Whispering-gallery mode resonator sensors based on liquid droplets

R. Zullo; A. Giorgini; S. Avino; P. Malara; P. De Natale; G. Gagliardi

doi:10.1117/12.2230623

22 April 2016 Whispering-gallery mode resonator sensors based on liquid droplets

R. Zullo, A. Giorgini, S. Avino, P. Malara, P. De Natale, G. Gagliardi

Proceedings Volume 9727, Laser Resonators, Microresonators, and Beam Control XVIII; 972713 (2016) https://doi.org/10.1117/12.2230623
Event: SPIE LASE, 2016, San Francisco, California, United States

Abstract

We present a simple and effective set-up to exploit the enhancement of passive optical cavities that are directly made from a liquid droplet. The optical resonances, corresponding to the so-called whispering-gallery modes (WGMs), are excited by a focused free-space beam edge-coupling scheme. Very narrow resonances are observed, both in the visible and near-infrared spectral regions, with quality (Q) factors ranging from 10⁵ to 10⁷ and beyond. Different methods for interrogation via frequency locking of a laser source to the WGM are shown. Locking of a diode laser to the equatorial modes of a liquid droplet resonator is demonstrated at 1560 nm and 663 nm. This approach makes high-performance optical sensing directly feasible in liquid samples with a number of advantages in view of their application for detection and quantification of bio-molecules.

Citation Download Citation

R. Zullo, A. Giorgini, S. Avino, P. Malara, P. De Natale, and G. Gagliardi "Whispering-gallery mode resonator sensors based on liquid droplets", Proc. SPIE 9727, Laser Resonators, Microresonators, and Beam Control XVIII, 972713 (22 April 2016); https://doi.org/10.1117/12.2230623

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