Highly sensitive refractive index sensor based on TiO2/Ag films coated D-type photonic crystal fibers

In this paper, we proposed a D-type highly sensitive surface plasmon resonance (SPR)sensor based on multilayer films coated with photonic crystal fiber (PCF). Silver was selected as the plasmon material because its SPR spectrum is sharper than gold. Meanwhile, we used the titania (TiO2) as the second layer film since it could prevent the oxidation of silver and enhance the SPR effect. We simulated the refractive index sensing performances using the finite element method (FEM). This paper optimized the air hole size, polishing depth, silver film thickness, and TiO2 thickness. The multilayer film structure showed a significant improvement in the wavelength sensitivity of the sensor. The result showed that the maximum sensitivity reached 11,000 nm/RIU, which was increased by 139% compared with a single silver film. The sensor was suitable for accurately detecting the medical treatment and organic chemicals because of its high sensitivity and FOM.

Automated summary

This paper proposes a D-type highly sensitive surface plasmon resonance (SPR) sensor based on multilayer films coated with photonic crystal fiber (PCF). Silver is chosen as the plasmon material due to its sharper SPR spectrum compared to gold. Additionally, titania (TiO2) is used as the second layer film to prevent silver oxidation and enhance the SPR effect. The refractive index sensing performances are simulated using the finite element method (FEM). The optimized multilayer film structure shows a significant improvement in the wavelength sensitivity of the sensor, with a maximum sensitivity of 11,000 nm/RIU, an increase of 139% compared to a single silver film. The high sensitivity and figure of merit (FOM) of this sensor make it suitable for accurately detecting medical treatments and organic chemicals.