Digital Backward Propagation for WDM Systems

Technology #31726

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System model diagram of an optical communication system including an embodiment of polarization-dependent nonlinearity impairment compensation logic.
Guifang Li, Ph.D.
Eduardo Mateo, Ph.D.
Fatih Yaman
Patent Protection

Compensation of transmission impairments in polarization multiplexed systems

US Patent 8,437,643 B2

Channel impairments in transmission systems result in signal degradation and thus limit the carrying capacity of these systems. As complex electrical signal propagates along each span of an optical channel, and is distorted by fiber impairments, polarization-dependent nonlinearity impairment compensation logic can undo signal degradation.

While backward propagation can be used to compensate for nonlinear impairments in wavelength-division multiplexed (WDM) systems, based on solving the nonlinear Schrodinger equation (NLSE), advanced transmission schemes such as polarization-division multiplexing or polarization-interleaving require a vectorial form of NLSE. UCF researchers have developed a method for backward propagation to undo the nonlinear impairments experienced by polarization-division multiplexed (PMD) WDM channels, using the Manakov equation (ME). The method accounts for PMD induced polarization scattering by monitoring the Jones matrix of the fiber for each WDM channel along the fiber length, e.g. at each span, to be used in the backward propagation.

Technical Details

Polarization-dependent nonlinearity impairment compensation logic solves the vectorial NLSE to model for compensation of various impairments, including non-linear impairments with their polarization dependence. The polarization-specific component of each compensated signal is then demultiplexed in order to estimate the originally transmitted data.


  • Improved data integrity/quality


  • Wavelength-division multiplexed optical communications systems

See related technology: “Digital Backward Propagation Method” Technology Number: 31725