High Sensitivity Fiber Optic SPR Refractive Index Sensor Based on Multimode-No-Core-Multimode Structure

In this paper, a surface plasmon resonance (SPR) fiber sensor based on a multimode-no-core-multimode (MNM) structure for refractive index (RI) measurement is proposed and experimentally investigated. The influence of the diameter and length of the no-core fiber on the performance of the sensor are studied. The results show that the sensitivity increases nonlinearly with RI in the range of 1.3330-1.4102, and a maximum sensitivity of 11792 nm/RIU is achieved. The maximum RI resolution of the sensor is 2.04 × 10-5 RIU. Compared with traditional SPR sensors, the proposed sensor has the merits of low cost, easy fabrication, high sensitivity, and a wide measuring range. It can be an important tool in many chemical and biological applications.