Support Tube Hollow-Core Fiber with 0.05 dB/km Attenuation

This study presents a support tube hollow-core fiber optimized via enhanced fabrication and structural design. The 9.1 km ST-HCF achieved $0.05 \pm 0.01 ~\text{dB} / \text{km}$ attenuation at 1550 nm. Batch tests on 733.3 km ST-HCF yielded an average attenuation of $0.147 ~\text{dB} / \text{km}$.