Optical nonlinearities and ultrafast carrier dynamics in semiconductor quantum dots

Low-dimensional semiconductors have attracted great interest due to the potential for tailoring their linear and nonlinear optical properties over a wide-range. Semiconductor nanocrystals (NCs) represent a class of quasi-zero-dimensional objects or quantum dots. In this paper we report femtosecond (fs) studies of ultrafast optical nonlinearities, and energy relaxation and trapping dynamics in three types of quantum-dot systems: semiconductor NC/glass composites made by high temperature precipitation, ion-implanted NCs, and colloidal NCs. Comparison of ultrafast data for different samples allows us to separate effects being intrinsic to quantum dots from those related to lattice imperfections and interface properties.