Suspended Ring-Core Photonic Crystal Fiber Gas Sensor With High Sensitivity and Fast Response

We demonstrate design and fabrication of an in-line evanescent field gas sensor based on a novel suspended ring core photonic crystal fiber (PCF) to further overcome limitations in sensing capability. The suspended ring core photonic crystal fiber is made by stack-and-draw technique with a large central capillary of ~60µm and adapted small capillaries in a larger cladding tube. Sensing capability of two variations of the proposed suspended ring core PCFs were investigated experimentally by detecting absorption lines of acetylene gas. The sensitivity of the two PCF structures was also numerically analyzed using a full-vectorial finite element method (FEM). The dynamic response of the sensors was quantified in detail. The results demonstrated significant improvements in both sensitivity and response time of the suspended ring core PCF as this special PCF can provide larger gas diffusion and higher overlap between