Revealing and Characterizing Dark Excitons Through Coherent Multidimensional Spectroscopy

TL;DR

This paper demonstrates how coherent multidimensional spectroscopy can effectively reveal and analyze dark excitons in quantum wells, providing detailed insights into their properties and interactions that are difficult to obtain with traditional methods.

Contribution

The study introduces a novel application of coherent multidimensional spectroscopy to identify and characterize dark excitons, including their lifetimes, linewidths, and coupling mechanisms.

Findings

Dark excitons identified in InGaAs/GaAs quantum wells.

Measured lifetimes and linewidths of dark excitons.

Evidence of coherent coupling between bright and dark excitons.

Abstract

Dark excitons are of fundamental importance in a broad range of contexts, but are difficult to study using conventional optical spectroscopy due to their weak interaction with light. We show how coherent multidimensional spectroscopy can reveal and characterize dark states. Using this approach, we identify different types of dark excitons in InGaAs/GaAs quantum wells and determine details regarding lifetimes, homogeneous and inhomogeneous linewidths, broadening mechanisms and coupling strengths. The observations of coherent coupling between bright and dark excitons hint at a role for a multi-step process by which excitons in the barrier can relax into the quantum wells.