Search

Compensation of Kerr nonlinearity-induced distortions has been shown to allow for increasing transmission rate and reach, with optical compensation techniques particularly attractive for broadband wavelength-division multiplexed (WDM) scenarios. However, they normally require additional devices within the link, which is particularly challenging for already deployed systems, and even more so for unrepeatered transmission. In this work, we focus on providing lumped optical nonlinearity suppression, either at the transmitter or at the receiver side, based on optical phase conjugation (OPC). The theory to design scaled-down OPC compensation modules is derived, and it allows to move beyond the standard mid-link OPC approach and to explore compensation modules with fibers types not directly linked to the dispersion properties of the transmission link. This design method is then validated both through numerical investigations and experimental demonstrations for a number of systems with a varying degree of complexity. Ultimately, significant performance improvement is shown by employing short OPC-based compensation structures which are carefully designed to match much longer transmission links. [ABSTRACT FROM AUTHOR]

Throughput optimization of optical communication systems is a key challenge for current optical networks. The use of gain-flattening filters (GFFs) simplifies the problem at the cost of insertion loss, higher power consumption and potentially poorer performance. In this work, we propose a component-wise model of a multi-span transmission system for signal-to-noise ratio (SNR) optimization. A machine-learning based model is trained for the gain and noise figure spectral profile of a C-band amplifier without a GFF. The model is combined with the Gaussian noise model for nonlinearities in optical fibers including stimulated Raman scattering and the implementation penalty spectral profile measured in back-to-back in order to predict the SNR in each channel of a multi-span wavelength division multiplexed system. All basic components in the system model are differentiable and allow for the gradient descent-based optimization of a system of arbitrary configuration in terms of number of spans and length per span. When the input power profile is optimized for flat and maximized received SNR per channel, the minimum performance in an arbitrary 3-span experimental system is improved by up to 8 dB w.r.t. a system with flat input power profile. An SNR flatness down to 1.2 dB is simultaneously achieved. The model and optimization methods are used to optimize the performance of an example core network, and 0.2 dB of gain is shown w.r.t. solutions that do not take into account fiber nonlinearities. The method is also shown to be beneficial for systems with ideal gain flattening, achieving up to 0.3 dB of gain w.r.t. a flat input power profile. [ABSTRACT FROM AUTHOR]

Presents a framework for a class of receivers that employ linearly-constrained interference cancellation in wideband code division multiple access. Background on the data model and formulation of the problem; Overview of the proposed multiuser detector; Advantages of interference subspace rejection.