Periodically poled lithium niobate optical parametric amplifier seeded with the narrow-band filtered output of an optical parametric generator

The results of a simple scheme to generate continuously tunable pulsed narrow-bandwidth (less than $0.1 {\mathrm{cm}}^{-1}$) light in the infrared are presented. A periodically poled lithium niobate (PPLN) optical parametric amplifier is seeded with the filtered output of a PPLN optical parametric generator. A high-finesse Fabry–Perot etalon is used as the filtering element, giving bandwidths as narrow as $0.08 {\mathrm{cm}}^{-1}$ and tunable over $18 {\mathrm{cm}}^{-1}$ without any adjustments to the PPLN crystals. High efficiency is obtained with a 15-ns 1-kHz Nd:YAG laser, giving energies of up to $180 \mathit{\mu }\mathrm{J}$ of signal at $1.6 \mathit{\mu }\mathrm{m}$ and $60 \mathit{\mu }\mathrm{J}$ of idler at $3.3 \mathit{\mu }\mathrm{m}$.