Direct Sensing in Liquids Using Whispering-Gallery-Mode Droplet Resonators

Year: 2014

Authors: Avino S., Krause A., Zullo R., Giorgini A., Malara P., De Natale P., Loock H.-P., Gagliardi G.

Autors Affiliation: CNR-Istituto Nazionale di Ottica, via Campi Flegrei 34, Comprensorio Olivetti, 80078 Pozzuoli (NA) Italy;
CNR-Istituto Nazionale di Ottica, Largo E. fermi 6, 50125 Arcetri Firenze, Italy;
Department of Chemistry, Queen’s Univetrsity Kingston Canada

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 similar to 0.5 mu L) using, for instance, a silica fiber with 250 mu 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.

Journal/Review: ADVANCED OPTICAL MATERIALS

Volume: 2 (12)      Pages from: 1115  to: 1226

More Information: This work has been partially funded by Italian Ministry for Education and Research (MIUR) with project PON 01_01525-MONICA. A. Krause acknowledges support from the Leonardoburo foundation (Cottbus, Germany). The authors wish to thank P. Ferraro, M. Capezzuto and H. Waechter for support and stimulating discussions. S.A., A.K.R.Z. and G.G. built the set-up and performed the experiments. S. A., A.G., P.M. and H.P.L. analysed the data. A.G. and R.Z. prepared the samples. All authors contributed to the discussion and wrote the manuscript. G.G. and S. A. conceived the idea and designed the system. P.D.N. and G.G. supervised and coordinated the project.
KeyWords: Cavity photon lifetimes; Chemical sensing; Laser frequency locking; Liquids; Microcavities; Particle detection; Whispering gallery modes
DOI: 10.1002/adom.201400322

Citations: 64
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