High-performance Opening-up Dual-core Photonic Crystal Fiber Sensors Based on Surface Plasmon Resonance

Abstract

Nowadays, plasmonic sensors based on photonic crystal fiber (PCF) attracted a great deal of attention in the field of optical sensing. Opening-up dual-core photonic crystal fibers based on surface plasmon resonance (SPR) are numerically demonstrated and analyzed for detecting a wide refractive index (RI) range by the finite-difference time-domain method (FDTD). Wavelength and amplitude integration methods as well as figures of merit are used to investigate the sensing performance. For improving sensing performance, a large hole between two cores in the opening-up section is introduced. The opening-up section as a sensing channel is coated with a gold film and a thin titanium dioxide ( $${TiO}_{2}$$ ) layer. By surface engineering including imposing of grating on the gold film, specification of optimized values of different layers located near the surface and sensing performance are investigated. Next, the effect of the fiber structural parameters is analyzed to enhance SPR and fundamental core mode coupling. The proposed sensor revealed maximum wavelength and amplitude sensitivities of 15,167 $$\left(\frac{nm}{RIU}\right)$$ and 207.19 $$\left({RIU}^{-1}\right)$$ , respectively. Due to the ease of infiltration of analyte and gold coating and thanks to the high wavelength and amplitude sensitivity, the sensors can be a promising candidate for physical and chemical sensing.