1.28-Tb/s (64 x 20 Gb/s) WDM Transmission Over 320 km of Single-Mode Fiber with 0.4- (bit/s) /Hz Spectral Efficiency

We demonstrated 1.28-Tb/s (64 ch $\times$ 20 Gb/s) WDM transmission with 50-GHz channel spacing over 320 km of conventional single mode fibers. The spectral efficiency was 0.4 (bit/s)/Hz. Thus, we could accommodate all the sixty-four WDM channels within the C-band of EDFA The average Q-factor was measured to be better than 17.8 dB after transmission over 320 km.