High efficiency nanosecond Raman lasers based on tetragonal PbWO4 crystals

We report on Laser action in linear and ring Raman oscillators based on nov el chi((3))-active PbWO4 crystals with scheelite structure (omega(R) = 901 cm(-1)). These resonators are pumped by the fundamental and the second harm onic wavelengths, respectively, of a Q-switched Nd3+:Y3Al5O12 laser. In the se preliminary measurements, conversion efficiencies as high as 20% are obs erved. To our knowledge, this is the first such demonstration of Raman lasi ng in lead tungstate in the nanosecond regime. Raman lasers based on PbWO4 are very promising for several applications, including the generation of wa velengths in the uv (in conjunction with other nonlinear processes) for ozo ne differential absorption lidar. This material has optical transparency fr om approximate to 0.33 to approximate to 5.5 mu m, making it also potential ly useful for trace gas detection in the infrared. Furthermore, it has a hi gh damage threshold and is not hydroscopic. Some new data on picosecond hig h-order Stokes and anti-Stokes generation are also presented. In particular , our SRS experiments with a 1-mu m Nd3+:Y3Al5O12 pump laser demonstrate mu ltiple anti-Stokes emission up to the 10th component with lambda(ASt10) = 0 .5433 mu m. (C) 2000 Published by Elsevier Science B.V.