Two independently tunable and synchronised femtosecond pulses generated in the visible at the repetition rate 40 kHz using optical parametric amplifiers

Abstract

We report on a 40 kHz repetition rate travelling wave optical parametric amplifier (OPA) system designed for ultrafast spectroscopy. Two independently tunable OPAs seeded from a single white light continuum source each generate 40–75 nJ per pulse over a 480–730 nm spectral range when pumped by 1 μJ, 130 fs, 400 nm pulses derived from a Ti:sapphire regenerative amplifier. After removal of chirp, the cross-correlation between the two OPAs was measured to be 150 fs. Bandwidth was 205 ± 85 cm −1, consistent with the transform limit of the compressed pulses. A single OPA gave up to 280 nJ per pulse signal energy when pumped with 3 μJ per pulse.