Liu Yun-Quan

Double Jet Emission of Hot Electrons from a Micro-droplet Spray

Spatial distribution of hot electrons with energies above 50 keV are investigated by an ethanol micro-droplet spray irradiated by linearly and elliptically polarized 150 fs laser pulses at an intensity of 1016W/cm2. Two symmetric hot electron jets with respect to the laser propagation direction are observed in the polarization plane for a linearly polarized laser field and in the plane of the long electric vector for an elliptically polarized laser field, respectively. Particle-in-cell simulations suggest that the resonance absorption on the spherical surface of the droplets is mainly responsible for the generation of the double-jet emission of hot electrons.

Interaction of femtosecond laser pulses with metal photocathode

The features of interaction of femtosecond laser pulses with photocathode are studied theoretically in this paper. The surface temperature of the metal cathode film while femtosecond laser pulses irradiation is studied with two-temperature model. With a simple photoelectric model we obtain the optimum metal film thickness for the back-illuminated photocathode. The generated ultrashort photocurrent pulses are strongly dependent on the temperature of the electron gas and the lattice during the femtosecond laser pulse irradiation on the photocathode.

Influence of initial pulse chirp on rainbow-like supercontinuum generation from filamentation in air

Supercontinuum (SC) generation from laser filamentation in air is found to depend strongly on the pulse duration. Rainbow-like SC generation is observed only for a pulse of appropriate negative chirp that agrees with the predictions put forward by Golubtsov et al. [Quantum Electron. 33 (2003) 525]. The conversion efficiency of an 800-nm laser light to rainbow-like SC is found to be the highest for 257 fs pulses with an initial negative chirp. A larger chirp will lead to filamentation surviving at longer distance.