“…The availability of periodically poled LiNbO 3 (PPLN) crystals has opened the way to very promising new devices in this frequency range, which is of particular interest for molecular spectroscopy and LIDAR applications [4]. Let us quote, in particular, a pulsed singly resonant OPO [5,6] with broad tunability and significant output power, and a pump-enhanced singly resonant single-mode CW OPO, with a minimum threshold well below 1 mW [7]. Here we describe another device based on a PPLN crystal, namely a Nd:YAG laser pumped, signal-idler-pump triply resonant CW OPO working in the region 2-2.3 µm, which has a threshold in the mW range.…”