Properties of transient and steady-state stimulated Raman scattering in KGd(WO4)2 and BaWO4 tungstate crystals

BaWO4 and KGd(WO4)(2) (KGW) tungstate crystals (33 mm and 40 mm of length, respectively) were investigated as Raman frequency converters of picosecond and nanosecond second-harmonic Nd:YAG pulses, During the experiment the threshold energy of stimulated Raman (SR) process, generated wavelengths, and energy for nanosecond and picosecond pump pulses with both nonlinear crystals were measured. For BaWO4 crystal, the threshold pumping intensity was measured to be 530 MW/cm(2) for psec pumping and 200 MW/cm(2) for nsec temporal region. The corresponding Raman gain values were 14.3 cm/GW (picosecond pump) and 38 cm/GW (nanosecond gain). For KGW crystal the threshold intensity values 530 MW/cm(2) for psec and 340 MW/cm(2) for nsec were measured with corresponding Raman gain values of 11.8 cm/GW (psec) and 18.6 cm/GW (nsec). The Stokes components up to the third order in both psec and nsec regions were detected. Temporal length measurements of pump and Stokes pulses in both crystals revealed pulse shortening by a factor of similar to2 during the SR process. Due to a high value of Raman gain of a new BaWO4 crystal under both nsec and psec pumping, this crystal can be considered as a unique candidate for utilization in solid-state Raman laser systems.