Method for predicting whispering gallery mode spectra of spherical microresonators

TL;DR

This paper introduces a 3D FDTD simulation toolkit for predicting whispering gallery mode spectra in microspheres, enhancing experimental design and analysis of optical resonators for biosensing.

Contribution

The paper presents a novel FDTD-based method that improves upon analytic models by allowing flexible flux collection regions and mode excitation scenarios.

Findings

FDTD toolkit accurately predicts whispering gallery mode spectra.

The method enables customized simulation of mode excitation scenarios.

The approach aids in designing microsphere-based biosensors.

Abstract

A full three-dimensional Finite-Difference Time-Domain (FDTD)-based toolkit is developed to simulate the whispering gallery modes of a microsphere in the vicinity of a dipole source. This provides a guide for experiments that rely on efficient coupling to the modes of microspheres. The resultant spectra are compared to those of analytic models used in the field. In contrast to the analytic models, the FDTD method is able to collect flux from a variety of possible collection regions, such as a disk-shaped region. The customizability of the technique allows one to consider a variety of mode excitation scenarios, which are particularly useful for investigating novel properties of optical resonators, and are valuable in assessing the viability of a resonator for biosensing.