Study on optimum optical pre-filtering condition for highly spectral-efficient ultralong-haul transmission using 40Gbit/s CS-RZ signal and all-Raman repeaters

We have studied the transmission characteristics of optically pre-filtered 32/spl times/42.7 Gbit/s CS-RZ signals in 57% and 80% spectral-efficient all-Raman repeatered transmission over > 4000km under various pre-filtering conditions. We found that the advantage of asymmetrical pre-filtering reduced with transmission distance.