Widely tunable femtosecond non-collinear optical parametric oscillator (NOPO) in VIS

Abstract

High repetition rate femtosecond VIS radiation has been generated in optical parametric oscillators (OPOs) either by generating VIS light through intra-cavity SHG or SFG [1, 2] or in VIS OPOs using frequency-doubled Ti:sapphire as a pump laser [3, 4]. Recently, we also demonstrated the generation of VIS light via efficient intra-cavity SFG in NIR NOPO pumped by a thin disk laser [5]. In this work, the third harmonic of a home-built high power femtosecond Kerr-lens mode-locked thin-disk (KLM TD) laser is used for the first time to directly pump a VIS non-collinear optical parametric oscillator (NOPO) which allows for ultra-broadband and fast tunability in a theoretical tuning range of 450 nm-650 nm. The ultrafast tuning over the whole range just by varying the cavity length is based on a non-collinear ultra-broadband phase-matching (PM) scheme that allows tuning the wavelength without changing the PM angle of the OPO crystal [6].