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Updated: Sep 2, 2025

Synthesis and Operation of Fluorescent-core Microcavities for Refractometric Sensing
Published on: March 13, 2013
Role of Symmetry Breaking in Observing Strong Molecule-Cavity Coupling Using Dielectric Microspheres
Adarsh B Vasista1,2, Eduardo J C Dias3, F Javier García de Abajo3,4
1Nanophotonic Systems Laboratory, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich 8092, Switzerland.
Abstract:
The emergence of dielectric open optical cavities has opened a new research avenue in nanophotonics. In particular, dielectric microspheres support a rich set of cavity modes with varying spectral characteristics, making them an ideal platform to study molecule-cavity interactions. The symmetry of the structure plays a critical role in the outcoupling of these modes and, hence, the perceived molecule-cavity coupling strength. Here, we experimentally and theoretically study molecule-cavity coupling mediated by the Mie scattering modes of a dielectric microsphere placed on a glass substrate and excited with far-field illumination, from which we collect scattering signatures both in the air and glass sides. Glass-side collection reveals clear signatures of strong molecule-cavity coupling (coupling strength 2g = 74 meV), in contrast to the air-side scattering signal. Rigorous electromagnetic modeling allows us to understand molecule-cavity coupling and unravel the role played by the spatial mode profile in the observed coupling strength.
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