Nd:YAG-pumped periodically poled LiNbO3 optical parametric generator seeded with the narrowband output of a 532-nm pumped optical parametric generator

We present a simple scheme to generate a continuously tunable pulsed narrow-bandwidth infrared wave. An Nd:YAG-pumped periodically poled lithium niobate optical parametric generator (OPG) is seeded with the output of another OPG pumped by the second harmonic (0.532 µm) of the Nd:YAG laser. A tunable idler wave from the 0.532-µm pumped OPG, operated away from the degenerate point, provides a narrow linewidth seed source for the 1.064-µm pumped broadband OPG. Seeding forces the second OPG to operate in a narrowband operation comparable with that of the seed source. Linewidth of the YAG-pumped OPG is 5–25 nm, in the tuning range of 1.61–1.83 µm (signal), narrowed to 1.48–1.05 nm. Methods of further reduction of linewidth also have been discussed.