Nested Antiresonant Hollow-Core Fiber with Ultra-Low Loss

This paper demonstrates a hollow-core anti-resonant fiber containing double cladding rings with nested elements which can reduce the leakage loss by about five orders of magnitude. The results show ultra-low leakage loss of $1.0 \times 10^{-3}$ dB/km at 1400 nm wavelength and able to maintain the leakage loss lower than 0.10 dB/km over wide bandwidth (around 320 nm) from 1280 nm to 1600 nm. Low bending loss as well as excellent single mode performance of the presented fiber (core diameter of 33 micron) are also noticeable; hence, the fiber may find applications in communication system.