Induced birefringence in CdSe quantum dots in phosphate glass matrix

Light-induced anisotropy (optical Kerr optical) caused by the third-order nonlinear susceptibility $\chi^{(3)}$ in a nanocomposite material consisting of CdSe quantum dots in phosphate glass is observed experimentally. The signs and values of the off-diagonal $\chi^{(3)}$ tensor components are determined using Z-scan technique and nonlinear ellipsometry. It is shown that the nonlinear response contains three time components; the fastest component duration does not exceed 20 ps, the intermediate component is exponential and decays for 90 $\pm$ 11 and 385 $\pm$ 30 ps for different samples, and the longest component is nonexponential with a duration on the order of nanoseconds. Switching of the optical signal with a time not exceeding 20 ps is demonstrated.