A tandem periodically-poled lithium niobate (PPLN) optical parametric oscillator (OPO)

The operation of a synchronously pumped optical parametric oscillator (OPO) that employs two periodically poled lithium niobate crystals within a sing le cavity has been investigated. The tandem OPO device is pumped at 1.064 m u m by an passively mode-locked Nd:YVO4 laser that has been amplified at a pulse repetition rate of 100 Hz by a pair of diode pumped Nd:YAG rods. The second crystal in the OPO device converts the signal beam produced in the f irst crystal and consequently three tunable wavelengths are generated withi n the mid-infrared atmospheric transmission window (2-5 mu m). The threshol d for parametric oscillation is 30 mW and a conversion efficiency, from 1.0 64 mu m to the 2-5 mu m band, of 42% has been achieved at a pump power of 3 60 mW. Crown Copyright (C) 2000 Published by Elsevier Science B.V. All righ ts reserved.