Open AccessSingle-channel 768 Tbit/s, 64 QAM coherent Nyquist pulse transmission over 150 km with a spectral efficiency of 97 bit/s/Hz
Author(s) -
Kosuke Kimura,
Junpei Nitta,
Masato Yoshida,
Keisuke Kasai,
Toshihiko Hirooka,
Makoto Nakazawa
Publication year - 2018
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.017418
Subject(s) - terabit , optics , nyquist–shannon sampling theorem , transmission (telecommunications) , quadrature amplitude modulation , qam , pulse shaping , channel (broadcasting) , physics , spectral efficiency , wavelength division multiplexing , telecommunications , bit error rate , computer science , wavelength , laser , computer vision
We achieved a record capacity of 7.68 Tbit/s in a single-channel OTDM transmission with a 9.7 bit/s/Hz spectral efficiency, where a polarization-multiplexed 640 Gbaud, 64 QAM coherent Nyquist pulse has been transmitted over 150 km. In this scheme, a 1.39 ps optical Nyquist pulse with an OSNR of 53 dB at a 0.1 nm resolution was generated by combining a mode-locked laser and a highly nonlinear fiber and used at both the transmitter and receiver. Phase synchronization was achieved between these pulse sources with an advanced optical phase-locked loop based on the higher harmonics of the mode-locked laser mode. In addition, we suppressed a nonlinear phase rotation at an EDFA in the transmitter by broadening the pulse width with second-order dispersion and recompressed it to the original pulse width before a 150 km transmission link. We succeeded in a bit error rate below 2 x 10 -2 for all tributaries.