Quantum fluctuations and lineshape anomaly in a high-$\beta$ silver-coated InP-based metallic nanolaser

TL;DR

This paper investigates the quantum optical behavior of high-$eta$ metallic nanolasers, revealing a lineshape anomaly indicating the transition to lasing through a spectral lineshape change from Lorentzian to Gaussian.

Contribution

It introduces a new spectral lineshape indicator for lasing in high-$eta$ nanolasers, advancing understanding of their quantum emission transition.

Findings

Identification of a lineshape transition from Lorentzian to Gaussian above threshold

Demonstration of stimulated emission causing spectral lineshape anomalies

Enhanced understanding of lasing physics in high-$eta$ nanolasers

Abstract

Metallic nanocavity lasers provide important technological advancement towards even smaller integrable light sources. They give access to widely unexplored lasing physics in which the distinction between different operational regimes, like those of thermal or a coherent light emission, becomes increasingly challenging upon approaching a device with a near-perfect spontaneous-emission coupling factor $\beta$. In fact, quantum-optical studies have to be employed to reveal a transition to coherent emission in the intensity fluctuation behavior of nanolasers when the input-output characteristic appears thresholdless for $\beta = 1$ nanolasers. Here, we identify a new indicator for lasing operation in high-$\beta$ lasers by showing that stimulated emission can give rise to a lineshape anomaly manifesting as a transition from a Lorentzian to a Gaussian component in the emission linewidth that dominates the spectrum above the lasing threshold.