This paper analytically investigates the interaction of light filaments generated by a femtosecond laser beam in air. It obtains the Hamiltonian of a total laser field and interaction force between two filaments with different phase shifts and crossing angles. The property of the interaction force, which leads the attraction or repulsion of filaments, is basically dependent on the phase shift between filaments. The crossing angle between two filaments can only determine the magnitude of the interaction force, but does not change the property of the force.
The jets driven by magnetic reconnection in laser-plasma interactions are investi- gated experimentally. The diagnostics in the optical and X-ray ranges provide detailed information about the jet characteristics. The plasma jets perpendicular to and along the target surface are observed clearly, which is evident signatures of laser driven magnetic reconnection. The jet formation is also investigated for different experimental parameters.
A new method based on a chirped optical pulse interferogram has been proposed to measure terahertz radiation. The frequency domain phase information of the interferogram is used to extract the time-domain terahertz pulse waveform. In principle, the resolution of our method can be as high as the unchirped probe pulse duration, with the advantages of relatively simple measurement setup and signal extracting techniques.
A powerful terahertz(THz) pulse was produced by a p-polarized,70 fs,800 nm laser interacting with solid targets at an incident angle of 45°.The polarization of the THz emission was measured out of the laser incident plane.The results showed that it was linearly polarized.We established a surface current model to explain this phenomenon,assuming that the transient current moving along the plasma surface was responsible for the generation of the THz emission.The model expectation and the experimental result were in good agreement.
DU FeiLI ChunZHOU MuLinWANG WeiMinSU LuNingZHENG YiLI YuTongMA JingLongSHENG ZhengMingCHEN LiMingLU XinWANG ZhaoHuaWEI ZhiYiZHANG Jie
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.
