Low crosstalk 125 μm-cladding multi-core fiber with limited air-holes fabricated with over-cladding bundled rods technique

We realized a 125 μm-cladding four-core fiber with four air-holes using novel fabrication technique without any drilling process. Core-to-core crosstalk was reduced to -63 dB/km at 1550 nm by intentionally constructing the air-holes during the fabrication.