ABSTRACT
We experimentally investigate the laser polarization effect on the supercontinuum (SC) generation through femtosecond laser filamentation in air. By tuning filamenting laser ellipticity from linear polarization to circular polarization, the spectral intensity of the SC after filamentation gradually increases, while the spectral bandwidth of the SC continuously decreases. The laser ellipticity-dependent spectral intensity modulation of the SC is stronger at higher filamenting pulse energy. Laser energy deposits more in linearly polarized laser filaments than in circularly polarized laser filaments. The experimental results are supported by numerical simulations. A physical picture based on the laser ellipticity-dependent clamped intensity inside the filament, together with the Kerr nonlinearity and plasma related self-phase modulations, is proposed to explain the observation.
ABSTRACT
We report on a method to experimentally generate ionic wind by coupling an external large electric field with an intense femtosecond laser induced air plasma channel. The measured ionic wind velocity could be as strong as >4 m/s. It could be optimized by increasing the strength of the applied electric field and the volume of the laser induced plasma channel. The experimental observation was qualitatively confirmed by a numerical simulation of spatial distribution of the electric field. The ionic wind can be generated outside a high-voltage geometry, even at remote distances.
