Open AccessUnrepeated 200-km transmission of 40-Gbit/s 16-QAM signals using digital coherent receiver
Author(s) -
Yojiro Mori,
Chao Zhang,
Koji Igarashi,
Kazuhiro Katoh,
K. Kikuchi
Publication year - 2009
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.17.001435
Subject(s) - optics , quadrature amplitude modulation , phase noise , physics , local oscillator , transmitter , laser linewidth , qam , transmission (telecommunications) , phase modulation , bit error rate , electronic engineering , computer science , telecommunications , laser , engineering , decoding methods , channel (broadcasting)
We demonstrate unrepeated 200-km transmission of 40-Gbit/s 16-QAM signals using a digital coherent receiver, where the decision-directed carrier-phase estimation is employed. The phase fluctuation is effectively eliminated in the 16-QAM system with such a phase-estimation method, when the linewidth of semiconductor lasers for the transmitter and the local oscillator is 150 kHz. Finite-impulse-response (FIR) filters at the receiver compensate for 4,000-ps/nm group-velocity dispersion (GVD) of the 200-km-long single-mode fiber and a part of self-phase modulation (SPM) in the digital domain. In spite of the launched power limitation due to SPM, the acceptable bit-error rate performance is obtained owing to high sensitivity of the digital coherent receiver.