Birefringent PCF-Based SPR Sensor for a Broad Range of Low Refractive Index Detection

An asymmetrical birefringence photonic crystal fiber based on a surface plasmon resonance (SPR) sensor designed to detect the low analyte refractive indexes is investigated by a novel birefringence analysis method. The results show that the birefringent analysis method can replace the conventional confinement loss method pertaining to the investigation SPR on the asymmetrical structures. The air holes in the sensor are arranged in a square lattice structure and two active plasmonic gold layers are deposited on the inner surface of the left and right channels to enhance the SPR phenomenon. The birefringence sensor shows a broad refractive index detection range from 1 to 1.43 with the maximum wavelength sensitivity of 6300 nm/RIU.