20 Msymbol/s, 64 and 128 QAM coherent optical transmission over 525 km using heterodyne detection with frequency-stabilised laser

Abstract

A 20 Msymbol/s, 64 and 128 QAM coherent signal has been successfully transmitted over 525 km using heterodyne detection with a frequency-stabilised fibre laser and an offset-locking technique. Error-free transmission (7 bit/symbol) has been achieved.