Field trial of a real-time, single wavelength, coherent 100 Gbit/s PM-QPSK channel upgrade of an installed 1800km link

We demonstrate a real-time, single-wavelength, coherent 100 G PM-QPSK upgrade of a field system. Performance sufficient for error-free operation after forward-error-correction was achieved over installed 900 km and 1800 km links, proving the viability of seamless 100 Gb/s upgrades.