A Refractive Index Sensor Based on the Resonant Coupling to Cladding Modes in a Fiber Loop

Autor: José Luis Cruz, Miguel V. Andrés, David Monzón-Hernández, Antonio Díez, Enrique Silvestre, Alejandro Martínez-Ríos, Mauricio Reyes
Jazyk: angličtina
Rok vydání: 2013
Předmět:
Zdroj: Sensors, Vol 13, Iss 9, Pp 11260-11270 (2013)
Druh dokumentu: article
ISSN: 1424-8220
DOI: 10.3390/s130911260
Popis: We report an easy-to-build, compact, and low-cost optical fiber refractive index sensor. It consists of a single fiber loop whose transmission spectra exhibit a series of notches produced by the resonant coupling between the fundamental mode and the cladding modes in a uniformly bent fiber. The wavelength of the notches, distributed in a wavelength span from 1,400 to 1,700 nm, can be tuned by adjusting the diameter of the fiber loop and are sensitive to refractive index changes of the external medium. Sensitivities of 170 and 800 nm per refractive index unit for water solutions and for the refractive index interval 1.40–1.442, respectively, are demonstrated. We estimate a long range resolution of 3 × 10−4 and a short range resolution of 2 × 10−5 for water solutions.
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