# Excitation mapping of whispering gallery modes in silica microcavities

## TL;DR

This paper introduces a novel method for directly mapping whispering gallery modes in silica microcavities using a tapered fiber coupler, simplifying the process by eliminating additional tools and enabling detailed near-field analysis.

## Contribution

The study presents a new technique for excitation mapping of whispering gallery modes using the coupler itself, applicable to microspheres and microtoroids, enhancing simplicity and precision.

## Key findings

- Successful near-field mapping of whispering gallery modes
- Application to both microspheres and microtoroids
- Elimination of additional mapping tools

## Abstract

We report the direct observation of the electromagnetic-field distribution of whispering?gallery modes in silica microcavities (spheres and toroids). It is revealed by their excitation efficiency with a tapered fiber coupler swept along the meridian. The originality of this method lies in the use of the coupler itself for the near field mapping, eliminating the need of additional tools used in previous work. This method is successfully applied to microspheres and microtoroids