Effect of capillary parameters on the performance of modified negative curvature hollow core fibers

Negative Curvature Hollow Core Fibers (NCHCFs) show great promise in the last couple of years due to their unique guiding properties and simplified structure. Recently, a new type of NCHCF has been proposed that combines circular lattice and revolver structures with an expectation to merge their conveniences. In this work, the effect of different important capillary parameters (such as capillary numbers, capillary gaps, and thickness) on the performance of the proposed combined structure has been rigorously studied. It has been found that the 5L-15S system exhibits the lowest loss at the wavelength ranging from 0.5 mu m to 1.7 mu m with an optimal capillary gap of 1.6 mu m. Most importantly, the investigation also reveals that the higher-order modes can be effectively suppressed by adjusting the capillary wall thickness. This information could be helpful for designing ultra-low loss and single mode combined NCHCFs.