A short pulse regenerative amplifier based on spectral reshaping

Abstract

The application discloses a short pulse regenerative amplifier based on spectrum shaping, and belongs to the technical field of femtosecond lasers.The short pulse regenerative amplifier comprises a seed light source, a spectrum shaping system, a broadening module, an amplification module and a pulse compression module which are sequentially arranged along an optical path, the seed light source is used for outputting an initial pulse light beam, the spectrum shaping system is used for performing nonlinear effect spectrum broadening and collimation shaping on the initial pulse light beam, the broadening module is used for sequentially adjusting the pulse light beam into vertical polarization light and horizontal polarization light, and the pulse time domain width of the vertical polarization light is broadened to the order of 100 ps, the amplification module is used for extracting gain through multiple rounds of back-and-forth of the incident horizontal polarization light, and outputs an amplified pulse light signal, the laser gain energy in the amplification module is controlled by a gain energy adjusting module, and the pulse compression module is used for compressing and exporting the amplified pulse light signal.The application eliminates the influence of gain narrowing in the amplification process, obtains an amplified pulse with a wider spectrum, and the compressed pulse width is less than 100 fs.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of femtosecond laser technology, and particularly relates to a short pulse regenerative amplifier based on spectral shaping. BACKGROUND

[0002] The chirped pulse amplification (CPA) technology invented by Gerard Mourou and Donna Strickland in 1985 provides a reliable idea for the energy improvement of femtosecond laser, and the two people won the Nobel Prize in Physics in 2018. In combination with the CPA technology, the all-solid-state Yb-doped femtosecond laser amplifier plays an important role in the fields of industrial ultrafast non-thermal micro machining, extreme ultraviolet optical frequency comb, high flux high harmonic generation and angle-resolved electron momentum spectrum.

[0003] The emergence of the regenerative amplifier enables the further improvement of the energy of the ultra-short pulse laser, and even a very low incident laser energy can achieve a large enough gain in multiple round-trip amplification. At present, the disclosed technology has a regenerative cavity based on double Yb:KGW crystals, each crystal is pumped by two LDs with an average power of 50W, and an average power of 30W laser amplification output is obtained at a repetition frequency of 100kHz, and the spectral width is 5.4nm, corresponding to a pulse width of less than 300fs. The disclosed technology has an oscillator output of 10nJ single pulse energy, and after the pulse width of the seed pulse is expanded, it is injected into a regenerative amplifier based on a Yb:CGA crystal, and an average power of 36W laser amplification result is obtained. Finally, an average power of 28W, a repetition frequency of 500kHz, a single pulse energy of 56μJ, and a pulse width of 217fs, and a peak power of 258MW of high repetition rate ultra-short pulse laser output are realized by a transmission grating compression. The disclosed technology has a regenerative cavity using a Yb:KGW double crystal configuration based on two tangentially orthogonally placed Yb:KGW double crystals, and a repetition frequency of 1kHz, a single pulse energy of 1.2mJ are obtained. While obtaining the energy of mJ level, the pulse width is shortened to 227fs. However, due to the different gains of different spectral components of the input pulse within the gain bandwidth, the input pulse spectrum will be lost after multiple gain, that is, the gain narrowing phenomenon, and it is difficult to obtain an amplified pulse with a pulse width of less than 100fs, which limits the application of the laser in some fields. Therefore, in order to make the amplified pulse finally obtained maintain the same time quality characteristics as the seed pulse, it is necessary to accurately control the seed spectrum phase and each order of chirp during the amplification process. SUMMARY

[0004] Technical problems to be solved:

[0005] In order to avoid the shortcomings of the prior art, the present application provides a short pulse regenerative amplifier based on spectral shaping, which adopts a spectral shaping system based on second-order nonlinear effect to broaden the incident laser pulse and form a saddle-shaped spectrum at the same time, and determines the wavelength dip position based on the center wavelength of the light source, so that the gain narrowing is relieved; at the same time, by limiting the optical axis direction of the laser gain crystal, the gain spectrum in different axial directions is combined, so that the bandwidth is greatly increased, which is beneficial to offset the influence of gain narrowing in the amplification process, and finally a wide-spectrum amplified pulse is obtained, and the compressed pulse width is less than 100 fs.

[0006] The technical scheme of the present application is: a short pulse regenerative amplifier based on spectral shaping, comprising a seed light source, a spectral shaping system, a broadening module, an amplification module and a pulse compression module arranged in sequence along the optical path,

[0007] The initial pulse light beam is output by the seed light source;

[0008] The initial pulse light beam is subjected to nonlinear effect spectral broadening and collimation shaping by the spectral shaping system;

[0009] The collimated and shaped pulse light beam is adjusted to be vertical polarization light and horizontal polarization light in sequence by the broadening module, and the pulse time domain of the vertical polarization light is broadened to the order of hundreds of ps;

[0010] The incident horizontal polarization light is extracted gain in the regenerative cavity of the amplification module for multiple times, and the amplified pulse light signal is output; the laser gain energy in the amplification module is controlled by a gain energy adjusting module;

[0011] The amplified pulse light signal is compressed and exported by the pulse compression module.

[0012] A further technical scheme of the present application is that the seed light source is a ytterbium-doped medium-based light source, the maximum output power is 7W, the pulse width is 122fs, and the center wavelength is 1030nm.

[0013] A further technical scheme of the present application is that the spectral shaping system comprises a focusing lens, a nonlinear medium and a collimating lens arranged in sequence along the optical path; the material of the nonlinear medium is a BIBO crystal, the length of the BIBO crystal is 13mm, the phase matching condition is: θ=0°, φ=90°, and the phase mismatching amount is Δk=77.5mm-1;

[0014] The incident horizontal polarization light is focused to the nonlinear medium by the focusing lens, the spectrum is broadened by the nonlinear effect, and then collimated and shaped by the collimating lens, and the shaped light beam is incident to the broadening module.

[0015] A further technical scheme of the present application is that the pulse stretcher is a concentric stretcher based on a transmission grating pair; the ruling density of the transmission grating pair is 1600 L / mm, and the two surfaces thereof are coated with an antireflection film with a center wavelength of 1040 nm.

[0016] A further technical scheme of the present application is that the pulse stretcher is a concentric stretcher based on a transmission grating pair; the ruling density of the transmission grating pair is 1600 L / mm, and the two surfaces thereof are coated with an antireflection film with a center wavelength of 1040 nm.

[0017] A further technical scheme of the present application is that the pulse stretcher is a concentric stretcher based on a transmission grating pair; the ruling density of the transmission grating pair is 1600 L / mm, and the two surfaces thereof are coated with an antireflection film with a center wavelength of 1040 nm.

[0018] The laser crystal comprises two laser gain crystals, the laser gain crystal is a CaYAlO4 crystal doped with Yb3+, and the surfaces thereof are coated with an antireflection film with a wavelength of 980 nm-1100 nm; and the laser gain crystals are orthogonally arranged, and the two optical axes thereof are vertically arranged on a water-cooled copper block.

[0019] A further technical scheme of the present application is that the TFP incident angle of the first TFP mirror and the second TFP mirror is 65°, and the TFP incident angle of the third TFP mirror is 45°, and the p light is highly transmissive and the s light is highly reflective in the film coating range of 1010 nm-1060 nm.

[0020] A further technical scheme of the present application is that the pulse compression module comprises a high reflection mirror and a pulse compressor arranged in sequence along an optical path, the polarization state of the amplified light beam is unchanged after passing through the second optical isolation system, the light beam is transmitted through the third TFP mirror and passes above the high reflection mirror, and the light beam is incident on the pulse compressor for compression, and the compressed pulse is guided out through the reflection of the high reflection mirror.

[0021] A further technical scheme of the present application is that the gain energy adjustment module comprises a first pump source, a first optical coupling system, a second pump source and a second optical coupling system, wherein the pump laser output by the first pump source is collimated and focused to a laser crystal through the first optical coupling system, and the pump laser output by the second pump source is collimated and focused to another laser crystal through the second optical coupling system.

[0022] A pulse amplification method of a short pulse regenerative amplifier based on spectral shaping, and the specific steps are as follows:

[0023] An initial pulse light beam is output by the seed light source;

[0024] The initial pulse light beam is incident on the spectral shaping system to complete nonlinear effect spectral broadening and collimation shaping;

[0025] The collimated and shaped pulse light beam is incident on the broadening module, and the pulse light beam is adjusted to be vertical polarization light and horizontal polarization light in sequence through the broadening module, and the pulse time domain of the vertical polarization light is broadened to the order of hundreds of picoseconds;

[0026] After the horizontal polarization light is incident on the amplification module, a quarter-wave voltage is applied to the optoelectronic modulator in the amplification module, so that the horizontal polarization light extracts gain in the amplification module multiple times, and an amplified pulse light signal is output;

[0027] The amplified pulse light signal is guided out after being compressed by the pulse compression module.

[0028] Advantages

[0029] The present application has the advantages that the present application is a narrow pulse width high power regenerative amplifier based on spectral shaping, a spectral shaping system is directly arranged after a seed light source, a seed pulse can be broadened by using cascaded second-order nonlinear effects, so that a seed spectrum with sufficient bandwidth is ensured, and two ytterbium-doped laser crystals are vertically arranged in different optical axes, a gain spectrum covering the seed spectrum bandwidth and capable of reducing gain narrowing effect is provided according to the gain of different axes of the crystals, a broadener and a compressor based on a transmission grating are combined, and a laser amplification output with a pulse width less than 100 fs and an average power greater than 50 W can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1Structure schematic diagram of regenerative amplifier of the embodiment of the present application;

[0031] Figure 2 Structure schematic diagram of spectrum shaping system of the embodiment of the present application;

[0032] Figure 3 Structure schematic diagram of laser crystal of the embodiment of the present application;

[0033] Figure 4 Structure schematic diagram of tangential and placement direction of laser gain crystal of the embodiment of the present application, wherein (a) is a structure schematic diagram of first laser crystal placement direction, and (b) is a structure schematic diagram of second laser crystal placement direction;

[0034] Figure 5 Gain spectrum of two-axis emission cross section superposition of laser gain crystal of the embodiment of the present application;

[0035] Figure 6 Spectrum of seed light source and spectrum of light source after shaping of the embodiment of the present application, wherein (a) is a spectrum diagram of seed light source, and (b) is a spectrum diagram of light source after shaping;

[0036] Legend: 1, seed light source; 2, spectrum shaping system; 3, polarization beam splitter; 4, first optical isolation system; 5, pulse stretcher; 6, third TFP mirror; 7, second optical isolation system; 8, first TFP mirror; 9, electro-optical modulation device; 10, first plane mirror; 11, second TFP mirror; 12, first concave mirror; 13, second concave mirror; 14, third concave mirror; 15, first dichroic mirror; 16, laser crystal; 17, second dichroic mirror; 18, fourth concave mirror; 19, second plane mirror; 20, first pump source; 21, first optical coupling system; 22, second pump source; 23, second optical coupling system; 24, high reflection mirror; 25, pulse compressor; 2a, focusing lens; 2b, nonlinear medium; 2c, collimating lens; 16a, first laser crystal; 16b, second laser crystal. DETAILED DESCRIPTION

[0037] The embodiments described below by reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0038] Based on the existing amplifier gain bandwidth, the gain of different frequency spectrum components of the input pulse is different, which will cause the loss of the input pulse spectrum after multiple gain, that is, the gain narrowing phenomenon, it is difficult to obtain shorter pulse width, and the application of the laser in some fields is limited, and the like, the present application provides a kind of short pulse regenerative amplifier based on spectrum shaping, including seed light source, spectrum shaping system, expansion module, amplification module, pulse compression module are sequentially arranged along the light path, and the initial pulse light beam is output through the seed light source;The initial pulse light beam is subjected to nonlinear effect expansion and collimation shaping by the spectrum shaping system;The collimated and shaped pulse light beam is sequentially adjusted to vertical polarization light and horizontal polarization light by the expansion module, and the pulse time domain width is expanded to the order of hundreds of ps when it is in vertical polarization light;The horizontal polarization light is output after amplification by the amplification module through multiple rounds of gain extraction in the regenerative cavity;The laser gain energy in the amplification module is controlled by the gain energy adjusting module;The amplified pulse light signal is compressed and exported by the pulse compression module.

[0039] The above technical solutions are further described in combination with the drawings and examples as follows:

[0040] In one embodiment, referring to Figure 1 The short pulse regenerative amplifier based on spectrum shaping includes a seed light source 1, a spectrum shaping system 2, a polarization beam splitter 3, a first optical isolation system 4, a pulse stretcher 5, a third TFP mirror 6, a second optical isolation system 7, a first TFP mirror 8, an electro-optic modulation device 9, a first plane mirror 10, a second TFP mirror 11, a first concave mirror 12, a second concave mirror 13, a third concave mirror 14, a first dichroic mirror 15, a laser crystal 16, a second dichroic mirror 17, a fourth concave mirror 18, a second plane mirror 19, a first pump source 20, a first optical coupling system 21, a second pump source 22, a second optical coupling system 23, a high-reflectivity mirror 24, and a pulse compressor 25.

[0041] The first pump source 20 outputs pump laser, which is collimated and focused to the laser crystal 16 through the first optical coupling system 21, and the second pump source 22 outputs pump laser, which is collimated and focused to the laser crystal 16 through the second optical coupling system 23.

[0042] The seed light source 1 provides horizontally polarized light, the horizontally polarized light is shaped by the spectrum shaping system 2, and after shaping, the light beam becomes vertically polarized light after passing through the polarization beam splitter 3 and the first optical isolation system 4, and the vertically polarized light is incident into the pulse stretcher 5 and the pulse time domain of the vertically polarized light is stretched to the order of 100 ps; after stretching, the light beam is reflected to the first optical isolation system 4 again, reflected to the second optical isolation system 7 through the polarization beam splitter 3 and the third TFP mirror 6, the second optical isolation system 7 changes the stretched light beam into horizontally polarized light, then passes through the first TFP mirror 8 and the electro-optical modulation device 9 without a quarter-wave voltage in turn, and is reflected by the first plane mirror 10; after reflection, the light beam passes through the electro-optical modulation device 9 again, and the polarization state is rotated by 90° after passing through the electro-optical modulation device twice, becomes vertically polarized light, and a quarter-wave voltage is applied to the electro-optical modulation device 9 after passing through, then is reflected by the first TFP mirror 8, the second TFP mirror 11, the first concave mirror 12, the second concave mirror 13, the third concave mirror 14 and the first dichroic mirror 15 in turn, extracts gain through the laser crystal 16, and then is incident into the second plane mirror 19 through the second dichroic mirror 17 and the fourth concave mirror 18; the angle of the second plane mirror 19 is adjusted to make the incident light beam return along the original path, extract gain again through the laser crystal 16 after passing through the second dichroic mirror 17 and the fourth concave mirror 18, then is reflected by the first dichroic mirror 15, the third concave mirror 14, the second concave mirror 13, the first concave mirror 12, the second TFP mirror 11 and the first TFP mirror 8, passes through the electro-optical modulation device 9 with a quarter-wave voltage, is reflected by the first plane mirror 10, passes through the electro-optical modulation device 9 with a quarter-wave voltage again, the polarization direction of the electro-optical modulation device 9 does not change after passing through twice, and the gain is extracted in the regenerative cavity multiple times, until the quarter-wave voltage on the electro-optical modulation device 9 is removed, the light passes through the first plane mirror 10 again, becomes horizontally polarized light by passing through the electro-optical modulation device 9 again, and is guided out of the cavity through the first TFP mirror 8 to obtain the amplified light beam; the polarization state of the amplified light beam does not change after passing through the second optical isolation system 7, is transmitted by the third TFP mirror 6 and passes through above the high reflector 24, is incident into the pulse compressor 25 for compression, the pulse compressor 25 is arranged to have a higher incident height than the height of the outgoing light beam, the compressed light beam is reflected by the high reflector 24, the pulse light compression is completed, and the compressed pulse light is guided out.

[0043] In one embodiment, the seed light source 1 is a ytterbium-doped medium-based light source, the maximum output power of the seed light source 1 is 7 W, the pulse width is 122 fs, and the center wavelength is 1030 nm.

[0044] In one embodiment, with reference to Figure 2As shown, the spectrum shaping system 2 comprises a focusing lens 2a, a nonlinear medium 2b and a collimating lens 2c; horizontal polarized light is focused by the focusing lens 2a to the nonlinear medium 2b, and after spectrum broadening by the nonlinear effect, the light is collimated and shaped by the collimating lens 2c, and the shaped light beam is incident to the polarizing beamsplitter 3.

[0045] Preferably, the material of the nonlinear medium 2b is BIBO crystal, the length of the BIBO crystal is 13 mm, the phase matching condition is θ = 0°, φ = 90°, and the phase mismatch is Δk = 77.5 mm. -1 .

[0046] In one embodiment, the polarizing beamsplitter is coated with antireflection film for 1028-1064 nm, and can pass p-polarized light and reflect s-polarized light.

[0047] In one embodiment, the first optical isolation system 4 and the second optical isolation system 7 are arranged to rotate the polarization by 90° in the forward direction and keep the polarization unchanged in the reverse direction.

[0048] In one embodiment, the pulse stretcher 5 is a concentric stretcher based on a pair of transmission gratings, which is used to stretch the seed pulse in time domain to the order of 100 ps,

[0049] Preferably, the grating density of the pair of transmission gratings is 1600 L / mm, and the two surfaces of the pair of transmission gratings are coated with antireflection film for 1040 nm.

[0050] In one embodiment, the TFP incident angle of the first TFP mirror 8 and the second TFP mirror 11 is 65°, and the TFP incident angle of the third TFP mirror 6 is 45°, and the film coating range is 1010 nm-1060 nm, and the first TFP mirror 8 and the second TFP mirror 11 have high transmission for p-polarized light and high reflection for s-polarized light.

[0051] In one embodiment, the electro-optical modulation device 9 is used to change the polarization state of the laser in the cavity, and is arranged to rotate the polarization direction by 45° each time the light beam passes through the electro-optical modulation device 9 without applying a quarter-wave voltage, and rotate the polarization direction by 90° each time the light beam passes through the electro-optical modulation device 9 when a quarter-wave voltage is applied.

[0052] In one embodiment, the reflectivity R of the first plane mirror 10 and the second plane mirror 19 is greater than 99.9%, and the first concave mirror 12, the second concave mirror 13, the third concave mirror 14 and the fourth concave mirror 18 are used to control the laser mode size at the gain crystal. In this embodiment, the relative distances of the first concave mirror 12, the second concave mirror 13, the third concave mirror 14 and the fourth concave mirror 18 are controlled so that the beam waists of the regenerative cavity laser are respectively located on the two laser crystals 16, and the good matching of the pump light spot and the seed laser spot on the laser crystal 16 is ensured, so that the seed pulse obtains higher gain when passing through the laser crystal 16.

[0053] In one embodiment, the first dichroic mirror 15 and the second dichroic mirror 17 are coated with high-transmission films of 900-980 nm and high-reflection films of 1020-1200 nm.

[0054] In one embodiment, referring to FIG. 1, the laser crystal 16 includes two laser gain crystals, a first laser crystal 16a and a second laser crystal 16b. Figure 3

[0055] Preferably, the laser gain crystal is a CaYAlO4 crystal doped with a rare earth ion Yb 3+ Preferably, the laser gain crystal is a CaYAlO4 crystal doped with a rare earth ion Yb

[0056] Preferably, the laser gain crystal is cut perpendicularly and placed vertically on a water-cooled copper block with the two optical axes.

[0057] In one embodiment, referring to FIG. 1, the laser crystal 16 includes two laser gain crystals, a first laser crystal 16a and a second laser crystal 16b. Figure 4 Figure 4 In one embodiment, referring to FIG. 1, the laser crystal 16 includes two laser gain crystals, a first laser crystal 16a and a second laser crystal 16b. Figure 4 In one embodiment, referring to FIG. 1, the laser crystal 16 includes two laser gain crystals, a first laser crystal 16a and a second laser crystal 16b. Figure 5 In one embodiment, referring to FIG. 1, the laser crystal 16 includes two laser gain crystals, a first laser crystal 16a and a second laser crystal 16b.

[0058] In one embodiment, the first pump source 20 and the second pump source 22 are fiber-coupled semiconductor lasers.

[0059] Preferably, the first pump source 20 and the second pump source 22 have a maximum output power of 130 W, a central wavelength of 981 nm, a numerical aperture of 0.15, and a fiber core diameter of 105 μm.

[0060] In one embodiment, the first optical coupling system 21 and the second optical coupling system 23 are 1:4 optical coupling systems for collimating and focusing the pump laser to the laser crystal 16.

[0061] In one embodiment, the pulse compressor 25 is a transmission grating pair-based compressor for compressing the amplified pulse to the femtosecond level.

[0062] Preferably, the transmission grating pair has a ruling density of 1600 L / mm, and the two surfaces of the transmission grating pair are coated with high-transmission films of a central wavelength of 1040 nm.

[0063] ​​In one embodiment, a pulse amplification method of a short pulse regenerative amplifier based on spectral shaping, the specific steps are as follows:

[0064] Step 1: output an initial pulse light beam from the seed light source;

[0065] Step 2: the initial pulse light beam is incident to the spectral shaping system to complete the nonlinear effect spectral broadening and collimation shaping;

[0066] Step 3: the collimated and shaped pulse light beam is incident to the broadening module, and the pulse light beam is adjusted to vertical polarization light, horizontal polarization light in turn by the broadening module, and the pulse time domain of the vertical polarization light is expanded to the order of hundreds of picoseconds;

[0067] Step 4: after the horizontal polarization light is incident to the amplification module, a quarter-wave voltage is applied to the photoelectric modulator in the amplification module, so that the horizontal polarization light extracts gain multiple times in it, and outputs the amplified pulse light signal;

[0068] Step 5: the amplified pulse light signal is compressed by the pulse compression module and then output.

[0069] In one embodiment, referring to Figure 6 , the spectrum of the seed light source 1 and the spectrum of the shaped light source, Figure 6 (a) is the spectrum diagram of the seed light source 1, Figure 6 (b) is the spectrum diagram of the shaped light source; when the seed light source 1 outputs an average power of 7W, a spectral half-width of 15nm, and a pulse width of 122fs, after the spectral system, an average power of 6W, a spectral half-width of 56nm, and a pulse width of 48fs are output, and the optical-to-optical conversion efficiency is 85.7%. The shaped spectrum is obviously broadened and presents a saddle shape, which is very beneficial to offset the influence of gain narrowing in the amplification process, so as to obtain an amplified pulse with a wider spectrum.

[0070] Although the embodiments of the present application have been shown and described above, it should be understood that the above-mentioned embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-mentioned embodiments without departing from the principles and purposes of the present application within the scope of the present application.

Claims

1. A spectral-shaping based short-pulse regenerative amplifier, characterized by: The seed light source, the spectrum shaping system, the broadening module, the amplification module and the pulse compression module are arranged along the light path in sequence. The initial pulse light beam is output by the seed light source; The initial pulse light beam is subjected to nonlinear effect spectrum broadening and collimation shaping by the spectrum shaping system; the spectrum shaping system comprises a focusing lens, a nonlinear medium and a collimating lens arranged along the light path in sequence; the nonlinear medium is made of BIBO crystal, the length of the BIBO crystal is 13 mm, the phase matching condition is θ=0° and φ=90°, and the phase mismatching amount is Δk=77.5 mm-1; The horizontal polarized light is focused by the focusing lens to the nonlinear medium, the spectrum is broadened by the nonlinear effect, and then the collimation shaping is performed by the collimating lens, and the shaped light beam is incident to the broadening module; The pulse light beam subjected to the collimation shaping is adjusted to be vertical polarized light and horizontal polarized light in sequence by the broadening module, and the pulse time domain width is broadened to the order of 100 ps when it is vertical polarized light; The horizontal polarized light is output by the amplification module, the gain is extracted in the regenerative cavity for multiple times, and the amplified pulse light signal is output; the laser gain energy in the amplification module is controlled by the gain energy adjusting module; The pulse compression module is used for compressing and exporting the amplified pulse light signal.

2. The spectrally shaped short pulse regenerative amplifier of claim 1, wherein: The seed light source is an ytterbium-doped medium-based light source, the maximum output power is 7 W, the pulse width is 122 fs, and the center wavelength is 1030 nm.

3. The spectrally shaped short pulse regenerative amplifier of claim 1, wherein: The broadening module comprises a polarization beam splitter, a first optical isolation system, a pulse stretcher, a third TFP mirror, a second optical isolation system arranged along the light path in sequence, wherein the first optical isolation system and the second optical isolation system are arranged to rotate the polarization by 90° when the light beam passes through in the forward direction, and the polarization remains unchanged when the light beam passes through in the reverse direction; the shaped light beam is converted into vertical polarized light after passing through the polarization beam splitter and the first optical isolation system, and then is incident to the pulse stretcher, the pulse time domain of the polarized light is broadened to the order of 100 ps by the pulse stretcher, the broadened light beam passes through the first optical isolation system again, is reflected by the polarization beam splitter and the third TFP mirror to the second optical isolation system, and is converted into horizontal polarized light by the second optical isolation system and then enters the amplification module.

4. The spectrally shaped short pulse regenerative amplifier of claim 3, wherein: The amplification module comprises a first TFP mirror, an electro-optic modulation device, a first plane mirror, a second TFP mirror, a first concave mirror, a second concave mirror, a third concave mirror, a first dichroic mirror, a laser crystal, a second dichroic mirror, a fourth concave mirror and a second plane mirror arranged along the light path in sequence; the polarization direction of the light pulse is rotated by 90° by applying a quarter-wave voltage to the electro-optic modulation device, the gain can be extracted in the amplification module for multiple times, until the quarter-wave voltage on the electro-optic modulation device is removed, the light pulse is changed from vertical polarized light to horizontal polarized light by the first plane mirror and the electro-optic modulation device again, and is guided out of the cavity by the first TFP mirror to obtain the amplified light beam. The laser crystal comprises two laser gain crystals, the laser gain crystals are Yb3+-doped CaYAlO4 crystals, surfaces of the laser gain crystals are coated with a 980nm-1100nm anti-reflection film, and the laser gain crystals are orthogonally arranged, and two optical axes of the laser gain crystals are vertically arranged on a water-cooled copper block.

5. The spectrally shaped short pulse regenerative amplifier of claim 4, wherein: The TFP incident angle of the first TFP mirror and the second TFP mirror is 65°, and the TFP incident angle of the third TFP mirror is 45°, and in the range of 1010nm-1060nm film coating, the p light is highly transparent and the s light is highly reflective.

6. The spectrally shaped short pulse regenerative amplifier of claim 4, wherein: The gain energy adjusting module comprises a first pump source, a first optical coupling system, a second pump source and a second optical coupling system, wherein the first pump source outputs pump laser which is collimated and focused to one laser crystal through the first optical coupling system, and the second pump source outputs pump laser which is collimated and focused to another laser crystal through the second optical coupling system.

7. The spectrally shaped short pulse regenerative amplifier of claim 4, wherein: The pulse compression module comprises a high reflection mirror and a pulse compressor arranged in sequence along an optical path, the polarization state of the amplified light beam is unchanged after passing through the second optical isolation system, the light beam is transmitted through the third TFP mirror and passes above the high reflection mirror, is incident to the pulse compressor for compression, and the compressed light beam is reflected by the high reflection mirror and is guided out.

8. A method of pulse amplification for a spectrally shaped regenerative amplifier according to any of claims 1-7, characterized by The specific steps are as follows: An initial pulse light beam is output from the seed light source; The initial pulse light beam is incident to the spectrum shaping system to complete nonlinear effect spectrum broadening and collimation shaping; The collimated and shaped pulse light beam is incident to the broadening module, the pulse light beam is adjusted to vertical polarization light and horizontal polarization light in sequence through the broadening module, and the pulse time domain of the vertical polarization light is broadened to the order of 100ps; The horizontal polarization light is incident to the amplification module, a quarter-wave voltage is applied to the optoelectronic modulator in the amplification module, the horizontal polarization light is extracted gain multiple times in the optoelectronic modulator, and an amplified pulse light signal is output; The amplified pulse light signal is compressed through the pulse compression module and is guided out.

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