Optical super-resonances in dielectric microsphere particles

TL;DR

This paper explores optical super-resonances in dielectric microspheres, revealing conditions for record-high electric field enhancements and demonstrating super-resolution focusing, advancing nanoscopy and photonics applications.

Contribution

It provides new insights into size and refractive index effects on super-resonances and demonstrates super-resolution focusing with various light sources.

Findings

Electric field enhancement can reach 10^9-10^11 under specific conditions.

Super-resonance modes enable super-resolution focusing with different lighting sources.

Enhanced understanding of super-resonance mechanisms for nanoscopy applications.

Abstract

Extreme field localization and giant field enhancement are often achieved by using plasmonic nanostructures and metamaterials such as strongly coupled silver nanoparticles.Dielectric particles and structures can focus light beyond the diffraction limit (photonic nanojet effect), but with much weaker strengths. Recently, we showed that dielectric microspheres could support high-order Mie resonance modes ("super resonance mode") that can generate similar level of electric field intensity enhancement as plasmonic structures on the order of 10^4 - 10^7. In this work, we aim to further advance our understanding of the super-resonance modes. New results on the effects of size parameter and refractive index on optical super-resonances across a wide parameter range and with improved numerical accuracies is presented. The results suggest that the electric field intensity enhancement could reach a record high level of 10^9-10^11 at specific conditions that surpass plasmonic enhancements. Moreover, super-resonance-enabled focusing by microsphere lens under different lighting sources (e.g., different color LEDs or lasers, halogen lamps) is investigated and compared for the first time. These results are important in understanding the super-resolution mechanism for microsphere nanoscopy and will find numerous potential applications in photonics.