Optical properties of gallium arsenide/aluminum gallium arsenide and gallium aluminum indium arsenide/indium aluminum arsenide multiple quantum well and superlattice structures grown by molecular beam epitaxy.

Abstract

Gain spectra are characterized as a function of the well-width in GaAs multiple quantum wells with AlGaAs barriers by nanosecond pump-probe spectroscopy. The gain bandwidth is larger for the same peak gain in wider well-width multiple quantum wells and is explained qualitatively. The Iinewidth broadening factor is calculated from the gain spectra and studied as a material parameter. It is shown that the linewidth broadening factor increases with wavelength and decreases with carrier density. MBE-grown integrated-mirror etalons made from GaAs/AlGaAs. in the 800 nm wavelength region. and GaAllnAs/InAlAs. in the 1.3 μm wavelength region. exhibit lasing by optical pumping. Below threshold. the 800 nm integrated-mirror etalon is used for nonlinear switching which. in the architecture presented. is capable of extracting a single 10 ps pulse from a pair of pulses spaced 40 ps apart. Nonlinear optical properties of type II GaAs/AlAs short-period superlattices are presented and show an apparent high energy shift of the absorption band edge at 10K and no shift at 77 K as the absorption is saturated. Type I multiple quantum well structures of similar dimensions show similar high energy band edge shifts for both temperatures. 10K and 77 K due to phase-space filling. In contrast. electrons in type II structures reside in the barrier and do not contribute to the chemical potential. Transitions in GaAs/AlGaAs coupled-well superlattices show transitions that are a function of the center barrier thickness and reveal shorter carrier lifetimes than a GaAs quantum well of equal thickness without a center barrier.