Chirped wideband pump and seed pulses are usually considered for backward Raman amplification（BRA） in plasmas to achieve an extremely high-power laser pulse. However, current theoretical models only contain either a...Chirped wideband pump and seed pulses are usually considered for backward Raman amplification（BRA） in plasmas to achieve an extremely high-power laser pulse. However, current theoretical models only contain either a chirped pump or a chirped seed. In this paper, modified three-wave coupling equations are proposed for the BRA in the plasmas with both chirped wideband pump and seed. The simulation results can more precisely describe the experiments, such as the Princeton University experiment. The optimized chirp and bandwidth are determined based on the simulation to enhance the output intensity and efficiency.展开更多
An ultrashort 10-GHz pulse generation scheme was successfully demonstrated using a bulk material InGaAsP electroabsorption modulator to generate the seed pulse. A self-phase modulation-based reshaper was used after th...An ultrashort 10-GHz pulse generation scheme was successfully demonstrated using a bulk material InGaAsP electroabsorption modulator to generate the seed pulse. A self-phase modulation-based reshaper was used after the adiabatic soliton compression in a comb-like dispersion profiled fiber. Experiments and simulations confirm that the reshaper effectively removes the pulse pedestal and improves the pulse extinction ratio. As a result, the 10-GHz pulse had no pedestal, a high extinction ratio, and a pulse width of only 1.4 ps.展开更多
Targets with microstructured front surfaces have shown great potential in improving high-intensity laser–matter interaction.We present cone-shaped microstructures made out of silicon and titanium created by ultrashor...Targets with microstructured front surfaces have shown great potential in improving high-intensity laser–matter interaction.We present cone-shaped microstructures made out of silicon and titanium created by ultrashort laser pulse processing with different characteristics.In addition,we illustrate a process chain based on moulding to recreate the laser-processed samples out of polydimethylsiloxane,polystyrol and copper.With all described methods,samples of large sizes can be manufactured,therefore allowing time-efficient,cost-reduced and reliable ways to fabricate large quantities of identical targets.展开更多
We propose a nanotube-based erbium-doped fiber laser that can deliver conventional soliton (CS) and stretched pulse (SP) based on D-shaped fiber saturable absorber (DF-SA) where evanescent-field interaction works. The...We propose a nanotube-based erbium-doped fiber laser that can deliver conventional soliton (CS) and stretched pulse (SP) based on D-shaped fiber saturable absorber (DF-SA) where evanescent-field interaction works. The novel Nanotube-based Fiber Laser can generate SP or CS by tuning pump power and polarization controller (PC) properly. The net cavity dispersion of laser is slightly negative. In our experiment, by optimizing the PC in the cavity, CS and SP can be obtained at the central wavelengths of 1530.6 nm and 1530.3 nm due to on carbon nanotubes and the spectral filtering effect induced by nonlinear polarization rotation. Although the acquired CS and SP nearly have the same central wavelengths, they show distinct optical spectra, 3-dB bandwidths. The proposed fiber laser with switchable CS and SP is attractive for ultrashort pulse generation and fast measurements in practical applications.展开更多
The electron behavior in laser field is described in detail. Based on the ID semiclassical model, a2D semiclassical model is proposed analytically using 3D DC-tunneling ionization theory. Lots of harmonic features are...The electron behavior in laser field is described in detail. Based on the ID semiclassical model, a2D semiclassical model is proposed analytically using 3D DC-tunneling ionization theory. Lots of harmonic features are explained by this model, including the analytical demonstration of the maximum electron energy 3.17U p Finally, some experimental phenomena such as the increase of the cutoff harmonic energy with the decrease of pulse duration and the “anomalous” fluctuations in the cutoff region are explained by this model.展开更多
The molecular wake-assisted interaction between two collinear femotosecond laser pulses is investigated in air,which leads to the generation of a controllable 1.8 mJ super-continuum pulse with an elongated self-guided...The molecular wake-assisted interaction between two collinear femotosecond laser pulses is investigated in air,which leads to the generation of a controllable 1.8 mJ super-continuum pulse with an elongated self-guided channel due to the cross-phase modulation of the impulsively aligned diatomic molecules in air. For two parallel launched femtosecond laser pulses with a certain spatial separation,controllable attraction and repulsion of the pulses are observed due to the counter-balance among molecular wakes,Kerr and plasma effects,where the molecular wakes show a longer interaction distance than the others to control the propagation of the intense ultrashort laser pulses.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11305157)the Development Foundation of China Academy of Engineering Physics Laboratory(CAEPL)(Grant No.2013A0401019)
文摘Chirped wideband pump and seed pulses are usually considered for backward Raman amplification（BRA） in plasmas to achieve an extremely high-power laser pulse. However, current theoretical models only contain either a chirped pump or a chirped seed. In this paper, modified three-wave coupling equations are proposed for the BRA in the plasmas with both chirped wideband pump and seed. The simulation results can more precisely describe the experiments, such as the Princeton University experiment. The optimized chirp and bandwidth are determined based on the simulation to enhance the output intensity and efficiency.
基金Supported by the Basic Research Foundation of Tsinghua Na-tional Laboratory for Information Science and Technology (TNList)the National Natural Science Foundation of China (No. 60577033)the Open Fund of the Key Laboratory of Optical Communication and Lightwave Technologies (Beijing University of Posts and Telecommunications), Ministry of Education, China
文摘An ultrashort 10-GHz pulse generation scheme was successfully demonstrated using a bulk material InGaAsP electroabsorption modulator to generate the seed pulse. A self-phase modulation-based reshaper was used after the adiabatic soliton compression in a comb-like dispersion profiled fiber. Experiments and simulations confirm that the reshaper effectively removes the pulse pedestal and improves the pulse extinction ratio. As a result, the 10-GHz pulse had no pedestal, a high extinction ratio, and a pulse width of only 1.4 ps.
基金the DFG in the framework of the Excellence Initiative,Darmstadt Graduate School of Excellence Energy Science and Engineering(GSC 1070)the BMBF(05P19RDFA1)and the Hessian Ministry for Science and the Arts(HMWK)through the LOEWE Research Cluster Nuclear Photonics at TU Darmstadt.
文摘Targets with microstructured front surfaces have shown great potential in improving high-intensity laser–matter interaction.We present cone-shaped microstructures made out of silicon and titanium created by ultrashort laser pulse processing with different characteristics.In addition,we illustrate a process chain based on moulding to recreate the laser-processed samples out of polydimethylsiloxane,polystyrol and copper.With all described methods,samples of large sizes can be manufactured,therefore allowing time-efficient,cost-reduced and reliable ways to fabricate large quantities of identical targets.
文摘We propose a nanotube-based erbium-doped fiber laser that can deliver conventional soliton (CS) and stretched pulse (SP) based on D-shaped fiber saturable absorber (DF-SA) where evanescent-field interaction works. The novel Nanotube-based Fiber Laser can generate SP or CS by tuning pump power and polarization controller (PC) properly. The net cavity dispersion of laser is slightly negative. In our experiment, by optimizing the PC in the cavity, CS and SP can be obtained at the central wavelengths of 1530.6 nm and 1530.3 nm due to on carbon nanotubes and the spectral filtering effect induced by nonlinear polarization rotation. Although the acquired CS and SP nearly have the same central wavelengths, they show distinct optical spectra, 3-dB bandwidths. The proposed fiber laser with switchable CS and SP is attractive for ultrashort pulse generation and fast measurements in practical applications.
文摘The electron behavior in laser field is described in detail. Based on the ID semiclassical model, a2D semiclassical model is proposed analytically using 3D DC-tunneling ionization theory. Lots of harmonic features are explained by this model, including the analytical demonstration of the maximum electron energy 3.17U p Finally, some experimental phenomena such as the increase of the cutoff harmonic energy with the decrease of pulse duration and the “anomalous” fluctuations in the cutoff region are explained by this model.
基金partly funded by the National Natural Science Foundation of China (Grant Nos. 10525416,10804032,and 10990101)the National Basic Research Program of China (Grant No. 2006CB806005)+1 种基金Projectsfrom Shanghai Science and Technology Commission (Grant Nos.08ZR1407100 and 09QA1402000)Shanghai Educational Development Foundation (Grant No. 2008CG29)
文摘The molecular wake-assisted interaction between two collinear femotosecond laser pulses is investigated in air,which leads to the generation of a controllable 1.8 mJ super-continuum pulse with an elongated self-guided channel due to the cross-phase modulation of the impulsively aligned diatomic molecules in air. For two parallel launched femtosecond laser pulses with a certain spatial separation,controllable attraction and repulsion of the pulses are observed due to the counter-balance among molecular wakes,Kerr and plasma effects,where the molecular wakes show a longer interaction distance than the others to control the propagation of the intense ultrashort laser pulses.
