D-type photonic crystal fiber refractive index sensor with ultra-high fabrication stability and ultra-wide detection range

To solve the problem of the narrow detection range of D-type photonic crystal fiber (PCF) sensor, a novel refractive index (RI) sensor with an ultra-wide detection range is proposed and analyzed by finite element method. The polishing design provides a flat coating platform for the metal film, ensuring the uniformity of the coating, thereby improving the performance of the sensor. The sensor mainly works in the visible and infrared bands with a detection range of 1.04–1.42, the detection range width can reach 0.38 RIU. To the best of our knowledge, the detection range of this sensor exceeds that of all D-type PCF sensors currently known. The parameters of the sensor are analyzed by numerical calculation and the result shows that the maximum wavelength sensitivity of the sensor is 12,100 nm/RIU, the maximum amplitude sensitivity is −846.4824 RIU−1, resolution can reach 8.2645 × 10−6 RIU, and the maximum figure of merit is 295.1807. In addition, the sensor also has extremely high fabrication stability, which greatly improves the practical application value of the PCF sensor, which is suitable for biomedical research, water quality monitoring, cancer detection and other fields.