Self modulation and scattering instability of a relativistic short laser pulse in an underdense plasma

Abstract

Characterization of self-consistent laser-plasma evolutions serves as a fundamental issue in the field of relativistic laser-plasma interactions. In this paper, we present an analysis framework for description of these evolutions during propagation of a short intense laser pulse in a sub-critical high-density plasma (the pulse length exceeds the plasma wavelength). In this context, the pulse evolutions are attributed to the wakefield induced self-modulation and destabilization via parametric exponentiation of the initial noise content. The self-consistent plasma evolutions are formulated in terms of quantities which used to be motion constants in the absence of pulse evolutions. This proves very useful both in understanding plasma evolutions during self-modulation and also in facilitating the instability studies in the strongly nonlinear regime, via refinement of unstable plasma perturbations.General analytical solutions, at arbitrary pulse conditions, are derived for selfmodulation, indicating that the envelop evolutions are driven by the induced spatial frequency-chirp. Also, these results state that the envelope attains fine modulations

Three-stage laser wakefield accelerator scheme for sub-Joule few-cycle laser pulses

“…By approaching the fewcycle regime not only the broad spectrum leads to enhanced plasma dispersion effects, but also the large gradient in the refractive index causes strong spectral modulations and red shifting. In the opposite extreme case of very long pulses longitudinal self-phase modulation leads to periodic bunching of the laser envelope, which has been studied extensively [24][25][26]. Those long pulses can be effectively self-guided, but the wakefield generation is highly nonlinear and the electron acceleration is not controllable.…”

Plasma modulator for high-power intense lasers

“…Different from electro-optic modulators [19,20], intense laser modulates itself by its ponderomotive force acting on plasma [21,22]. Self-modulation of short pulses have been widely studied, such as wakefield generation, laser self-focusing and electromagnetic soliton.…”