Unrepeatered Transmission of 6.3 Tb/s ( \(63 \times 128\) Gb/s) Over 402-km Fiber Link

We demonstrated 6.3-Tb/s (63 \(\times 128\) Gb/s) unrepeatered transmission over 402-km fiber link. This was achieved by employing a high-power Yb-free clad-pumped \(L\) -band erbium-doped fiber amplifier (EDFA) as a booster amplifier in the transmitter station, a combination of ultralarge-area fiber, low loss and zero-water-peak loss fibers, and a remote optically pumped amplifier (ROPA), which was counter-propagating second-order Raman pumped from receiver station. This letter also describes the design and characteristics of Yb-free clad-pumped \(L\) -band EDFA, and discusses the system performance optimization of ROPA and Raman impact on large capacity long reach unrepeatered transmission.