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Direct Sensing in Liquids Using Whispering‐Gallery‐Mode Droplet Resonators
Author(s) -
Avino Saverio,
Krause Anika,
Zullo Rosa,
Giorgini Antonio,
Malara Pietro,
De Natale Paolo,
Loock Hans Peter,
Gagliardi Gianluca
Publication year - 2014
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.201400322
Subject(s) - whispering gallery wave , resonator , materials science , surface tension , resonance (particle physics) , volume (thermodynamics) , whispering gallery , drop (telecommunication) , optics , optical cavity , laser , optoelectronics , nanotechnology , computer science , telecommunications , physics , particle physics , quantum mechanics
Liquid droplets suspended by the tip of a thin wire , a glass capillary, or a needle form high‐Q optical resonators, thanks to surface tension. Under gravity equilibrium conditions, the maximum drop diameter is approximately 1.5 mm for paraffin oil (volume ∼ 0.5 μL) using, for instance, a silica fiber with 250 μm thickness. Whispering gallery modes are excited by a free‐space near‐infrared laser that is frequency locked to the cavity resonance. The droplet cavity serves as a miniature laboratory for sensing of chemical species and particles.