The effect of Co-60 gamma irradiation on optical properties of some nonlinear optical (NLO) single crystals

Abstract

The nonlinear optical single crystals like L-alanine cadmium chloride (LACC), L-alanine doped potassium dihydrogen orthophosphate (KDP) and L-arginine doped KDP were grown by slow evaporation method at room temperature. The grown crystals were exposed to Co-60 gamma radiation in the total doses ranging from 100 krad to 6 Mrad. The structural properties, change in absorption spectra, refractive index (RI) and second harmonic generation (SHG) performance of these crystals were investigated before and after irradiation. An X-ray diffraction studies reveal that the compressive strains are generated in the irradiated crystals. The ultraviolet - visible spectra show that the optical absorption increases with increase in radiation dose in the case of LACC crystal. There is no systematic behaviour in the optical absorption of L-alanine and L-arginine doped KDP crystals with increase in the radiation dose. A considerable change in the values of RI was observed due to irradiation. The SHG efficiency of LACC crystals were found to decrease with increase in radiation dose where as in case of L-alanine doped KDP crystals, the SHG efficiency was found to increase with increase in radiation dose.