Spectral manipulation of Raman amplifiers
Backward Raman amplifiers provide a promising path to the next generation of short pulse high-intensity lasers that can go beyond the damage limit of conventional materials . The main idea is to couple a short seed and a long counter-propagating pump through an electron plasma wave in such a way that the pump energy is transferred to the seed that is amplified and compressed via Raman backscattering. In the talk, I will give a short introduction on the physics of Raman amplifiers and review three recent developments in the field: (a) mitigating the relativistic phase-mismatch and the resulting saturation by detuning of the pump pulse , (b) multi-frequency amplification of pulses with a beat-wave waveform , and (c) a new configuration for Raman amplifiers in which, the laser seed is replaced by a plasma wave seed .
 V. M. Malkin, G. Shvets, and N. J. Fisch, Phys. Rev. Lett. 82, 4448 (1999).
 I. Barth, Z. Toroker, A. A. Balakin, and N. J. Fisch, Phys. Rev. E 93, 063210 (2016).
 I. Barth and N. J. Fisch, Phys. Rev. E 97, 033201 (2018).
 K. Qu, I. Barth, and N. J. Fisch, Phys. Rev. Lett. 118, 164801 (2017).