title: Surface plasmon resonance optical cavity enhanced refractive index sensing.
abstract: We report on a method for surface plasmon resonance (SPR) refractive index sensing based on direct time-domain measurements. An optical resonator is built around an SPR sensor, and its photon lifetime is measured as a function of loss induced by refractive index variations. The method does not rely on any spectroscopic analysis or direct intensity measurement. Time-domain measurements are practically immune to light intensity fluctuations and thus lead to high resolution. A proof of concept experiment is carried out in which a sensor response to liquid samples of different refractive indices is measured. A refractive index resolution of the current system, extrapolated from the reproducibility of cavity-decay time determinations over 133 s, is found to be about 10(-5) RIU. The possibility of long-term averaging suggests that measurements with a resolution better than 10(-7) RIU/√Hz are within reach.
authors.affiliation: Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica, via Campi Flegrei, 34—Comprensorio A. Olivetti, 80078 Pozzuoli, Naples, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Giorgini
authors.forename: S
authors.initials: S
authors.lastname: Avino
authors.forename: P
authors.initials: P
authors.lastname: Malara
authors.forename: G
authors.initials: G
authors.lastname: Gagliardi
authors.forename: M
authors.initials: M
authors.lastname: Casalino
authors.forename: G
authors.initials: G
authors.lastname: Coppola
authors.forename: M
authors.initials: M
authors.lastname: Iodice
authors.forename: P
authors.initials: P
authors.lastname: Adam
authors.forename: K
authors.initials: K
authors.lastname: Chadt
authors.forename: J
authors.initials: J
authors.lastname: Homola
authors.forename: P
authors.initials: P
authors.lastname: De Natale
mesh_terms: D055620:Optical Phenomena; D020349:Surface Plasmon Resonance / Q000379:methods*; D013997:Time Factors