In this report,we start from Lagrange equation and analyze theoretically the electron dynamics in electromagnetic field.By solving the relativistic government equations of electron,the trajectories of an electron in p...In this report,we start from Lagrange equation and analyze theoretically the electron dynamics in electromagnetic field.By solving the relativistic government equations of electron,the trajectories of an electron in plane laser pulse,focused laser pulse have been given for different initial conditions.The electron trajectory is determined by its initial momentum,the amplitude,spot size and polarization of the laser pulse.The optimum initial momentum of the electron for LSS(laser synchrotron source)is obtained.Linear polarized laser is more advantaged than circular polarized laser for generating harmonic radiation.展开更多
The spatially and time resolved 2D images of x-ray emission of line-shaped Ti laser plasmas have been obtained with a pinhole transmission grating spectrometer coupled with a x-ray streak camera.The x-ray emission non...The spatially and time resolved 2D images of x-ray emission of line-shaped Ti laser plasmas have been obtained with a pinhole transmission grating spectrometer coupled with a x-ray streak camera.The x-ray emission nonuniformity of the plasma is quantitatively analyzed using a perturbation spectrum analysis method.The results show that the nonuniformity has a minimum value at a time corresponding to the peak time of the pumping laser pulse,and increases after that.A brief discussion on the nonuniformity mechanism has also been presented.展开更多
The Bloch-like equations for the intracavityinteraction of coherent light with semiconductors below the Mott density are derived.These equations include the many-body Coulomb effects.Steady state analysis reveals the ...The Bloch-like equations for the intracavityinteraction of coherent light with semiconductors below the Mott density are derived.These equations include the many-body Coulomb effects.Steady state analysis reveals the characteristics of bistability and hysteresis in such systems.It is shown that the hysteresis loops increase and that the bistability can be realized more easily due to the many-body effects.展开更多
Line-focused high power laser was used to irradiate a magnesium slab target in order to generate line-shaped laser-plasma.Plasma parameter profile distribution(electron temperature and electron density)on the directio...Line-focused high power laser was used to irradiate a magnesium slab target in order to generate line-shaped laser-plasma.Plasma parameter profile distribution(electron temperature and electron density)on the direction perpendicular to the target surface was obtained by spectroscopic diagnostic method,which is quite different from that of the spot-shaped laser-plasmas.New experimental phenomena that can be interpreted as“plasma satellites”were also observed.展开更多
Numerical calculations are used to study the initial temporal evolution of the wake-field produced by a short laser pulse.Results are compared to the previous quasi-static solutions.The usually adopted quasi-static ap...Numerical calculations are used to study the initial temporal evolution of the wake-field produced by a short laser pulse.Results are compared to the previous quasi-static solutions.The usually adopted quasi-static approximation is found not appropriate for describing the wake-field generation at initial stages.展开更多
A laser model which may operate in the absence of population inversion is proposed.It is found that the realization of lasing without inversion in this model is due to the change of noninversion condition along with t...A laser model which may operate in the absence of population inversion is proposed.It is found that the realization of lasing without inversion in this model is due to the change of noninversion condition along with the creation of atomic coherence,instead of a coherence-term-induced gain enhancement.展开更多
Phase-matched high-order harmonic generation in Ar gas-filled cell was investigated experimentally. We obtained phase-matched 27th order harmonic driven by a commercially available solid-state femtosecond laser system...Phase-matched high-order harmonic generation in Ar gas-filled cell was investigated experimentally. We obtained phase-matched 27th order harmonic driven by a commercially available solid-state femtosecond laser system at 0.55 mJ/pulse energy level and 1 kHz repetition rate. To our knowledge, this is the lowest driving laser energy used to obtain phase-matched 27th order harmonic in a static gas cell. High-order harmonic generation at different gas density was studied systematically. Spectral blueshift and broadening of high harmonics under different pressure were analyzed. We found that the source size and spatial distribution of high-order harmonics are quite different under the phase-matching condition from those of the phase-mismatching case.展开更多
When a relativistic laser pulse of high photon density interacts with a specially tailored thin foil target,a strong torque is exerted on the resulting spiral-shaped foil plasma,or"light fan".Because of its ...When a relativistic laser pulse of high photon density interacts with a specially tailored thin foil target,a strong torque is exerted on the resulting spiral-shaped foil plasma,or"light fan".Because of its structure,the latter can gain significant orbital angular momentum(OAM),and the opposite OAM is imparted to the reflected light,creating a twisted relativistic light pulse.Using such a relativistic LaguerreGaussian(LG)laser interaction with a solid foil,we can get intense high order vortex harmonics.Besides that,proton acceleration using LG laser and hollow screw-like drill in plasma using LG laser are studied.All interaction scenarios are demonstrated by particle-in-cell simulation as well as analytical modeling,and should be verifiable in the laboratory.As important characteristics,twisted relativistic light pulse has strong torque and ultra-high OAM density,which may lead to many more new effects.展开更多
基金The project supported by the National Natural Science Foundation of China(No.10375083)National High-Technology ICF Committee in Chinathe National key Basic Research Special Foundation(No.TG1999075206-2)
文摘In this report,we start from Lagrange equation and analyze theoretically the electron dynamics in electromagnetic field.By solving the relativistic government equations of electron,the trajectories of an electron in plane laser pulse,focused laser pulse have been given for different initial conditions.The electron trajectory is determined by its initial momentum,the amplitude,spot size and polarization of the laser pulse.The optimum initial momentum of the electron for LSS(laser synchrotron source)is obtained.Linear polarized laser is more advantaged than circular polarized laser for generating harmonic radiation.
基金Supported by the National Natural High Technology Program.
文摘The spatially and time resolved 2D images of x-ray emission of line-shaped Ti laser plasmas have been obtained with a pinhole transmission grating spectrometer coupled with a x-ray streak camera.The x-ray emission nonuniformity of the plasma is quantitatively analyzed using a perturbation spectrum analysis method.The results show that the nonuniformity has a minimum value at a time corresponding to the peak time of the pumping laser pulse,and increases after that.A brief discussion on the nonuniformity mechanism has also been presented.
基金Supported by the National Natural Science Foundation of China.
文摘The Bloch-like equations for the intracavityinteraction of coherent light with semiconductors below the Mott density are derived.These equations include the many-body Coulomb effects.Steady state analysis reveals the characteristics of bistability and hysteresis in such systems.It is shown that the hysteresis loops increase and that the bistability can be realized more easily due to the many-body effects.
文摘Line-focused high power laser was used to irradiate a magnesium slab target in order to generate line-shaped laser-plasma.Plasma parameter profile distribution(electron temperature and electron density)on the direction perpendicular to the target surface was obtained by spectroscopic diagnostic method,which is quite different from that of the spot-shaped laser-plasmas.New experimental phenomena that can be interpreted as“plasma satellites”were also observed.
基金Supported by the Association for Plasma Studies of China.
文摘Numerical calculations are used to study the initial temporal evolution of the wake-field produced by a short laser pulse.Results are compared to the previous quasi-static solutions.The usually adopted quasi-static approximation is found not appropriate for describing the wake-field generation at initial stages.
文摘A laser model which may operate in the absence of population inversion is proposed.It is found that the realization of lasing without inversion in this model is due to the change of noninversion condition along with the creation of atomic coherence,instead of a coherence-term-induced gain enhancement.
基金The work was supported by the National Natural Science Foundation of China(Grant Nos.69925513 and 19974058)the Chinese National Major Basic Research Project(Grant No.G1999075204).
文摘Phase-matched high-order harmonic generation in Ar gas-filled cell was investigated experimentally. We obtained phase-matched 27th order harmonic driven by a commercially available solid-state femtosecond laser system at 0.55 mJ/pulse energy level and 1 kHz repetition rate. To our knowledge, this is the lowest driving laser energy used to obtain phase-matched 27th order harmonic in a static gas cell. High-order harmonic generation at different gas density was studied systematically. Spectral blueshift and broadening of high harmonics under different pressure were analyzed. We found that the source size and spatial distribution of high-order harmonics are quite different under the phase-matching condition from those of the phase-mismatching case.
基金supported by the Ministry of Science and Technology (Grant Nos.2011DFA11300and 2011CB808104)the National Natural Science Foundation of China(Grant Nos.61221064,11125526, 11335013and 11127901)
文摘When a relativistic laser pulse of high photon density interacts with a specially tailored thin foil target,a strong torque is exerted on the resulting spiral-shaped foil plasma,or"light fan".Because of its structure,the latter can gain significant orbital angular momentum(OAM),and the opposite OAM is imparted to the reflected light,creating a twisted relativistic light pulse.Using such a relativistic LaguerreGaussian(LG)laser interaction with a solid foil,we can get intense high order vortex harmonics.Besides that,proton acceleration using LG laser and hollow screw-like drill in plasma using LG laser are studied.All interaction scenarios are demonstrated by particle-in-cell simulation as well as analytical modeling,and should be verifiable in the laboratory.As important characteristics,twisted relativistic light pulse has strong torque and ultra-high OAM density,which may lead to many more new effects.
