Light Spring amplification in a multi-frequency Raman amplifier

TL;DR

This paper demonstrates the amplification and compression of a helical Light Spring laser pulse using a multi-frequency Raman amplifier, revealing new insights into plasma wave excitation and pulse shaping.

Contribution

It introduces a method to amplify and compress Light Spring laser pulses with multiple frequencies, establishing criteria for independent frequency amplification and analyzing wave interactions.

Findings

Successful amplification and compression of Light Spring pulses observed.

Excitation of two different types of helical plasma waves.

Final pulse profile similar to Gaussian-shaped seed pulses.

Abstract

We propose to amplify and compress an ultrashort Light Spring laser seed with a long Gaussian-shaped laser pump through Raman amplification. This Light Spring, which has a helical spatio-temporal intensity profile, can be built on the superposition of three distinct laser frequency components. In order to get an independent frequency amplification, two criteria are established. Besides these criteria, a non equal frequency separation is necessary to avoid resonance overlapping when three or more frequencies are involved. The independent set of equations, which describes the wave-wave interaction in a plasma, is solved numerically for two different Light Spring configurations. In both cases, the amplification and transversal compression of the seed laser pulse have been observed, with a final profile similar to that of the usual Gaussian-shaped seed pulses. In addition, two different kinds of helical plasma waves are excited.