115.2-THz Aggregate Bandwidth O-band Coherent DWDM Transmission Over a High-Density 250-$\mu$m Coating Multicore Fibre

The rising demand for high transmission bandwidths in optical fibres for short-distance applications can be addressed by increasing the number of cores. Higher core densities in the fibres can be paired with the bandwidth enhancements provided by a bismuth-doped fibre amplifier (BDFA) operating in the O-band due to the lower intercore-crosstalk. In this study, we showcase an ultrawide O-band coherent transmission using a 12-core fibre with a standard 250-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula>m coating diameter. By using bidirectional transmission, inter-core crosstalk was effectively reduced to below <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula>45 dB across a distance of 31.7 km (including multi-core connectors). The total aggregate bandwidth achieved was 115.2 THz, while retaining the conventional coating diameter, confirming the fibre's suitability for space-constrained environments.