Third order nonlinear optical response of PbS quantum dots

Abstract

PbS quantum dots of the average size 10 nm are synthesized in the polymer matrix (PVA) following chemical route. Optical absorption spectra reveal a large blue shift from the bulk absorption cutoff wavelength. Instead of using a high power laser, we have measured for the first time the third order nonlinear susceptibility (χ³) of PbS quantum dots using a low power continuous wave laser with the Degenerate Four Wave Mixing (DFWM) technique. The result is encouraging in nonlinear optical application at room temperature.