Investigation of longitudinal uniformity of the core structure in a hollow-core photonic bandgap fiber

In this study, a low-noise Fabry-Perot interference-based method is promoted to measure the longitudinal uniformity of the distance between six pairs of opposite silica-air interfaces within the core of a seven-cell hollow-core photonic bandgap fiber. The experimental results demonstrate that the precision of the method is improved to the subnanometer scale. Based on the test results, a model is established to study the effect of the longitudinal uniformity of the core structure on the fiber loss, and the simulation results indicate that the fiber loss could reach similar to 22.73 dB/km, which is consistent with the practical loss value. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement