Abstract

SWIR laser systems with ultrashort output pulses are a powerful tool for studying the light-matter interaction. However, obtaining isolated attosecond pulses by high harmonics generation (HHG) require CEP-stable pulses. A good candidate for driving HHG in a water window is an Optical Parametric Chirped Pulse Amplification (OPCPA) at ~2 μm center wavelength, pumped by ~1 μm radiation [1]. The simplest approach to generating CEP-stable idler pulses in OPCPA with no angular chirp and well spectrally separated from the signal is to use a collinear configuration. However, the possibility of direct upscaling of the peak power of a CEP-stable pulse in a collinear OPCPA by improving the conversion efficiency has not yet been sufficiently studied. One way to increase the energy of an idler pulse is transient stimulated Raman chirped-pulse amplification (TSRCPA). We report a novel approach to efficient signal-to-idler energy transfer, providing more than a 30% increase in the idler pulse energy.

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