Angular position detection of single nanoparticles on rolled-up optical microcavities with lifted degeneracy

Abstract

Nanoparticle position detection is prevented in highly symmetric whispering-gallery-mode optical microcavities due to the redistributable electric field of resonant light therein. In asymmetric tubular microcavities formed by a rolled-up slab waveguide, the optical resonant modes are split and locked to the spiral-shaped geometry which provides a reference point for the nodes and antinodes of the electric field within the microcavity. The discriminative responses of neighboring resonant modes to a local disturbance provide a method for angular position detection of a single nanoparticle on a rolled-up optical microcavity. These findings add functionality to microcavity applications and a deeper understanding of cavity electrodynamics.