# Scatterer assisted whispering gallery mode microprobe

## TL;DR

This paper presents a fiber-based whispering-gallery-mode microprobe that uses a nanotip to efficiently excite WGMs with high coupling efficiency, enabling practical sensing and imaging applications.

## Contribution

It introduces a novel nanotip scattering method for efficient far-field WGM excitation in a fiber microprobe, achieving high coupling efficiency and integrated fiber-based operation.

## Key findings

- Achieved 16.8% WGM excitation efficiency.
- Demonstrated fiber-based input and output propagation.
- Enabled practical sensing and imaging applications.

## Abstract

Fiber based whispering-gallery-mode (WGM) microprobe, combining both the high optical field enhancement of the WGMs and the practicability of the fiber probe, is highly demanded in sensing and imaging. Here in this paper, we experimentally report the efficient far-field coupling of WGMs by scattering the focused laser beam through a nanotip. With the help of Purcell effect as well as the two-step focusing technique, a WGM excitation efficiency as high as 16.8% has been achieved. Both the input and output of the probe light propagate along the same fiber, which makes the whole coupling system a fiber based WGM microprobe for sensing/imaging applications.

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Source: https://tomesphere.com/paper/1802.10232