Whispering Gallery Modes in Standard Optical Fibres for Fibre Profiling Measurements and Sensing of Unlabelled Chemical Species

Anna Boleininger,Claire Vallance,Thomas Lake,Sophia Hami

doi:10.3390/s100301765

Abstract

Whispering gallery mode resonances in liquid droplets and microspheres have attracted considerable attention due to their potential uses in a range of sensing and technological applications. We describe a whispering gallery mode sensor in which standard optical fibre is used as the whispering gallery mode resonator. The sensor is characterised in terms of the response of the whispering gallery mode spectrum to changes in resonator size, refractive index of the surrounding medium, and temperature, and its measurement capabilities are demonstrated through application to high-precision fibre geometry profiling and the detection of unlabelled biochemical species. The prototype sensor is capable of detecting unlabelled biomolecular species in attomole quantities.

Highlights

Whispering gallery mode (WGM) resonances have been observed in liquid droplets and a variety of man-made resonators, including microspheres, toroidal resonators, and of particular interest for the work presented in this paper, optical fibres
Vahala and coworkers have claimed that single molecule detection sensitivities are possible for unlabelled biomolecules when WGM frequency shifts are monitored in custom-fabricated toroidal resonators [22]
We provide a brief introduction to the physical principles behind whispering gallery mode spectroscopy, before describing our experimental setup and a range of experiments carried out to characterise the technique and explore its potential applications

Summary

Introduction

Whispering gallery mode (WGM) resonances have been observed in liquid droplets and a variety of man-made resonators, including microspheres, toroidal resonators, and of particular interest for the work presented in this paper, optical fibres. Each time the laser wavelength comes into resonance with a WGM, light is coupled efficiently from the delivery fibre into the sensor fibre.

Results

Conclusion