250-MHz synchronously pumped optical parametric oscillator at 2.25-2.6 mu m and 4.1-4.9 mu m

A compact and versatile femtosecond mid-IR source is presented, based on an optical parametric oscillator (OPO) synchronously pumped by a commercial 250-MHz Er: fiber laser. The mid-IR spectrum can be tuned in the range 2.25-2.6 mu m (signal) and 4.1-4.9 mu m (idler), with average power from 20 to 60 mW. At 2.5 mu m a minimum pulse duration of 110 fs and a power of 40 mW have been obtained. Active stabilization of the OPO cavity length has been achieved in the whole tuning range. (C) 2012 Optical Society of America