# Excitation of whispering gallery modes with a "point-and-play", fiber-based, optical nano-antenna

## TL;DR

This paper introduces a simple, fiber-based nano-antenna technique for efficiently exciting and detecting whispering gallery modes in microresonators, maintaining high Q-factors suitable for advanced optical applications.

## Contribution

It presents a novel, low-cost coupling method using a fiber-based nano-antenna that preserves high Q-factors over a wide range of coupling conditions.

## Key findings

- Coupling efficiency around 13% achieved.
- Q-factor maintained at 10^8 across various coupling gaps.
- Spectral features include Lorentzian dips, Fano shapes, and peaks.

## Abstract

We demonstrate the excitation and detection of whispering gallery modes in optical microresonators using a "point-and-play", fiber-based, optical nano-antenna. The coupling mechanism is based on cavity-enhanced Rayleigh scattering. Collected spectra exhibit Lorentzian dips, Fano shapes, or Lorentzian peaks, with a coupling efficiency around 13\%. The spectra are characterized by the coupling gap, polarization, and fiber tip position. The coupling method is simple, low-cost and, most importantly, the \textit{Q}-factor can be maintained at $10^8$ over a wide coupling range, thereby making it suitable for metrology, sensing, or cavity quantum electrodynamics (cQED) experiments.