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 ?L) using, for instance, a silica fiber with 250 ?m 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.
Direct Sensing in Liquids Using Whispering-Gallery-Mode Droplet Resonators
GIORGINI, ANTONIO;DE NATALE, PAOLO;GAGLIARDI, GIANLUCA;MALARA, PIETRO;AVINO, SAVERIO
2014
Abstract
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 ?L) using, for instance, a silica fiber with 250 ?m 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.File in questo prodotto:
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