An optical-fiber sensor with double loss peaks based on surface plasmon resonance

A novel D-shaped photonic crystal fiber sensor based on surface plasmon resonance has been designed in this paper. The refractive index sensing with double loss peaks are studied in detail. Numerical simulation shows that the average wavelength sensitivities of the primary peak and the secondary peak can reach 18900 and 17500 nm/RIU in the refractive index range of 1.35-1.38, and the corresponding resolutions are 5.291 x 10(-6) and 5.714 x 10(-6) RIU, respectively. In addition, it is found that the resonance wavelengths do not shift as the sensing length increases. Moreover, the coupling characteristics between fundamental mode and the surface plasmon polarization (SPP) mode are investigated. It worth noting that the sketch diagram about specific operation is presented. It can except that the research results can be applied into the fields of double-loss-peak detection, which improves the practicability of the sensor.