Theory of lasing in a two-dimensional array of plasmonic nanolasers

TL;DR

This paper develops a first-principles theory for lasing in a 2D array of plasmonic nanolasers, highlighting the role of molecular layer thickness and shape in lasing thresholds and inversion conditions.

Contribution

It introduces a rigorous theoretical model for plasmonic nanolaser arrays, predicting lasing thresholds and switching behavior based on geometry and molecular layer parameters.

Findings

Lasing threshold depends on emission angle, nanoparticle shape, and molecular layer thickness.

The theory predicts switching from conventional lasing to lasing without inversion.

Numerical calculations align with recent experimental results.

Abstract

A theory of lasing in a two-dimensional array of metal nanoparticles (MNPs) covered with a thin layer of fluorescent molecules is developed from first principles. The approach is based on a rigorous account of the local field in a close vicinity of a reflective surface which provides a feedback for molecular dipole oscillations. The theory predicts the lasing threshold in such an open cavity in terms of the polar angle of laser emission, MNPs shape and the molecular layer thickness. It is demonstrated that the latter parameter plays a crucial role in the lasing condition and controls a switching from conventional lasing to lasing without inversion. This research is inspired by recent experiments in this field [N. Toropov et al, Adv. Photonics Res. {\bf 2}, 2000083 (2021)] and provides the numerical calculations carried out for the experimental conditions.