Pulsed Laser and Laser System

Abstract

The present invention discloses a pulsed laser and a laser system. The pulsed laser includes: a pulsed light source for generating an initial laser pulse; a stretcher coupled to the pulsed light source for pulse stretching the initial laser pulse to generate a first laser pulse; a pulse selector coupled to the stretcher for selecting the first laser pulse and obtaining a second laser pulse; a cryogenic vacuum amplifier coupled to the pulse selector for amplifying the second laser pulse; and a pulse compressor coupled to the cryogenic vacuum amplifier for compressing the second laser pulse and generating a target laser pulse. The pulsed laser in the embodiments of the present invention can provide ultrashort pulses with a high repetition rate and ultra-high power.

Description

Technical Field

[0001] The present invention relates to the technical field of laser pulse technology, and in particular to a pulsed laser and a laser system. Background Art

[0002] With the continuous development of laser technology, the peak power of an ultra-intense and ultra-short laser system can reach the petawatt (10 15 W) level, and it is widely used in experiments on ultra-intense field laser-matter interactions, such as ultra-short X-ray radiation, high-order harmonic generation, laser wakefield particle acceleration, and fast ignition laser fusion.

[0003] In related technologies, an ultra-intense and ultra-short laser system generally uses a Ti:Sapphire crystal as the laser crystal. However, the upper energy level lifetime of the Ti:Sapphire crystal is short, resulting in low electro-optical efficiency. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a pulsed laser that can provide ultra-short pulses with a high repetition frequency and ultra-high power.

[0005] The present invention also provides a laser system having the above pulsed laser.

[0006] The pulsed laser according to the first aspect embodiment of the present invention includes: a pulsed light source for generating an initial laser pulse; a stretcher coupled to the pulsed light source for pulse stretching the initial laser pulse to generate a first laser pulse; a pulse selector coupled to the stretcher for selecting the first laser pulse and obtaining a second laser pulse; a regenerative amplifier coupled to the pulse selector for pulse amplifying the second laser pulse; a cryogenic vacuum amplifier coupled to the pulse selector for amplifying the second laser pulse; and a pulse compressor coupled to the cryogenic vacuum amplifier for compressing the second laser pulse and generating a target laser pulse.

[0007] The pulsed laser according to the embodiment of the present invention has at least the following beneficial effects: The initial laser pulse is provided by the pulsed light source, and the stretcher expands the initial laser pulse according to the wavelength of the initial laser pulse to form a pulse train. The pulse selector selects the laser pulse to be amplified in the pulse train according to preset parameters. After the laser pulse to be amplified is amplified by a preset value by the regenerative amplifier, the laser pulse to be amplified is transmitted to the cryogenic vacuum amplifier and is secondarily amplified. After the laser pulse to be amplified is amplified, a laser pulse to be compressed is generated, and the pulse compressor compresses the laser pulse to be compressed and generates a target laser pulse.

[0008] According to some embodiments of the present invention, it further includes: a pulse selection controller, connected to the pulse selector, for controlling the pulse selector;

[0009] According to some embodiments of the present invention, the cryogenic vacuum amplifier includes: a first laser window; a third laser crystal, coupled to the first laser window; a cryogenic controller, connected to the third laser crystal, for controlling the temperature of the third laser crystal; a third pumping device, coupled to the third laser crystal, for exciting the third laser crystal; a second laser window, coupled to the third laser crystal; wherein, the first laser window and the second laser window are oppositely arranged to define an amplification cavity.

[0010] According to some embodiments of the present invention, the third laser crystal is a Yb:KGW crystal.

[0011] According to some embodiments of the present invention, the pulse selector includes: a first polarizer, for receiving the first laser pulse; a first half-wave plate, coupled to the first polarizer, for performing phase adjustment on the first laser pulse and forming a first polarized pulse; a polarization state rotator, coupled to the first half-wave plate, for performing polarization processing on the polarization state of the first polarized pulse and generating the second laser pulse; a second polarizer, coupled to the polarization state rotator, for adjusting the polarization state and / or propagation direction of the second laser pulse.

[0012] According to some embodiments of the present invention, the pulse selector further includes: a first quarter-wave plate, for performing phase adjustment on the second laser pulse; a Pockels cell, coupled to the first quarter-wave plate, for performing phase adjustment on the second laser pulse; a first high-reflection mirror, coupled to the Pockels cell, for reflecting the second laser pulse.

[0013] According to some embodiments of the present invention, the regenerative amplifier further includes: a first pumping device, for performing a first amplification process on the second laser pulse; a second pumping device, coupled to the first pumping device, for performing a second amplification process on the second laser pulse.

[0014] According to some embodiments of the present invention, the first pumping device includes: a first laser crystal; a first dichroic mirror coupled to the first laser crystal; a first convex lens group coupled to the first dichroic mirror and disposed on a side of the first dichroic mirror away from the first laser crystal; a first pumping optical fiber coupled to the first convex lens group; a first semiconductor pumping source coupled to the first pumping optical fiber for exciting the first laser crystal; the second pumping device includes: a second laser crystal; a second dichroic mirror coupled to the second laser crystal; a second convex lens group coupled to the second dichroic mirror and disposed on a side of the second dichroic mirror away from the second laser crystal; a second pumping optical fiber coupled to the second convex lens group; a second semiconductor pumping source coupled to the second pumping optical fiber for exciting the second laser crystal.

[0015] According to some embodiments of the present invention, the pulse compressor includes: a first pulse compressor coupled to the cryogenic vacuum amplifier for compressing the second laser pulse and generating a first target pulse; a second pulse compressor coupled to the first pulse compressor for non-linearly compressing the first target pulse and generating a second target pulse.

[0016] The laser system according to the second aspect embodiment of the present invention includes the pulsed laser in any of the above embodiments.

[0017] The laser system according to the embodiment of the present invention has at least the following beneficial effects: By using the above pulsed laser, an ultrashort pulse with a high repetition frequency and ultra-high power can be provided to the laser system.

[0018] The additional aspects and advantages of the present invention will be partially given in the following description, partially become apparent from the following description, or be understood through the practice of the present invention. Description of the Drawings

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, where:

[0020] Figure 1 is a schematic structural diagram of a pulsed laser in an embodiment of the present invention;

[0021] Figure 2 is a schematic structural diagram of a pulse selector and a regenerative amplifier in an embodiment of the present invention;

[0022] Figure 3 is a schematic structural diagram of a cryogenic vacuum amplifier in an embodiment of the present invention.

[0023] Reference Signs:

[0024] 100, Pulse light source; 200, Isolator; 300, Expander; 410, Pulse selection controller; 420, Pulse selector; 500, Regenerative amplifier; 700, Cryogenic vacuum amplifier; 800, Pulse compressor; 801, First pulse compressor; 802, Second pulse compressor; 421, First polarizer; 422, First half-wave plate; 423, Polarization state rotator; 424, Second polarizer; 425, First quarter-wave plate; 426, Pockels cell; 427, First high reflector; 501, First semiconductor pump source; 502, First pump fiber; 503, First convex lens group; 504, First dichroic mirror; 505, First laser crystal; 506, Second semiconductor pump source; 507, Second pump fiber; 508, Second convex lens group; 509, Second dichroic mirror; 510, Second laser crystal; 511, Fourth high reflector; 512, Second high reflector; 513, Third high reflector; 514, Fourth high reflector; 600, Pump source; 701, First laser window plate; 702, Third laser crystal; 703, Second laser window plate; 704, Cryogenic controller; 705, Third dichroic mirror; 706, Third quarter-wave plate; 707, Second cavity mirror; 708, Convex lens group; 709, Third transmission fiber; 710, Third pump device; 711, First cavity mirror. Detailed implementation mode

[0025] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0026] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as up, down, front, back, left, right, etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0027] In the description of the present invention, the meaning of several is one or more, and the meaning of multiple is more than two. Understandings such as greater than, less than, exceeding, etc. do not include the present number, and understandings such as above, below, within, etc. include the present number. If there is a description of first and second, it is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0028] In the description of the present invention, unless otherwise clearly defined, terms such as "set", "installed", "connected", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0029] Referring to Figure 1 , the pulsed laser includes: a pulsed light source 100 for generating an initial laser pulse; a stretcher 300 coupled to the pulsed light source 100 for pulse stretching the initial laser pulse to generate a first laser pulse; a pulse selector 420 coupled to the stretcher 300 for selecting the first laser pulse and obtaining a second laser pulse; a regenerative amplifier 500 coupled to the pulse selector 420 for pulse amplifying the second laser pulse; a cryogenic vacuum amplifier 700 coupled to the pulse selector 420 for amplifying the second laser pulse; and a pulse compressor 800 coupled to the cryogenic vacuum amplifier 700 for compressing the second laser pulse and generating a target laser pulse.

[0030] An initial laser pulse is provided by the pulsed light source 100, and the stretcher 300 expands the initial laser pulse according to the wavelength of the initial laser pulse to form a first laser pulse (pulse train). The pulse selector 420 selects the laser pulse to be amplified in the pulse train according to preset parameters, and transmits the laser pulse to be amplified to the cryogenic vacuum amplifier 700 to amplify the laser pulse to be amplified. After the laser pulse to be amplified is amplified, a laser pulse to be compressed is generated, and the pulse compressor 800 compresses the laser pulse to be compressed and generates a target laser pulse. Among them, the pulse compressor 800 re-converges the amplified second laser pulse according to the spectrum and restores the pulse width, thereby forming a femtosecond laser pulse with high instantaneous power.

[0031] The pulse selector selects the laser pulse to be amplified in the pulse train according to preset parameters. After the laser pulse to be amplified is amplified by a preset value through the regenerative amplifier, the laser pulse to be amplified is transmitted to the cryogenic vacuum amplifier and is amplified twice.

[0032] In some embodiments, the pulsed light source 100 may be a femtosecond pulsed light source 100 for providing femtosecond pulses. For example, the pulsed light source 100 is a mode-locked fiber femtosecond laser, which can output femtosecond laser pulses. The pulse power of the femtosecond laser pulses can be about 1 nJ, the pulse width can be about 200 fs, and the repetition frequency can be 40 MHz.

[0033] A femtosecond-level initial laser pulse is provided by the femtosecond pulsed light source 100, and pulse selection is performed on the initial laser pulse to perform amplification processing and compression processing on the target pulse to obtain a target laser pulse. Among them, the target laser pulse is an ultrashort pulse with a high repetition frequency and ultra-high power.

[0034] In addition, the pump source 600 is used to supply energy to the laser crystals in the regenerative amplifier 500 and the cryogenic vacuum amplifier 700 to achieve population inversion.

[0035] In some embodiments, by setting the initial laser pulse and device parameters, a high-repetition-rate ultra-intense and ultra-short pulse with a pulse energy reaching 25 mJ, a pulse width less than 25 fs, a peak power reaching 1 TW (10^12 W), and a repetition rate reaching 1 kHz can be provided.

[0036] In some embodiments, a laser isolator 200 is provided between the pulse light source 100 and the stretcher 300. The laser isolator 200 is used to construct a unidirectional pulse channel. The unidirectional pulse channel allows the initial laser pulse generated by the pulse light source 100 to be transmitted to the stretcher 300, while the high-repetition-rate ultra-intense and ultra-short pulse generated in the pulse laser cannot pass through the laser isolator 200, thereby isolating and protecting the pulse light source 100. Among them, the laser isolator 200 includes: an isolation half-wave plate; an isolation polarizer, which is disposed opposite to the isolation half-wave plate; and a Faraday rotator, which is disposed between the isolation half-wave plate and the isolation polarizer. The isolation half-wave plate and the isolation polarizer are disposed opposite to each other, and the included angle is not 0. By means of the laser isolator 200, while the initial laser pulse enters the stretcher 300, the amplified laser pulse is blocked from re-entering the pulse light source 100, thereby realizing the protection of the pulse light source 100.

[0037] In some embodiments, the stretcher 300 is a Martinez stretcher 300. A transmissive grating is provided in the Martinez stretcher 300, and the line density of the transmissive grating is 1600 lines / mm. The pulse width of the initial laser pulse provided by the pulse light source 100 is broadened from about 200 fs to about 0.5 ns after being broadened by the stretcher 300, that is, the initial laser pulse is broadened from the femtosecond level to the sub-nanosecond level.

[0038] Furthermore, the Martinez stretcher 300 can be a standard achromatic Martinez stretcher 300.

[0039] In some embodiments, the pulse laser further includes: a pulse selection controller 410, which is connected to the pulse selector 420 and is used to control the pulse selector 420.

[0040] Among them, the pulse selector 420 sequentially selects the pulse sequence formed by broadening the initial laser pulse according to the preset switching frequency of the pulse selection controller 410, and only one sub-nanosecond-level pulse is selected each time. Among them, the sub-nanosecond-level pulse can be the second laser pulse described above.

[0041] The regenerative amplifier 500 amplifies the second sub-nanometer laser pulse. For example, the second laser pulse travels back and forth between the pulse selector 420 and the regenerative amplifier 500 multiple times. The second laser pulse increases its energy through the working medium and the pump source in the regenerative amplifier 500, and the pulse energy can be increased to more than 2 mJ.

[0042] When the pulse energy of the second laser pulse increases to a preset value, the second laser pulse is transmitted into the cryogenic vacuum amplifier 700 and amplified to form a laser pulse to be compressed. The cryogenic vacuum amplifier 700 amplifies the pulse energy of the second laser pulse to 40 mJ. Among them, the part of the first laser pulse not selected by the pulse selector 420 will be reflected outside the pulse laser and will not enter the cryogenic vacuum amplifier 700.

[0043] By compressing the amplified second laser pulse, the width of the second laser pulse is compressed within a preset width.

[0044] In some embodiments, the cryogenic vacuum amplifier 700 includes: a first laser window 701; a third laser crystal 702, which is coupled to the first laser window 701; a cryogenic controller 704, which is connected to the third laser crystal 702 and is used to control the temperature of the third laser crystal 702; a third pump device 710, which is coupled to the third laser crystal 702 and is used to excite the third laser crystal 702; a second laser window 703, which is coupled to the third laser crystal 702; wherein, the first laser window 701 and the second laser window 703 are arranged opposite to each other to define an amplification cavity.

[0045] A vacuum chamber is constructed through the first laser window 701 and the second laser window 703 to form an amplification cavity. The temperature of the third laser crystal 702 is controlled by the cryogenic controller 704 to convert the energy level of the third laser crystal 702, thereby adjusting the thermal conductivity of the third laser crystal 702.

[0046] In some embodiments, the third laser crystal 702 is a Yb:KGW crystal. The vacuum chamber constructed by the first laser window 701 and the second laser window 703 can reach at least the order of 10-2 Pa, and the cryogenic controller 704 adjusts the temperature of the third laser crystal 702 to 77 K to 200 K, so that the Yb:KGW crystal is transformed from a three-level structure at room temperature to a four-level structure.

[0047] Please refer to Figure 1 、 Figure 2, in some embodiments, the pulse selector 420 includes: a first polarizer 421 for receiving a first laser pulse; a first half-wave plate 422 coupled to the first polarizer 421 for phase-adjusting the first laser pulse and forming a first polarized pulse; a polarization state rotator 423 coupled to the first half-wave plate 422 for polarizing the polarization state of the first polarized pulse and generating a second laser pulse; and a second polarizer 424 coupled to the polarization state rotator 423 for adjusting the polarization state and / or propagation direction of the second laser pulse. The first polarizer 421 is coupled to the stretcher 300 to receive the first laser pulse obtained by pulse stretching via the stretcher 300.

[0048] Among them, the first laser pulse has the same polarization angle as the first polarizer 421, and the first laser pulse is adjusted by the first half-wave plate 422 and the polarization state rotator 423. The second laser pulse has a different polarization angle from the first laser pulse. For example, the polarization angle of the first laser pulse matches that of the first polarizer 421, and the first laser pulse is transmitted through the first polarizer 421 to the first half-wave plate 422; the polarization angle of the second laser pulse does not match that of the first polarizer 421, and the second laser pulse is reflected by the first polarizer 421 to the fourth high reflector 511.

[0049] The pulse sequence of the first laser pulse is selected by the pulse selection controller 410 and the pulse selector 420 to obtain the second laser pulse. The first laser pulse enters the pulse selector 420, and the polarization direction of the first laser pulse is consistent with that of the first polarizer 421; the first half-wave plate 422 adjusts the phase of the first laser pulse and forms a first polarized pulse, and the polarization state rotator 423 polarizes the polarization state of the first polarized pulse and generates a second laser pulse.

[0050] The polarization state and / or propagation direction of the second laser pulse is adjusted by the second polarizer 424 so that the second laser pulse enters the regenerative amplifier 500. Among them, the polarization state rotator 423 can be a Faraday rotator.

[0051] In some embodiments, the pulse selector 420 further includes: a first quarter-wave plate 425 coupled to the second polarizer 424 for phase-adjusting the second laser pulse; a Pockels cell 426 coupled to the first quarter-wave plate 425 for phase-adjusting the second laser pulse; and a first high reflector 427 coupled to the Pockels cell 426 for reflecting the second laser pulse.

[0052] The second laser pulse sequentially passes through the first quarter-wave plate 425, the Pockels cell 426, and the first high reflector 427 and is reflected on the surface of the first high reflector 427; the second laser pulse passes through the Pockels cell 426 and the first quarter-wave plate 425 again and is reflected by the second polarizer 424 and then transmitted into the regenerative amplifier 500.

[0053] In some embodiments, a pulse voltage is generated by the pulse selection controller 410 to control the operating state of the Pockels cell 426. For example, the pulse selection controller 410 generates a high-voltage pulse of about 4 KV to control the polarization state of the Pockels cell 426, so that the optical characteristics of the Pockels cell 426 are equivalent to those of a quarter-wave plate.

[0054] When the pulse selection controller 410 has no voltage output, the second laser pulse enters the pulse selector 420 and is reflected by the second high reflector 512 and the third high reflector 513 and then enters the regenerative amplifier 500. Among them, after being amplified by the regenerative amplifier 500, the second laser pulse enters the pulse selector 420 again. At this time, the pulse selection controller 410 outputs a high-voltage pulse, so that the second laser pulse enters the regenerative amplifier 500 again, while the subsequent incoming laser pulses are reflected or absorbed by the pulse selector 420. Since the subsequent incoming laser pulses are absorbed or reflected, the regenerative amplifier 500 only amplifies the second laser pulse.

[0055] Among them, the third high reflector 513 and the fourth high reflector 514 can form a resonant cavity to enable the second laser pulse to be stably transmitted in the regenerative amplifier 500.

[0056] In some embodiments, the second high reflector 512 and the first cavity mirror 711 are the same multiplexed mirror to adjust the transmission path of the laser pulse.

[0057] Among them, the second laser pulse enters the regenerative amplifier 500 and undergoes two amplification processes, so that the energy of the second laser pulse is increased to a preset power.

[0058] In some embodiments, the regenerative amplifier 500 further includes: a first pumping device for performing a first amplification process on the second laser pulse; a second pumping device, which is coupled to the first pumping device, for performing a second amplification process on the second laser pulse.

[0059] The second laser pulse enters the regenerative amplifier 500, and makes two round trips and is respectively fiber-coupled and output to the corresponding laser crystal for pulse amplification. Among them, the first pumping device and the second pumping device are symmetrically arranged.

[0060] In some embodiments, the first pumping device includes: a first laser crystal 505; a first dichroic mirror 504, coupled to the first laser crystal 505; a first convex lens group 503, coupled to the first dichroic mirror 504 and disposed on a side of the first dichroic mirror 504 away from the first laser crystal 505; a first pumping optical fiber 502, coupled to the first convex lens group 503; and a first semiconductor pumping source 501, coupled to the first pumping optical fiber 502 and configured to excite the first laser crystal 505. The second pumping device includes: a second laser crystal 510; a second dichroic mirror 509, coupled to the second laser crystal 510; a second convex lens group 508, coupled to the second dichroic mirror 509 and disposed on a side of the second dichroic mirror 509 away from the second laser crystal 510; a second pumping optical fiber 507, coupled to the second convex lens group 508; and a second semiconductor pumping source 506, coupled to the second pumping optical fiber 507 and configured to excite the second laser crystal 510.

[0061] Wherein, the Ng directions of the first laser crystal 505 and the second laser crystal 510 are tangent to each other, and the axes of the first laser crystal 505 and the second laser crystal 510 parallel to the polarization direction of the second laser pulse are Nm and Np, respectively.

[0062] The first laser crystal 505 and the second laser crystal 510 are pumped by corresponding pumping sources to cause population inversion in the laser crystals.

[0063] When the second laser pulse is amplified to a preset power, the pulse selection controller 410 stops outputting high-voltage pulse signals, such that the amplified second laser pulse is transmitted to the cryogenic vacuum amplifier 700 via the pulse selector 420. Wherein, in this embodiment, the output pulse energy of the amplified second laser pulse is about 2 mJ, and the square-wave high-voltage signal output by the pulse selection controller 410 is about 4 kV, with a frequency of 1000 Hz.

[0064] In some embodiments, the first laser crystal 505 and the second laser crystal 510 are Yb:KGW crystals. By symmetrically arranging the first pumping device and the second pumping device, a double-crystal regenerative amplifier 500 is constructed to perform secondary amplification on the laser pulse. By using a semiconductor pumping source to excite the Yb:KGW crystal, the active Yb ions in the Yb:KGW crystal are pumped from the ground state to a high energy level to achieve population inversion. For example, the semiconductor pumping source is a multimode fiber-coupled semiconductor laser, its transmission fiber is a multimode fiber, the working mode is continuous (CW) or quasi-continuous (QCW), and the output wavelength is 808 nm to 985 nm.

[0065] In some embodiments, the pulse compressor 800 includes: a first pulse compressor 801, coupled to the cryogenic vacuum amplifier 700, for compressing the second laser pulse and generating a first target pulse; and a second pulse compressor 802, coupled to the first pulse compressor 801, for nonlinearly compressing the first target pulse and generating a second target pulse.

[0066] Among them, the first pulse compressor 801 is a Treacy pulse compressor. The first pulse compressor 801 can compress the laser pulse to be compressed amplified by the cryogenic vacuum amplifier 700 to generate a first target pulse of about 28 mJ. The second pulse compressor 802 can nonlinearly compress the first target pulse to obtain a second target pulse. Among them, the first target pulse is a femtosecond pulse with a pulse width less than 300 fs; the second target pulse is a femtosecond pulse with a pulse width less than 25 fs.

[0067] In some embodiments, the Treacy pulse compressor is a standard Treacy pulse compressor, which is used to compress the pulse width of the second laser pulse to the limit width and obtain a first target pulse. For example, the standard Treacy pulse compressor is provided with a transmissive grating, which can compress the pulse width of a high-energy laser pulse of sub-nanosecond to about 280 fs. The second laser pulse is a chirped pulse.

[0068] In some embodiments, the second pulse compressor 802 is a nonlinear pulse compressor 800. The nonlinear pulse compressor 800 compresses the second laser pulse (femtosecond-level pulse) that has reached the compression limit into a second target pulse (ultrashort pulse) through a nonlinear crystal. For example, the second laser pulse or the first target pulse is nonlinearly compressed through a Herriott-type multi-pass gas cell. Specifically, the first target pulse of the order of hundreds of femtoseconds is transmitted to a Herriott-type multi-pass cavity filled with an inert gas, and the spectral broadening is carried out by using the nonlinear effect (self-phase modulation effect) to perform dispersion compensation compression on the first target pulse, so as to compress the pulse width of the first target pulse to less than or equal to one-tenth of the initial pulse width.

[0069] Combined with the above embodiments, a specific embodiment is adaptively described.

[0070] Please refer to Figure 1 、 Figure 2 、 Figure 3, a pulsed light source 100 generates initial femtosecond laser pulses; a laser isolator 200 serves as a unidirectional pulse transmission channel, and the initial laser pulses can be transmitted to a stretcher 300 via the laser isolator 200. The stretcher 300 stretches the initial femtosecond laser pulses into first laser pulses with a pulse width in the sub-nanosecond range. The laser isolator 200 prevents high-repetition-rate ultra-intense and ultra-short pulses from entering the pulsed light source 100 to isolate and protect the pulsed light source 100.

[0071] The first laser pulses are transmitted to a pulse selector 420, and the pulse selector 420 selects the pulse sequence of the first laser pulses according to the control signal of a pulse selection controller 410 to obtain second laser pulses that meet preset parameters.

[0072] For example, the pulse selection controller 410 includes a first polarizer 421, a first half-wave plate 422, a polarization state rotator 423, a second polarizer 424, a first quarter-wave plate 425, a Pockels cell 426, and a first high-reflection mirror 427 that are sequentially coupled. Among them, the polarization state rotator 423 can be a Faraday rotator.

[0073] The polarization angle of the second laser pulses is consistent with that of the first polarizer 421. The second laser pulses pass through the first half-wave plate 422 to adjust the phase and the polarization state rotator 423 to adjust the polarization angle to obtain second laser pulses. The polarization angle of the second laser pulses is consistent with that of the second polarizer 424. When the second laser pulses first pass through the first quarter-wave plate 425, the Pockels cell 426, and the first high-reflection mirror 427, the pulse selection controller 410 outputs no control signal, and the second laser pulses are amplified by a regenerative amplifier 500 for the first time and then transmitted to the pulse selector 420 again.

[0074] When the second laser pulses pass through the first quarter-wave plate 425, the Pockels cell 426, and the first high-reflection mirror 427 again, the pulse selection controller 410 outputs a high-voltage signal. The instantaneous state of the Pockels cell 426 is equivalent to a quarter-wave plate, and the second laser pulses are folded back into the regenerative amplifier 500 again and amplified for the second time. And when the pulse selection controller 410 outputs a high-voltage signal, the subsequent laser pulses entering the pulse selector 420 are reflected or absorbed and cannot enter the regenerative amplifier 500 for amplification.

[0075] Among them, the second laser pulses are amplified to a preset power, the pulse selection controller 410 stops outputting the high-voltage signal, and the second laser pulses amplified to the preset power are transmitted to a cryogenic vacuum amplifier 700 via the pulse selector 420. Under low-temperature and vacuum conditions, the Yb:KGW crystal (the third laser crystal 702) is transformed from a three-level structure at room temperature to a four-level structure.

[0076] Among them, the operating temperature of the cryogenic vacuum amplifier 700 is 77K to 200K, and the operating pressure is on the order of 10-2 Pa.

[0077] The cryogenic vacuum amplifier 700 includes a first laser window plate 701, a third laser crystal 702, and a second laser window plate 703 arranged in sequence. The cryogenic controller 704 is connected to the third laser crystal 702 to control the temperature of the third laser crystal 702; the third pumping device 710 is coupled to the third laser crystal 702 to pump the third laser crystal 702.

[0078] An amplification cavity is constructed by the first cavity mirror 711 and the second cavity mirror 707, and a Yb:KGW crystal in a vacuum cryogenic state with a four-level system is used as the gain medium. Among them, the first cavity mirror 711 can be coupled to the pulse selector 420, and a third quarter-wave plate 706 and a third dichroic mirror 705 are arranged in sequence between the second cavity mirror 707 and the cryogenic vacuum amplifier 700.

[0079] The first cavity mirror 711, the second polarizer 424, the cryogenic vacuum amplifier 700, the third dichroic mirror 705, the third quarter-wave plate 706, and the second cavity mirror 707 are arranged in sequence to construct a complete amplification cavity. The third pumping device 710 is coupled to the third laser crystal 702 in the cryogenic vacuum amplifier 700 through the third dichroic mirror 705, thereby realizing population inversion of the third laser crystal 702.

[0080] Among them, a convex lens group 708 can be arranged between the third pumping device 710 and the third dichroic mirror 705 to optimize the pumping performance. The operating power of the third pumping device 710 is about 200W. The second laser pulse is amplified four times by the Yb:KGW crystal to increase the pulse energy to 40mJ.

[0081] In some embodiments, a laser system includes the pulsed laser in any of the above embodiments. By using the above pulsed laser, an ultrashort pulse with a high repetition rate and ultra-high power is provided to the laser system. The laser system can provide an experimental environment with an ultra-strong electromagnetic field, an ultra-high energy density, and an ultra-strong light pressure for experimental research.

[0082] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, that is, they may be located in one place, or they may be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0083] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc., mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0084] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. Pulse laser, characterized in that, Comprising: A pulsed light source for generating an initial laser pulse; A stretcher, coupled to the pulsed light source, for stretching the initial laser pulse to generate a first laser pulse; A pulse selector, coupled to the stretcher, for selecting the first laser pulse and obtaining a second laser pulse; A regenerative amplifier, coupled to the pulse selector, for amplifying the second laser pulse; A cryogenic vacuum amplifier, coupled to the pulse selector, for amplifying the second laser pulse; A pulse compressor, coupled to the cryogenic vacuum amplifier, for compressing the second laser pulse and generating a target laser pulse; A pulse selection controller, connected to the pulse selector, for controlling the pulse selector; The pulse selector includes: A first polarizer for receiving the first laser pulse; A first half-wave plate, coupled to the first polarizer, for adjusting the phase of the first laser pulse to form a first polarized pulse; A polarization state rotator, coupled to the first half-wave plate, for processing the polarization state of the first polarized pulse to generate the second laser pulse; A second polarizer, coupled to the polarization state rotator, for adjusting the polarization state and / or propagation direction of the second laser pulse; A first quarter-wave plate, coupled to the second polarizer, for adjusting the phase of the second laser pulse; A Pockels cell, coupled to the first quarter-wave plate, for adjusting the phase of the second laser pulse; A first high reflector, coupled to the Pockels cell, for reflecting the second laser pulse.

2. The pulsed laser according to claim 1, wherein The cryogenic vacuum amplifier includes: A first laser window plate; A third laser crystal, coupled to the first laser window plate; A cryogenic controller, connected to the third laser crystal, for controlling the temperature of the third laser crystal; A third pumping device, coupled to the third laser crystal, for exciting the third laser crystal; A second laser window plate, coupled to the third laser crystal; Wherein, the first laser window plate and the second laser window plate are oppositely arranged to define an amplification cavity.

3. The pulsed laser according to claim 2, characterized in that, The third laser crystal is a Yb:KGW crystal.

4. The pulsed laser according to claim 1, wherein The regenerative amplifier further includes: A first pumping device for performing a first amplification process on the second laser pulse; A second pumping device, coupled to the first pumping device, for performing a second amplification process on the second laser pulse.

5. The pulsed laser according to claim 4, wherein The first pumping device includes: A first laser crystal; A first dichroic mirror, coupled to the first laser crystal; A first convex lens group, coupled to the first dichroic mirror, disposed on a side of the first dichroic mirror away from the first laser crystal; A first pumping optical fiber, coupled to the first convex lens group; A first semiconductor pumping source, coupled to the first pumping optical fiber, for exciting the first laser crystal; The second pumping device includes: A second laser crystal; A second dichroic mirror, coupled to the second laser crystal; A second convex lens group, which is coupled and connected to the second dichroic mirror and is disposed on two sides of the second dichroic mirror away from the second laser crystal; A second pump fiber, which is coupled and connected to the second convex lens group; A second semiconductor pump source, which is coupled and connected to the second pump fiber and is used for exciting the second laser crystal.

6. The pulsed laser according to claim 4, wherein The pulse compressor includes: A first pulse compressor, which is coupled and connected to the cryogenic vacuum amplifier and is used for compressing the second laser pulse and generating a first target pulse; A second pulse compressor, which is coupled and connected to the first pulse compressor and is used for nonlinearly compressing the first target pulse and generating a second target pulse.

7. A laser system, characterized in that, A pulse laser according to any one of claims 1 to 6.

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