Design and Optimization of Surface Plasmon Resonance Sensor Based on Polymer-Tipped Optical Fiber

In this study, a novel surface plasmon resonance (SPR) sensor based on a single-mode polymer-tipped optical fiber (PTOF) is designed and optimized. The refractive index (RI) measurement is achieved by exciting SPR at the interface between gold film and TiO2 layer coated on the polymer-tip. Finite-difference time-domain (FDTD) method based commercial optiFDTD software is used to optimize the design of the proposed sensor for a better performance related to the materials of the metal film, the shape of polymer-tips, and the thickness of TiO2 layer. The results show that the sensitivity of optimal single-mode PTOF SPR sensor reaches 3798 nm/RIU when analyte RI is 1.333, and reaches 5708 nm/RIU when analyte RI is 1.383. Compared with conventional optical fiber SPR sensors, the single-mode PTOF SPR sensor proposed in the paper is simpler in fabrication, smaller in size, and higher in sensitivity, which has broad application prospect in biomedical sensing.