High-Resolution Spectroscopic Measurements of InGaAs/GaAs Self-Assembled Quantum Dots

Abstract

We report development of two absorption-based spectroscopic methods that have been adapted from atomic physics techniques to elucidate the basic physical properties of InGaAs/GaAs self-assembled quantum dots(SAQDs). Absorptive spectroscopic measurements allow the examination of the SAQDs optical transitions free from carrier relaxation effects. In addition, we employ these techniques to study SAQDs' optical transition with a level of spectral resolution not available using ultra-fast techniques. The first of the two approaches we discuss is cavity ring-down spectroscopy (CRDS), which permits an absolute measurement of absorption. We report on initial application of CRDS to SAQDs and present an assessment based on these measurements for single SAQD spectroscopy using this technique. The second method, spectral hole burning, is applied to SAQDs in a semiconductor ridge waveguide and permits the homogeneous linewidth of the SAQDs to be separated from the broad inhomogeneous spectrum.