126-Tb/s C+L-Band 2-Core Fiber Transmission Over 114.6 km × 5 Spans

We present an experimental demonstration of full C+L-band 2-core fiber transmission over 114.6 km × 5 spans. The span length of 114.6 km is the longest span reported for weakly-coupled multicore fibers (MCFs), which enables cost-effective MCF systems by reducing amplifier-related costs. To achieve a long-span MCF system, we develop ultra-low-loss fan-in/fan-out devices with a minimum insertion loss of 0.20 dB, and utilize ultra-low-loss 2-core fiber with an average loss of 0.149 dB/km. In the transmission, all the 740 channels with 24-Gbaud 16-quadrature amplitude modulation have sufficient Q<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula>-factors <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$&gt;$</tex-math></inline-formula>6.5 dB, corresponding to a total capacity of 126 Tb/s. Through experimental and theoretical investigations, we clarify that the degradation of the Q<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula>-factors due to inter-core crosstalk is less than 0.30 dB, and that amplified spontaneous emission noise added by amplifiers mainly limits the transmission performance.