A high-power pulse width and repetition frequency tunable laser

Abstract

This application relates to the field of laser technology. This application provides a high-power pulse width and repetition rate tunable laser, including: an input / output optical path configured to input seed light and output amplified laser light; a regenerative amplifier optical path configured to amplify the input seed light; a pulse width compression module configured to compress the pulse width of the amplified seed light and output high-power pulsed laser with tunable pulse width. The pulse width compression module includes: a third polarization beam splitter, a third half-wave plate, a first electrically controlled laterally moving plane mirror, a second electrically controlled laterally moving plane mirror, a nonlinear crystal, and a fourth plane mirror. Based on the multi-pass compression method of the nonlinear crystal, the present invention constructs a high-power disk laser, which contains a nonlinear crystal and a half-wave plate or a ring cavity with a Pockels cell for pulse width compression, and finally obtains a high-power pulse width and repetition rate tunable pulse train through the electrically controlled laterally moving plane mirror.

Description

Technical Field

[0001] This application relates to the field of laser technology. Specifically, it relates to a high-power pulse width and repetition frequency tunable laser. Background Art

[0002] The innovation moment of high-power ultrashort laser technology promotes the development and expansion of application fields such as high-energy physics, fusion energy, precision measurement, fine micromachining, and biomedicine. The size of the laser pulse width directly affects the energy density and peak power of the laser pulse, and thus affects the effect of the interaction between the laser and matter. Existing laser pulse width compression generally uses a grating pair compressor. The working principle of the grating pair compressor is that a positively chirped pulse experiences different optical paths for different spectral components when passing through parallel gratings. The optical path experienced by the long wavelength is greater than that of the short wavelength, and negative dispersion conjugate to the stretcher is introduced to compensate for the positive chirp to achieve pulse compression. However, it is difficult to solve the technical problems of high-power laser pulse compression. Summary of the Invention

[0003] Some embodiments of this application provide a high-power pulse width and repetition frequency tunable laser, including:

[0004] An input / output optical path configured to input seed light and output amplified laser. The input / output optical path includes: a seed light source, a first plane mirror, a first half-wave plate, a first polarization beam splitter, a Faraday rotator, and a second half-wave plate;

[0005] A regenerative amplifier optical path configured to amplify the input seed light. The regenerative amplifier optical path includes: a second polarization beam splitter, a first Pockels cell, a quarter-wave plate, a second plane mirror, a concave mirror, a spherical mirror, a third plane mirror, and a disk module;

[0006] A pulse width compression module configured to compress the pulse width of the amplified seed light and output high-power pulsed laser with tunable pulse width. The pulse width compression module includes: a third polarization beam splitter, a third half-wave plate, a first electrically controlled laterally moving plane mirror, a second electrically controlled laterally moving plane mirror, a nonlinear crystal 17, and a fourth plane mirror;

[0007] Wherein, the seed light source outputs broadened ns-level s-polarized seed light. The seed light becomes p-polarized seed light via the first plane mirror and the first half-wave plate. Then, it passes through the first polarization beam splitter, the Faraday rotator, and the second half-wave plate and enters the regenerative amplifier optical path;

[0008] The seed light entering the optical path of the regenerative amplifier passes through the first Pockels cell, a quarter-wave plate, a second plane mirror, a concave mirror, and after being reflected by the concave mirror, returns along the original path and passes through the second plane mirror, the quarter-wave plate, the first Pockels cell, a second polarization beam splitter, a spherical mirror, and a third plane mirror in sequence and then reaches the disk module. After being amplified by the disk module, it returns along the original path and undergoes amplification by traveling back and forth in the resonant cavity. The amplified seed light is output from the first polarization beam splitter to the first Pockels cell of the pulse width compression module;

[0009] The laser is cyclically compressed within the pulse width compression module. By rotating the angle of the third half-wave plate, the polarization direction of the linearly polarized light can be rotated, and the amount of compression is controlled by controlling the dispersion amount of the nonlinear crystal. The pulse width can be compressed once every round, thereby outputting a pulse train with tunable pulse width.

[0010] In some embodiments, the pulse width compression module further includes: a second Pockels cell, disposed between the third polarization beam splitter and the second half-wave plate.

[0011] In some embodiments, the repetition frequency of the pulse train is adjusted by adjusting the first electrically controlled laterally moving plane mirror and the second electrically controlled laterally moving plane mirror.

[0012] In some embodiments, the optical path of the regenerative amplifier further includes:

[0013] A pump source, configured to output pump light to pump the disk module 21.

[0014] In some embodiments, the disk module includes at least one of the following: Yb:YAG, Yb:KGW, Yb:CALGO, Yb:LuScO3, Ho:YAG, Ho:KYW, Tm:YAG, Tm:KYW, Cr:ZnSe, and Tm:LLF.

[0015] In some embodiments, it further includes:

[0016] A control module, by adjusting the falling-edge voltage of the second Pockels cell, while the pulse width of the pulse train gradually decreases, the polarization state is changed, thereby outputting a high-power pulse train with tunable pulse width.

[0017] In some embodiments, the pulse width of the pulse train is a ps-level pulse.

[0018] In some embodiments, the minimum diameter of the light spot in the amplification optical path of the disk regenerative amplifier cavity is 2 mm - 2.1 mm.

[0019] The above solution of the embodiment of the present application has at least the following beneficial effects compared with the related art:

[0020] The present invention proposes a novel laser with adjustable output pulse width and repetition frequency, and can realize pulsed train laser output. Based on the multi-pass compression method of nonlinear crystals, a high-power disk laser is built, which contains a nonlinear crystal and a half-wave plate or a ring cavity with a Pockels cell for pulse width compression, and finally a high-power tunable pulsed train is obtained. Description of the Drawings

[0021] The drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts. In the drawings:

[0022] Figure 1 is a schematic structural diagram of a laser provided by some embodiments of the present application;

[0023] Figure 2 is a schematic structural diagram of a pulse width compression module provided by some other embodiments of the present application;

[0024] Figure 3 is a schematic structural diagram of a pulse width compression module provided by some other embodiments of the present application;

[0025] Figure 4 is a schematic diagram of the control process of a pulse width compression module provided by some other embodiments of the present application.

[0026] Description of the Reference Numerals:

[0027] Seed light source 14, first plane mirror 13, first half-wave plate 12, first polarization beam splitter 11, Faraday rotator 10, second half-wave plate 9, second polarization beam splitter 7, first Pockels cell 2, quarter-wave plate 3, second plane mirror 4, concave mirror 5, spherical mirror 8, third plane mirror 6, disk module 21, third polarization beam splitter 15, third half-wave plate 22, first electrically controlled laterally moving plane mirror 19, second electrically controlled laterally moving plane mirror 18, nonlinear crystal 17, fourth plane mirror 16, second Pockels cell 20, pump source 1. Detailed Embodiments

[0028] In order to make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0029] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms unless the context clearly dictates otherwise. "Plural" generally includes at least two.

[0030] It should be understood that the term "and / or" used herein is merely a description of the relationship between associated objects, indicating that three relationships may exist. For example, A and / or B may represent: the sole existence of A, the simultaneous existence of A and B, and the sole existence of B. Additionally, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0031] It should be understood that although terms such as first, second, third, etc. may be used in the embodiments of the present application, these should not be limited to these terms. These terms are only used for distinction. For example, without departing from the scope of the embodiments of the present application, the first may also be referred to as the second, and similarly, the second may also be referred to as the first.

[0032] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a commodity or device comprising a series of elements not only includes those elements but also includes other elements not explicitly listed, or further includes elements inherent to such commodity or device. Without further limitation, an element defined by the statement "comprising one" does not exclude the existence of additional identical elements in the commodity or device comprising said element.

[0033] The magnitude of the laser pulse width directly affects the energy density and peak power of the laser pulse, and thus affects the effect of the interaction between the laser and the substance. The chirped pulse amplification technique (CPA) can be applied to an ultrashort pulse laser. First, the ultrashort optical pulse is broadened in the time domain, then amplified to high energy, and finally the pulse width is compressed back. This method effectively reduces the peak power of the pulse in the amplifier and gets rid of the limitation of the nonlinear effect. Ultrashort pulses with high peak power can be obtained from such a laser system.

[0034] The present invention adopts a multi-pass compression method for non-linear crystals to solve the problem of high-power laser pulse width compression. By using the non-linear crystal in the ring cavity, different spectral components experience different optical paths, with the optical path experienced by the long wavelength being greater than that of the short wavelength. A negative dispersion conjugate to the stretcher is introduced to compensate for the positive chirp to achieve pulse compression. At the same time, the half-wave plate and / or Pockels cell in the ring cavity modulate the light beam through the electro-optic effect, and can block the transmission of the light beam under specific conditions to achieve the fast switch or Q-switch function of the light beam, thereby realizing the generation of high-energy pulses or the precise control of optical signals in the laser system. By adjusting the electrical pulse width and delay of the Pockels cell, controlling the number of circulations of the light in the ring cavity and thus the number of turns through the ring cavity, the output pulse width can be changed. Since different numbers of turns can result in different amounts of dispersion, by adjusting the falling-edge voltage of the Pockels cell, the laser pulse width gradually narrows, and by changing the polarization state, a high-power pulsed laser with tunable pulse width can be output. Or directly add a half-wave plate and output pulsed train laser by rotating the angle.

[0035] The following will describe the present application in detail with reference to the accompanying drawings.

[0036] As Figure 1 shown, the present application provides a high-power pulse width and repetition frequency tunable disk laser, including an input / output optical path, a regenerative amplifier optical path, and a pulse width compression module. The input / output optical path is configured to input seed light and output amplified laser. The input / output optical path includes: a seed light source 14, a first plane mirror 13, a first half-wave plate 12, a first polarization beam splitter 11, a Faraday rotator 10, and a second half-wave plate 9.

[0037] The regenerative amplifier optical path is configured to amplify the input seed light. The regenerative amplifier optical path includes: a second polarization beam splitter 7, a first Pockels cell 2, a quarter-wave plate 3, a second plane mirror 4, a concave mirror 5, a spherical mirror 8, a third plane mirror 6, and a disk module 21.

[0038] The pulse width compression module is configured to compress the pulse width of the amplified seed light and output a high-power pulsed laser with tunable pulse width. The pulse width compression module includes: a third polarization beam splitter 15, a third half-wave plate 22, a first electrically controlled laterally moving plane mirror 19, a second electrically controlled laterally moving plane mirror 18, a non-linear crystal 17, and a fourth plane mirror 16.

[0039] Among them, the seed light source outputs broadened ns-level s-polarized state seed light. The seed light becomes p-polarized state seed light after passing through the first plane mirror 13 and the first half-wave plate 12, and then enters the regenerative amplifier optical path through the first polarization beam splitter 11, the Faraday rotator 10, and the second half-wave plate 9. The seed source is a ps-level pulsed laser generated by a fiber mode-locked oscillator. After passing through a fiber stretcher, the laser pulse width is broadened to the ns level, and the broadened s-polarized state seed light that is well matched with the amplifier cavity is output and injected into the regenerative amplification optical path constructed by the disk module. Among them, the Faraday rotator 10 uses the non-reciprocal property of the magneto-optical material to change the phase of the incident laser, and together with the second half-wave plate 9, can effectively prevent the backward light generated by reflection or backscattering in the optical path from having an adverse effect on the light source.

[0040] In some embodiments, the seed light source 14 can be a fiber laser. The laser emitted by the fiber laser is the seed light to be amplified. The picosecond light generated by the fiber laser is frequency selected by an acousto-optic modulator after being amplified and broadened, and the repetition frequency range is 10 Hz - 100 MHz. The seed light in the s polarization state undergoes beam transformation so that the light spot entering the disk regenerative amplifier resonant cavity matches the characteristics of the resonant cavity mode. The s-polarized seed light after beam transformation becomes p-polarized after passing through the 45-degree first plane mirror 13 and the first half-wave plate 12. The p-polarized seed light remains in the p-polarized state after passing through the first polarization beam splitter 11, passing through the Faraday rotator 10 and the second half-wave plate 9, and then is coupled into the disk regenerative amplifier resonant cavity through the second polarization beam splitter 7. The p-polarized seed light entering the disk regenerative amplifier resonant cavity sequentially passes through the first Pockels cell 2 without voltage applied, the quarter-wave plate 3, the 45-degree second plane mirror 4, and the concave mirror 5. After being reflected by the concave mirror 5, it returns along the original path and sequentially passes through the 45-degree second plane mirror 4 and the quarter-wave plate 3 and becomes s-polarized. The s-polarized seed light passes through the first Pockels cell 2 without voltage applied and is reflected by the second polarization beam splitter 7, and then sequentially passes through the spherical mirror 8 and the third plane mirror 6 to reach the in-cavity gain medium disk module 21, and the seed light energy is amplified and returns along the original path after being reflected by the disk module 21. During this process, the s-polarized seed light passes through the quarter-wave plate 3 twice and the first Pockels cell 2 that maintains the working state by applying a quarter-wave voltage, and the polarization state remains unchanged. Therefore, it oscillates back and forth in the resonant cavity after being reflected by the second polarization beam splitter 7, passes through the disk module 21 multiple times to obtain gain and amplify the energy. When the seed light energy is amplified to the target value, the quarter-wave voltage applied to the first Pockels cell 2 is removed to keep it in the non-working state. The amplified s-polarized seed light in the cavity becomes p-polarized after passing through the quarter-wave plate 3 twice and the first Pockels cell 2 without electricity applied. The amplified p-polarized light is coupled and output through the second polarization beam splitter 7, and then becomes s-polarized after passing through the second half-wave plate 9 and the Faraday rotator 10, and is reflected and output to the pulse width compression module after passing through the first polarization beam splitter 11.

[0041] By controlling the working state and working time of the first Pockels cell 2, the round-trip time of the seed light in the resonator is controlled, and after the energy of the seed light is amplified to the target value, it is output from the first polarization beam splitter 11. Among them, the second plane mirror 4 totally reflects the laser incident at 45 degrees, folds the optical path of the resonator and facilitates the adjustment of the optical path. The function of the concave mirror 5 is to reduce the divergence angle of the incident laser and totally reflect the laser incident at 0 degrees. The 45-degree second polarization beam splitter 7 has the function of highly transmitting the laser in the p polarization state and highly reflecting the laser in the s polarization state, and the included angle between the incident light and the normal of the lens is 45 degrees. The function of the quarter-wave plate 3 is to change the phase of the seed light, convert linearly polarized light into circularly polarized light, and convert circular polarization into linear polarization. When a voltage is applied to the first Pockels cell 2, the first Pockels cell is equivalent to a quarter-wave plate, that is, the phase change after the laser passes through is 45 degrees. The second plane mirror 4 totally reflects the laser incident at 45 degrees, folds the optical path of the resonator and facilitates the adjustment of the optical path.

[0042] As Figure 2 shown, the laser input into the pulse width compression module is cyclically compressed by the pulse width compression module. By rotating the angle of the third half-wave plate 22, the polarization direction of the linearly polarized light can be rotated, and the dispersion amount of the nonlinear crystal 17 is controlled to control the compression amount. The pulse width can be compressed once every round, so as to output a pulse train with tunable pulse width. In some embodiments, the pulse width of the pulse train is a ps-level pulse.

[0043] In some embodiments, as Figure 3 shown, the pulse width compression module further includes a second Pockels cell 20, which is arranged between the third polarization beam splitter 15 and the third half-wave plate 22. The laser input into the pulse width compression module passes through the third polarization beam splitter 15, allowing the light to enter the pulse compression module. By adjusting the falling-edge voltage of the second Pockels cell 20 in the ring cavity, while the pulse width gradually decreases, the polarization state is changed, and a high-power pulsed laser string with tunable pulse width can be output. In some embodiments, a control module is further included, and the control module is used to adjust the falling-edge voltage of the second Pockels cell 20. As Figure 3 shown, when the laser passes through the second Pockels cell 20 for the first time, it is in the off state. The optical axis direction of the third half-wave plate 22 forms a 45° angle with the polarization direction of the incident light, so the polarization changes after passing through the third half-wave plate 22. Then the Pockels cell is pressurized, and the light is continuously compressed in the ring cavity, which can further improve the compression ratio. By adjusting the falling-edge voltage of the Pockels cell in the ring cavity to make the voltage drop slowly, while the pulse width gradually decreases, the polarization state is changed, and a high-power pulsed laser with tunable pulse width can be output. The power can be kept stable through the Pockels cell, so as to obtain a pulse train with tunable pulse width and consistent power, and the compression degree is higher than the previous scheme.

[0044] In some embodiments, asFigure 4 As shown, the optical path is folded by the first electrically controlled laterally moving plane mirror 19 and the second electrically controlled laterally moving plane mirror 18. The control module controls the lateral movement of the first electrically controlled laterally moving plane mirror 19 and the second electrically controlled laterally moving plane mirror 18 to adjust the pulse compression path in the ring cavity, thereby changing the pulse period size, that is, changing the repetition frequency size. Finally, a high-power pulse train with tunable pulse width and repetition frequency is obtained through the electrically controlled laterally moving plane mirror. By introducing a nonlinear crystal 17, such as a beta barium borate (BBO) crystal, into the ring cavity, different spectral components experience different optical paths, where the optical path experienced by the long-wavelength component is greater than that of the short-wavelength component. The pulse width compression module introduces negative dispersion conjugate to the stretcher to compensate for the positive chirp and achieve effective compression of the pulse.

[0045] In some embodiments, the entire pulse width compression module is built into a single-piece aluminum housing, which has high thermal stability and mechanical stability. The multi-pass compression structure based on the nonlinear crystal recompresses the output pulse to a pulse with a duration at the ps level, and the output beam has excellent beam quality and uniformity.

[0046] In some embodiments, the regenerative amplifier optical path further includes a pump source 1 for outputting pump light to pump the disk module 21. The pump source 1 provides energy for the laser medium to achieve population inversion and thus generate laser. In some embodiments, the pump source 1, for example, is a semiconductor laser, which outputs pump light with a central wavelength of 969 nm or 940 nm. The pump light output by the pump source 1 pumps the disk module 21. Among them, to make the laser output by the disk regenerative amplifier have good beam quality, the size of the laser spot at the disk needs to meet certain mode matching requirements with the size of the pump spot, that is, the size of the laser spot should be 0.7 - 0.8 times the size of the pump spot to achieve the output of the fundamental transverse mode laser.

[0047] In some embodiments, the first Pockels cell 2 is controlled to work or not by the electrical pulse generated by the digital delay signal generator. By controlling the delay and width of the electrical pulse, it jointly controls the output of the seed light and the number of round trips in the cavity with the second polarization beam splitter 7. The disk laser crystal includes at least one of the following: Yb:YAG, Yb:KGW, Yb:CALGO, Yb:LuScO3, Ho:YAG, Ho:KYW, Tm:YAG, Tm:KYW, Cr:ZnSe, and Tm:LLF. The diameter of the disk laser crystal is 5 - 50 mm. For example, for the Yb:YAG disk laser crystal, its thickness is on the order of hundreds of micrometers, the diameter is 5 - 50 mm, the doping concentration is 0.3 - 10%, the front surface of the disk is coated with an antireflection film for the pump light wavelength and the seed light wavelength, and the back surface is coated with a high-reflection film for the pump light wavelength and the seed light wavelength.

[0048] In some embodiments, the minimum diameter of the light spot of the amplification optical path in the disc regeneration amplifier cavity is 2 mm - 2.1 mm.

[0049] The present invention provides a novel laser with adjustable output pulse width and repetition frequency, and can achieve pulsed train laser output. Based on the multi-pass compression method of nonlinear crystals, a high-power disc laser is built, which contains a nonlinear crystal and a 1 / 2 wave plate or a ring cavity with a Pockels cell for pulse width compression, and finally a high-power tunable pulse width pulsed train is obtained.

[0050] The present invention effectively compresses pulses by introducing a nonlinear crystal into the ring cavity. High-power laser can obtain a large compression factor by running multi-pass in the ring cavity, and by adjusting the Pockels cell or 1 / 2 wave plate in the ring cavity, high-power pulsed laser with tunable pulse width is output. After passing through two electrically controlled laterally moving plane mirrors, the optical path is folded, and the pulse compression path in the ring cavity is adjusted by lateral movement to change the pulse period. This application is simple to operate and low in cost, opening up more directions for ultrafast optics to achieve higher power and higher energy pulse compression.

[0051] Finally, it should be noted that: the various embodiments in this specification are described by way of example, and the key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. For the systems or devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0052] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present application.

Claims

1. A high-power pulse width and repetition frequency tunable laser, characterized in that , including: Input and output optical path, configured to input seed light and output amplified laser. The input and output optical path includes: a seed light source (14), a first plane mirror (13), a first half-wave plate (12), a first polarization beam splitter (11), a Faraday rotator (10), and a second half-wave plate (9); Regenerative amplifier optical path, configured to amplify the input seed light. The regenerative amplifier optical path includes: a second polarization beam splitter (7), a first Pockels cell (2), a quarter-wave plate (3), a second plane mirror (4), a concave mirror (5), a spherical mirror (8), a third plane mirror (6), and a disk module (21); Pulse width compression module, configured to compress the pulse width of the amplified seed light and output high-power pulsed laser with tunable pulse width. The pulse width compression module includes: a third polarization beam splitter (15), a third half-wave plate (22), a first electrically controlled laterally moving plane mirror (19), a second electrically controlled laterally moving plane mirror (18), a nonlinear crystal (17), and a fourth plane mirror (16); Among them, the seed light source outputs broadened ns-level s-polarized state seed light. The seed light passes through the first plane mirror (13) and the first half-wave plate (12), and the s-polarized state seed light becomes p-polarized state seed light, and then passes through the first polarization beam splitter (11), the Faraday rotator (10), and the second half-wave plate (9) to enter the regenerative amplifier optical path; The seed light entering the regenerative amplifier optical path passes through the first Pockels cell (2), the quarter-wave plate (3), the second plane mirror (4), and the concave mirror (5). After being reflected by the concave mirror (5), it returns along the original path and passes through the second plane mirror (4), the quarter-wave plate (3), the first Pockels cell (2), the second polarization beam splitter (7), the spherical mirror (8), and the third plane mirror (6) in turn and then reaches the disk module (21). After being amplified by the disk module (21), it returns along the original path and travels back and forth in the resonant cavity for amplification. The amplified seed light is output from the first polarization beam splitter (11) to the pulse width compression module; The laser is cyclically compressed in the pulse width compression module. By rotating the angle of the third half-wave plate (22), the polarization direction of the linearly polarized light can be rotated, and the dispersion amount of the nonlinear crystal (17) is controlled to control the compression amount. The pulse width can be compressed once every round, thereby outputting a train of pulses with tunable pulse width.

2. The laser according to claim 1, wherein , the pulse width compression module further includes: a second Pockels cell (20), which is arranged between the third polarization beam splitter (15) and the third half-wave plate (22).

3. The laser according to claim 1, wherein , the repetition frequency of the train of pulses is adjusted by adjusting the first electrically controlled laterally moving plane mirror (19) and the second electrically controlled laterally moving plane mirror (18).

4. The laser according to claim 1, characterized in that , the regenerative amplifier optical path further includes: A pump source (1), which is used to output pump light to pump the disk module (21).

5. The laser according to claim 1, characterized in that , The disc module includes at least one of the following: Yb:YAG, Yb:KGW, Yb:CALGO, Yb:LuScO3, Ho:YAG, Ho:KYW, Tm:YAG, Tm:KYW, Cr:ZnSe, and Tm:LLF.

6. The laser according to claim 2, characterized in that , Further included is: A control module, by adjusting the falling-edge voltage of the second Pockels cell (20), while the pulse width of the pulse train gradually decreases, the polarization state is changed, so as to output a high-power pulse train with tunable pulse width.

7. The laser according to claim 1, characterized in that , The pulse width of the pulse train is a ps-level pulse.

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