Nonlinear saturable absorption of vertically stood WS2 nanoplates

We report the nonlinear optical (NLO) properties of vertically stood WS2 nanoplates excited by 532-nm picosecond laser light. The nanoplates were synthesized by a no-catalyst thermal evaporation process. Raman spectroscopy and x-ray diffraction pattern indicate that the nanoplates are of high crystal quality. The nanoplates exhibit large nonlinear saturable absorption but negligible nonlinear refraction. Mechanisms of the NLO response are proposed. (C) 2014 Optical Society of America