Interpreting Purcell Enhancement of Non-Hermitian Metasurfaces with Spectral Parameters

TL;DR

This paper introduces an analytical spectral parameter-based model to predict Purcell enhancement in non-Hermitian metasurfaces, simplifying measurement challenges and aiding optimization of photoluminescence enhancement.

Contribution

The paper presents a new spectral parameter-based analytical approach to predict Purcell enhancement without nearfield measurements, verified through experiments and simulations.

Findings

Model accurately predicts Purcell enhancement from spectral data.

Experimental validation confirms the model's effectiveness.

Applicable to arbitrarily-shaped photoluminescent media.

Abstract

The Purcell effect describes the enhancement of the spontaneous emission rate of an emitter near a resonant structure. However, evaluating the Purcell factor quantitatively and empirically is difficult due to the difficulties in measuring the electromagnetic nearfield of an optical resonance for calculation of the exact effective modal volume, especially with non-Hermitian resonators. Therefore, we propose a new analytical approach to circumvent the need to measure the nearfield and predict the Purcell enhancement with spectral parameters, which can be directly measured in farfield or fitted from such spectral measurements. Our proposed model predicts the averaged Purcell enhancement by metasurfaces on a photoluminescent medium, and is verified with experimental measurements and numerical simulations of nanoparticle arrays coupled to a fluorescent thin film. The model directly analyzes the photoluminescence enhancement and extraction efficiency of metasurface, and can be generalized to work with arbitrarily-shaped photoluminescent medium that is coupled to a resonator. This discovery provides a practical and accessible way to understand the underlying mechanisms of photoluminescence enhancement and will facilitate optimization of metasurfaces for efficient extraction of the enhanced luminescence.