Low-Loss and Robust Arc-Discharge Fusion-Splicing Between Anti-Resonant Hollow-Core Fibers

Fusion splicing between anti-resonant hollow-core fibers (AR-HCFs) is the key enabler that opens practical applications of those fibers in low-latency and low-loss fiber optical communication. Here, the impact of angular misalignment and fiber overlap on the splicing loss, higher-order modes (HOMs) excitation, and polarization-dependent loss (PDL) of commonly-used AR-HCF with 5-nested tubes are comprehensively characterized. Simulation and experimental results reveal that the misalignment angle can introduce a maximum coupling loss of 0.12 dB while having almost no impact on HOMs excitation and PDL variation. Then, under the condition of perfect angular alignment, the parameter of fiber overlap during the splicing is optimized, and an average splicing loss of 0.05 dB over 10 times experiment is obtained, which is equivalent to the loss result of standard single mode fiber (SSMF) splicing. Spectral analysis shows that the normalized LP11 mode power has a slight increase from -31.62 dB to -28.33 dB, and the variation in PDL is less than 0.01 dB under the optimal fiber overlap of $8~\mu $ m, indicating that no structural deformation of AR-HCF thin tubes is introduced during the fusion splicing. Moreover, the mechanical robustness of the splicing is examined with a standard proof test returning a damage threshold of 250 gf @1 s. Our proposed fusion splicing technique can be extended to various AR-HCFs, providing the benefit of low-loss, robust, and repeatable interconnection between AR-HCFs.