CN104577690A - Ultra-broadband coherent synthesis chirp pulse amplification laser system - Google Patents

Abstract

The invention provides an ultra-broadband coherent synthesis chirp pulse amplification laser system. The system comprises an ultra-broadband seed source, a pulse broadening compression and spectral beam splitting and beam combination unit, an optical parameter amplification unit, a reflector and a mirror lens. The pulse broadening compression and spectral beam splitting and beam combination unit comprises a high-dispersion transmission panel and eight diffraction grisms. The optical parameter amplification unit comprises three optical parameter amplifiers of different gain bandwidth. By means of the ultra-broadband coherent synthesis chirp pulse amplification laser system, high gain amplification can be conducted on ultra-broadband laser pulses, the gain-narrowing effect, the nonlinear effect and gain medium damage are avoided, and joule-level monocyclic laser pulses can be generated.

Description

Ultra-broadband coherent synthesis chirped pulse amplification laser system

technical field

The invention relates to the field of lasers, in particular to an ultra-broadband coherent synthesis chirped pulse amplification laser system, which is mainly applicable to ultra-broadband laser systems, coherent synthesis laser systems, single-cycle laser systems, and Joule-level high-energy single-cycle laser systems.

Background technique

High-energy single-period (~3fs) laser pulses are one of the forefronts of current international laser technology research. In 2009, Gunther Krauss et al. coherently combined two femtosecond fiber lasers with the same source but in different wavelength bands to generate nanojoule 4.3fs single-cycle laser pulses (Gunther Krauss, et.al.Synthesis of a single cycle of light with compact erbium-doped fiber technology, Nature photonics, Vol 4, pp33, 2010.). In 2011, Shu-Wei Huang et al. coherently synthesized two optical parametric amplification lasers with the same source but different wavelength bands to produce a 15uJ single-cycle laser pulse (Shu-Wei Huang, et.al. High-energy pulse synthesis with sub-cycle waveform control for strong-field physics, Nature photonics, Vol 5, pp 475, 2011.). Although the above two methods have achieved single-period laser pulses, the single-pulse energy is very small. The main reasons include:

1. Both of the above two methods perform coherent synthesis on the conversion limit short pulse, so the nonlinear effect of the high-power pulse in the transmission medium and the damage threshold of the medium limit the energy increase of the synthesized pulse;

2. Both of the above two methods use a dichromatic chip to achieve coherent synthesis of two pulses, so the nonlinear effect of high-power transmitted light and the damage threshold of the dichromatic chip limit the energy increase of the synthesized pulse.

In 2013, Bruno E. Schmidt et al. carried out frequency domain sub-band optical parametric amplification on the Fourier surface of the grating-based 4f system to avoid the gain narrowing effect, and at the same time, the amplified single pulse energy was increased due to the Fourier transform limit pulse broadening , resulting in a 1.43mJ double-period laser pulse (Bruno E. Schmidt, et.al. Frequency domain optical parametric amplification, Nature communications, ncomms4643, 2014.). Although this method increases the energy of periodic laser pulses to the level of millijoules, it is difficult to increase it to the level of joules, several joules, or even tens of joules. The main reason is that this method amplifies the pulses of different frequency bands on the Fourier surface, and the limited bandwidth of each frequency band avoids the gain narrowing of the amplifying medium. At the same time, the broadened time pulse width reduces the nonlinear effect and improves the damage. threshold. However, if the bandwidth of each frequency band is further reduced, a very high-density grating, as well as a very large-aperture and very long-focus concave mirror are required, so the system scale will be extremely large and become unfeasible.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art, and propose an ultra-broadband coherent synthesis chirped pulse amplification laser system. The system can perform high-gain amplification on ultra-broadband laser pulses, avoids gain-narrowing effects, nonlinear effects and gain medium damage, and can generate Joule-level single-period laser pulses.

In order to achieve the above-mentioned purpose of the invention, the technical scheme of the present invention is as follows:

An ultra-broadband coherent synthesis chirped pulse amplification laser system is characterized in that the system includes an ultra-broadband seed source, pulse stretching and compression, and a spectral beam splitting and combining unit, an optical parametric amplification unit, a mirror and a folding mirror. The pulse stretching compression and spectral beam splitting and combining unit includes a high dispersion transmission plate and eight diffraction gratings: the first diffraction grating, the second diffraction grating, the third diffraction grating, the fourth diffraction grating, the fifth Diffraction grating, the sixth diffraction grating, the seventh diffraction grating and the eighth diffraction grating, the optical parametric amplification unit includes three optical parametric amplifiers with different gain bandwidths: the first optical parametric amplifier, the second optical parametric amplifier amplifier and the third optical parametric amplifier, the positional relationship of the above components is as follows:

The signal light output by the ultra-broadband seed source enters the pulse stretching and compression and spectrum beam splitting and beam combining unit: after being diffracted by the first diffraction grating and the second diffraction grating, the light beam spreads in space based on the spectrum to generate spatial chirp, and the transmission After passing through the plate with excessive dispersion, it is divided into high-frequency band beams, intermediate-frequency band beams and low-frequency band beams:

The high-frequency band light beam is diffracted by the third diffraction grating and the fourth diffraction grating to eliminate spatial chirp, reflected by the first reflector and enters the first optical parametric amplifier, and the amplified idler light passes through the first reflector Turning back and changing the height position, reflected by the second reflector, diffracted again by the fourth diffraction grating and the third diffraction grating, transmitted by the high-dispersion transmission plate, diffracted by the second diffraction grating and the first diffraction grating to output;

The intermediate frequency band light beam is diffracted by the fifth diffraction grating and the sixth diffraction grating to eliminate spatial chirp, reflected by the third reflector and enters the second optical parametric amplifier, and the amplified idler frequency light is returned by the second reflector And change the height position, reflected by the fourth reflector, diffracted by the sixth diffraction grating and the fifth diffraction grating, transmitted by the high-dispersion transmission plate, and output by the second diffraction grating and the first diffraction grating;

The low-frequency band beam is diffracted by the seventh and eighth diffraction gratings to eliminate spatial chirp, reflected by the fifth mirror and enters the third optical parametric amplifier, and the amplified idler light is returned by the third mirror And change the height position, reflected by the sixth reflector, diffracted by the eighth diffraction grating and the seventh diffraction grating, transmitted by the high-dispersion transmission plate, and output by the second diffraction grating and the first diffraction grating.

In the pulse stretching and compression and spectral beam splitting and combining unit, the first diffraction grating is parallel to the second diffraction grating, the third diffraction grating, the fourth diffraction grating, the fifth diffraction grating, and the sixth diffraction grating , the seventh diffraction grating and the eighth diffraction grating are parallel to each other, the first diffraction grating, the second diffraction grating and the third diffraction grating, the fourth diffraction grating, the fifth diffraction grating, and the sixth diffraction grating , The seventh diffraction prism and the eighth diffraction prism are antiparallel to the mirror images of the high dispersion transmission plate.

The second-order dispersion introduced by the pulse stretching and compression and spectral beam splitting and combining unit is negative, and the third-order dispersion is zero.

The gain bandwidths of the first optical parametric amplifier, the second optical parametric amplifier and the third optical parametric amplifier in the optical parametric amplification unit are different, and respectively amplify the high-frequency band beam, the intermediate-frequency band beam and the low-frequency band beam.

The first folded mirror, the second folded mirror and the third folded mirror all have a translation adjustment mechanism along the direction of the folded optical path, so as to realize the delay adjustment of coherent combination.

The pulse stretching compression and spectral beam splitting and combining unit implements chirp-based time stretching and spectrum-based spatial beam splitting for the signal light before the optical parametric amplification unit, and implements based on the idler light after the optical parametric amplification unit. Chirp temporal compression and spectral-based spatial beam combining.

Technical effect of the present invention is as follows:

In the ultra-broadband coherent synthesis chirped pulse amplification laser system of the present invention, in the first pass through the pulse stretching compression and spectral beam splitting and combining unit, the signal light spreads out in space based on the spectrum after passing through the first diffraction grating and the second diffraction grating, After passing through the high-dispersion transmission plate, it is divided into high-frequency band beams by the third and fourth diffraction gratings, the fifth and sixth diffraction gratings, and the seventh and eighth diffraction gratings , mid-frequency band beams, and low-frequency band beams, while fully compensating for spatial chirp, spatial beam splitting based on spectrum is realized. In addition, the signal light is introduced into the second-order negative time chirp in this process to realize the time stretching of the pulse.

In the optical parametric amplifying unit, the high frequency band beam, the intermediate frequency band beam and the low frequency band beam are amplified by the first optical parametric amplifier, the second optical parametric amplifier and the third optical parametric amplifier respectively, thereby avoiding the gain narrowing effect. Since the time-stretched pulse is amplified, nonlinear effects and damage to the gain medium are avoided. The idler light amplified by the optical parametric amplification unit has a time chirp opposite to that of the signal light, thereby realizing time chirp inversion, that is, the idler light has a positive time chirp.

In the pulse stretching and compression and spectral beam splitting and combining unit again, the idler light of the high-frequency band beam, the idler light of the intermediate-frequency band beam, and the idler light of the low-frequency band beam are separated by the fourth diffraction prism and the third diffraction prism respectively. , the sixth diffraction grating and the fifth diffraction grating, and the eighth diffraction grating and the seventh diffraction grating, after passing through the high-dispersion transmission plate and diffracting through the second diffraction grating and the first diffraction grating, completely The spectral-based spatial beam combining is realized while compensating the spatial chirp. In addition, the idler light is introduced into the second-order negative time chirp in this process to realize the time compression of the pulse.

Compared with the prior art, the ultra-broadband coherent synthesis chirped pulse amplification laser system of the present invention has the following technical characteristics:

The invention can perform high-gain amplification on ultra-broadband laser pulses, avoids gain narrowing effects, nonlinear effects and gain medium damage, and can generate Joule-level single-period laser pulses.

Description of drawings

Fig. 1 is a schematic diagram of an embodiment of an ultra-broadband coherent synthesis chirped pulse amplification laser system of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments, in order to understand the structure, composition and work flow of the present invention more clearly, but this should not limit the protection scope of the patent of the present invention.

Fig. 1 is a schematic diagram of an embodiment of an ultra-broadband coherent synthesis chirped pulse amplification laser system of the present invention. It can be seen from the figure that the present invention includes an ultra-broadband seed source 1, a pulse stretching and compression and spectral beam splitting and combining unit, an optical parametric amplification unit, and a mirror and catadioptric mirrors, the described pulse broadening compression and spectrum beam splitting and beam combining unit includes a high dispersion transmission plate 4 and eight diffraction gratings: the first diffraction grating 2, the second diffraction grating 3, the third diffraction grating Grating 5, the fourth diffraction grating 6, the fifth diffraction grating 11, the sixth diffraction grating 12, the seventh diffraction grating 17 and the eighth diffraction grating 18, the optical parametric amplification unit includes three different gain Bandwidth optical parametric amplifiers: the first optical parametric amplifier 8, the second optical parametric amplifier 14 and the third optical parametric amplifier 20, the positional relationship of the above components is as follows:

The ultra-broadband seed source 1 outputs 600nm-1200nm ultra-broadband signal light and enters the pulse stretching and compression and spectrum beam splitting and combining unit: after being diffracted by the first diffraction grating 2 and the second diffraction grating 3, the beam is dispersed in space based on the spectrum to generate a space Chirp, after passing through the high-dispersion transmission plate 4, it is divided into 600nm-800nm high-frequency band beams, 800nm-1000nm intermediate-frequency band beams and 1000nm-1200nm low-frequency band beams:

The 600-800nm high-frequency band light beam is diffracted by the third diffraction grating 5 and the fourth diffraction grating 6 to eliminate spatial chirp, is reflected by the first mirror 7 and enters the first optical parametric amplifier 8, and the amplified idler light passes through the second A folding mirror 9 turns back and changes the height position, and then enters the pulse broadening and compression and spectrum beam splitting and combining unit after being reflected by the second mirror 10: diffracted by the fourth diffraction grating 6, diffracted by the third diffraction grating 5, The high-dispersion transmission plate 4 transmits, diffracts through the second diffraction grating 3, and diffracts through the first diffraction grating 2 to output.

The 800nm-1000nm intermediate frequency band light beam is diffracted by the fifth diffraction grating 11 and the sixth diffraction grating 12 to eliminate spatial chirp, reflected by the third mirror 13 and enters the second optical parametric amplifier 14, and the amplified idler frequency light passes through the second The folding mirror 15 turns back and changes the height position, and then enters the pulse broadening and compression and spectrum beam splitting and combining unit after being reflected by the fourth reflecting mirror 16: diffracting through the sixth diffraction grating 12, diffracting through the fifth diffraction grating 11, and diffracting through the high The dispersive transmission plate 4 transmits, diffracts through the second diffraction grating 3 , and diffracts through the first diffraction grating 2 to output.

The 1000nm-1200nm low-frequency band light beam is diffracted by the seventh diffraction grating 17 and the eighth diffraction grating 18 to eliminate spatial chirp, reflected by the fifth reflector 19 and enters the third optical parametric amplifier 20, and the amplified idler light passes through the third The folding mirror 21 turns back and changes the height position, and then enters the pulse broadening and compression and spectrum beam splitting and combining unit after being reflected by the sixth reflecting mirror 22: diffracting through the eighth diffraction grating 18, diffracting through the seventh diffraction grating 17, and diffracting through the high The dispersive transmission plate 4 transmits, diffracts through the second diffraction grating 3 , and diffracts through the first diffraction grating 2 to output.

The first diffraction grating 2 and the second diffraction grating 3 in the pulse stretching compression and spectrum beam splitting and combining unit are parallel, the third diffraction grating 5, the fourth diffraction grating 6, the fifth diffraction grating 11, The sixth diffraction grating 12, the seventh diffraction grating 17 and the eighth diffraction grating 18 are parallel to each other, and the first and second diffraction gratings and the third, fourth, fifth, sixth, seventh and eighth diffraction gratings have high dispersion transmission Plate 4 mirrors antiparallel. The second-order dispersion introduced by the pulse stretching and compression and spectral beam splitting and combining unit is negative, and the third-order dispersion is zero.

In the optical parametric amplification unit, the first optical parametric amplifier 8, the second optical parametric amplifier 14 and the third optical parametric amplifier 20 have different gain bandwidths, corresponding to 600-800nm high-frequency band beams, 800nm-1000nm intermediate-frequency band beams and 1000nm-1200nm low-frequency band beam completes energy amplification.

The idler light amplified by the first optical parametric amplifier 8, the second optical parametric amplifier 14 and the third optical parametric amplifier 20 is returned and changed by the first turning mirror 9, the second turning mirror 15 and the third turning mirror 21 respectively. height position. The first turning mirror 9 , the second turning mirror 15 and the third turning mirror 21 all have translational adjustment along the direction of the turning light path, so as to realize the delay adjustment of coherent combination.

The pulse stretching compression and spectral beam splitting and combining unit implements chirp-based time stretching and spectrum-based spatial beam splitting for the signal light before the optical parametric amplification unit, and implements based on the idler light after the optical parametric amplification unit. Chirp temporal compression and spectral-based spatial beam combining.

In the first pass through the pulse stretching and compression and spectral beam splitting and combining unit, the signal light passes through the first diffraction grating 2 and the second diffraction grating 3 and spreads out in space based on the spectrum, and passes through the high-dispersion transmission plate 4 and is transmitted by the third The diffraction grating 5 and the fourth diffraction grating 6, the fifth diffraction grating 11 and the sixth diffraction grating 12, and the seventh diffraction grating 17 and the eighth diffraction grating 18 are divided into 600-800nm high-frequency band beams, The 800nm-1000nm mid-frequency band beam and the 1000nm-1200nm low-frequency band beam fully compensate for spatial chirp while realizing spectrum-based spatial beam splitting. In addition, the signal light is introduced into the second-order negative time chirp in this process to realize the time stretching of the pulse.

In the optical parametric amplifying unit, the 600-800nm high frequency band light beam, the 800nm-1000nm intermediate frequency band light beam and the 1000nm-1200nm low frequency band light beam are respectively fed by the first optical parametric amplifier 8, the second optical parametric amplifier 14 and the third optical parametric amplifier 20 Sub-band amplification avoids gain-narrowing effects. Since the time-stretched pulse is amplified, nonlinear effects and damage to the gain medium are avoided. The idler light amplified by the optical parametric amplification unit has a time chirp opposite to that of the signal light, thereby realizing time chirp inversion, that is, the idler light has a positive time chirp.

In the pulse stretching and compression and spectral beam splitting and combining unit again, the idler light of the 600-800nm high-frequency band beam, the 800nm-1000nm intermediate frequency band beam idler light, and the 800nm-1000nm low-frequency band beam idler light are respectively separated by the fourth After the diffraction grating 6 and the third diffraction grating 5, the sixth diffraction grating 12 and the fifth diffraction grating 11, and the eighth diffraction grating 18 and the seventh diffraction grating 17 are diffracted, they pass through the high dispersion transmission plate 4 After being diffracted by the second diffraction grating 3 and the first diffraction grating 2, the spatial chirp is completely compensated, and at the same time, spatial beam combining based on spectrum is realized. In addition, the idler light is introduced into the second-order negative time chirp in this process to realize the time compression of the pulse.

Experiments show that, compared with the prior art, the invention can perform high-gain amplification on 600nm-1200nm ultra-broadband laser pulses, avoid gain narrowing effects, nonlinear effects and gain medium damage, and can generate Joule-level single-period laser pulses.

Finally, it should be noted that in the present invention, the ultra-broadband laser is divided into three beams based on the spectrum, that is, three frequency bands for broadening, beam splitting, amplification, combining, and compression. According to the method of the present invention, the ultra-broadband laser can be divided into three beams based on the spectrum. Any beam, that is, any frequency band, can be broadened, split, amplified, combined, and compressed. Those skilled in the art should understand that modifications or equivalent replacements to the technical solutions of the present invention will not depart from the spirit and scope of the present invention, and all of them should be covered by the claims of the present invention.

Claims (4)

1. a ultra broadband optics coherence tomography Chirp pulse amplification laser system, it is characterized in that, this system comprises ultra broadband seed source (1), Shu Danyuan is closed in pulse strenching compression and spectrum beam splitting, optically erasing unit, catoptron and catadioptric mirror, described pulse strenching compression and spectrum beam splitting are closed Shu Danyuan and are comprised one piece high dispersion transmission flat board (4), first diffraction rib grid (2), second diffraction rib grid (3), 3rd diffraction rib grid (5), 4th diffraction rib grid (6), 5th diffraction rib grid (11), 6th diffraction rib grid (12), 7th diffraction rib grid (17) and the 8th diffraction rib grid (18), described optically erasing unit comprises first photoparametric amplifier (8) with different gains bandwidth, second photoparametric amplifier (14) and the 3rd photoparametric amplifier (20), the position relationship of above-mentioned component is as follows:

The flashlight that described ultra broadband seed source (1) exports enters pulse strenching compression and Shu Danyuan is closed in spectrum beam splitting: scatter in space generation space chirp after the first diffraction rib grid (2) and the second diffraction rib grid (3) diffraction, is divided into high frequency band light beam, mf band light beam and low-frequency band light beam through after described high dispersion transmission flat board (4):

Described high frequency band light beam eliminates space chirp through the 3rd diffraction rib grid (5) and the 4th diffraction rib grid (6) diffraction, the first photoparametric amplifier (8) is entered through the first catoptron (7) reflection, ideler frequency light after amplification is turned back through the first catadioptric mirror (9) and changes height and position, through the second catoptron (10) reflection through the 4th diffraction rib grid (6) diffraction, through the 3rd diffraction rib grid (5) diffraction, through the transmission of high dispersion transmission flat board (4), through the second diffraction rib grid (3) diffraction, export through the first diffraction rib grid (2) diffraction;

Described mf band light beam eliminates space chirp through the 5th diffraction rib grid (11) and the 6th diffraction rib grid (12) diffraction, the second photoparametric amplifier (14) is entered through the 3rd catoptron (13) reflection, ideler frequency light after amplification is turned back through the second catadioptric mirror (15) and changes height and position, through the 4th catoptron (16) reflection, through the 6th diffraction rib grid (12) and the 5th diffraction rib grid (11) diffraction, through the transmission of high dispersion transmission flat board (4), export through the second diffraction rib grid (3) with through the first diffraction rib grid (2) diffraction;

Described low-frequency band light beam eliminates space chirp through the 7th diffraction rib grid (17) and the 8th diffraction rib grid (18) diffraction, the 3rd photoparametric amplifier (20) is entered through the 5th catoptron (19) reflection, ideler frequency light after amplification is turned back through the 3rd catadioptric mirror (21) and changes height and position, through the 6th catoptron (22) reflection, through the 8th diffraction rib grid (18) and the 7th diffraction rib grid (17) diffraction, through the transmission of high dispersion transmission flat board (4), export through the second diffraction rib grid (3) and the first diffraction rib grid (2) diffraction.

2. ultra broadband optics coherence tomography Chirp pulse amplification laser system according to claim 1, it is characterized in that, the first described diffraction rib grid (2) are parallel with the second diffraction rib grid (3), 3rd diffraction rib grid (5), 4th diffraction rib grid (6), 5th diffraction rib grid (11), 6th diffraction rib grid (12), 7th diffraction rib grid (17) and the 8th diffraction rib grid (18) are parallel to each other, first diffraction rib grid, second diffraction rib grid and the 3rd diffraction rib grid, 4th diffraction rib grid, 5th diffraction rib grid, 6th diffraction rib grid, 7th diffraction rib grid, 8th diffraction rib grid are about high dispersion transmission flat board (4) mirror image antiparallel, the 2nd order chromatic dispersion that Shu Danyuan introducing is closed in described pulse strenching compression and spectrum beam splitting is negative, third-order dispersion is zero.

3. ultra broadband optics coherence tomography Chirp pulse amplification laser system according to claim 1, it is characterized in that, described the first photoparametric amplifier (8), the second photoparametric amplifier (14) are different with the gain bandwidth (GB) of the 3rd photoparametric amplifier (20), amplify respectively to high frequency band light beam, mf band light beam and low-frequency band light beam.

4. ultra broadband optics coherence tomography Chirp pulse amplification laser system according to claim 1, it is characterized in that, described first mirror (9), second mirror (15) and the 3rd mirror (21) of turning back of turning back of turning back all has along turning back the translational controlling mechanism of optical path direction, realizes the delay adjustment of optics coherence tomography.