A transmission system with adjustable data rate for single carrier coherent optical transmission is proposed, which enables high speed transmission close to the Shannon limit. The proposed system is based on probabilistically shaped 64-QAM modulation formats. Adjustable shaping is combined with a fixed QAM modulation and a fixed forward error correction code to realize a system with adjustable net data rate that can operate over a large reach range. At the transmitter, an adjustable distribution matcher performs the shaping. At the receiver, an inverse distribution matcher is used. Probabilistic shaping is implemented into a coherent optical transmission system for 64- QAM at 32 Gbaud to realize adjustable operation modes for net data rates ranging from 200 Gb/s to 300 Gb/s. It is experimentally demonstrated that the optical transmission of probabilistically shaped 64-QAM signals outperforms the transmission reach of regular 16-QAM and regular 64-QAM signals by more than 40% in transmission reach.     «

A transmission system with adjustable data rate for single carrier coherent optical transmission is proposed, which enables high speed transmission close to the Shannon limit. The proposed system is based on probabilistically shaped 64-QAM modulation formats. Adjustable shaping is combined with a fixed QAM modulation and a fixed forward error correction code to realize a system with adjustable net data rate that can operate over a large reach range. At the transmitter, an adjustable distribution...     »