Revealing single emitter spectral dynamics from intensity correlations in an ensemble fluorescence spectrum

TL;DR

This paper introduces a method to extract individual emitter spectral linewidths from ensemble fluorescence spectra by analyzing intensity correlations, enabling high-resolution single emitter characterization even under weak excitation.

Contribution

The study presents a novel correlation-based technique using a Michelson interferometer and avalanche photodiodes to determine single emitter linewidths from ensemble data.

Findings

Successfully extracts single emitter linewidths from ensemble spectra.

Overcomes inhomogeneous broadening effects in fluorescence measurements.

Applicable under weak, broadband excitation conditions.

Abstract

We show that the single emitter linewidth underlying a broadened ensemble emission spectrum can be extracted from correlations among the stochastic intensity fluctuations in the ensemble spectrum. Spectral correlations can be observed at high temporal and spectral resolutions with a cross-correlated pair of avalanche photodiodes placed at the outputs of a scanning Michelson interferometer. As illustrated with simulations in conjunction with Fluorescence Correlation Spectroscopy, our approach overcomes ensemble and temporal inhomogeneous broadening to provide single emitter linewidths, even for emitters under weak, continuous, broadband excitation.