Generation of sub-40 fs pulses using a green-pumped noncollinear parametric amplifier

Summary form only given.Extremely short pulses can be generated in the visible, the near-IR and more recently in the UV by means of a noncollinear optical parametric amplifier (NOPA). All these devices demonstrate that NOPA can produce pulses shorter by a factor 6.5 in routine up to the record 25 than the pulse used to pump them. The output characteristics of the NOPA are mainly determined by the interplay of three major parameters: the white light continuum (WLC) chirp, the duration of the pump pulse and the signal/pump and idler/pump group velocity mismatch (GVM). The need for low WLC chirp is mainly dictated by the pump pulse duration and the GVM. To our knowledge, only sub-200 fs Ti:sapphire has been used to pump this kind of parametric device. Here we report on a NOPA system pumped by the second harmonic of 1026 nm 500 fs pulses produced by a diode pumped Yb:KGW chirped pulse amplifier (CPA). Taking advantage of the long pump pulse, no particular caution was made to control the WLC chirp. We demonstrate 30 fs pulses tunable from 750 to 850 nm. The output NOPA was 5 /spl mu/J over most of the tuning range. The amplified light converted with 25% quantum efficiency presents a good spatial quality and 1.8% rms stability. We observed the same performance for repetition rates ranging from 1 to 3 kHz.