Speaker
Callum Doolin
(University of Alberta)
Description
Optical microdisks are intriguing devices due to their small size, compatibility with standard planar micro/nano-fabrication techniques, and ability to support high-Q whispering gallery modes. We fabricate and explore the use of thin (130 nm) Si$_3$N$_4$ disks with diameters of 15 - 30 μm as refractive index sensors, using a dimpled-tapered fiber to couple with the optical modes under water. The thin disks cause evanescent fields to extend far into the surrounding medium, providing large shifts of > 200 nm/refractive index units (RIU) of the optical modes in response to Lithium salts added to the environment. Loaded quality factors of ~$10^4$ let the resonant frequencies to be determined with great accuracy, providing a limit of detection near $10^{-6}$ RIU, comparable with state-of-the-art RI sensors.
Primary author
Callum Doolin
(University of Alberta)
Co-authors
Ms
B Lewis
(University of Alberta)
Mr
John Davis
(University of Alberta)
Mr
P Doolin
(University of Alberta)
