Ultrafast laser time-domain shaping and calibration device

Abstract

The application discloses an ultrafast laser time domain shaping and calibration device, and belongs to the field of ultrafast laser processing. The device comprises a time domain shaping module and a self-correlation calibration module. The time domain shaping module divides linearly polarized ultrafast laser into a fixed optical arm and a delay optical arm. The time delay of the double pulses is regulated through an optical delay line, and the laser parameters of the two optical arms are independently controlled to ensure that the polarization states of the double pulses are orthogonal to each other. The self-correlation calibration module is connected with the time domain shaping module through a coaxial optical path. A type II phase matching nonlinear crystal is used to convert the double pulses into a second harmonic (SHG) signal. The SHG signal intensity under different time sequences is collected through a scanning delay line to generate an intensity self-correlation curve. The delay zero point is calibrated, and the pulse width is calculated. The measured parameters are fed back to the time domain shaping module to correct the delay parameters. The application can be applied to an existing laser processing platform, provides the function of time domain shaping double pulse laser processing, effectively reduces the heat accumulation phenomenon, and improves the quality of ultrafast laser processing.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ultrafast laser processing, in particular to an ultrafast laser time-domain shaping and calibration device. BACKGROUND

[0002] Ultrafast laser has extremely short pulse width (picosecond to femtosecond level, i.e. 10 -12 s to 10 -15 s) and high instantaneous power, as an important basis for precision machining and pump ultrafast imaging technology, it has been widely used in mechanical, material, photoelectric and biomedical fields. In the field of ultrafast laser processing, through the time-domain shaping method of ultrafast laser, the electronic dynamics behavior and thermal relaxation process of the material can be controlled, thereby reducing the accumulation of processing debris, reducing the thermal effect and improving the quality of laser processing. As a kind of all-optical control laser technology, the typical implementation method of time-domain shaping of ultrafast laser is to obtain a double-pulse ultrafast laser sequence with picosecond time difference through a series of operations such as light splitting and time delay (similar to Michelson interferometer). However, due to factors such as light path adjustment error and relative position uncertainty of components, the time delay zero point of the time-domain shaping system is difficult to find, resulting in uncertainty of the time-domain parameters of the ultrafast laser. Therefore, how to accurately calibrate the time delay between the double pulses and the time-domain parameters such as laser pulse width is a key technical problem in this field.

[0003] In order to solve the problem of time non-overlapping of time-domain shaping ultrafast laser, it is generally necessary to pre-calibrate the zero point of the delay line to obtain an accurate double-pulse ultrafast laser sequence. Since the pulse width of ultrafast laser is in picosecond or even femtosecond level, and the response time of conventional photoelectric detector is in nanosecond level, the time sequence of ultrafast laser cannot be directly measured on an oscilloscope by using electrical signal method. Current ultrafast laser time-domain parameter measurement methods include intensity autocorrelation method, interference autocorrelation method, frequency-resolved optical gating (FROG), self-referenced spectral phase interferometry for direct electric-field reconstruction (SPIDER), real-time measurement method and system of transient ultra-short pulse time width (CN 110567595A) and the like. Although the FROG method can measure the complete information of ultrafast laser, it needs complex iterative algorithm for post-processing, and the operation speed is slow, and it cannot measure single pulse in real time. The SPIDER method and the "real-time measurement method of transient ultra-short pulse time width" cannot calibrate the zero point position of the delay line due to fixed optical path. In addition, the traditional intensity autocorrelation method has the problem of light path separation, and cannot be used for coaxial optical path, which brings inconvenience for subsequent laser processing; the interference autocorrelation method based on coaxial optical path has the problem of coupling of autocorrelation component and interference component, and cannot solve the unique pulse time-domain distribution.

[0004] Therefore, there is an urgent need for an ultrafast laser time delay measurement method of coaxial optical path system to measure and calibrate the time-domain shaping laser system. SUMMARY

[0005] In order to solve the problems of pulse width measurement and delay zero calibration of time domain shaping ultrafast laser, the application provides an ultrafast laser time domain shaping and calibration device, which has two core functions of ultrafast laser double pulse generation and intensity autocorrelation calibration based on coaxial optical path. By inserting attenuation pieces, dispersion elements, wave plates or nonlinear crystals and other elements on the optical arm, the energy, pulse width, polarization and wavelength of the double pulse sequence can be independently regulated, and the all-optical regulated ultrafast laser precision machining can be realized.

[0006] In order to achieve the above purpose, the technical scheme adopted by the application is as follows:

[0007] In the first aspect, the application provides an ultrafast laser time domain shaping and calibration device, which comprises:

[0008] The time domain shaping module is used for splitting the linearly polarized ultrafast laser into a fixed optical arm and a delay optical arm, and independently controlling the laser parameters of the two optical arms by regulating the time delay of the double pulse through an optical delay line, wherein the polarization states of the laser pulses of the two optical arms are orthogonal to each other.

[0009] The autocorrelation calibration module is directly connected with the optical output end of the time domain shaping module through a coaxial optical path, and receives the double pulse sequence generated by the time domain shaping module.

[0010] The autocorrelation calibration module comprises a type II phase-matched nonlinear crystal, which is used for converting the received double pulse into a second harmonic (SHG) signal; by scanning the optical delay line in the time domain shaping module to change the time delay of the double pulse, the SHG signal intensity under different time sequences is collected; based on the collected SHG signal intensity distribution, an intensity autocorrelation curve is generated, the delay zero is calibrated and the pulse width is calculated.

[0011] The output end of the time domain shaping module is coupled to a laser processing platform and the autocorrelation calibration module respectively, forming a calibration feedback mechanism, and the parameters measured by the autocorrelation calibration module are fed back to the time domain shaping module for correcting the delay parameters.

[0012] Preferably, the time domain shaping module comprises:

[0013] The first beam splitting prism is used for splitting the incident ultrafast laser into a first laser pulse and a second laser pulse, which enter the fixed optical arm and the delay optical arm respectively.

[0014] The fixed optical arm receives the first laser pulse from the first beam splitting prism, and is used for guiding the propagation direction of the first laser pulse and regulating the polarization state of the first laser pulse.

[0015] Delay arm: receiving the second laser pulse from the first beam splitter prism, for guiding the propagation direction of the second laser pulse and regulating the second laser pulse polarization state and the double-pulse time delay;

[0016] Second beam splitter prism: for combining the two laser pulses returned from the fixed arm and the delay arm respectively, outputting coaxial ultrafast laser double-pulse sequence, and guiding to the self-correlation calibration module and the laser processing platform respectively.

[0017] Preferably, the optical path of the fixed arm includes in sequence a first mirror pair, a first half-wave plate and a first mirror, the first mirror pair as the entrance of the optical path, receiving the first laser pulse after beam splitting from the first beam splitter prism and guiding the optical path; the first half-wave plate regulates the polarization state of the first laser pulse to form P polarization state; the first mirror guides the first laser pulse after polarization regulation to the beam combination interface of the second beam splitter prism.

[0018] Preferably, the optical path of the delay arm includes in sequence a second mirror, a second mirror pair, an optical delay line and a second half-wave plate, the second mirror as the entrance of the optical path, receiving the second laser pulse after beam splitting from the first beam splitter prism and guiding the optical path; the second mirror pair is installed on the optical delay line, changing the optical path of the second laser pulse by linear displacement, thereby changing the double-pulse time delay, and the second half-wave plate is located between the optical delay line and the beam combination interface of the second beam splitter prism, regulating the polarization state of the second laser pulse to form S polarization state orthogonal to the first laser pulse.

[0019] Preferably, the optical delay line is a single-axis linear motorized stage, and the double-pulse time delay is regulated by controlling the displacement of the stage.

[0020] Preferably, the self-correlation calibration module further includes a low-pass filter, a convex lens and a detector, the low-pass filter is used to filter the residual fundamental frequency light and retain the frequency-doubled SHG signal; the convex lens is used to focus the SHG signal to the photosensitive surface of the detector, and the SHG signal intensity is collected by the detector.

[0021] Preferably, the calibration delay zero point and the calculation of pulse width include:

[0022] Scanning the intensity self-correlation curve, identifying the peak point position x0 of the curve as the delay zero point;

[0023] According to the formula Δt=(2x / c)-x0, the displacement coordinate x of the optical delay line is converted into the double-pulse time delay Δt, wherein c is the speed of light;

[0024] According to the proportional relationship between the pulse width and the half-width of the intensity self-correlation curve, the actual laser pulse width is calculated.

[0025] Preferably, the optical breadboard, the time-domain shaping module and the autocorrelation calibration module are integrated on the optical breadboard to form an integrated structure.

[0026] Preferably, the type II phase-matched nonlinear crystal is a BBO, KTP or LBO crystal, and the incidence angle θ and the azimuth angle φ of the nonlinear crystal are adjustable to meet the phase-matching condition.

[0027] In a second aspect, the present application provides a time-domain shaping ultrafast laser system, comprising:

[0028] An ultrafast laser for generating linearly polarized and pulse-width adjustable ultrafast laser;

[0029] An ultrafast laser time-domain shaping and calibration device having an input end receiving laser output by the ultrafast laser;

[0030] A laser processing platform coupled to an output end of the ultrafast laser time-domain shaping and calibration device for receiving time-domain shaped laser for processing.

[0031] The present application has the beneficial effects of:

[0032] The present application provides an ultrafast laser time-domain shaping and calibration device suitable for a time-domain shaping ultrafast laser system, mainly comprising a time-domain shaping module and an autocorrelation calibration module, which respectively realize the generation of ultrafast laser double pulse sequence and the calibration of time-domain parameters. By using type II phase matching principle, intensity autocorrelation measurement can be realized in a coaxial optical system, solving the problem of spatial separation of traditional autocorrelation optical path and improving its compatibility. The device can be applied to an existing laser processing platform to provide time-domain shaping double pulse laser processing function, which can effectively reduce heat accumulation phenomenon and improve the processing quality of ultrafast laser processing. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a schematic diagram of a time-domain shaping ultrafast laser system based on the ultrafast laser time-domain shaping and calibration device of the present application;

[0034] Figure 2 is a schematic diagram of an ultrafast laser time-domain shaping and calibration optical path principle;

[0035] Figure 3 is a coaxial SHG autocorrelation measurement principle based on type II phase matching;

[0036] Figure 4 is a physical assembly diagram of an integrated ultrafast laser time-domain shaping and calibration device;

[0037] Figure 5are the SHG signal measurement results at different time delays, wherein (a) is a two-dimensional trace graph of FROG, (b) is an intensity autocorrelation graph at a wavelength of λ = 520.85 nm;

[0038] In the figure: 001-first broadband spectrometer prism, 002-second broadband spectrometer prism, 003-autocorrelation calibration module, 004-optical breadboard, 101-first mirror pair, 102-first half-wave plate, 103-first mirror, 201-second mirror, 202-second mirror pair, 203-optical delay line, 204-second half-wave plate, 301-third mirror, 302-nonlinear crystal, 303-low-pass filter, 304-convex lens, 305-detector, 306-residual near-infrared light, 307-green light, 308-two-dimensional fine adjustment mirror frame, 309-single-axis sliding table, 310-multimode optical fiber. DETAILED DESCRIPTION

[0039] In order for those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application or the claims of the present application, all other embodiments obtained by those of ordinary skill in the art without any creative work should fall within the protection scope of the present application.

[0040] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present application should be understood as the common meanings understood by those of ordinary skill in the art to which the present application belongs. The terms "first", "second" and similar terms used in the present application do not represent any order, number or importance, but are only used to distinguish different components.

[0041] As Figure 1As shown, the ultrafast laser time domain shaping and calibration device provided by the application includes a time domain shaping module and a self-correlation calibration module, which are installed between an ultrafast laser and a laser processing platform, and can realize an ultrafast laser time domain shaping system. The ultrafast laser is used to provide an ultrafast laser light source, can realize control of laser power, wavelength, repetition frequency and pulse width, and outputs linearly polarized ultrafast laser. Generally, the linearly polarized ultrafast laser is first subjected to pretreatment operations such as beam expansion, collimation and filtering, and then enters the time domain shaping module. The time domain shaping module can split the linearly polarized ultrafast laser into a fixed light arm and a delay light arm, adjust the time delay Δt of the double-pulse sequence through an optical delay line, and independently control the laser parameters of the two light arms to generate an ultrafast laser double-pulse sequence, and has two output ports, one of which is output to the self-correlation calibration module, and the other of which is output to the laser processing platform. The self-correlation calibration module can not only calibrate the time delay zero position of the double-pulse sequence, but also measure the pulse width of the ultrafast laser. Hereinafter, the time shaping module and the self-correlation calibration module will be described in detail, and the specific optical path design is shown in Figure 2

[0042] The time domain shaping module includes a first light splitting prism 001, a second light splitting prism 002, a fixed light arm and a delay light arm. The first light splitting prism 001 is used to split the incident ultrafast laser into a first laser pulse and a second laser pulse, which enter the fixed light arm and the delay light arm, respectively. The fixed light arm receives the first laser pulse, and the optical path thereof includes a first mirror pair 101, a first half-wave plate 102 and a first mirror 103 in sequence. The first mirror pair 101 serves as an optical path entrance for guiding the optical path; the first half-wave plate 102 adjusts the polarization state of the first laser pulse to form a P-polarization state; and the first mirror 103 guides the adjusted pulse to a beam combination interface of the second light splitting prism 002. The delay light arm is used to receive the second laser pulse, and the optical path thereof includes a second mirror 201, a second mirror pair 202, an optical delay line 203 and a second half-wave plate 204 in sequence. The second mirror 201 serves as an optical path entrance for guiding the optical path; the second mirror pair 202 is installed on the optical delay line 203 and adjusts the time delay by changing the optical path through linear displacement; and the second half-wave plate 204 adjusts the polarization state of the second laser pulse to form an S-polarization state, which is orthogonal to the P-polarization state of the fixed light arm. The second light splitting prism 002 is used to combine the two laser pulses returned from the fixed light arm and the delay light arm, output a coaxial double-pulse sequence, and guide the double-pulse sequence to the self-correlation calibration module and the laser processing platform, respectively.

[0043] ​Specifically, the linearly polarized ultrafast laser is input to the time-domain shaping module from port 1 after being expanded, collimated and filtered. In the time-domain shaping module, the linearly polarized ultrafast laser is first split into two beams by a first beam splitter prism: the first laser pulse passes through a fixed first mirror pair 101, the polarization direction is adjusted by a first half-wave plate 102, and then the first laser pulse is coupled to a second beam splitter prism 002 through a first mirror 103, which is referred to as a fixed arm. The second laser pulse first passes through a second mirror 201, and then passes through a second mirror pair 202 installed on an optical delay line to guide the light beam, and then the polarization direction is adjusted by a second half-wave plate 204, and finally the second laser pulse is coupled to the second beam splitter prism 002, which is referred to as a delay arm. The two beams converged at the second beam splitter prism form a double-pulse sequence, and the ultrafast laser double-pulse sequence is output to the autocorrelation calibration module and the laser processing platform at two output ports of port 3 and port 2. Here, the second beam splitter prism 002 can be a polarization beam splitter prism to control the energy ratio of the laser at port 2 and port 3, or even to realize single-end output at only port 2 or port 3, so as to increase the utilization rate of laser energy.

[0044] In the time-domain shaping module, by adding a half-wave plate in the fixed arm and the delay arm respectively, the polarization states of the two beams can be independently controlled to meet the subsequent autocorrelation measurement.

[0045] In a specific embodiment of the present application, the optical delay line can use a single-axis linear slide. By adjusting the position of the delay line, the relative distance difference between the fixed arm and the delay arm can be changed, so as to control the time delay Δt, which is represented by the following formula:

[0046]

[0047] In the formula, Δt is the time delay of the double pulse, ΔL is the displacement of the delay line, and c is the speed of light. In this embodiment, the stroke of the delay line is ΔL = 100 mm, and the maximum delay of the double pulse is Δt = 2ΔL / c = 0.667 ns.

[0048] In addition, in the fixed arm and the delay arm, attenuation pieces, wave plates, dispersive elements or nonlinear crystals can be added to realize independent control of the energy, polarization, pulse width and wavelength of the two laser beams. It is worth noting that symmetric optical elements are preferably added to the fixed arm and the delay arm at the same time to avoid affecting the delay zero point. In order to ensure the accuracy of the double pulse delay parameters, after symmetric optical elements are added to the fixed arm and the delay arm at the same time, recalibration operation is also needed.

[0049] The double pulse sequence generated by the time domain shaping module is further input to the autocorrelation calibration module, in which the delay zero point between the double pulses is calibrated and the laser pulse width is measured based on the principle of intensity autocorrelation of second harmonic (SHG). In the embodiment, the double pulse sequence generated by the time domain shaping module enters the autocorrelation calibration module 003 after the third mirror 301.

[0050] The autocorrelation calibration module is a coaxial optical system, including a type II phase-matched nonlinear crystal 302, a low-pass filter 303, a convex lens 304 and a detector 305. The type II phase-matched nonlinear crystal (optional crystal materials such as BBO, KTP and LBO, etc.) is used to convert the double pulse into an SHG signal, and by adjusting the incident angle θ and the azimuth angle φ of the crystal, the phase matching condition is met to avoid interference effect; the low-pass filter 303 is used to filter the residual fundamental frequency light and retain the SHG signal of frequency multiplication; the convex lens 304 is used to focus the SHG signal to the detector; the detector 305 can be a photodiode detector or a fiber spectrometer, which is used to collect the SHG signal intensity.

[0051] It should be noted that the type II phase matching is to use the fundamental frequency laser of ordinary light (o light) and extraordinary light (e light) to generate the frequency multiplication of e light. In type II phase matching, since the polarization states of the two coaxial laser pulses are orthogonal to each other, they will not appear interference phenomenon. On the contrary, if the polarization states of the two laser pulses are parallel to each other, interference phenomenon will occur and interference autocorrelation result will be obtained. The interference autocorrelation is relatively complex and not intuitive for laser pulse width measurement, which brings inconvenience in practical application.

[0052] Given the laser wavelength, the nonlinear crystal phase matching angle can be determined according to the phase matching condition Δk = 0.

[0053] Then:

[0054]

[0055] In the formula, k e (2ω) is the frequency multiplication wave vector, k e (ω) is the original frequency e light wave vector, k o(ω) is the wave vector of the original frequency o. The type II phase matching angle can be obtained using the graphical method of the refractive index ellipsoid, thus allowing for the customization of the nonlinear crystal. However, due to crystal processing errors or deviations in laser wavelength, the nonlinear crystal often cannot precisely achieve the aforementioned phase matching condition when incident perpendicularly. Therefore, it is usually necessary to adjust the angles in two directions of the nonlinear crystal to satisfy the type II SHG phase matching. Firstly, the incident angle θ is adjusted to compensate for the phase matching angle; secondly, the azimuth angle φ of the optical axis is adjusted to make the optical axis parallel or perpendicular to the laser polarization.

[0056] Based on the principle of intensity autocorrelation, scanning the extension line can acquire the time-domain curve of SHG intensity autocorrelation, where the position x0 of the peak point is the desired zero-delay point.

[0057] Furthermore, by subtracting the bias of x0, the displacement coordinate x of the delay line can be converted into the delay amount Δt, which is expressed by the following formula:

[0058]

[0059] Thus, the intensity autocorrelation plot as a function of time Δt is obtained.

[0060] Full width at half maximum (FWHM) of the autocorrelation function FWHM The pulse width τ of the original time-domain function is not equal to that of the pulse pulse in the original time-domain function, but rather there is a proportional relationship between them. For example, for a Gaussian distributed laser pulse, its time-domain pulse width is τ = τ FWHM / 1.414; for sech 2 The laser pulse has a time-domain pulse width of τ = τ FWHM / 1.543. Ideal ultrafast lasers are typically sech... 2 Given the time-domain distribution, a scaling factor of 1.543 is chosen, i.e., τ = τ FWHM / 1.543.

[0061] Based on the above steps, the intensity autocorrelation curve can be obtained, and the offset zero point x0 of the delay and the pulse width τ of the super-optical laser can be obtained, thus completing the calibration of the time-domain shaping module.

[0062] The output of the aforementioned time-domain shaping module is coupled to both the laser processing platform and the autocorrelation calibration module, forming a calibration feedback mechanism. The delay zero point x0 and pulse width τ measured by the autocorrelation calibration module are fed back to the time-domain shaping module to correct the delay parameters and ensure system accuracy.

[0063] In fact, the time-shaping module and autocorrelation calibration module of this invention can be integrated onto an optical breadboard 004, such as... Figure 4 As shown, with Figure 2 The positions correspond to those shown in the optical path schematic diagram.

[0064] The working process of the above device is as follows:

[0065] First, the polarization states of the two laser pulses are adjusted to make them perpendicular to each other. For example, the first half-wave plate 102 is adjusted to make the first laser pulse P-polarized; the second half-wave plate 204 is adjusted to make the second laser pulse S-polarized, and they are coupled to the same optical axis through the second beam splitter 002 to form a double pulse. Here, the nonlinear crystal in the correlation calibration module is preferably a BBO crystal, and the fundamental laser wavelength is known to be 1040 nm, thus the type II phase matching angle of the BBO crystal is calculated to be 32.4°. Due to crystal processing errors and laser wavelength deviations, the phase matching angle needs to be adjusted according to the actual situation. For example, by adjusting the incident angle θ and azimuth angle φ of the nonlinear crystal to maximize the SHG light intensity, the actual phase matching conditions can be met, such as... Figure 3 As shown.

[0066] Next, a dual-pulse incident on the nonlinear crystal 302 is used, and the near-infrared fundamental frequency light is converted into frequency-doubled green light, generating an SHG signal, with some residual near-infrared light. Figure 3 In the diagram, the solid line represents residual near-infrared light 306, while the dashed line represents frequency-doubled green light 307. For clarity, the solid and dashed lines are displayed offset. After passing through a low-pass filter, the residual near-infrared light 306 is absorbed, leaving only the frequency-doubled green light 307. The light is then focused by a convex lens and sampled by detector 305. By changing the double-pulse time delay Δt using the optical delay line in the scanning time-domain shaping module, the SHG signal intensity at different time intervals can be acquired, and the intensity autocorrelation plot can be measured. Alternatively, a spectrometer can be selected as the detector.

[0067] In this embodiment, a fiber optic spectrometer is used as the detector, such as... Figure 4 As shown, the near-infrared laser light, after passing through a nonlinear crystal, is frequency-doubled and focused onto a fiber optic coupler. This coupler is mounted on a three-dimensional adjustable mechanism composed of a two-dimensional fine-tuning mirror mount 308 and a single-axis slide 309, used for adjusting the focal position. The optical signal finally enters the spectrometer 305 via a multimode fiber 310. By scanning the delay line 203, a two-dimensional FROG trajectory map is acquired, as shown below. Figure 5 As shown in (a) of the diagram. Taking the one-dimensional intensity data of the SHG signal with a center wavelength λ = 520.85 nm, an intensity autocorrelation diagram can be obtained. The peak point coordinate x0 of the intensity autocorrelation diagram is the position where the first and second laser pulse times coincide, i.e., the zero-delay point x0. From equation (3), the distance parameter of the x-axis can be converted into a time parameter, thus obtaining the FROG two-dimensional trajectory diagram and intensity autocorrelation diagram with the delay amount Δt as the x-axis, as shown in equation (3). Figure 5 As shown in (b) of the diagram.

[0068] If a photodiode is used as a detector, the intensity autocorrelation map can be obtained directly.

[0069] In this embodiment, the ultrafast laser's pulse width can be varied, with an adjustable range of 300-4300 fs. To test the feasibility of autocorrelation calibration, several sets of different pulse width parameters were tested, and the results are shown in Table 1 below:

[0070] Table 1 Pulse width test results

[0071]

[0072] The data in Table 1 confirms that the present invention can accurately measure the pulse width of ultrafast lasers and the time zero point of a double-pulse laser sequence, with a relative error of better than 3% in pulse width measurement. Since pulse width adjustment changes the time-domain waveform of the laser, causing the time origin to drift, the time delay zero point of the double pulse will also drift. Therefore, the present invention is particularly suitable for ultrafast laser systems with adjustable pulse width.

[0073] The above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. An ultrafast laser time-domain shaping and calibration device, characterized in that, include: Time-domain shaping module: used to split linearly polarized ultrafast laser beams into fixed optical arms and delayed optical arms, adjust the time delay of the dual pulses through optical delay lines, and independently control the laser parameters of the two optical arms, wherein the polarization states of the laser pulses of the two optical arms are orthogonal to each other; Autocorrelation calibration module: directly connected to the optical output of the time-domain shaping module via a coaxial optical path, and receives the double pulse sequence generated by the time-domain shaping module; The autocorrelation calibration module includes a type II phase-matched nonlinear crystal (302) for converting the received double pulses into SHG signals; the time delay of the double pulses is changed by scanning the optical delay line in the time-domain shaping module to acquire the SHG signal intensity under different timings. An intensity autocorrelation curve is generated based on the intensity distribution of the acquired SHG signal, the zero-delay point is calibrated, and the pulse width is calculated. The output of the time-domain shaping module is coupled to the laser processing platform and the autocorrelation calibration module to form a calibration feedback mechanism. The parameters measured by the autocorrelation calibration module are fed back to the time-domain shaping module to correct the delay parameters.

2. The ultrafast laser time-domain shaping and calibration device according to claim 1, characterized in that, The time-domain shaping module includes: First beam splitter (001): used to split the incident ultrafast laser beam into a first laser pulse and a second laser pulse, which enter the fixed optical arm and the delayed optical arm respectively; Fixed optical arm: Receives the first laser pulse from the first beam splitter (001) and is used to guide the propagation direction of the first laser pulse and regulate the polarization state of the first laser pulse; Delayed optical arm: Receives the second laser pulse from the first beam splitter (001), and is used to guide the propagation direction of the second laser pulse and adjust the polarization state and the amount of time delay of the double pulse; The second beam splitter (002) is used to combine two laser pulses returning from the fixed optical arm and the delayed optical arm respectively, outputting a coaxial ultrafast laser double pulse sequence, which is then directed to the autocorrelation calibration module and the laser processing platform respectively.

3. The ultrafast laser time-domain shaping and calibration device according to claim 1, characterized in that, The optical path of the fixed optical arm includes a first pair of mirrors (101), a first half-wave plate (102), and a first mirror (103). The first pair of mirrors (101) serves as the optical path entrance, receiving the first laser pulse after it is split from the first beam splitter (001) and guiding the optical path. The first half-wave plate (102) modulates the polarization state of the first laser pulse to form a P-polarization state. The first mirror (103) guides the polarization-modulated first laser pulse to the beam combining interface of the second beam splitter (002).

4. The ultrafast laser time-domain shaping and calibration device according to claim 1, characterized in that, The optical path of the delay arm includes a second mirror (201), a pair of second mirrors (202), an optical delay line (203), and a second half-wave plate (204) in sequence. The second mirror (201) serves as the optical path entrance, receiving the second laser pulse after it is split from the first beam splitter (001) and guiding the optical path. The second mirror pair (202) is mounted on the optical delay line (203) and changes the optical path length of the second laser pulse by linear displacement, thereby changing the time delay of the double pulse. The second half-wave plate (204) is located between the optical delay line (203) and the beam combining interface of the second beam splitter (002) and modulates the polarization state of the second laser pulse to form an S-polarization state orthogonal to the first laser pulse.

5. The ultrafast laser time-domain shaping and calibration device according to claim 4, characterized in that, The optical delay line (203) is a single-axis linear electric slide, and the time delay of the double pulse is adjusted by controlling the displacement of the slide.

6. The ultrafast laser time-domain shaping and calibration device according to claim 1, characterized in that, The autocorrelation calibration module also includes a low-pass filter (303), a convex lens (304), and a detector (305). The low-pass filter (303) is used to filter out residual fundamental frequency light and retain the SHG signal of the harmonics. The convex lens (304) is used to focus the SHG signal onto the photosensitive surface of the detector (305) and the detector (305) collects the SHG signal intensity.

7. The ultrafast laser time-domain shaping and calibration device according to claim 1, characterized in that, The calibration of the zero-delay point and calculation of the pulse width include: Scan the intensity autocorrelation curve and identify the peak point position x0 of the curve as the zero delay point; According to the formula The optical delay line displacement coordinate x is converted into a double pulse time delay Δt, where c is the speed of light; The actual laser pulse width is calculated based on the proportional relationship between the pulse width and the full width at half maximum (FWHM) of the autocorrelation curve of intensity.

8. The ultrafast laser time-domain shaping and calibration device according to claim 1, characterized in that, It also includes an optical breadboard, a time-domain shaping module, and an autocorrelation calibration module, all integrated on the optical breadboard to form a unified structure.

9. The ultrafast laser time-domain shaping and calibration device according to claim 1, characterized in that, The type II phase-matching nonlinear crystal is a BBO, KTP, or LBO crystal. The incident angle θ and azimuth angle φ of the nonlinear crystal are adjustable to meet the phase-matching conditions.

10. A time-domain shaping ultrafast laser system, characterized in that, include: Ultrafast lasers are used to generate linearly polarized and pulse-width-tunable ultrafast lasers. The ultrafast laser time-domain shaping and calibration apparatus as described in any one of claims 1 to 9 has its input terminal receiving the laser output from the ultrafast laser; The laser processing platform is coupled to the output of the ultrafast laser time-domain shaping and calibration device, and is used to receive the time-domain shaped laser for processing.

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