High Refractive Index Surface Plasmon Resonance Sensor Based on a Silver Wire Filled Hollow Fiber

A surface plasmon resonance (SPR) sensor based on a hollow fiber (HF) is proposed to realize high analyte refractive index (RI) detection. The hole in the HF as a microfluidic channel for the analyte is filled with a silver wire to replace the metal coating. The sensitivity of the proposed SPR sensor with analyte RI from 1.47 to 1.51 is theoretically investigated both in the wavelength and amplitude interrogation methods. The results show that the sensor can support two disparate resonance peaks, with orthogonal polarizations (x-and y-polarized peaks), and the sensitivity of the y-polarized peak is higher than that of x-polarized peak. Moreover, contrary to the performances of the resonance peaks supported by the low RI SPR sensors, the two polarized peaks shift to shorter wavelength as analyte RI increasing and show a higher sensitivity at low analyte RI. These results and analyses, including the abnormal behaviors of resonance peaks and the coupling condition between the core modes and the plasmon modes, are very helpful for the design and improvement of high RI SPR sensors.