wireless network interface and an input / output interface for input and output. The embodiments of the present application are not described in detail here.

[0090] It should be understood that determining B based on A does not mean determining B only based on A. B can also be determined based on A and / or other information.

[0091] A computer-readable storage medium is also provided, which stores instructions. When the instructions are executed on a computer, the computer executes a method and system for generating an ultrafast pulse train with time-varying spatiotemporal characteristics.

[0092] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for generating an ultrafast pulse train with time-varying spatiotemporal characteristics, It is characterized in that The following steps are involved: After the incident light pulse is reflected by the first grating and collimated by the first cylindrical lens, its spectral components are spread out along the space in the plane where the phase plate is located, realizing the time domain forward Fourier transform to form a two-dimensional space-spectral distribution; Phase plate modulation, using the phase plate to perform complex amplitude modulation on the two-dimensional space-spectrum distribution to obtain a space-spectrum; The modulated space-spectrum passes through the second lens and the second grating to achieve time domain inverse Fourier transform to obtain output pulses; the output pulses form ultrafast pulse trains with time-varying spatiotemporal characteristics after being transmitted a certain distance on the rear surface of the grating.

2. A method for generating an ultrafast pulse train with time-varying spatiotemporal characteristics according to claim 1, Features: The incident pulse is a single pulse output by a narrow linewidth ultrafast laser.

3. A method for generating an ultrafast pulse train with time-varying spatiotemporal characteristics according to claim 2, It is characterized in that The modulation function includes amplitude and phase information; the modulation function of the phase plate is adjusted to control the number of sub-pulses, time intervals and space-time shapes of the pulse train.

4. A method for generating an ultrafast pulse train with time-varying spatiotemporal characteristics according to claim 3, It is characterized in that The mathematical expression of the transmittance function of the phase plate is: The transmittance function consists of four parts, where the first term Arg[] represents the complex angle, the second term π is the phase compensation factor, asinc[] represents the inverse Singer function, and the third term represents the linear grating, g represents the linear grating frequency, and the fourth term GDD·Ω 2 represents group delay dispersion, and GDD represents the dispersion size.

5. A method for generating an ultrafast pulse train with time-varying spatiotemporal characteristics according to claim 4, It is characterized in that The free space transmission after the second lens and the second grating can realize the two-dimensional Fourier transform of time and space, and the space-time distribution of the pulse train is expressed as: where u n (x,tt n ) represents the spatiotemporal distribution of the nth sub-pulse of the generated pulse train, t n =1 / f n is the time position of the sub-pulse.

6. A method for generating an ultrafast pulse train with time-varying spatiotemporal characteristics according to claim 5, It is characterized in that The distance between each element in the 4f pulse shaper is the focal length f of the cylindrical lens.

7. A system for generating an ultrafast pulse train with time-varying spatiotemporal characteristics, based on the implementation of a method for generating an ultrafast pulse train with time-varying spatiotemporal characteristics as claimed in any one of claims 1 to 6, Features: A 4f pulse shaper is included, wherein the 4f pulse shaper includes two identical gratings, two identical cylindrical lenses and a phase plate; After the incident light pulse is reflected by the first grating and collimated by the first cylindrical lens, its spectral components are spread out along the space in the plane where the phase plate is located, realizing the time domain forward Fourier transform to form a two-dimensional space-spectral distribution; Phase plate modulation, using the phase plate to perform complex amplitude modulation on the two-dimensional space-spectrum distribution to obtain a space-spectrum; The modulated space-spectrum passes through the second lens and the second grating to achieve time domain inverse Fourier transform to obtain output pulses; the output pulses form ultrafast pulse trains with time-varying spatiotemporal characteristics after being transmitted a certain distance on the rear surface of the grating.

8. An electronic device, Features: include: A processor and a memory, wherein the memory stores a computer program that can be called by the processor; The processor executes the method and system for generating an ultrafast pulse train with time-varying spatiotemporal characteristics as described in any one of claims 1 to 6 by calling the computer program stored in the memory.

9. A computer-readable storage medium, Features: Instructions are stored, and when the instructions are executed on a computer, the computer is caused to execute a method and system for generating an ultrafast pulse train with time-varying spatiotemporal characteristics as described in any one of claims 1 to 6.

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