Two-photon- photoluminescence excitation spectroscopy of single quantum-dots

TL;DR

This study combines experimental and theoretical approaches to analyze two-photon photoluminescence excitation spectra of single quantum dots using resonant lasers, revealing detailed insights into exciton and biexciton states.

Contribution

It provides a comprehensive experimental and theoretical analysis of biexciton photoluminescence excitation in single quantum dots with polarized, resonant laser excitation.

Findings

Mapped biexciton photoluminescence excitation spectra

Analyzed complex resonance spectra with a many-carrier model

Confirmed Coulomb interactions govern the excitation processes

Abstract

We present experimental and theoretical study of single semiconductor quantum dots excited by two non-degenerate, resonantly tuned variably polarized lasers. The first laser is tuned to excitonic resonances. Depending on its polarization it photogenerates a coherent single exciton state. The second laser is tuned to biexciton resonances. By scanning the energy of the second laser for various polarizations of the two lasers, while monitoring the emission from the biexciton and exciton spectral lines, we map the biexciton photoluminescence excitation spectra. The resonances rich spectra of the second photon absorption are analyzed and fully understood in terms of a many carrier theoretical model which takes into account the direct and exchange Coulomb interactions between the quantum confined carriers.