title: Heterodyne coherent detection of WDM PDM-QPSK signals with spectral efficiency of 4b/s/Hz.
abstract: 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.
authors.affiliation: Department of Communication Science and Engineering, Fudan University, 220 Handan Road, Shanghai 200433, China.
authors.forename: Xinying
authors.initials: X
authors.lastname: Li
authors.forename: Ze
authors.initials: Z
authors.lastname: Dong
authors.forename: Jianjun
authors.initials: J
authors.lastname: Yu
authors.forename: Jianguo
authors.initials: J
authors.lastname: Yu
authors.forename: Nan
authors.initials: N
authors.lastname: Chi
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D013685:Telecommunications / Q000295:instrumentation*