High efficiency nanosecond Raman lasers based on tetragonal PbWO4 crystals

Abstract We report on laser action in linear and ring Raman oscillators based on novel χ (3) -active PbWO 4 crystals with scheelite structure ( ω R =901 cm −1 ). These resonators are pumped by the fundamental and the second harmonic wavelengths, respectively, of a Q-switched Nd 3+ :Y 3 Al 5 O 12 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 PbWO 4 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 ≈0.33 to ≈5.5 μm, 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-μm Nd 3+ :Y 3 Al 5 O 12 pump laser demonstrate multiple anti-Stokes emission up to the 10th component with λ ASt10 =0.5433 μm.