Polariton propagation in weak confinement quantum wells

TL;DR

This paper develops a microscopic variational theory to analyze exciton-polariton propagation in quantum wells, accurately modeling center-of-mass quantization and matching experimental transmission spectra in GaAs samples.

Contribution

It implements an analytical model for exciton center-of-mass quantization in quantum wells, including interface effects, and compares theoretical eigenstates with experimental spectra.

Findings

The model reproduces center-of-mass quantization across various well thicknesses.

Theoretical spectra agree well with experimental data.

Exciton-polariton dips are linked to Wannier exciton states.

Abstract

Exciton-polariton propagation in a quantum well, under centre-of-mass quantization, is computed by a variational self-consistent microscopic theory. The Wannier exciton envelope functions basis set is given by the simple analytical model of ref. [1], based on pure states of the centre-of-mass wave vector, free from fitting parameters and "ad hoc" (the so called additional boundary conditions-ABCs) assumptions. In the present paper, the former analytical model is implemented in order to reproduce the centre-of-mass quantization in a large range of quantum well thicknesses (5a_B < L < inf.). The role of the dynamical transition layer at the well/barrier interfaces is discussed at variance of the classical Pekar's dead-layer and ABCs. The Wannier exciton eigenstates are computed, and compared with various theoretical models with different degrees of accuracy. Exciton-polariton transmission spectra in large quantum wells (L>> a_B) are computed and compared with experimental results of Schneider et al.\cite{Schneider} in high quality GaAs samples. The sound agreement between theory and experiment allows to unambiguously assign the exciton-polariton dips of the transmission spectrum to the pure states of the Wannier exciton center-of-mass quantization.