Pulse compression device based on multi-stage multi-through cavity

Abstract

The invention discloses a pulse compression device based on a multistage multi-pass cavity, which comprises a pulse laser and a plurality of compression modules arranged along a light path of the pulse laser, the compression module comprises a pulse laser spot matching module, a multi-pass cavity module, a light beam collimating lens and a pulse dispersion compensation module which are arranged along a light path of the pulse laser; according to the pulse compression device based on the multi-stage multi-pass cavity, the pulse width is continuously compressed by using the two-stage or multi-stage multi-pass cavity, and the pulse from hundred femtoseconds to picoseconds can be compressed to be below 10fs; the device is suitable for femtosecond or picosecond laser pulse beams with different pulse peak powers, the intensity of a nonlinear effect is adjusted by changing the thickness and position of a solid nonlinear medium or changing the type and pressure of a gas medium, and pulses with different energy and widths are optimized and debugged differently; the compression ratio can be effectively improved, and the problem that the compression ratio of a single-stage multi-way cavity is limited is solved.

Description

Technical Field

[0001] The invention relates to the field of laser technology, and in particular to a pulse compression device based on a multi-stage multi-pass cavity. Background Art

[0002] Matter is composed of microscopic particles such as molecules, atoms, and electrons. Changes in the structure of microscopic particles lead to changes in the physical and chemical properties of macroscopic matter. The movement time of microscopic particles is mostly in picoseconds (ps, 1ps = 10 -12 s), femtosecond (fs, 1fs = 10 -15 s) or even attoseconds (as, 1as=10 -18 s), and to measure these particles and their motion processes, tools with corresponding time resolution capabilities are needed. The emergence and development of ultrashort pulse laser technology has solved this problem. Based on chirped pulse amplification (CPA) and nonlinear compression technology, the use of Ti:sapphire laser systems has been able to generate femtosecond pulses of the order of period or even sub-period. Due to the short energy and lifetime of the Ti:sapphire crystal (about 3.2μs), this type of pulse laser requires a Q-switched green light mode-locked pulse laser for pumping, resulting in a large laser system and low electro-optical conversion efficiency. With the development of semiconductor light-emitting diode manufacturing and packaging technology, semiconductor laser-pumped ytterbium (Yb) femtosecond laser systems have the advantages of high electro-optical conversion efficiency, compact size, and amplified laser pulse repetition frequency that can reach megahertz (MHz), becoming an important technical route for the generation of a new generation of high-throughput attosecond pulses. The emission spectrum of Yb-doped laser gain media is relatively narrow (the output laser spectrum range is 1020-1060nm), and the typical pulse energy can reach the millijoule level, but the output spectrum only supports pulses with a temporal width of more than 200fs, which limits the application of Yb-doped laser systems in the field of ultrashort and ultra-intense lasers.

[0003] Nonlinear compression technology refers to the technology of expanding the spectral width of the pulse through the nonlinear effects (self-phase modulation, ionization, etc.) generated when the laser pulse interacts with matter, and obtaining short pulses in the time domain after dispersion compensation. Commonly used nonlinear compression technologies include hollow-core optical fiber, multiple solid sheets, and multi-pass cavities. This technology can solve the limitation problem caused by the output pulse length of the laser. However, hollow-core optical fiber and multiple solid sheets are only suitable for pulse compression below 200fs. In 2016, the University of Munich proposed a nonlinear compression scheme of the multi-pass cavity structure (Multi-Pass Cell, MPC). This scheme uses the Herriott telescope as a chamber for inert gas, allowing the laser to propagate freely in the cavity multiple times and act with the inert gas to broaden the spectrum. This scheme can achieve high-efficiency compression of picosecond pulse lasers. However, for pulses above 200fs, it is difficult to compress the pulse to less than 100 femtoseconds using a single-stage multi-pass cavity. Therefore, it is necessary to use two or more multi-pass cavities to compress the pulse width to less than 10fs. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a pulse compression device based on a multi-stage multi-pass cavity to solve the problem that the devices in the prior art are difficult to compress high-energy laser pulses to less than 100 femtoseconds.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems: a pulse compression device based on a multi-stage multi-pass cavity includes a pulse laser and a plurality of compression modules arranged along the optical path of the pulse laser.

[0006] The compression module comprises a pulse laser spot matching module, a multi-pass cavity module, a beam collimating lens and a pulse dispersion compensation module arranged along the pulse laser optical path.

[0007] The present invention also has the following technical features:

[0008] The multi-pass cavity module is a gas multi-pass cavity, and the gas multi-pass cavity comprises:

[0009] A first entrance reflector, a first import mirror, a first concave mirror, a second concave mirror, a first export mirror and a first exit reflector are arranged along the optical path of the pulse laser, the concave surfaces of the first concave mirror and the second concave mirror are arranged oppositely, and a multi-pass cavity is formed between the first concave mirror and the second concave mirror.

[0010] The gas multi-pass cavity further comprises a vacuum chamber and a gas nonlinear medium filled in the vacuum chamber.

[0011] The first entrance reflector, the first introduction mirror, the first concave mirror, the second concave mirror, the first export mirror and the first exit reflector are arranged in the vacuum chamber.

[0012] The multi-pass cavity module is a solid multi-pass cavity, and the solid multi-pass cavity comprises:

[0013] A second entrance reflector, a second import mirror, a third concave mirror, a fourth concave mirror, a second export mirror and a second exit reflector are arranged along the optical path of the pulse laser. The concave surfaces of the third concave mirror and the fourth concave mirror are arranged opposite to each other, and a multi-pass cavity is formed between the third concave mirror and the fourth concave mirror.

[0014] The solid multi-pass cavity further comprises a solid nonlinear medium arranged between the third concave mirror and the fourth concave mirror.

[0015] The multi-pass cavity module is a solid-gas multi-pass cavity, and the solid-gas multi-pass cavity comprises:

[0016] The third entrance reflector, the third import mirror, the fifth concave mirror, the sixth concave mirror, the third export mirror and the third exit reflector are arranged along the optical path of the pulse laser, the concave surfaces of the fifth concave mirror and the sixth concave mirror are arranged opposite to each other, and a multi-pass cavity is formed between the fifth concave mirror and the sixth concave mirror.

[0017] The solid-gas multi-pass cavity further comprises a vacuum chamber and a solid nonlinear medium and a gas nonlinear medium arranged between the fifth concave mirror and the sixth concave mirror.

[0018] The third entrance reflector, the third import mirror, the fifth concave mirror, the sixth concave mirror, the third export mirror, the third exit reflector, the solid nonlinear medium and the gas nonlinear medium are all arranged in the vacuum chamber.

[0019] The gas nonlinear medium is an inert gas, including helium, neon, argon or krypton.

[0020] The solid nonlinear medium includes silicon dioxide, calcium fluoride, aluminum oxide, or yttrium aluminum garnet.

[0021] The gas nonlinear medium is preferably neon or argon.

[0022] The solid nonlinear medium is preferably silicon dioxide, aluminum oxide or yttrium aluminum garnet.

[0023] The pulse width of the pulse laser emitted by the pulse laser is 100fs-10ps.

[0024] The power of the pulse laser emitted by the pulse laser is 10W-300W.

[0025] The repetition frequency of the pulse laser emitted by the pulse laser is 100 Hz-1 MHz.

[0026] The wavelength of the pulse laser emitted by the pulse laser is 400nm-2000nm.

[0027] The pulse width of the pulse laser emitted by the pulse laser is optimally 200fs-2ps.

[0028] The optimal power of the pulse laser emitted by the pulse laser is 10W-200W.

[0029] The optimal repetition frequency of the pulse laser emitted by the pulse laser is 1kHz-100kHz.

[0030] The optimal wavelength of the pulse laser emitted by the pulse laser is 800-1200nm.

[0031] The energy of the pulse laser emitted by the pulse laser is optimally 1mJ-50mJ.

[0032] The pulse laser spot matching module is composed of two lenses or three lenses.

[0033] The curvature radius of the concave mirror constituting the multi-pass cavity is 300mm-6000mm.

[0034] The beam collimating lens is composed of two lenses or concave mirrors, or three lenses or concave mirror groups.

[0035] The pulse dispersion compensation module is selected from one or more of the following: a chirped mirror, a grating, and a prism pair.

[0036] The pulse laser spot matching module is preferably a three-lens group.

[0037] The curvature radius of the concave mirror constituting the multi-pass cavity is preferably 400mm-4000mm.

[0038] The beam collimating lens is preferably a two-lens or concave mirror group.

[0039] The pulse dispersion compensation module is preferably a chirped mirror.

[0040] Compared with the prior art, the present invention has the following technical effects:

[0041] (I) The pulse compression device based on the multi-stage multi-pass cavity provided by the present invention can compress pulses of the order of hundreds of femtoseconds to picoseconds to less than 10 fs by continuously compressing the pulse width using two or more stages of multi-pass cavities.

[0042] (II) The pulse compression device based on a multi-stage multi-pass cavity provided by the present invention is suitable for femtosecond or picosecond laser pulse beams with different pulse peak powers. By changing the thickness and position of the solid nonlinear medium, or the type and pressure of the gas medium, the intensity of the nonlinear effect is adjusted, and pulses of different energies and widths are optimized and debugged differently, which can effectively improve the compression ratio and solve the problem of limited compression ratio of a single-stage multi-pass cavity.

[0043] (III) The pulse compression device based on a multi-stage multi-pass cavity provided by the present invention has a simple structure, is easy to install, easy to operate, safe and reliable, and has strong adaptability, and can well solve the existing problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of a multi-pass cavity pulse compression device based on a two-stage gas cascade according to the present invention.

[0045] Figure 2 It is a schematic diagram of the spectrum change before and after the first-stage gas multi-pass cavity is broadened in the multi-pass cavity pulse compression device based on two-stage gas cascade in the present invention.

[0046] Figure 3 It is a schematic diagram of the change of pulse width before and after the first-stage gas multi-pass cavity compression in the multi-pass cavity pulse compression device based on two-stage gas cascade of the present invention.

[0047] Figure 4 It is a schematic diagram of the spectrum change before and after the second-stage gas multi-pass cavity is broadened in the multi-pass cavity pulse compression device based on two-stage gas cascade in the present invention.

[0048] Figure 5 It is a schematic diagram of the change in pulse width before and after the second-stage gas multi-pass cavity compression in the multi-pass cavity pulse compression device based on two-stage gas cascade of the present invention.

[0049] Figure 6 It is a schematic diagram of a multi-cavity pulse compression device based on a cascade of a primary solid and a primary gas according to the present invention.

[0050] Figure 7 It is a schematic diagram of the spectrum change before and after the first-stage solid multi-pass cavity is broadened in the multi-pass cavity pulse compression device based on the cascade connection of a first-stage solid and a first-stage gas in the present invention.

[0051] Figure 8 It is a schematic diagram of the change in pulse width before and after the first-stage gas multi-pass cavity compression in the multi-pass cavity pulse compression device based on the cascade connection of a first-stage solid and a first-stage gas of the present invention.

[0052] Fig. 9 A schematic diagram of the spectrum change before and after the second-stage gas multi-pass cavity is widened in a multi-pass cavity pulse compression device based on a cascade connection of a first-stage solid and a first-stage gas in the present invention.

[0053] Fig.10 It is a schematic diagram of the change in pulse width before and after the second-stage gas multi-pass cavity compression in the multi-pass cavity pulse compression device based on the cascade connection of a first-stage solid and a first-stage gas according to the present invention.

[0054] The meaning of each symbol in the accompanying drawings:

[0055] 1- pulse laser, 2- compression module, 3- pulse laser spot matching module, 4- multi-pass cavity module, 5- beam collimating lens, 6- pulse dispersion compensation module.

[0056] 7-a first reflector, 8-a second reflector, 9-a third reflector, 10-a fourth reflector, 11-a fifth reflector, 12-a sixth reflector, 13-a seventh reflector, 14-a eighth reflector, 15-a ninth reflector, 16-a first chirped mirror, 17-a second chirped mirror, 18-a third chirped mirror, 19-a fourth chirped mirror.

[0057] 4-1-Gas multi-pass cavity, 4-2-Solid multi-pass cavity.

[0058] 4-1-1-first entrance reflector, 4-1-2-first import mirror, 4-1-3-first concave mirror, 4-1-4-second concave mirror, 4-1-5-first export mirror, 4-1-6-first exit reflector, 4-1-7-vacuum chamber, 4-1-8-gas nonlinear medium.

[0059] 4-2-1-second entrance reflector, 4-2-2-second import mirror, 4-2-3-third concave mirror, 4-2-4-fourth concave mirror, 4-2-5-second export mirror, 4-2-6-second exit reflector, 4-2-7-solid nonlinear medium.

[0060] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0061] All components in the present invention, unless otherwise specified, are components known in the prior art.

[0062] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0063] Embodiment 1:

[0064] This embodiment provides a pulse compression device based on a multi-stage multi-pass cavity, such as Figure 1-Figure 10 As shown, the pulse laser 1 also includes a plurality of compression modules 2 arranged along the optical path of the pulse laser 1 .

[0065] The compression module 2 comprises a pulse laser spot matching module 3, a multi-pass cavity module 4, a beam collimating lens 5 and a pulse dispersion compensation module 6 which are arranged along the optical path of the pulse laser 1.

[0066] Pulse laser 1, used to generate picosecond and femtosecond pulse lasers.

[0067] The pulse laser spot matching module 3 is used to adjust the spot size and divergence angle of the picosecond and femtosecond pulse lasers to be consistent with the eigenmode of the multi-pass cavity.

[0068] The multi-pass cavity module 4 uses two concave mirrors separated by a certain distance to form a multi-pass cavity. This module is used to propagate the picosecond and femtosecond lasers passing through the spot matching module back and forth in the cavity for multiple times, and to interact nonlinearly with the nonlinear medium in the cavity to achieve spectrum broadening.

[0069] The beam collimating lens 5 is used to collimate and change the size of the expanded light spot.

[0070] The pulse dispersion compensation module 6 is used to compensate for the dispersion of the pulsed laser after being broadened and to compress the pulse width.

[0071] Among them, the pulse laser spot matching module 3, the multi-pass cavity module 4, the beam collimating lens 5, and the pulse dispersion compensation module 6 constitute the compression module 2, which is a one-stage complete compression process. The multi-stage multi-pass cavity refers to two or more times of this complete compression process.

[0072] The multi-stage multi-pass cavity refers to passing through a complete first-stage compression process twice or more, wherein the first-stage multi-pass cavity compression process refers to the pulse laser completely passing through the pulse laser spot matching module, the multi-pass cavity module, the beam collimating lens, and the dispersion compensation module. The multi-stage means that the pulse passes through the complete multi-pass cavity compression process twice or more, and the pulse laser is compressed twice or more.

[0073] The high-power pulse laser generates a pulse laser which enters the first-stage compression module 2, passes through the pulse laser spot matching module 3 to make the spot and divergence angle of the pulse laser consistent with the eigenmode in the multi-pass cavity module 4, and then enters the multi-pass cavity module 4, performs multiple round-trip transmissions to broaden the spectrum, and is sequentially exported from the multi-pass cavity module 4 through the plane mirror, passes through the beam collimating lens 5 to form a collimated spot, and then passes through the pulse dispersion compensation module 6 to perform dispersion compensation, compress the pulse width, and complete the first-stage multi-pass cavity compression.

[0074] The laser pulses compressed in the first stage enter the second stage compression module 2, pass through the pulse laser spot matching module 3 to make the spot and divergence angle of the pulse laser consistent with the eigenmode in the second stage multi-pass cavity module 4, then enter the second stage multi-pass cavity module 4 for multiple round trip transmissions to broaden the spectrum, and then sequentially lead out of the second stage multi-pass cavity module 4 through the plane mirror, pass through the second stage beam collimating lens 5 to form a collimated spot, and then pass through the second stage pulse dispersion compensation module 6 for dispersion compensation to compress the pulse width. The third or fourth stage compression can be set according to the pulse compression result.

[0075] As a preferred embodiment of this invention:

[0076] The multi-pass chamber module 4 is a gas multi-pass chamber 4-1, and the gas multi-pass chamber 4-1 includes:

[0077] The first entrance reflector 4-1-1, the first import mirror 4-1-2, the first concave mirror 4-1-3, the second concave mirror 4-1-4, the first export mirror 4-1-5 and the first exit reflector 4-1-6 are arranged along the optical path of the pulse laser 1, the concave surfaces of the first concave mirror 4-1-3 and the second concave mirror 4-1-4 are arranged opposite to each other, and a multi-pass cavity is formed between the first concave mirror 4-1-3 and the second concave mirror 4-1-4.

[0078] The gas multi-pass cavity 4-1 also includes a vacuum chamber 4-1-7 and a gas nonlinear medium 4-1-8 filled in the vacuum chamber 4-1-7.

[0079] The first entrance reflector 4-1-1, the first import mirror 4-1-2, the first concave mirror 4-1-3, the second concave mirror 4-1-4, the first export mirror 4-1-5 and the first exit reflector 4-1-6 are arranged in the vacuum chamber 4-1-7.

[0080] As a preferred embodiment of this invention:

[0081] The multi-pass cavity module 4 is a solid multi-pass cavity 4-2, and the solid multi-pass cavity 4-2 includes:

[0082] The second entrance reflector 4-2-1, the second import mirror 4-2-2, the third concave mirror 4-2-3, the fourth concave mirror 4-2-4, the second export mirror 4-2-5 and the second exit reflector 4-2-6 are arranged along the optical path of the pulse laser 1, the concave surfaces of the third concave mirror 4-2-3 and the fourth concave mirror 4-2-4 are arranged opposite to each other, and a multi-pass cavity is formed between the third concave mirror 4-2-3 and the fourth concave mirror 4-2-4.

[0083] The solid multi-pass cavity 4-2 also includes a solid nonlinear medium 4-2-7 arranged between the third concave mirror 4-2-3 and the fourth concave mirror 4-2-4.

[0084] As a preferred embodiment of this invention:

[0085] The multi-pass cavity module 4 is a solid-gas multi-pass cavity, and the solid-gas multi-pass cavity includes:

[0086] The third entrance reflector, the third import mirror, the fifth concave mirror, the sixth concave mirror, the third export mirror and the third exit reflector are arranged along the optical path of the pulse laser 1, the concave surfaces of the fifth concave mirror and the sixth concave mirror are arranged opposite to each other, and a multi-pass cavity is formed between the fifth concave mirror and the sixth concave mirror.

[0087] The solid-gas multi-pass cavity also includes a vacuum chamber and a solid nonlinear medium 4-2-7 and a gas nonlinear medium 4-1-8 arranged between the fifth concave mirror and the sixth concave mirror.

[0088] The third entrance reflector, the third import mirror, the fifth concave mirror, the sixth concave mirror, the third export mirror, the third exit reflector, the solid nonlinear medium 4-2-7 and the gas nonlinear medium 4-1-8 are all arranged in the vacuum chamber.

[0089] Both the solid and gas nonlinear media can be used for broadening the spectrum of pulsed lasers in a multi-pass cavity, wherein the solid medium has a higher nonlinearity, but is easily ionized and damaged during short pulse compression, while the gas medium has a low nonlinearity, has a higher ionization threshold and is not easily damaged. Solid, gaseous media or both can be used simultaneously in the spectrum broadening of the first-stage long pulse. After the first-stage multi-pass cavity pulse compression, the pulse width is relatively narrow, so the gaseous medium is selected for the second-stage multi-pass cavity compression.

[0090] The concave mirror spacing is selected to be appropriate according to laser parameters under steady-state conditions of laser propagation, so as to meet the requirements of spectrum broadening on the size of the intracavity light spot.

[0091] As a preferred embodiment of this invention:

[0092] The gas nonlinear medium 4-1-8 is an inert gas, including helium, neon, argon or krypton.

[0093] The solid nonlinear medium 4-2-7 includes: silicon dioxide, calcium fluoride, aluminum oxide, or yttrium aluminum garnet.

[0094] As a preferred embodiment of this invention:

[0095] The gas nonlinear medium 4-1-8 is neon or argon.

[0096] The solid nonlinear medium 4-2-7 is silicon dioxide, aluminum oxide or yttrium aluminum garnet.

[0097] As a preferred embodiment of this invention:

[0098] The pulse width of the pulse laser emitted by the pulse laser 1 is 100fs-10ps.

[0099] The power of the pulse laser emitted by the pulse laser 1 is 10W-300W.

[0100] The repetition frequency of the pulse laser emitted by the pulse laser 1 is 100 Hz-1 MHz.

[0101] The wavelength of the pulse laser emitted by the pulse laser 1 is 400nm-2000nm.

[0102] The energy of the pulse laser emitted by the pulse laser 1 is 0.1mJ-300mJ.

[0103] As a preferred embodiment of this invention:

[0104] The pulse width of the pulse laser emitted by the pulse laser is optimally 200fs-2ps.

[0105] The optimal power of the pulse laser emitted by the pulse laser is 10W-200W.

[0106] The optimal repetition frequency of the pulse laser emitted by the pulse laser is 1kHz-100kHz.

[0107] The optimal wavelength of the pulse laser emitted by the pulse laser is 800-1200nm.

[0108] The energy of the pulse laser emitted by the pulse laser is optimally 1mJ-50mJ.

[0109] As a preferred embodiment of this invention:

[0110] The pulse laser spot matching module 3 is composed of two lenses or three lenses; the focal length is -3000-3000mm, and the spacing is 0-1000mm according to the spot size.

[0111] The curvature radius of the concave mirror constituting the multi-pass cavity is 200-2500 mm.

[0112] The beam collimating lens 5 is composed of two lenses or concave mirrors, or three lenses or concave mirror groups.

[0113] When the laser beam waist radius is 30 mm, fused silica lenses with focal lengths of 1000 mm, -2100 mm, and -150 mm are used and placed 434 mm and 627 mm apart.

[0114] The pulse dispersion compensation module 6 is selected from one or more of the following: a chirped mirror, a grating, and a prism pair.

[0115] As a preferred embodiment of this invention:

[0116] The pulse laser spot matching module 3 is preferably a three-lens group.

[0117] The curvature radius of the concave mirror constituting the multi-pass cavity is preferably 400-2000 mm.

[0118] The beam collimating lens 5 is preferably a two-lens or concave mirror group.

[0119] The pulse dispersion compensation module 6 is preferably a chirped mirror.

[0120] The specific usage method of this embodiment is as follows:

[0121] The present invention proposes a pulse compression method based on a multi-stage multi-pass cavity. According to the above device module, the compression method comprises the following steps:

[0122] (1) Femtosecond pulse lasers emit pulsed laser beams. The laser pulses are collimated beams with a pulse width of 100 fs to 10 ps.

[0123] (3) Realize the matching of the pulse laser spot and the transmission mode of the multi-pass cavity: The pulse laser beam is input to the pulse laser spot matching module, and the pulse laser spot matching module matches the pulse laser spot with the intrinsic beam waist mode of the multi-pass cavity, so that the waist of the transformed beam is located at the center of the multi-pass cavity.

[0124] (4) Nonlinear spectrum broadening of pulsed laser: The pulsed laser is introduced into the multi-pass cavity through a coupling mirror. The curvature radius of the multi-pass cavity mirrors, the cavity mirror spacing and the pulsed laser beam form a closed loop optical path under stable conditions, and the beam is reflected and propagated multiple times between the two cavity mirrors. The nonlinear medium used for broadening can be a solid material, a gas medium or both. When a gas medium is used, the multi-pass cavity is placed in a stainless steel cavity filled with an inert gas used for broadening. The spectrum broadening depends on the nonlinear interaction between the pulsed laser and the nonlinear medium, including self-phase modulation, self-steepening and other processes. The pulsed laser propagates in the cavity and interacts nonlinearly with the nonlinear medium, which broadens the spectrum of the pulsed laser.

[0125] (5) Collimation of pulsed laser: The pulsed laser after spectral broadening is guided out of the multi-pass cavity through a reflector to a beam collimating lens. Since the divergence angle of the pulsed laser beam after broadening is large, a lens group is required to collimate it and adjust the light spot to a size that is easy to propagate.

[0126] (6) Dispersion compensation of pulsed laser after spectral broadening: After collimation, the pulsed laser with spectral broadening has dispersion, so the pulse width is not the shortest width. It is necessary to compensate for the dispersion and compress the pulse width to the shortest. The chirped mirror has different reflection depths for different spectral components through the multi-layer dielectric film, which can provide precise dispersion compensation and compress the pulse width to the shortest. After spectral broadening, the pulsed laser passes through the chirped mirror for multiple reflections and dispersion compensation, and finally obtains the shortest narrow pulse width.

[0127] (7) Multi-stage compression of pulsed lasers: For pulses with a pulse width higher than 200 fs, it is difficult to compress the pulse width to less than 10 fs using a single-stage multi-pass cavity. The pulse width can be compressed to less than 10 fs by continuous compression using a multi-stage multi-pass cavity. The pulse compressed at the first stage is passed through a pulse laser spot matching module again to match the spot with the intrinsic mode of the second-stage multi-pass cavity. The pulsed laser is introduced into the second-stage multi-pass cavity through a coupling mirror for spectrum broadening. The pulsed laser with spectrum broadened by the second-stage multi-pass cavity is guided to a beam collimating lens for collimation and spot size adjustment. The pulse width is then compressed by compensating for dispersion using a chirped mirror. The third and fourth-stage multi-pass cavities can be set according to the pulse compression results until the pulse width is less than 10 fs.

[0128] Embodiment 2:

[0129] like Figure 1 As shown, the pulse compression device based on the multi-stage multi-pass cavity provided by the present invention includes:

[0130] The 1030nm high-power laser 1 is used to output pulsed laser, with an output energy range of 1-100mJ; a repetition frequency of 1-100kHz; and a pulse width of 1ps. In this embodiment, a high-power laser with an output energy of 10kHz and 10mJ is selected.

[0131] The pulse laser spot matching module 3, the spot and divergence angle of the incident laser are consistent with the eigenmode in the multi-pass cavity, to avoid large differences between the two modes, which affects the multiple stable propagation of the light beam in the multi-pass cavity. The typical mode matching module has two lens groups and three lens groups; the first stage compression of this embodiment uses lens groups with focal lengths of 300mm, -200mm and 600mm to form the pulse laser spot matching module 3.

[0132] The laser beam emitted by the 1030nm high-power pulse laser 1 enters the first-stage compression module 2, vertically passes through the pulse laser spot matching module 3, and then changes direction through the first reflector 7 and the second reflector 8 to enter the first-stage multi-pass cavity module 4.

[0133] The first-stage multi-pass cavity module 4 is used for the laser to propagate back and forth multiple times inside the cavity to produce nonlinear interaction with the argon gas in the cavity to achieve spectral broadening, and is composed of a vacuum chamber 4-1-7, a first concave mirror 4-1-3, a first entrance reflector 4-1-1, a first import mirror 4-1-2, a first export mirror 4-1-5, a first exit reflector 4-1-6, and a second concave mirror 4-1-4.

[0134] Vacuum chamber 4-1-7: used to form a vacuum chamber, so that the inert gas is filled therein, and a nonlinear effect occurs with the pulse laser. In this example, the first-stage multi-pass cavity module 4 is filled with 1 bar of argon gas.

[0135] The first reflector 7, the second reflector 8, the third reflector 9, the fourth reflector 10, the first import mirror 4-1-2 and the first export mirror 4-1-5 are reflectors with a reflectivity higher than 99.9%, and the wavelength band covers 950nm-1100nm.

[0136] The first concave mirror 4-1-3 and the second concave mirror 4-1-4 form a Herriott type multi-pass cavity. The two concave mirrors have a curvature radius of 1800 mm and are 2000 mm apart. The reflectivity is higher than 99.9% and the wavelength covers 950nm-1100nm.

[0137] The divergent light beam after the first stage widening enters the light beam collimating lens 5 through the third reflector 9 and the fourth reflector 10. The light beam collimating lens 5 is used to collimate the divergent light beam after the first stage widening. The focal length of the lens is 600 mm.

[0138] The first-stage pulse dispersion compensation module 6 is used to compensate for the dispersion of the spectrally broadened pulse laser and compress the pulse width. In this example, a chirped mirror with a bandwidth of 950-1100nm is selected, and a single reflection can provide -300fs 2 The dispersion of Figure 1 The first chirped mirror 16 and the second chirped mirror 17 in the middle and upper part.

[0139] The pulsed laser that has completed the first-stage compression enters the second-stage compression module 2.

[0140] The first-stage laser beam vertically passes through the second-stage pulse laser spot matching module 3, and the second pulse laser spot matching module 3 is composed of lens groups of 200 mm, -150 mm and 800 mm respectively.

[0141] The second-stage multi-pass cavity module 4 is used for the laser to propagate back and forth multiple times inside the cavity to produce nonlinear interaction with the argon gas in the cavity to achieve spectral broadening. The structure is the same as that of the first-stage multi-pass cavity module 4. The difference is that the vacuum chamber 4-1-7 in the second-stage multi-pass cavity module 4 is filled with 0.5 bar of argon gas.

[0142] The fifth reflector 11, the sixth reflector 12, and the first introduction mirror 4-1-2 in the second-stage multi-pass cavity module 4 are reflectors with a reflectivity higher than 99.9%, and the wavelength band covers 950nm-1100nm.

[0143] The seventh reflector 13, the eighth reflector 14, the ninth reflector 15, and the first export mirror 4-1-5 in the second-stage multi-pass cavity module 4 are reflectors with a reflectivity higher than 99%, and the wavelength band covers 600nm-1300nm.

[0144] The first concave mirror 4-1-3 of the second-stage multi-pass cavity and the second concave mirror 4-1-4 of the multi-pass cavity form a Herriott-type multi-pass cavity. The two concave mirrors have a curvature radius of 1900 mm and a spacing of 2000 mm. The reflectivity is higher than 99%, and the wavelength covers 600nm-1300nm.

[0145] The divergent light beam after the second stage widening enters the second stage light beam collimating lens 5 through the seventh reflector 13 and the eighth reflector 14. The second stage light beam collimating lens 5 is used to collimate the divergent light beam after the second stage widening. The focal length of the lens is 800 mm.

[0146] In this example, the second stage compression uses a chirped mirror with a bandwidth of 600nm-1300nm, and a single reflection can provide -50fs 2 dispersion, as shown in the third chirped mirror 18 and the fourth chirped mirror 19 in the figure.

[0147] The following is combined with Figure 1 The technical solution of the present invention is further described.

[0148] The 10mJ, 1ps pulse emitted by the 1030nm high-power pulse laser 1 passes through the pulse laser spot matching module 2 and matches the intrinsic mode of the multi-pass cavity module 4 in the first-stage compression module 2; the pulse laser enters the first-stage multi-pass cavity module 4 through the first reflector 7, the second reflector 8, the first entrance reflector 4-1-1 in the first-stage compression module 2, and the first introduction mirror 4-1-2 in the first-stage compression module 2. The pulse laser is between the first concave mirror 4-1-3 and the second concave mirror 4-1-4 in the first-stage multi-pass cavity module 4. The multiple round trips between the laser beams interact nonlinearly with the argon gas to broaden the spectrum of the pulsed laser. The pulsed laser after spectrum broadening passes through the first export mirror 4-1-5 in the first-stage compression module 2, the first exit reflector 4-1-6 in the first-stage compression module 2, and the first-stage multi-pass cavity module 4, and then enters the beam collimating lens 5 in the first-stage compression module 2 through the third reflector 9 and the fourth reflector 10 to collimate the divergent pulsed laser. The first chirped mirror 16 and the second chirped mirror 17 are used to perform dispersion compensation on the pulsed laser to complete the first-stage compression.

[0149] The pulsed laser after the first-stage compression is matched with the eigenmode of the second-stage multi-pass cavity module 4 through the second-stage pulsed laser spot matching module 3; the pulsed laser enters the second-stage multi-pass cavity module 4 through the fifth reflector 11, the sixth reflector 12, the first entrance reflector 4-1-1 of the second-stage multi-pass cavity module 4 and the first introduction mirror 4-1-2 of the second-stage multi-pass cavity module 4, and the pulsed laser propagates back and forth for multiple times in the first concave mirror 4-1-3 and the second concave mirror 4-1-4 of the second-stage multi-pass cavity module 4 to interact nonlinearly with the argon gas, and the spectrum of the pulsed laser is broadened; the pulsed laser after spectrum broadening is exported from the second-stage multi-pass cavity module 4 through the first export mirror 4-1-5 and the first exit reflector 4-1-6 in the multi-pass cavity module 4, and then enters the beam collimating lens 5 in the second-stage compression module 2 through the seventh reflector 13 and the eighth reflector 14 to collimate the divergent laser; the third chirped mirror 18 and the fourth chirped mirror 19 are used to perform dispersion compensation on the pulsed laser to complete the second-stage compression, and finally output through the ninth reflector 15.

[0150] The spectrum broadened by the first-stage multipass cavity is as follows Figure 2 As shown in Figure 2, the pulse width after compression by the chirped mirror is Figure 3 The spectrum broadened by the second-stage multi-pass cavity is shown in Figure 4 As shown in Figure 2, the pulse width after compression by the chirped mirror is Figure 5 shown.

[0151] Figure 2 In the experiment of Example 1, a 1ps pulse passes through the first-stage multi-pass cavity to broaden the spectrum. The half-width of the spectrum is widened from nearly 1nm to 60nm. The time domain pulse corresponding to the spectrum is as follows: Figure 3 As shown, the compressed pulse width is compressed from the original 1ps of the laser output to 47fs.

[0152] Figure 4 In the first experiment, the 47fs pulse obtained by the first stage compression was passed through the second stage multi-pass cavity to broaden the spectrum. The half-height width of the spectrum was broadened from 60nm to nearly 500nm. The time domain pulse corresponding to the spectrum is as follows: Figure 5 As shown, the pulse width is compressed from 50 fs of the initial laser output to 5 fs. The pulse compression ratio is increased to 200 times by the two-stage cascade multi-pass cavity device of the present invention.

[0153] Embodiment 3:

[0154] like Figure 6 As shown, the pulse compression device based on the multi-stage multi-pass cavity provided by the present invention includes: a 1030nm high-power laser 1 for outputting pulsed laser, with an output energy range of 1-100mJ; a repetition frequency of 1-100kHz; a pulse width of 1ps; this embodiment selects a high-power laser with an output energy of 10kHz and 10mJ.

[0155] The pulse laser spot matching module 3, the spot and divergence angle of the incident laser are consistent with the eigenmode in the multi-pass cavity, to avoid large differences between the two modes, which affects the multiple stable propagation of the light beam in the multi-pass cavity. The typical mode matching module has two lens groups and three lens groups; the first stage compression of this embodiment uses lens groups with focal lengths of 300mm, -200mm and 600mm to form the pulse laser spot matching module 3.

[0156] The laser beam emitted by the 1030nm high-power pulse laser 1 enters the first-stage compression module 2, vertically passes through the pulse laser spot matching module 3, and then changes direction through the first reflector 7 and the second reflector 8 to enter the first-stage multi-pass cavity module 4.

[0157] The first-stage multi-pass cavity module 4 is used for the laser to propagate back and forth multiple times inside the cavity to produce nonlinear interaction with the solid medium in the cavity to achieve spectral broadening, and is composed of a second entrance reflector 4-2-1, a second import mirror 4-2-2, a third concave mirror 4-2-3, a fourth concave mirror 4-2-4, a second export mirror 4-2-5, a second exit reflector 4-2-6 and a solid nonlinear medium 4-2-7; the solid nonlinear medium 4-2-7 is a circular fused quartz plate with a thickness of 1 mm and a radius of 25.4 mm, which is placed 500 mm away from one side of the concave mirror.

[0158] The solid nonlinear medium 4-2-7 is 1 mm thick fused quartz and 50 mm in diameter.

[0159] The first reflector 7, the second reflector 8, the third reflector 9, the fourth reflector 10, the second import mirror 4-2-2 and the second export mirror 4-2-5 are reflectors with a reflectivity higher than 99.9%, and the wavelength band covers 950nm-1100nm.

[0160] The third concave mirror 4-2-3 and the fourth concave mirror 4-2-4 form a Herriott type multi-pass cavity. The two concave mirrors have a curvature radius of 1800 mm and a spacing of 2000 mm. The reflectivity is higher than 99.9%, and the wavelength covers 950nm-1100nm.

[0161] The divergent light beam after the first stage widening enters the second stage light beam collimating lens 5 through the third reflector 9 and the fourth reflector 10. The first stage light beam collimating lens 5 is used to collimate the divergent light beam after the first stage widening, and the focal length of the lens is 600 mm.

[0162] The first-stage dispersion compensation module 6 is used to perform dispersion compensation on the spectrally broadened pulse laser and compress the pulse width. In this example, a chirped mirror with a bandwidth of 950-1100nm is selected, and a single reflection can provide -300fs 2 The dispersion of Figure 6The first chirped mirror 16 and the second chirped mirror 17 in the middle and upper part.

[0163] The pulsed laser that has completed the first-stage compression enters the second-stage compression module 2.

[0164] The first-stage laser beam vertically passes through the second-stage pulse laser spot matching module 3, and the second-stage laser spot matching module 3 is composed of lens groups of 200mm, -150mm and 800mm respectively.

[0165] The second-stage multi-pass cavity module 4 is used for the laser to propagate back and forth multiple times inside the cavity to produce nonlinear interaction with the argon gas in the cavity to achieve spectral broadening, and consists of a vacuum chamber 4-1-7, a first concave mirror 4-1-3, a first entrance reflector 4-1-1, a first import mirror 4-1-2, a first export mirror 4-1-5, a first exit reflector 4-1-6, and a second concave mirror 4-1-4.

[0166] Vacuum chamber 4-1-7: used to form a vacuum chamber, which is filled with inert gas to produce nonlinear interaction with the pulse laser. In this example, the vacuum chamber 4-1-7 is filled with 0.5 bar of argon gas.

[0167] The fifth reflector 11, the sixth reflector 12, and the first introduction mirror 4-1-2 in the second-stage multi-pass cavity module 4 are reflectors with a reflectivity higher than 99.9%, and the wavelength band covers 950nm-1100nm.

[0168] The seventh reflector 13, the eighth reflector 14, the ninth reflector 15, and the first export mirror 4-1-5 in the second-stage multi-pass cavity module 4 are reflectors with a reflectivity higher than 99%, and the wavelength band covers 600nm-1300nm.

[0169] The first concave mirror 4-1-3 of the second-stage multi-pass cavity and the second concave mirror 4-1-4 of the multi-pass cavity form a Herriott-type multi-pass cavity. The two concave mirrors have a curvature radius of 1900 mm and a spacing of 2000 mm. The reflectivity is higher than 99%, and the wavelength covers 600nm-1300nm.

[0170] The divergent light beam after the second stage widening enters the second stage light beam collimating lens 5 through the seventh reflector 13 and the eighth reflector 14. The second stage light beam collimating lens 5 is used to collimate the divergent light beam after the second stage widening. The focal length of the lens is 800 mm.

[0171] In this example, the second stage compression uses a chirped mirror with a bandwidth of 600nm-1300nm, and a single reflection can provide -50fs 2 The dispersion of Figure 6 The third chirped mirror 18 and the fourth chirped mirror 19 in.

[0172] The following is combined with Figure 1The technical solution of the present invention is further described.

[0173] The 10mJ, 1ps pulse emitted by the 1030nm high-power pulse laser 1 is matched with the eigenmode of the multi-pass cavity module 4 in the first-stage compression module 2 through the pulse laser spot matching module 2; the pulse laser enters the first-stage multi-pass cavity module 4 through the first reflector 7, the second reflector 8, the second entrance reflector 4-2-1 and the second introduction mirror 4-2-2, and the pulse laser propagates back and forth multiple times in the first-stage multi-pass cavity module 4 to interact nonlinearly with the solid nonlinear medium 4-2-7, so that the spectrum of the pulse laser is broadened; the pulse laser after spectral broadening is exported from the first-stage multi-pass cavity module 4 through the second export mirror 4-2-5 and the second exit reflector 4-2-6, and then enters the beam collimating lens 5 in the first-stage compression module 2 through the third reflector 9 and the fourth reflector 10 to collimate the divergent pulse laser; the first chirped mirror 16 and the second chirped mirror 17 are used to perform dispersion compensation on the pulse laser to complete the first-stage compression.

[0174] The pulsed laser after the first-stage compression passes through the pulsed laser spot matching module 3 and the second-stage multi-pass cavity, and the eigenmode matching of the multi-pass cavity module 4; the pulsed laser enters the second-stage multi-pass cavity module 4 via the fifth reflector 11, the sixth reflector 12, the first entrance reflector 4-1-1 of the second-stage multi-pass cavity module 4 and the first introduction mirror 4-1-2 of the second-stage multi-pass cavity module 4, and the pulsed laser propagates back and forth between the first concave mirror 4-1-3 and the second concave mirror 4-1-4 in the second-stage multi-pass cavity for multiple times to interact nonlinearly with the argon gas, and the spectrum of the pulsed laser is broadened; the first export mirror 4-1-5 and the first exit reflector 4-1-6 in the multi-pass cavity module 4 of the pulsed laser after spectrum broadening are exported from the second-stage multi-pass cavity module 4, and then enter the beam collimating lens 5 in the second-stage compression module 2 through the seventh reflector 13 and the eighth reflector 14 to collimate the divergent laser; the third chirped mirror 18 and the fourth chirped mirror 19 are used to perform dispersion compensation on the pulsed laser to complete the second-stage compression, and finally output through the ninth reflector 15.

[0175] The spectrum broadened by the first-stage multipass cavity is as follows Figure 7 As shown in Figure 2, the pulse width after compression by the chirped mirror is Figure 8 shown.

[0176] The spectrum broadened by the second-stage multipass cavity is as follows Fig. 9 As shown in Figure 2, the pulse width after compression by the chirped mirror is Fig.10 shown.

[0177] Figure 7 In the experiment of Example 2, a 1ps pulse passes through the first-stage multi-pass cavity to broaden the spectrum. The half-width of the spectrum is broadened from nearly 1nm to nearly 60nm. The time domain pulse corresponding to the spectrum is as follows: Figure 8As shown, the compressed pulse width is compressed from the original 1ps of the laser output to 50fs.

[0178] Fig. 9 In the experiment of Example 2, the 50fs pulse obtained by the first stage compression is passed through the second stage multi-pass cavity to broaden the spectrum. The half-width of the spectrum is broadened from nearly 60nm to nearly 500nm. The time domain pulse corresponding to the spectrum is as follows: Fig.10 As shown, the pulse width is compressed from 50 fs of the initial laser output to 5 fs. The pulse compression ratio is increased to 200 times by the two-stage cascade multi-pass cavity device of the present invention.

[0179] The above technical solutions are only preferred specific implementation methods of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be conceived by any technician familiar with the field within the technical scope disclosed by the present invention without creative work are all covered within the protection scope of the present invention.

Claims

1. A pulse compression device based on a multi-stage multi-pass cavity, comprising a pulse laser (1), characterized in that: It also includes a plurality of compression modules (2) arranged along the optical path of the pulse laser (1); The compression module (2) comprises a pulse laser spot matching module (3), a multi-pass cavity module (4), a beam collimating lens (5) and a pulse dispersion compensation module (6) arranged along the optical path of the pulse laser (1).

2. The pulse compression device based on a multi-stage multi-pass cavity as claimed in claim 1, characterized in that: The multi-pass chamber module (4) is a gas multi-pass chamber (4-1), and the gas multi-pass chamber (4-1) comprises: A first entrance reflection mirror (4-1-1), a first introduction mirror (4-1-2), a first concave mirror (4-1-3), a second concave mirror (4-1-4), a first export mirror (4-1-5) and a first exit reflection mirror (4-1-6) are arranged along an optical path of a pulse laser (1), the concave surfaces of the first concave mirror (4-1-3) and the second concave mirror (4-1-4) being arranged opposite to each other, and a multi-pass cavity is formed between the first concave mirror (4-1-3) and the second concave mirror (4-1-4); The gas multi-pass cavity further comprises a vacuum chamber (4-1-7) and a gas nonlinear medium (4-1-8) filled in the vacuum chamber (4-1-7); The first entrance reflector (4-1-1), the first import mirror (4-1-2), the first concave mirror (4-1-3), the second concave mirror (4-1-4), the first export mirror (4-1-5) and the first exit reflector (4-1-6) are arranged in a vacuum chamber (4-1-7).

3. The pulse compression device based on a multi-stage multi-pass cavity as claimed in claim 1, characterized in that: The multi-pass cavity module (4) is a solid multi-pass cavity (4-2), and the solid multi-pass cavity (4-2) comprises: A second entrance reflection mirror (4-2-1), a second introduction mirror (4-2-2), a third concave mirror (4-2-3), a fourth concave mirror (4-2-4), a second export mirror (4-2-5) and a second exit reflection mirror (4-2-6) are arranged along the optical path of a pulse laser (1), the concave surfaces of the third concave mirror (4-2-3) and the fourth concave mirror (4-2-4) are arranged relative to each other, and a multi-pass cavity is formed between the third concave mirror (4-2-3) and the fourth concave mirror (4-2-4); The solid multi-pass cavity (4-2) further comprises a solid nonlinear medium (4-2-7) arranged between the third concave mirror (4-2-3) and the fourth concave mirror (4-2-4).

4. The pulse compression device based on a multi-stage multi-pass cavity as claimed in claim 1, characterized in that: The multi-pass cavity module (4) is a solid-gas multi-pass cavity, and the solid-gas multi-pass cavity comprises: A third entrance reflector, a third import mirror, a fifth concave mirror, a sixth concave mirror, a third export mirror and a third exit reflector are arranged along the optical path of the pulse laser (1), the concave surfaces of the fifth concave mirror and the sixth concave mirror are arranged opposite to each other, and a multi-pass cavity is formed between the fifth concave mirror and the sixth concave mirror; The solid-gas multi-pass cavity further comprises a vacuum chamber and a solid nonlinear medium (4-2-7) and a gas nonlinear medium (4-1-8) arranged between the fifth concave mirror and the sixth concave mirror; The third entrance reflector, the third import mirror, the fifth concave mirror, the sixth concave mirror, the third export mirror, the third exit reflector, the solid nonlinear medium (4-2-7) and the gas nonlinear medium (4-1-8) are all arranged in the vacuum chamber.

5. The pulse compression device based on a multi-stage multi-pass cavity according to claim 2, 3 or 4, characterized in that: The gas nonlinear medium (4-1-8) is an inert gas, including: helium, neon, argon or krypton; The solid nonlinear medium (4-2-7) includes: silicon dioxide, calcium fluoride, aluminum oxide, or yttrium aluminum garnet.

6. The pulse compression device based on a multi-stage multi-pass cavity as claimed in claim 5, characterized in that: The gas nonlinear medium (4-1-8) is neon or argon; The solid nonlinear medium (4-2-7) is silicon dioxide, aluminum oxide or yttrium aluminum garnet.

7. The pulse compression device based on a multi-stage multi-pass cavity as claimed in claim 1, characterized in that: The pulse width of the pulse laser emitted by the pulse laser (1) is 100fs-10ps; The power of the pulse laser emitted by the pulse laser (1) is 10W-300W; The repetition frequency of the pulse laser emitted by the pulse laser (1) is 100 Hz-1 MHz; The wavelength of the pulse laser emitted by the pulse laser (1) is 400nm-2000nm; The energy of the pulse laser emitted by the pulse laser (1) is 0.1 mJ-300 mJ.

8. The pulse compression device based on a multi-stage multi-pass cavity as claimed in claim 7, characterized in that: The pulse width of the pulse laser emitted by the pulse laser (1) is 200fs-2ps; The power of the pulse laser emitted by the pulse laser (1) is 10W-200W; The repetition frequency of the pulse laser emitted by the pulse laser (1) is 1kHz-100kHz; The wavelength of the pulse laser emitted by the pulse laser (1) is 800-1200nm; The energy of the pulse laser emitted by the pulse laser (1) is 1 mJ-50 mJ.

9. The pulse compression device based on a multi-stage multi-pass cavity as claimed in claim 2, 3 or 4, characterized in that: The pulse laser spot matching module (3) is composed of two lenses or three lenses; The curvature radius of the concave mirror constituting the multi-pass cavity is 300mm-6000mm; The beam collimating lens (5) is composed of two lenses or concave mirrors, or three lenses or concave mirror groups; The pulse dispersion compensation module (6) is selected from one or more of the following: a chirped mirror, a grating, and a prism pair.

10. The pulse compression device based on a multi-stage multi-pass cavity as claimed in claim 9, characterized in that: The pulse laser spot matching module (3) is preferably a three-lens group; The curvature radius of the concave mirror constituting the multi-pass cavity is preferably 400 mm-4000 mm; The beam collimating lens (5) is preferably a two-lens or concave mirror group; The pulse dispersion compensation module (6) is preferably a chirped mirror.

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