Design and optimization of surface plasmon resonance fiber sensor based on square gold nano-rod array

Abstract

Using finite element method (FEM), a D-shaped surface plasmon resonance (SPR) fiber sensor based on square gold nano-rod array was designed and optimized. Here the core radius of single mode fiber is 8μm. The simulations show that the resonant wavelengths of 45th∼50th propagation modes and their wavelength redshifts due to the ambient refractive index change are all the same. Among the SPR spectrums for different modes, higher order mode will induce deeper notch and larger extinction ratio. By tracing the wavelength shift of the 45th mode, the sensor was optimized. The optimized sensor has 70nm square gold nano-rods thickness and 50nm distance between square nano-rods coated on D-shaped single mode fiber. Its average sensitivity of 6266 nm/RIU can be attained, which is much higher than 3150 nm/RIU of the single mode SPR fiber sensor in the ref. [1].