Investigation of refractive index sensing based on Fano resonance in fiber Bragg grating ring resonators

Year: 2015

Authors: Campanella C. E., De Leonardis F, Mastronardi L., Malara P., Gagliardi G., Passaro V. M. N.

Autors Affiliation: Dipartimento di Ingegneria Elettrica e dell’informazione, Politecnico di Bari, via Edoardo Orabona 4, 70125 Bari, Italy;
Istituto Nazionale di Ottica, Consiglio nazionale delle Ricerche, via Campi Flegrei 34, Comprensorio Olivetti 80078 Pozzuoli (Napoli) Italy

Abstract: In this paper we theoretically investigate a ring resonant cavity obtained by closing on itself a pi-shifted fiber Bragg grating, to be used for refractive index sensing applications. Differently from a conventional pi-shifted fiber Bragg grating, the spectral structure of this cavity is characterized by an asymmetric splitting doublet composed by a right side resonance having an asymmetric Fano profile and a left side resonance having a symmetric Lorentzian profile. The right side resonance shows a narrower and sharper peak than all the other kinds of resonance achievable with both conventional ring resonators and pi-shifted fiber Bragg gratings. A reduction of the resonant linewidth with respect to a conventional pi-shifted Fiber Bragg grating and a fiber ring resonator, having the same physical parameters, is theoretically proved, achieving up to five orders of magnitude improvement with respect to the usual ring resonator. Due to these resonance features, the pi-shifted Bragg grating ring resonator results suitable for RI sensing applications requiring extremely narrow resonances for high resolution measurements. In particular, by assuming a refractive index sensing to detect the presence of sugar in water, the sensor can show a theoretical resolution better than 10(-9) RIU. (C)2015 Optical Society of America

Journal/Review: OPTICS EXPRESS

Volume: 23 (11)      Pages from: 14301  to: 14313

More Information: This work has been partially supported by Politecnico di Bari under Fondo Ricerca di Ateneo (FRA) 2012 funding scheme.
KeyWords: Bragg gratings; Fiber Bragg gratings; Fibers; Optical resonators; Resonance; Resonators, Asymmetric splitting; Fiber ring resonators; High-resolution measurements; In-fiber Bragg gratings; Orders of magnitude; Physical parameters; Refractive index sensing; Sensing applications; Refractive index
DOI: 10.1364/OE.23.014301

Citations: 28
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