Formation and amplification of flat top picosecond pump pulses for OPCPA systems

摘要

OPCPA systems based on non-collinear parametric amplification provides amplification bandwidths sufficient for formation of sub-10 fs pulses with peak powers of terawatt level [1], however both total gain and gain spectral bandwidth sensitively depend on spatial shape of the pump pulses [1]. Contrary to the Gaussian pulses, the pump pulses with a rectangular temporal profile would provide a uniform gain for all chirped seed spectral components, thereby avoiding spectral distortion and would allow to achieve higher pump-to-signal conversion efficiency and improve amplified pulse contrast ration with reference to parametric super fluorescence background [2]. For the pump pulses of 30–100 ps duration the application of spectral and electro optical pulse shaping methods is rather limited due to narrow pulse spectrum (fractions of nanometer) and insufficient temporal resolution of optoelectronic schemes, while pulse shape obtained by using pulse stacking methods is extremely sensitive to mechanical and thermal perturbations in the interferometric scale.