Subnanosecond spectral diffusion measurement using photon correlation

TL;DR

This paper introduces a novel photon correlation technique for measuring spectral diffusion with subnanosecond resolution, enabling detailed insights into local environments of emitters in various media.

Contribution

A new experimental method using photon correlations within a spectral line to measure spectral diffusion times with unprecedented temporal resolution.

Findings

Achieved spectral diffusion measurement with 90 ps resolution.

Demonstrated the method on single light emitters.

Exceeded previous resolution limits by four orders of magnitude.

Abstract

Spectral diffusion is a result of random spectral jumps of a narrow line as a result of a fluctuating environment. It is an important issue in spectroscopy, because the observed spectral broadening prevents access to the intrinsic line properties. However, its characteristic parameters provide local information on the environment of a light emitter embedded in a solid matrix, or moving within a fluid, leading to numerous applications in physics and biology. We present a new experimental technique for measuring spectral diffusion based on photon correlations within a spectral line. Autocorrelation on half of the line and cross-correlation between the two halves give a quantitative value of the spectral diffusion time, with a resolution only limited by the correlation set-up. We have measured spectral diffusion of the photoluminescence of a single light emitter with a time resolution of 90 ps, exceeding by four orders of magnitude the best resolution reported to date.