Enhanced whispering gallery mode sensors

Cheng Li, M. H. Teimourpour, Euan McLeod, Judith Su

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Optical whispering gallery mode (WGM) biochemical sensors operate by tracking changes in resonant frequency as materials enter the evanescent near-field of the resonator. To achieve the smallest limit of detection, it is desirable for WGM sensors to exhibit as large a frequency shift as possible for a material of a given size and refractive index, as well as the ability to track as small a frequency shift as possible. Previously, plasmonic nanoantennas have been coupled to WGM resonators to increase the magnitude of resonance shifts via plasmonic enhancement of the electric field, however this approach also results in increased scattering from the WGM, which degrades its quality factor, making it less sensitive to extremely small frequency shifts. This degradation is caused by the ohmic and scattering dissipation caused by metallic nanoantennas. Using simulations, we show here that the precise positioning of nanoantennas coupled to a microtoroid WGM resonator can be used to overcome this drawback and achieve ultrahigh-Q plasmonic cavity modes simultaneously with electric field enhancement. It is shown that a nanoantenna composed of two similarly coupled nanorods supports higher Q modes than a single nanorod antenna. Our results have immediate application in the context of optical sensing.

Original languageEnglish (US)
Title of host publicationChemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XIX
EditorsChris R. Howle, Jason A. Guicheteau, Augustus Way Fountain
ISBN (Electronic)9781510617698
StatePublished - 2018
EventChemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XIX 2018 - Orlando, United States
Duration: Apr 16 2018Apr 18 2018

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceChemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XIX 2018
Country/TerritoryUnited States


  • Microcavity
  • nanoantenna
  • plasmonic cavity mode

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


Dive into the research topics of 'Enhanced whispering gallery mode sensors'. Together they form a unique fingerprint.

Cite this