Fluoride glass-based surface plasmon resonance sensor in infrared region: performance evaluation

Excitation parameters shown by a plasmonic structure are different in the near infrared (NIR) region as compared with that of the visible region. Fluoride-based glass materials show high transparency in the infrared (IR) region, which plays an important role from an experimental point of view. In order to explore optical sensors based on a heavy metal doped fluoride substrate, performance of a surface plasmon resonance (SPR) based sensor having HBL glass as the substrate material to couple direct light in the NIR region is discussed. The proposed sensor's structure is based on Kretschmann configuration with gold (Au) deposited on an HBL glass substrate. Experimental refractive index values of water samples containing different NaCl concentrations are taken as the sensing medium for design and modelling of the sensor. The analysis was carried out for some different samples also. An HBL-based SPR sensor is able to provide significantly enhanced sensing performance compared with other conventional glass substrates operated in different spectral regions (SF10 in visible and SiO₂ in NIR). The study paves the way for designing SPR sensor probes based on fluoride optical fibers in the IR region for different biological and chemical applications. (paper)