High-sensitivity ring-down evanescent-wave sensing in fiber resonators

Year: 2014

Authors: Avino S., Richmond C., Giorgini A., Malara P., Zullo R., De Natale P., Gagliardi G.

Autors Affiliation: Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica (INO), via Campi Flegrei 34 — Comprensorio A. Olivetti,
80078 Pozzuoli (Naples), Italy;
Centre for Metrology and Accreditation (MIKES), Tekniikantie 1, FI-02150 Espoo, Finland;
Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica (INO), Largo E. Fermi 6, 50125 Firenze, Italy

Abstract: We report on optical-fiber cavity ring-down spectroscopy (CRDS) in the liquid phase using a laser emitting at telecommunication wavelengths. A fiber-ring cavity, comprising a short evanescent-wave coupler for radiation-matter interaction, is used as a sensor while its resonance modes are frequency locked to the laser. Exploiting the intrinsic sensitivity and noise immunity of the CRDS technique, we show that liquid absorption can be detected down to a level that is nearly a factor of 20 above the shot noise limit. We provide a thorough comparison between the experimental results and various noise contributions and address different expressions that can be used to calculate the shot noise equivalent absorbance. As a proof of principle, polyamine detection in aqueous solutions is carried out demonstrating a minimum detectable absorbance of 1.8 x 10(-7) Hz(-1/2), which, to our knowledge, is the best sensitivity limit reported to date for evanescent-wave sensors. (C) 2014 Optical Society of America

Journal/Review: OPTICS LETTERS

Volume: 39 (19)      Pages from: 5725  to: 5728

More Information: The experimental work was funded by MIUR with Programma Operativo Nazionale (PON) through projects PON01_01525-MONICA and PON01_01209-BACKOP. C. Richmond acknowledges support from the Magnus Ehrnrooth Foundation and the Academy of Finland. The authors are grateful to J. Hodges for helpful discussions and G. Notariale for technical assistance.
KeyWords: High-sensitivity; In-fiber
DOI: 10.1364/OL.39.005725

Citations: 5
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