Optical parametric amplification pumped by a phase-aberrated beam.

In this paper we theoretically study the spatial characteristics of optical parametric amplification (OPA) or chirped pulse OPA (OPCPA) pumped with a phase-aberrated beam. Due to the fact that pump-to-signal phase transfer caused by walk-off effect is highly gain-dependent, in a high gain OPA system the signal beam-quality will be significantly degraded even for a weak walk-off, accompanied with beam tilting and converging or diverging. It is demonstrated that an OPA configuration with walkoff-compensated crystal pair is capable of reducing the phase transfer and hence ensuring signal beam-quality, which may be of importance for designing high-energy OPCPA systems.