Accurate modeling of structural distortions in hollow-core photonic bandgap fibers based on feature points location

Structural distortions have a significant impact on the optical properties of hollow-core photonic bandgap fibers (HC-PBFs). However, due to the complex structure of these fibers, there has long been a lack of methods capable of rapidly and accurately modeling or reconstructing such structural distortions. We propose a modeling method based on feature points location for accurately characterizing structural distortions in HC-PBFs. This approach enables both the construction of idealized HC-PBF models with high flexibility and parameter adjustability, and the precise reconstruction of fabricated HC-PBFs from scanning electron microscope images. By locating airhole centers and silica nodes, we efficiently generate geometric models incorporating length, angle, thickness, and fillet features. The method supports quantitative simulation of structural distortion effects-including core scaling, ellipticity, and offset-on key optical properties such as loss and birefringence. Experimental validation shows that reconstructed models achieve sub-wavelength accuracy and yield simulation results in closer agreement with measured data than traditional airhole-based models. This work facilitates the design and rapid fabrication optimization of low-loss and high-birefringence HC-PBFs.