Abstract
High spectral efficiency is the key to cost-effective capacity expansion in WDM systems, since it can relax the requirements for the transmission line. This paper reviews enabling technologies to achieve higher spectral efficiency in 40 Gbit/s-based DWDM transmission. As examples of 40 Gbit/s-based highly spectral-efficient WDM transmissions, 100% spectral-efficient transmission with asymmetrically bandlimited CS-RZ signal and 80% spectral-efficient transpacific transmission with bandlimited CS-RZ DPSK signal are described.
