Title :
Reducing nonlinear waveform distortion in IM/DD systems by optimized receiver filtering
Author :
Zhou, Y.R. ; Watkins, L.R.
Author_Institution :
Sch. of Electron. Eng. & Comput. Syst., Univ. Coll. of North Wales, Bangor, UK
Abstract :
Nonlinear waveform distortion caused by the combined effect of fiber chromatic dispersion, self-phase modulation, and amplifier noise limits the attainable performance of high bit-rate, long haul optically repeatered systems. Signal processing in the receiver is investigated and found to be effective in reducing the penalty caused by this distortion. Third order low pass filters, with and without a tapped delay line equalizer are considered. The pole locations or the tap weights are optimized with respect to a minimum bit error rate criterion which accommodates distortion, pattern effects, decision time, threshold setting and noise contributions. The combination of a third order Butterworth filter and a five-tap, fractionally spaced equalizer offers more than 4 dB benefit at 4000 km compared with conventional signal processing designs.<>
Keywords :
delay lines; fibre lasers; intermodulation; low-pass filters; optical communication equipment; optical dispersion; optical fibres; optical information processing; optical links; optical modulation; phase modulation; repeaters; 4000 km; IM/DD systems; amplifier noise; attainable performance; decision time; distortion; fiber chromatic dispersion; five-tap; high bit-rate; long haul optically repeatered systems; minimum bit error rate criterion; noise contributions; nonlinear waveform distortion; optimized receiver filtering; pattern effects; pole locations; self-phase modulation; signal processing; tap weight optimisation; tapped delay line equalizer; third order Butterworth filter; third order low pass filters; threshold setting; Chromatic dispersion; Equalizers; Low pass filters; Nonlinear distortion; Optical distortion; Optical fiber amplifiers; Optical noise; Optical receivers; Optical signal processing; Semiconductor optical amplifiers;
Journal_Title :
Photonics Technology Letters, IEEE
