Active Control of Plasmonic–Photonic Interactions in a Microbubble Cavity

Abstract

Active control of light–matter interactions using nanophotonic structures is critical for new modalities for solar energy production, cavity quantum electrodynamics (QED), and sensing, particularly at the single-particle level, where it underpins the creation of tunable nanophotonic networks. Coupled plasmonic–photonic systems show great promise toward these goals because of their subwavelength spatial confinement and ultrahigh-quality factors inherited from their respective components. Here, we present a microfluidic approach using microbubble whispering-gallery mode cavities to actively control plasmonic–photonic interactions at the single-particle level. By changing the solvent in the interior of the microbubble, control can be exerted on the interior dielectric constant and, thus, on the spatial overlap between the photonic and plasmonic modes. Qualitative agreement between experiment and simulation reveals the competing roles mode overlap and mode volume play in altering coupling strengths.

Molecular Polaritons for Chemistry, Photonics and Quantum Technologies

“…A prevalent approach in creating such plasmonic−photonic coupled cavities involves the hybridization between whispering-gallery mode (WGM, as the photonic component) and metal nanostructure mode (as the plasmonic component). 142,149,150 As shown in Figure 7c, the localized excitation of metal nanorods can shift the refractive index of the optical microresonator owing to the photothermal effect upon plasmonic excitations. Consequently, the WGM frequency can be flexibly adjusted in response to factors such as the power fluence, plasmonic structure geometries and Q-factors of the WGMs.…”

“…While plasmonic and photonic cavities distinctly hold their strength within the realms of molecular strong coupling, with the former featuring stronger field strength and the latter possessing high Q and tunability, it is intriguing to build a hybrid cavity combining advantages of both plasmonic and photonic modes, ,− offering augmented tunability and signal enhancement. A prevalent approach in creating such plasmonic–photonic coupled cavities involves the hybridization between whispering-gallery mode (WGM, as the photonic component) and metal nanostructure mode (as the plasmonic component). ,, As shown in Figure c, the localized excitation of metal nanorods can shift the refractive index of the optical microresonator owing to the photothermal effect upon plasmonic excitations. Consequently, the WGM frequency can be flexibly adjusted in response to factors such as the power fluence, plasmonic structure geometries and Q-factors of the WGMs.…”