OTDM-WDM Propagation Impairments and Techniques to Improve Performance

C.C. Hiew, F.M. Abbou, H.T. Chuah (Malaysia), S.P. Majumder (Bangladesh), and A.A.R. Hairu


Fiber optic communication, wavelength division multiplexing, optical time division multiplexing, nonlinear effects


: Optical time division multiplexing wavelength division multiplexing (OTDM-WDM), intensity modulation (IM) systems employing optical amplification and dispersion management (DM) are analyzed. Interchannel nonlinear effects present the input power limit to system performance. Therefore, a lumped DM system performed better than a fully inline DM system through reduction of coherent channel interaction. With proper channel spacing, all demultiplexed OTDM channels and the multiplexed signal show the same performance. Introducing an optical narrowband bandpass filter (OTDM filter) after OTDM demultiplexing improves the performance of the channels significantly by reducing amplitude jitter while possessing high intersymbol interference (ISI) tolerance. The OTDM WDM link shows good performance up to 2000 km with the OTDM filter providing a Q gain of 0.7 1.1 dB. The optimal input power reduces for longer distances due to increased significance of nonlinear effects. A 900 km link showed good performance for spectral efficiencies as low as 0.52 bits/s/Hz, though the Q gain provided by the OTDM filter reduces as channel spacing decreases.

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