1.14 b/s/Hz spectrally-efficient 50/spl times/85.4 Gb/s transmission over 300 km using copolarized CS-RZ DQPSK signals

1.14 b/s/Hz spectrally-efficient 50/spl times/85.4 Gb/s transmission over 300 km (75 km/spl times/4 spans) of NZ-DSF has been successfully demonstrated with copolarized CS-RZ DQPSK signals. 42.7 Gsymbol/s-based 4 Tb/s DQPSK transmission has been achieved for the first time without polarization multiplexing.