Broadly tunable femtosecond OPA pumped by 1030 nm Yb: KGW laser with a range of non-linear crystals tested

Abstract

We present a carrier-envelope phase-stable laser pulse source continuously tunable in the 2–4 µm wavelength range. The source relies on two-stage optical-parametric amplification, with the first stage pumped with the second harmonic of the 200-fs ytterbium pump laser. In contrast, the fundamental 1030 nm beam pumps the second stage directly. AgGaS2 (AGS), KTiOAsO4 (KTA), GaSe, LiGaS2 (LGS), and LiIO3 (LIO3) non-linear crystals were tested and the KTA crystal proved to be the most robust. We demonstrate operation without crystal damage at higher than previously reported peak intensities for AGS (290 GW/cm2) and LGS (214 GW/cm2) and report new values of damage threshold for GaSe (85 GW/cm2) and LIO3 (159 GW/cm2).