INVITED: Ultra-High-Spectral-Efficiency Transmission

: We discuss the generation, transmission, and coherent detection of 112-Gb/s polarizationdivision multiplexed, 16-ary quadrature-amplitude-modulation (16-QAM) signals at a line rate of 14 Gbaud. We attain 630-km and 1020-km wavelength-division-multiplexed transmission with spectral efficiencies of 6.2 b/s/Hz and 4.1 b/s/Hz, respectively. ©2010 Optical Society of America OCIS Codes: (060.2360) Fiber optics links and subsystems; (060.4080) Modulation; (060.4510) Optical communications