Dual-band highly-sensitive SPR photonic crystal fiber sensor based on birefringence analysis

In this paper, a dual-band highly-sensitive D-shaped photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) is proposed and numerically analyzed. Au-TiO2 grating is deposited on the flat surface of D-shaped PCF, thus surface plasmon resonances are excited to detect the change of refractive index (RI) of analyte. Rabi-like splitting spectrum is achieved by the introduction of a small air hole in the fiber. Besides spectrum analysis, it is found that the resonance wavelengths can be located by the abnormal change of birefringence. Moreover, complete coupling and incomplete coupling of the guided mode and plasmonic mode can be distinguished from our simulation results. The influences of structural parameters are also analyzed systematically. Simulation results show that the two loss peaks have different RI detection ranges, and the maximum sensitivity reaches 26700 nm/RIU. The proposed sensor could be applied widely in biomedical and chemical fields.