Theoretical Analysis and Fabrication of a Nested Antiresonant Hollow-Core Fiber With low Tight Bend Loss

The low tight bend-loss of antiresonant hollow-core fibers (AR-HCFs) is critical for many practical applications. In this paper, we provide an approximate analytical formula for the nested AR-HCFs to predict its critical bend radius for the first time, deepening physical insight of its bending mechanism and allowing straightforward design of low tight bend-loss nested AR-HCFs. We further carried out fabrication experiments of nested AR-HCFs and characterized their bending performance. A low bend loss of 0.039 dB/m at 1550 nm under a tightest bend radius of 1.8 cm is achieved. Our theoretical and experimental investigation of tight bend loss in nested AR-HCFs can provide useful design strategies and enhance the applicability of nested AR-HCFs in tight bend circumstances.