Surface plasmon resonance sensor for low refractive index detection based on microstructured fiber

Abstract

A surface plasmon resonance sensor based on microstructured fiber (MSF) is proposed for low refractive index (RI) detection in the range of 1.20–1.34. The MSF is composed of substrate and sector air rings with negative curvature. Gold is coated on the external cladding surface. A finite element method is applied to analyze the performance of the sensor. Results show that the sensor is independent of polarization, and the resonance wavelength has a negative shift with RI variation in the near-infrared (near-IR) spectrum. The average sensitivity is $ - 8892\,\,{\rm nm/RIU}$−8892nm/RIU, and the maximum resolution is ${6.54} \times {{10}^{ - 6}}$6.54×10−6. Owing to the high sensitivity in the low RI range, the sensor offers a promising approach for water pollution measuring, humidity monitoring, and liquid concentration testing.