High-repetition-rate femtosecond amplifiers and applications to semiconductor dynamics.

Abstract

This dissertation describes the development of a high-repetition-rate broadly-tunable ultrafast laser system, and experiments that employ this system to examine carrier dynamics in low-temperature-grown GaAs and in InGaAs quantum dots. The first part of the dissertation describes: the development of a chirped-pulse amplification system for a 250-kHz Ti:sapphire regenerative amplifier, a pulse characterization technique (STRUT) that allows complete analysis of femtosecond pulses in real-time, an alignment-insensitive technique for generating tunable amounts of third-order dispersion in a CPA system, and the design of a femtosecond optical parametric amplifier. The second part of this dissertation investigates carrier dynamics in two semiconductor systems via experiments that utilize the unique properties of this laser system. High-carrier-density two-color pump-probe measurements characterized the free-electron dynamics in low-temperature-grown GaAs and for the first time allowed determination of the trapped-electron lifetimes. Very-low-carrier-density broad-b and -probe measurements determined the carrier relaxation rates in InGaAs quantum dots and indicated the electron relaxation was very rapid in spite of a theoretical predicted phonon bottleneck.