title: Adaptive 4~64 QAM real-time coherent optical transmission over 320 km with FPGA-based transmitter and receiver.
abstract: We demonstrate the first real-time adaptive optical coherent QAM transmission with variable multiplicities (4-, 16- and 64-QAM) using an FPGA-based transmitter and receiver. Rate-variable transmission (20~60 Gbit/s) was successfully achieved with a polarization multiplexing scheme at 5 Gsymbol/s over 320 km, where the OSNR margins were increased by 9 and 17 dB, respectively, by changing the modulation level from 64 to 16 and 4.
authors: Masato
authors: M
authors: Yoshida
authors: Toshihiko
authors: T
authors: Hirooka
authors: Keisuke
authors: K
authors: Kasai
authors: Masataka
authors: M
authors: Nakazawa