The spatial chirp generated in the Ti：sapphire multipass amplifier is numerically investigated based on the one- dimensional （1D） and two-dimensional （2D） Frantz-Nodvik equations. The simulation indicates that th...The spatial chirp generated in the Ti：sapphire multipass amplifier is numerically investigated based on the one- dimensional （1D） and two-dimensional （2D） Frantz-Nodvik equations. The simulation indicates that the spatial chirp is induced by the spatially inhomogeneous gain, and it can be almost eliminated by utilization of proper beam profiles and spot sizes of the signal and pump pulses, for example, the pump pulse has a top-hatted beam profile and the signal pulse has a super-Gaussian beam profile with a relatively larger spot size. In this way, a clear understanding of spatial chirp mechanisms in the Ti：sapphire multipass amplifier is proposed, therefore we can effectively almost eliminate the spatial chirp and improve the beam quality of a high-power Ti：sapphire chirped pulse amplifier system.展开更多
We demonstrate a 100-TW-class femtosecond Ti:sapphire laser running at a repetition rate of 0.1Hz based on a 20TW/10 Hz laser facility (XL-Ⅱ).Pumping the new stage amplifier with a 25J green Nd:glass laser,we success...We demonstrate a 100-TW-class femtosecond Ti:sapphire laser running at a repetition rate of 0.1Hz based on a 20TW/10 Hz laser facility (XL-Ⅱ).Pumping the new stage amplifier with a 25J green Nd:glass laser,we successfully improve the laser energy to 3.4J with duration of 29 fs,corresponding to a peak power of 11 7 TW.展开更多
We develop a splicing technology of Ti:sapphire crystals for a high-energy chirped pulse amplifier laser system that can suppress the parasitic lasing to improve the amplification efficiency compared to a large-size s...We develop a splicing technology of Ti:sapphire crystals for a high-energy chirped pulse amplifier laser system that can suppress the parasitic lasing to improve the amplification efficiency compared to a large-size single Ti:sapphire crystal amplifier. Theoretical investigations on the characteristics of the amplifier with four splicing Ti:sapphire crystals,such as parasitic-lasing suppression and amplification efficiencies, are carried out. Some possible issues resulting from this splicing technology, including spectral modulation, stretching or splitting of the temporal profile, and the sidelobe generation in the spatial domain(near field and far field), are also investigated. Moreover, the feasibility of the splicing technology is preliminarily demonstrated in an experiment with a small splicing Ti:sapphire crystals amplifier. The temporal profile and spatial distribution of the output pulse from the splicing Ti:sapphire crystal amplifier are discussed in relation to the output pulse from a single Ti:sapphire crystal amplifier.展开更多
A novel tiled Ti:sapphire(Ti:S)amplifier was experimentally demonstrated with>1 J amplified chirped pulse output.Two Ti:S crystals having dimensions of 14 mm×14 mm×25 mm were tiled as the gain medium in a...A novel tiled Ti:sapphire(Ti:S)amplifier was experimentally demonstrated with>1 J amplified chirped pulse output.Two Ti:S crystals having dimensions of 14 mm×14 mm×25 mm were tiled as the gain medium in a four-pass amplifier.Maximum output energy of 1.18 J was obtained with 2.75 J pump energy.The energy conversion efficiency of the tiled Ti:S amplifier was comparable with a single Ti:S amplifier.The laser pulse having the maximum peak power of 28 TW was obtained after the compressor.Moreover,the influence of the beam gap on the far field was discussed.This novel tiled Ti:S amplifier technique can provide a potential way for 100 PW or EW lasers in the future.展开更多
Amplified spontaneous emission (ASE) and its restraint in a femtosecond Ti: sapphire chirped-pulse amplifier were investigated. The noises arising from ASE were effectively filtered out in the spatial, temporal and sp...Amplified spontaneous emission (ASE) and its restraint in a femtosecond Ti: sapphire chirped-pulse amplifier were investigated. The noises arising from ASE were effectively filtered out in the spatial, temporal and spectral domain. Pulses as short as 38 fs were amplified to peak power of 1.4 MI. The power ratio between the amplified femtosecond pulse and the ASE was higher than 106: 1.展开更多
We experimentally compare the output abilities of lightly and heavily doped Ti：Sapphire（Ti：S） amplifiers with diameters as large as 150 mm. Although a lightly doped Ti：S is more favorable to overcome parasitic la...We experimentally compare the output abilities of lightly and heavily doped Ti：Sapphire（Ti：S） amplifiers with diameters as large as 150 mm. Although a lightly doped Ti：S is more favorable to overcome parasitic lasing（PL）and transverse amplified spontaneous emission（TASE）, the self-phase-modulation（SPM） effect becomes more pronounced when a longer crystal is used. Recompression of the amplified, stretched pulses can be seriously affected by the SPM effect. We then propose a temporal multi-pulse pump scheme to suppress PL and TASE in a thin, heavily doped Ti：S crystal. This novel temporal multi-pulse pump technique can find potential applications in 10 PW chirped-pulse amplification laser systems.展开更多
We demonstrate a harmonic mode-locked ytterbium-doped fibre ring laser, which consists of a polarization-sensitive isolator, two polarization controllers, two 976nm laser diodes as the pump source and a two-segment yt...We demonstrate a harmonic mode-locked ytterbium-doped fibre ring laser, which consists of a polarization-sensitive isolator, two polarization controllers, two 976nm laser diodes as the pump source and a two-segment ytterbium-doped fibre. Utilizing an additive pulse mode-locked technique based on nonlinear polarization evolution, the ytterbium-doped fibre laser can operate in mode-locked state by adjusting the position of polarization controllers. The cavity fundamental repetition rate is 23.78 MHz. We also observe the second- and third-harmonic mode locking in the normal dispersion region, and their repetition rates are 47.66 MHz and 71.56 MHz, respectively. Over-driving of the saturable absorber in the harmonic mode-locking pulse is analysed and discussed in detail.展开更多
基金Project supported by 100 Talents Program of Chinese Academy of Sciencesthe National Natural Science Foundation of China(Grant Nos.61475169,61521093,and 11127901)the Youth Innovation Promotion Association of Chinese Academy of Sciences
文摘The spatial chirp generated in the Ti：sapphire multipass amplifier is numerically investigated based on the one- dimensional （1D） and two-dimensional （2D） Frantz-Nodvik equations. The simulation indicates that the spatial chirp is induced by the spatially inhomogeneous gain, and it can be almost eliminated by utilization of proper beam profiles and spot sizes of the signal and pump pulses, for example, the pump pulse has a top-hatted beam profile and the signal pulse has a super-Gaussian beam profile with a relatively larger spot size. In this way, a clear understanding of spatial chirp mechanisms in the Ti：sapphire multipass amplifier is proposed, therefore we can effectively almost eliminate the spatial chirp and improve the beam quality of a high-power Ti：sapphire chirped pulse amplifier system.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11074298,91126008,10804128 and 10925421the National Basic Research Program of China under Grant No 2007CB815104the Instrument Developing Project of Chinese Academy of Sciences under Grant No 2010004.
文摘We demonstrate a 100-TW-class femtosecond Ti:sapphire laser running at a repetition rate of 0.1Hz based on a 20TW/10 Hz laser facility (XL-Ⅱ).Pumping the new stage amplifier with a 25J green Nd:glass laser,we successfully improve the laser energy to 3.4J with duration of 29 fs,corresponding to a peak power of 11 7 TW.
基金partially supported by the National Basic Research Program of China (Grant No. 2011CB808101)the National Natural Science Foundation of China (NSFC) (Grant Nos. 61221064, 61078037, 11127901, 11134010)the International S&T Cooperation Program of China (Grant No. 2011DFA11300)
文摘We develop a splicing technology of Ti:sapphire crystals for a high-energy chirped pulse amplifier laser system that can suppress the parasitic lasing to improve the amplification efficiency compared to a large-size single Ti:sapphire crystal amplifier. Theoretical investigations on the characteristics of the amplifier with four splicing Ti:sapphire crystals,such as parasitic-lasing suppression and amplification efficiencies, are carried out. Some possible issues resulting from this splicing technology, including spectral modulation, stretching or splitting of the temporal profile, and the sidelobe generation in the spatial domain(near field and far field), are also investigated. Moreover, the feasibility of the splicing technology is preliminarily demonstrated in an experiment with a small splicing Ti:sapphire crystals amplifier. The temporal profile and spatial distribution of the output pulse from the splicing Ti:sapphire crystal amplifier are discussed in relation to the output pulse from a single Ti:sapphire crystal amplifier.
基金the National Key R&D Program of China(No.2017YFE0123700)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB1603)+2 种基金the National Natural Science Foundation of China(No.61925507)the Program of Shanghai Academic/Technology Research Leader(No.18XD1404200)the Shanghai Municipal Science and Technology Major Project(No.2017SHZDZX02)。
文摘A novel tiled Ti:sapphire(Ti:S)amplifier was experimentally demonstrated with>1 J amplified chirped pulse output.Two Ti:S crystals having dimensions of 14 mm×14 mm×25 mm were tiled as the gain medium in a four-pass amplifier.Maximum output energy of 1.18 J was obtained with 2.75 J pump energy.The energy conversion efficiency of the tiled Ti:S amplifier was comparable with a single Ti:S amplifier.The laser pulse having the maximum peak power of 28 TW was obtained after the compressor.Moreover,the influence of the beam gap on the far field was discussed.This novel tiled Ti:S amplifier technique can provide a potential way for 100 PW or EW lasers in the future.
文摘Amplified spontaneous emission (ASE) and its restraint in a femtosecond Ti: sapphire chirped-pulse amplifier were investigated. The noises arising from ASE were effectively filtered out in the spatial, temporal and spectral domain. Pulses as short as 38 fs were amplified to peak power of 1.4 MI. The power ratio between the amplified femtosecond pulse and the ASE was higher than 106: 1.
文摘We experimentally compare the output abilities of lightly and heavily doped Ti：Sapphire（Ti：S） amplifiers with diameters as large as 150 mm. Although a lightly doped Ti：S is more favorable to overcome parasitic lasing（PL）and transverse amplified spontaneous emission（TASE）, the self-phase-modulation（SPM） effect becomes more pronounced when a longer crystal is used. Recompression of the amplified, stretched pulses can be seriously affected by the SPM effect. We then propose a temporal multi-pulse pump scheme to suppress PL and TASE in a thin, heavily doped Ti：S crystal. This novel temporal multi-pulse pump technique can find potential applications in 10 PW chirped-pulse amplification laser systems.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60577019 and 60137010.
文摘We demonstrate a harmonic mode-locked ytterbium-doped fibre ring laser, which consists of a polarization-sensitive isolator, two polarization controllers, two 976nm laser diodes as the pump source and a two-segment ytterbium-doped fibre. Utilizing an additive pulse mode-locked technique based on nonlinear polarization evolution, the ytterbium-doped fibre laser can operate in mode-locked state by adjusting the position of polarization controllers. The cavity fundamental repetition rate is 23.78 MHz. We also observe the second- and third-harmonic mode locking in the normal dispersion region, and their repetition rates are 47.66 MHz and 71.56 MHz, respectively. Over-driving of the saturable absorber in the harmonic mode-locking pulse is analysed and discussed in detail.
