Advanced design and sensitivity analysis of hollow-core fiber Bragg rating for enhanced biosensing applications

Hollow-core fibers (HCFs) with an air-filled core and a periodic array of micro-structured cladding can be used to make a Fiber Bragg grating. The micro-structured cladding makes the grating. This work uses COMSOL program. For bio-sensing and chemical analyte detection, an HCF-based FBG must have the right number of grating lines and average refractive index. The hollow core of the proposed fiber changes between (1.34974–1.35845) RIU. The computed Bragg frequency and spectrum width sensitivity to RI change is (−) 2.23472 (THz/RIU) and (−) 0.998 (nm/RIU). It demonstrate that the gratings number effect the reflectivity, where the reflectivity increased proportionally as the gratings number increases. When the number of gratings raches approximately 7500 the curve of reflectivity begins to saturate. The bandwidth narrows as the gratings number increases. The reduction of the bandwidth reaches the saturation point at approximately 10,000 gratings. For bio-sensing, the FBG-HCF has great sensitivity and low loss.