24 Gbit/s, 64 QAM-OFDM coherent transmission with a bandwidth of 2.5 GHz

We demonstrate 2-Gsymbol/s polarisation-multiplexed coherent optical OFDM transmission with QAM subcarrier modulation as high as 64-states using an optical PLL. 24-Gbit/s data were successfully transmitted over 160 km with a demodulation bandwidth of 2.5 GHz.