Chirped pulse Raman amplification in plasma: high gain measurements

摘要

High power short pulse lasers are usually based on chirped pulse amplification (CPA), where a frequency chirped and temporarily stretched "seed" pulse is amplified by a broad-bandwidth solid state medium, winch is usually pumped by a monochromatic "pump" laser. Here, we demonstrate the feasibility of using chirped pulse Raman amplification (CPRA) as a means of amplifying short pulses in plasma.. In this scheme, a short seed pulse is amplified by a stretched and chirped pump pulse through Raman backscattering in a plasma channel. Unlike conventional CPA, each spectral component of the seed is amplified at different longitudinal positions determined by the resonance of the seed, pump and plasma wave, which excites a density echelon that acts as a "chirped" mirror and simultaneously backscatters and compresses the pump. Experimental evidence shows that, it has potential as an ultra-broad bandwidth linear amplifier which dispenses with the need for large compressor gratings.