Exploring the Photon-Number Distribution of Bimodal Microlasers

TL;DR

This study uses a photon-number resolving sensor to analyze the emission characteristics of bimodal microlasers, revealing complex emission behaviors and mode switching that are not detectable with traditional methods.

Contribution

It demonstrates the effectiveness of photon-number resolving sensors in uncovering detailed emission dynamics in bimodal microlasers, including thermal and Poissonian distributions and mode bistability.

Findings

High-$eta$ microlasers show thermal and coherent emission near threshold.

At higher pump powers, one mode emits Poissonian photons, the other thermal.

Photon-number resolving sensors reveal mode switching and subtle emission effects.

Abstract

A photon-number resolving transition edge sensor (TES) is used to measure the photon-number distribution of two microcavity lasers. The investigated devices are bimodal microlasers with similar emission intensity and photon statistics with respect to the photon auto-correlation. Both high-$\beta$ microlasers show partly thermal and partly coherent emission around the lasing threshold. For higher pump powers, the strong mode of microlaser A emits Poissonian distributed photons while the emission of the weak mode is thermal. In contrast, laser B shows a bistability resulting in overlayed thermal and Poissonian distributions. While a standard Hanbury Brown and Twiss experiment cannot distinguish between simple thermal emission of laser A and the mode switching of laser B, a TES allows us to measure the photon-number distribution which provides important insight into the underlying emission processes. Indeed, our experimental data and its theoretical description by a master equation approach show that TESs are capable of revealing subtle effects like temporal mode switching of bimodal microlasers. As such our studies clearly demonstrate the huge benefit and importance of investigating nanophotonic devices via photon-number resolving sensors.