Femtosecond fiber-feedback optical parametric oscillator

We demonstrate what is to our knowledge the first synchronously pumped high -gain optical parametric oscillator (OPO) with feedback through a single-mo de fiber. This device generates 2.3-2.7 W of signal power in 700-900-fs pul ses tunable in a wavelength range from 1429 to 1473 nm. The necessary high gain was obtained from a periodically poled LiTaO3 crystal pumped with as m uch as 8.2 W of power at 1030 nm from a passively mode-locked Yb:YAG laser with 600-fs pulse duration and a 35-MKz repetition rate. The fiber-feedback OPO setup is compact because most of the resonator feedback path consists of a standard telecom fiber. Because of the high parametric gain, the fiber -feedback OPO is highly insensitive to intracavity losses. For the same rea son, the synchronization of the cavity with the pump laser is not critical, so active stabilization of the cavity length is not required. (C) 2001 Opt ical Society of America.