Quasi Single-Mode Fiber With Record-Low Attenuation of 0.1400 dB/km

We report a quasi single-mode fiber setting an absolute low attenuation record of 0.1400 dB/km at 1560 nm or 0.1407 at 1550 nm. The fiber core is silica-based, doped with halides (Cl, F) and an alkali oxide (K2O). This core composition, along with the improved profile design, glass making and draw process conditions, provides an exceptionally low Rayleigh scattering coefficient and small angle scattering loss. The record low loss was achieved in a fiber with higher mode field confinement in the core and reduced intensity at the core-clad interface and in the cladding.