D-Type Photonic Crystal Fiber Sensor with a Single-Center Hole Based on Surface Plasmon Resonance

A low-loss D-type photonic crystal fiber (PCF) sensor with a central hole has been proposed. The analysis was performed with refractive indices (RIs) ranging from 1.32 to 1.40 under the conditions that the thickness of the gold film was 20 nm, the radius of the pore was 0.2 mu m, and the distance between the pore and the core was 1.0 mu m. The D-type sensor has an average wavelength sensitivity of 2566 nm/RIU in the x-polarized direction, which means that the sensor wavelength can be shifted by 2566 nm per unit refractive index shift. When the refractive index of the analyte is 1.36, the maximum loss of the sensor in the x-polarized direction is only 11.77 dB/m. The high sensitivity and low loss of the sensor makes it suitable for high-precision optical sensing applications. This research result provides an essential reference and guidance for the development of high-performance optical fiber sensors, which are expected to play an essential role in the fields of biomedicine, environmental monitoring, and chemical analysis.