The role of transient plasma photonic structures in plasma-based amplifiers

This is the authors' abstract. We don't add key points for this paper.

High power lasers have become useful scientific tools, but their large size is determined by their low damage-threshold optical media. A more robust and compact medium for amplifying and manipulating intense laser pulses is plasma. Here we demonstrate, experimentally and through simulations, that few-millijoule, ultra-short seed pulses interacting with 3.5-J counter-propagating pump pulses in plasma, stimulate back-scattering of nearly 100 mJ pump energy with high intrinsic efficiency, when detuned from Raman resonance. This is due to scattering off a plasma Bragg grating formed by ballistically evolving ions. Electrons are bunched by the ponderomotive force of the beat-wave, which produces space-charge fields that impart phase correlated momenta to ions. They inertially evolve into a volume Bragg grating that backscatters a segment of the pump pulse. This, ultra-compact, two-step, inertial bunching mechanism can be used to manipulate and compress intense laser pulses. We also observe stimulated Compton (kinetic) and Raman backscattering.