Polarization control of quantum dot emission by chiral photonic crystal slabs

TL;DR

This paper theoretically demonstrates that chiral photonic crystal slabs can induce high degrees of circular polarization in quantum dot emission without external magnetic fields, depending on the structure's geometry.

Contribution

It introduces a novel approach to control quantum dot emission polarization using achiral materials and chiral structures at room temperature.

Findings

Up to 99% circular polarization for randomly distributed quantum dots.

Near 100% circular polarization achievable for some single quantum dots.

Polarization depends on the chiral structure geometry and radiation frequency.

Abstract

We investigate theoretically the polarization properties of the quantum dot's optical emission from chiral photonic crystal structures made of achiral materials in the absence of external magnetic field at room temperature. The mirror symmetry of the local electromagnetic field is broken in this system due to the decreased symmetry of the chiral modulated layer. As a result, the radiation of randomly polarized quantum dots normal to the structure becomes partially circularly polarized. The sign and degree of circular polarization are determined by the geometry of the chiral modulated structure and depend on the radiation frequency. A degree of circular polarization up to 99% can be achieved for randomly distributed quantum dots, and can be close to 100% for some single quantum dots.