Diode-pumped singly resonant continuous-wave optical parametric oscillatorwith wide continuous tuning of the near-infrared idler wave

We demonstrate wide, continuous tuning of the single-frequency idler wave o f a cw singly resonant optical parametric oscillator (SRO). The SRO consist s of a periodically poled LiNbO3 crystal for quasi-phase matching in a four -mirror signal-resonant ring cavity. The SRO, excited by 2.25 W of 924-nm r adiation from an InGaAs diode laser, generates as much as 200 mW of single- frequency 2.1-mu m idler radiation. We tune the idler frequency continuousl y within a range as large as 56 GHz by changing the wavelength of the diode pump laser. The versatility of this continuously tunable single-frequency infrared source is demonstrated by recording of N2O rovibrational absorptio n lines near 2.1 mu m. (C) 2000 Optical Society of America. OCIS codes: 190 .4360, 190.4410, 190.4970, 300.1030, 300.6340, 300.6390.