Hybrid 10/40-G transmission on a 50-GHz grid through 2800 km of SSMF and seven optical add-drops

We experimentally demonstrate copolarized 42.7-Gb/s return-to-zero (RZ) differential quadrature phase-shift keying and 10.7-Gb/s RZ ON-OFF keying wavelength-division-multiplexing transmission on a 50-GHz grid through 28 100-km spans of standard single-mode fiber in a 400-km recirculating loop. The loop contains an add-drop node on a 50-GHz channel grid.