PCF sensor coated with Au-graphene/MXene for a low refractive index and a wide detection range

Abstract

A photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) for detecting low refractive index (RI) and a wide detection range is proposed and analyzed by the full vector finite element method. The PCF is designed as a polishing construction and contains three different sizes of air holes. The Au and protective layer are coated on the grinding and polishing surface. The unique physical structure enables the sensor to detect trace substances. The sensor works in the near-infrared and mid-infrared bands. When Au-graphene is used, the RI detection range is 1.11–1.31, the maximum wavelength sensitivity is 18,600 nm/RIU, the maximum resolution is 5.38 × 10 − 6 , and the linearity reaches 0.99023. In this paper, MXene ( 2 D − T i 3 C 2 ) is compared with graphene for the first time, to the best of our knowledge, and applied to the field of PCF-SPR sensing. The maximum wavelength sensitivity of the sensor can be enhanced when using Au-MXene to 22,000 nm/RIU with a maximum resolution of 4.55 × 10 − 6 . Because of its high sensitivity and wide detection range at low RI, this sensor provides a promising method for drug detection, water pollution monitoring, aerosol concentration, and optical film detection.