Picosecond random Raman lasing in the spectral range of 360-630 nm using powders of potassium, sodium and strontium nitrates

Stimulated Raman scattering (SRS) of picosecond laser radiation at 532 and 355 nm in microcrystalline powders of potassium, sodium, and strontium nitrates has been studied. One anti-Stokes and three Stokes components were generated in all samples when pumping at 532 nm. For the first time to our knowledge, random Raman lasing in the used nitrates has been obtained upon their excitation at 355 nm. In this case, the multifrequency Stokes SRS is also observed in all nitrates. We have analyzed all possible loss channels when ultraviolet radiation is used for excitation of SRS. In general, picosecond random SRS generation has been obtained at 19 spectral lines in the spectral range of 360-630 nm. In all cases, the SRS process is due to the internal symmetric mode of the (NO3)(-) ion with the frequency shifts of 1050 cm(-1) (KNO3), 1069 cm(-1) (NaNO3), and 1057 cm(-1) (Sr(NO3)(2)).