Femtosecond noncollinear and collinear parametric generation and amplification in BBO crystal

Abstract.

We perform comprehensive theoretical and experimental analysis of ultrafast noncollinear and collinear parametric generation and amplification in type-I phase-matched BBO crystal, pumped with 390 nm wavelength, 150-fs-duration pulses from a frequency-doubled regenerative-amplified Ti:sapphire laser. We investigate conditions for group-velocity-matched generation and amplification, seeded with white-light continuum pulses by considering mean propagation velocity of pump and parametric pulses. We show that under certain conditions, effective matching can be achieved for noncollinear geometry with a 390-nm pump. We report detailed energy, spectral, and temporal measurement of the parametric processes in BBO and show that our effective matching conditions agree with experimentally observed angular and spectral properties of the parametric gain. The maximum tuning range for noncollinear process was from 460 nm to 2.56 μm, with the highest conversion efficiency of up to 20%. For collinear geometry, no effective matching of average group velocity was found. Because of this, the maximum conversion efficiency with UV pump in single-pass OPA is limited to 1.5%.