High-speed optical modulation and transmission technologies for highly spectrally efficient WDM systems

Summary form only given. Demands for ultra-high-capacity lightwave transmission systems and networks are growing rapidly. To achieve ultra-high-capacity systems, high spectral efficiencies are indispensable because of limitation of transmission bandwidth. To utilize transmission bandwidth efficiently, high-speed channels must be densely multiplexed in wavelength region. Several dense-wavelength-division-multiplexing (DWDM) transmission experiments using high-speed channels have been reported. Spectral efficiencies of these experiments are shown. All these experiments achieved spectral efficiency over 0.1 bit/s/Hz on high-speed channels operating at more than 10 Gbit/s.