Capacity-Approaching Transmission Over 6375 km Using Hybrid Quasi-Single-Mode Fiber Spans

Increasing the capacity and spectral efficiency of high speed optical transmission over transoceanic lengths of single-mode fiber is a great challenge due to limited signal to noise ratio at the receiver. Capacity can be optimized by tailoring modulation formats. However, beyond 6 bits/symbol in four-dimensional space, it is still not clear if high dimensional modulation formats can outperform two...