A robust plasma-based laser amplifier via stimulated Brillouin scattering

E P Alves,K A Humphrey,R Bingham,R M G M Trines,R A Cairns,F Fiúza,R A Fonseca,L O Silva

doi:10.1088/1361-6587/ac2613

Abstract

Brillouin amplification in plasma is more resilient to fluctuations in the laser and plasma parameters than Raman amplification, making it an attractive alternative to Raman amplification. In this work, we focus on high plasma densities, , where stimulated Raman scattering is not possible and laser beam filamentation is the dominant competing process. Through analytic theory and multi-dimensional particle-in-cell simulations, we identify a parameter regime for which Brillouin amplification can be efficient while maintaining filamentation of the probe at a controlled level. We demonstrate pump-to-probe compression ratios of up to 72 and peak amplified probe fluences over 1 kJ cm−2 with efficiency. High pulse quality is maintained through control of parasitic filamentation, enabling operation at large beam diameters. Provided the pump and probe pulse diameters can be increased to mm, our results suggest that Brillouin amplification can be used to produce sub-picosecond pulses of petawatt power.

Highlights

We further derive new scalings for sc-Brillouin amplification performance that take into account the limiting effects of probe filamentation. These scalings describe how sc-Brillouin amplification and compression vary with pump intensity for a fixed tolerance level of probe filamentation; we show that filamentation can be offset by operating at lower pump intensities, improving overall sc-Brillouin amplification performance
We define the compression ratio as the duration of the pump pulse divided by the duration of the amplified probe, and the amplification ratio as the intensity of the amplified probe divided by the intensity of the pump
We find compression ratios of 40, 60 and 72, and amplification ratios of 15, 30 and 40, for pump intensities of 1016, 1015 and 1014 W cm−2 respectively

Summary

Introduction

Amplification of laser beams via parametric instabilities in plasma (stimulated Raman and Brillouin scattering) has been proposed a number of times [1,2,3,4,5], but came into its own only relatively recently [6,7,8,9,10,11,12,13,14,15,16,17,18,19] This has been accompanied by an increasing effort to optimize the parameters for the interaction via numerical simulations [20,21,22,23,24,25,26]. Brillouin amplification yields lower peak intensities or amplification ratios, but is far more robust to parameter fluctuations or frequency mismatch, more efficient (as less laser energy stays behind in the plasma wave) and more suitable for the production of pulses with a high total power or energy. We present 2D PIC simulations that self-consistently capture the interplay between sc-Brillouin amplification and filamentation, which support our theoretical scalings

Scaling laws in the self-similar regime

Simulations

Discussion

Findings

Conclusions