Abstract:
In this paper, the non-linearity mitigation of the fully loaded coherent optical networks like Dense Wavelength Division Multiplexing (DWDM) and Coarse Wavelength Division Multiplexing (CWDM) were investigated and experimentally demonstrated. The objective of this optical network is to expand the system capacity in terms of high data rate and bandwidth. However, it has associated with its nonlinear interference noise (NLIN) which degraded the optical system capacity. It is not easy but, achievable by using proper digital Nonlinearity Compensation (NLC) techniques such as Back Propagation (BP) and equalization of nonlinear Phase and Polarization Rotation Noise (PPRN). Such a technique is applied in the above system whose configuration includes a different modulation format from QPSK to 16-QAM with single-carrier and digital subcarrier multiplexed (SCM) optical super-channels through both point-to-point line systems and optically-routed networks (ORNs). The test result conveys that the system gain of the single-carrier has improved by adding more number of BP channels, that is, beyond three joint BP channels; the gain of the NLIN is limited to 0.1 dB after adding per BP channel and also requires PPRN removal at the receiver. However, for a wide range of system configurations, SCM is suitable for the potential benefits of BP and PPRN removal. Here, it has achieved almost similar gain as compared to BP and also PPRN removal is much stronger than BP for higher-order modulation formats which in turn induces high spectral efficiency system. On the whole, the overall context of SCM shows that it not only limits nonlinearity but also induces significantly smaller performance variations in various ORN scenarios.
