High efficiency nanosecond Raman lasers based on tetragonal PbWO4 crystals

We report on Laser action in linear and ring Raman oscillators based on novel chi((3))-active PbWO4 crystals with scheelite structure (omega(R) = 901 cm(-1)). These resonators are pumped by the fundamental and the second harmonic wavelengths, respectively, of a Q-switched Nd3+:Y3Al5O12 laser. In these preliminary measurements, conversion efficiencies as high as 20% are observed. To our knowledge, this is the first such demonstration of Raman lasing in lead tungstate in the nanosecond regime. Raman lasers based on PbWO4 are very promising for several applications, including the generation of wavelengths in the uv (in conjunction with other nonlinear processes) for ozone differential absorption lidar. This material has optical transparency from approximate to 0.33 to approximate to 5.5 mu m, making it also potentially useful for trace gas detection in the infrared. Furthermore, it has a high damage threshold and is not hydroscopic. Some new data on picosecond high-order Stokes and anti-Stokes generation are also presented. In particular, our SRS experiments with a 1-mu m Nd3+:Y3Al5O12 pump laser demonstrate multiple anti-Stokes emission up to the 10th component with lambda(ASt10) = 0.5433 mu m. (C) 2000 Published by Elsevier Science B.V.