Design of a novel D-shaped SPR sensor with high sensitivity based on PCF for ultra-low refractive index detection

In this paper, a novel D-shaped plasmon resonance sensor based on photonic crystal fiber (PCF) is proposed to detect analytical materials with low refractive index. There are three arc-shaped small holes on both upper and lower edges of the fiber core, which can enhance the surface plasmon effect. The operation wavelength of the sensor is from 2243 nm to 2651 nm when its measurable refractive index range is between 1.17 and 1.27. The maximum spectral sensitivity of the sensor can be reached to 20 300 nm RIU-1, and the optimal resolution is 4.93 x 10-6 RIU. In our knowledge, the current literature indicates that when the refractive index is less than 1.3, this is the sensor with the highest spectral sensitivity among the reported low refractive index PCF-surface plasmon resonance sensors.