Performance evaluation of a bilayer SPR-based fiber optic RI sensor with TiO2 using FDTD solutions

Abstract

Abstract:We proposed a new bilayer surface plasmon resonance-based fiber-optic refractive index sensor with silver and an over-layer of TiO 2 . We numerically investigated the optimal thickness of TiO 2 over-layer in the proposed sensor and compared its performance to that based on typical bimetallic layers of silver-and-gold in the aqueous media using finite-difference time domain approach. We show that the use of TiO 2 over-layer greatly improves the sensor performance in terms of sensitivity and signal-to-noise ratio compared to that with gold as the over-layer. Not only does the TiO 2 over-layer offer a cost-effective alternative to gold for overcoming the oxidation problem, but also it allows resonance wavelength-tunability.

A Simple Optical Fiber SPR Sensor With Ultra-High Sensitivity for Dual-Parameter Measurement

“…A matching condition met when there is continuity between the longitudinal component of the light propagation constant and surface plasmon oscillations at the interface of dielectric and metallic layers. Permittivity of the Ag layer is derived by using the Drude dispersion model [4], which is used to determine the wavelength-dependent dielectric constant of the metal layer as, ( )…”

“…SPR sensors have been widely reported for RI sensing only [4]- [9], with the dual-parameter sensing aspect being neglected. One reason is that a single resonance SPR sensor is unreliable for dual-parameter measurement due to the temperature-RI crosstalk.…”

Highly sensitive fiber-optic SPR sensor with surface coated TiO2/MWCNT composite film for hydrogen sulfide gas detection

“…More recently, a favorable method to improve the adsorption capability of SPR sensors by depositing nanomaterials onto the metal film has been investigated for highly sensitive detection, where the amount of gas molecular can be efficiently adsorbed on the nanomaterials film that induces a larger change of local dielectric constant. Metal oxide-based nanomaterials sensing films, such as WO 3 [19], SnO 2 [20], ZnO [21], CuO [22], and TiO 2 [23], have been employed to detect gas on account of the potential compatibility with low cost and high chemical stability. As a n-type oxide semiconductor (E g = 3.2 eV), TiO 2 has served as the most potential candidates for H 2 S detection, since the surface of TiO 2 material exhibits strong adsorption ability for H 2 S [24,25], rendering noticeable modification in the electronic structure.…”