Influence of random initial amplitude perturbations on the lilamentation ot prefocused femtosecond laser pulses is numerically studied. Simulations are performed for the filamentation of laser pulses with different mo...Influence of random initial amplitude perturbations on the lilamentation ot prefocused femtosecond laser pulses is numerically studied. Simulations are performed for the filamentation of laser pulses with different modulation degrees and initial geometric focusings. The transverse waist of the laser beam is 5 mm. The behavior of the filament is strongly affected by the initial non-uniformity of the laser pulse envelope for a short initial focal length （f = 1 m）. In this case, the filament and plasma channel can survive for a longer distance with a small initial amplitude perturbation. For a laser pulse focused by a lens with a long focal length （f = 4 m）, decrease in the initial perturbation does not contribute to the length of the filament and the plasma channel.展开更多
In this paper we present for the first time the effects of Rayleigh scattering on the long distance propagation of ultraviolet （UV） light filament in air based on the stationary analysis. The simulation results show...In this paper we present for the first time the effects of Rayleigh scattering on the long distance propagation of ultraviolet （UV） light filament in air based on the stationary analysis. The simulation results show that the effects of Rayleigh scattering on the propagation of UV laser filaments may not be ignored. These influences are slightly dependent on the laser wavelength. We also compare the UV filament propagations at different input powers in the presence and the absence of the Rayleigh scattering and discuss the mechanisms of power loss and beam defocusing. In the absence of Rayleigh scattering, the filament propagation is determined by the oscillating behaviour of the beam size. In the presence of the scattering, the propagation lengths of filament are close to each other at different initial powers and determined by the Rayleigh scattering.展开更多
In the experiments on line-focused laser irradiating planar and cylindrical targets,we have observed, for the first time, a line-focused laser breakup into small filamentsin a plasma. We have also observed small-scale...In the experiments on line-focused laser irradiating planar and cylindrical targets,we have observed, for the first time, a line-focused laser breakup into small filamentsin a plasma. We have also observed small-scale plasma iet-like structures. Such phenom-ena may become obstacles in the experimental research on X-ray laser using line-focusedlaser-produced plasma as a gain medium.展开更多
The chirped optical pulses undergoing self-focusing and splitting into multiple filamentation passing through a Kerr medium-carbon disulfide (CS2) are studied experimentally and numerically. At the particular spatial ...The chirped optical pulses undergoing self-focusing and splitting into multiple filamentation passing through a Kerr medium-carbon disulfide (CS2) are studied experimentally and numerically. At the particular spatial position, modulation growth takes place from the experimental result. The process of modulation growth with different pulsed chirp is analyzed. It is found that with the pulsed chirp in-creasing (equal to the pulse width increasing), modulation growth of chirped opti-cal pulses is delayed and the average input power also increases. The simulation results are in agreement with the experimental results.展开更多
基金supported by National Natural Science Foundation of China(Nos.60621063,10634020,10734130 and 10521002)the National Basic Research Program of China(973 Program)(Nos.2007CB815101,2006CB806007)
文摘Influence of random initial amplitude perturbations on the lilamentation ot prefocused femtosecond laser pulses is numerically studied. Simulations are performed for the filamentation of laser pulses with different modulation degrees and initial geometric focusings. The transverse waist of the laser beam is 5 mm. The behavior of the filament is strongly affected by the initial non-uniformity of the laser pulse envelope for a short initial focal length （f = 1 m）. In this case, the filament and plasma channel can survive for a longer distance with a small initial amplitude perturbation. For a laser pulse focused by a lens with a long focal length （f = 4 m）, decrease in the initial perturbation does not contribute to the length of the filament and the plasma channel.
文摘In this paper we present for the first time the effects of Rayleigh scattering on the long distance propagation of ultraviolet （UV） light filament in air based on the stationary analysis. The simulation results show that the effects of Rayleigh scattering on the propagation of UV laser filaments may not be ignored. These influences are slightly dependent on the laser wavelength. We also compare the UV filament propagations at different input powers in the presence and the absence of the Rayleigh scattering and discuss the mechanisms of power loss and beam defocusing. In the absence of Rayleigh scattering, the filament propagation is determined by the oscillating behaviour of the beam size. In the presence of the scattering, the propagation lengths of filament are close to each other at different initial powers and determined by the Rayleigh scattering.
文摘In the experiments on line-focused laser irradiating planar and cylindrical targets,we have observed, for the first time, a line-focused laser breakup into small filamentsin a plasma. We have also observed small-scale plasma iet-like structures. Such phenom-ena may become obstacles in the experimental research on X-ray laser using line-focusedlaser-produced plasma as a gain medium.
基金the National Natural Science Foundation of China (Grant Nos. 10776008, 10576012 and 60538010)the National High Technology Research and Development Program of China (Grant No. 2007AA804505)+2 种基金the Program of the Ministry of Education of China for New Century Excellent Talents in Universitythe Natural Science Foundation of Hunan Province (Grant No. 06JJ20017)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant Nos. 20040532005 and 20070532075)
文摘The chirped optical pulses undergoing self-focusing and splitting into multiple filamentation passing through a Kerr medium-carbon disulfide (CS2) are studied experimentally and numerically. At the particular spatial position, modulation growth takes place from the experimental result. The process of modulation growth with different pulsed chirp is analyzed. It is found that with the pulsed chirp in-creasing (equal to the pulse width increasing), modulation growth of chirped opti-cal pulses is delayed and the average input power also increases. The simulation results are in agreement with the experimental results.
