Open AccessHeterodyne coherent detection of WDM PDM-QPSK signals with spectral efficiency of 4b/s/Hz
Author(s) -
Xinying Li,
Ze Dong,
Jianjun Yu,
Junsheng Yu,
Nan Chi
Publication year - 2013
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.21.008808
Subject(s) - polarization division multiplexing , optics , heterodyne detection , wavelength division multiplexing , phase shift keying , physics , bit error rate , multiplexing , local oscillator , homodyne detection , phase noise , electronic engineering , computer science , telecommunications , wavelength , engineering , laser , channel (broadcasting)
We experimentally demonstrate heterodyne coherent detection of 8 × 112-Gb/s ultra-density wavelength-division-multiplexing (WDM) polarization-division-multiplexing quadrature-phase-shift-keying (PDM-QPSK) signal after 1120-km single-mode fiber-28 (SMF-28) transmission. The spectral efficiency (SE) is 4b/s/Hz. It is the first time to realize WDM signal transmission with high SE by adopting heterodyne coherent detection. At the heterodyne coherent receiver, intermediate frequency (IF) down conversion is realized in digital frequency domain after analog-to-digital conversion. A digital post filter and 1-bit maximum likelihood sequence estimation (MLSE) adopted after carrier phase estimation (CPE) in the conventional digital-signal-processing (DSP) process is used to suppress the enhanced noise and crosstalk as well as overcome the filtering effects. The bit-error ratio (BER) for all channels is under the forward-error-correction (FEC) limit of 3.8 × 10(-3) after 1120-km SMF-28 transmission.