Ge[formula omitted]Sb[formula omitted]Te[formula omitted]-coated fiber optic SPR sensor: Improving sensitivity

Abstract

This paper proposes and demonstrates a fiber optic surface plasmon resonance (SPR) sensor based on Au–Ge2 Sb2Te5 (GST). The GST is deposited on the Au film, which increases the dielectric constant of the metal layer due to the high refractive index (RI) of GST. Therefore, compared with conventional Au SPR sensor, the resonance wavelength of the Au–GST SPR sensor red-shifts, and the sensitivity is improved. When environmental RI varies in the range of 1.333∼1.403, the experimental results show that the sensor performs the best when the thicknesses of Au film is 50 nm and the GST layer’s thickness is 25 nm. The proposed sensor’s sensitivity is 5210 nm/RIU (refractive index unit), which is much higher than that of the conventional Au-based SPR sensor (2418 nm/RIU). The sensor achieves relatively high sensitivity based on a very simple structure, and it has potential applications in biological and biochemical such as DNA hybridization, cancer screenings, environmental temperature and humidity detection, and chemical analysis.