Lifetime and Emission Characteristics of Electronic Excitations in 2D Optical Lattices

TL;DR

This paper investigates the lifetime and emission properties of excitons in 2D optical lattices, revealing how their radiative behavior depends on wave number, polarization, and confinement, with implications for energy storage and transfer.

Contribution

It provides a detailed analysis of exciton lifetimes and emission patterns in 2D optical lattices, highlighting conditions for superradiance and metastability, which are novel insights into exciton dynamics.

Findings

Long-lived excitons can store energy and transfer excitation over long distances.

Excitons exhibit superradiance with short lifetimes at long wavelengths and orthogonal polarization.

Metastable excitons with infinite lifetime can occur beyond a critical wave number.

Abstract

Collective electronic excitations "excitons" in planar optical lattices exhibit strong modifications of the radiative damping rate and directional emission pattern as compared to a single excited atom. Excitons for long wave numbers and polarizations orthogonal to the lattice plane exhibit superradiance with a very short life time and a tightly confined emission direction. For shorter wavelength and in plane polarization they can posses a long life time, which beyond a critical wave number tends to infinity. Those excitons thus become metastable and decoupled from the free radiation field. They can store a single energy quantum for a long time and transfer the excitation over long distances. In general the spatial, polarization and frequency dependence of the emission pattern can provide us with optical and electronic properties of optical lattices.