An Intracavity Optical Parametric Oscillator With Very High Repetition Rate and Broad Tunability Based Upon Room Temperature Periodically Poled $\hbox {MgO}:\hbox {LiNbO}_{3}$

We report a low-pump-threshold, very high-repetition-rate, singly resonant optical parametric oscillator (OPO) pumped internally to a diode-pumped, Q-switched Nd:YVO₄ laser. The OPO, based upon a 27.0-32.5-mum periodically poled MgO:LiNbO₃ crystal with fan grating design, exhibits a broad tunability range of 1.38-1.79 mum (Deltalambda_s = 411 nm) and 2.62-4.64 mum (Deltalambda_i = 2019 nm) in the signal and idler fields, respectively. For an external diode pump power of only 3 W, up to 150 mW of idler were extracted from the device or, when the signal field was output coupled, 330 and 100 mW of signal and idler, respectively, were simultaneously obtained. By taking advantage of the intracavity parametric cavity dumping process, repetition rates in excess of 350 kHz were achieved whilst maintaining high down-conversion efficiency. We demonstrate the potential of this device in spectroscopic applications with an absorption measurement of low concentration CH₄.