Mid-infrared refractive index photonic crystal fiber sensor based on surface plasmon resonance for ultra-high sensitivity

An ultra-high sensitivity photonic crystal fiber mid-infrared refractive index (RI) sensor based on surface plasmon resonance is proposed, whose properties are investigated by the finite element method. Gold can be utilized to create excitation between the fundamental mode and surface plasmon polaritons mode. The simulation results indicate that, at the wavelength of 1.7–4.0 μm, the proposed sensor could detect a RI in the range of 1.00–1.31, a maximum sensitivity of 37 000 nm RIU−1, and an optimal resolution of 2.70 × 10−6 RIU is achieved. The result of curve fitting is 0.98185. The proposed mid-infrared RI sensor plays an important role in organic chemistry detection, medical detection, and related fields.