Journal
MEASUREMENT SCIENCE AND TECHNOLOGY
Volume 21, Issue 11, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.1088/0957-0233/21/11/115206
Keywords
whispering-gallery mode; humidity sensor; water vapor concentration; optical resonance shift; ultra-fine resolution
Funding
- National Science Foundation [CBET-0651737]
- US Department of Agriculture under CSREES [2008-01336]
- Rutgers University
Ask authors/readers for more resources
The spectral shift response of optical whispering-gallery modes due to the adsorption and desorption of water molecules into a SiO2 nano-coating is investigated. This coating is applied to a silica microsphere and optical-shift measurements are made at a very low humidity level (<10%). The micro-optical coupling system is incorporated into a sealed vacuum chamber for controlled humidity testing. The experimental observation of the whispering-gallery-mode spectral shift with refractive index is consistent with a theoretical analysis using Mie theory. A significant hysteresis effect is observed in the spectral shift of individual whispering-gallery modes during variable humidity tests. To understand the hysteresis mechanism, tests with step changes in humidity are performed, which reveal complex and dynamic water molecule transport phenomena between the nano-coating and surrounding environment.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available