Dynamics in semiconductor and other materials are studied using optical and THz pump-probe methods. Rapid changes in optical properties of materials are measured using spectral interferometry, electro-optic sampling, and other techniques. Coherent control techniques for all-optical injection of charge and spin currents, coupled with spatially-resolved pump-probe measurements, are used to study carrier transport. Changes in linear and nonlinear optical susceptibilities in an applied DC or THz electric field are also of interest, including the Franz-Keldysh effect. Materials of interest include layered semiconductors, novel 2D materials, and topological materials. Research is done in close collaboration with other groups at NIST with expertise in complementary techniques and materials growth.