Hollow-fiber-based surface plasmon resonance sensor with large refractive index detection range and high linearity

A surface plasmon resonance (SPR) sensor based on the gold-coated hollow fiber (HF) is proposed to realize the detection of refractive index (RI). The large hollow core of the HF is utilized as the microfluidic channel of the analyte, and gold is coated inside the air holes surrounding the core to generate surface plasmons. Benefitting from the unique structure of HF and liquid filling into the core, the sensor can work in a large RI range from 1.27 to 1.45 at the near-infrared region, overcoming the limitation of 1.42, as other side-hole-filled photonic crystal fiber-based SPR sensors reported. Moreover, the relations between the resonance wavelength and RI are highly linear and more suitable for standardization, while almost all similar works show higher sensitivity for the high RI change than for the low. The average spectral sensitivity 5653.57 nm/RIU is obtained. Other structure parameters, such as gold-coated air hole numbers and gold layer thicknesses, are also investigated.