Controlled plasmon-enhanced fluorescence by spherical microcavity

TL;DR

This paper demonstrates how a photonic microcavity can control plasmon-enhanced fluorescence, allowing for tunable emission properties useful in sensing and imaging, by engineering the local electromagnetic environment around quantum emitters.

Contribution

It introduces a method to modulate plasmon-enhanced fluorescence using a photonic microcavity, combining nanorod and nanodiamond emitters with a polystyrene sphere to control emission spectra and decay rates.

Findings

Resonant enhancement of emission at photonic modes

Spectral shape independence from emitter-sphere separation

Coupling strength affects fluorescence decay rate modulation

Abstract

A surrounding electromagnetic environment can engineer spontaneous emissions from quantum emitters through the Purcell effect. For instance, a plasmonic antenna can efficiently confine an electromagnetic field and enhance the fluorescent process. In this study, we demonstrate that a photonic microcavity can modulate plasmon-enhanced fluorescence by engineering the local electromagnetic environment. Consequently, we constructed a plasmon-enhanced emitter (PE-emitter), which comprised a nanorod and a nanodiamond, using the nanomanipulation technique. Furthermore, we controlled a polystyrene sphere approaching the PE-emitter and investigated in situ the associated fluorescent spectrum and lifetime. The emission of PE-emitter can be enhanced resonantly at the photonic modes as compared to that within the free spectral range. The spectral shape modulated by photonic modes is independent of the separation between the PS sphere and PE-emitter. The band integral of the fluorescence decay rate can be enhanced or suppressed after the PS sphere couples to the PE-emitters, depending on the coupling strength between the plasmonic antenna and the photonic cavity. These findings can be utilized in sensing and imaging applications.