Generation of High Power Far-Infrared Radiation and Ionization of Sodium Stark States by Sub-Single Pulses.

This dissertation summarizes research in the areas of high power Far-Infrared electromagnetic radiation in terahertz regime, nonlinear optical effects in Zinc-blende semiconductor materials, and ionization of Stark states using sub-single-cycle pulses. Using ultra-short (120 fsec) laser pulses from a Chirped Pulse Amplifier System, we have successfully generated 500 fsec FIR pulses of mu J energy from GaAs wafers biased with a large electric field. This pulse energy is two orders of magnitude higher than results reported previously. Study of FIR radiation from <111 > InP emitters revealed 2nd order, 3rd order, and 4th order nonlinear frequency mixings. We have also studied ionization of Na Stark states using this new source of FIR radiation. Results show dramatic asymmetry in the ionization probabilities for FIR pulses of opposite polarities. Numerical simulation using classical mechanics are used to explain many of the features observed in the experiments.