Nonlinear signal multiplexing for communication beyond the Kerr nonlinearity limit

Current optical fibre transmission systems rely on modulation, coding and multiplexing techniques that were originally developed for linear communication channels. However, linear transmission techniques are not fully compatible with a transmission medium with a nonlinear response, which is the case for an optical fibre. As a consequence, the Kerr nonlinearity in fibre imposes a limit on the performance and the achievable transmission rate of the conventional optical fibre communication systems. Here we show that a transmission performance beyond the conventional Kerr nonlinearity limit can be achieved by encoding all the available degrees of freedom and nonlinearly multiplexing signals in the so-called nonlinear Fourier spectrum, which evolves linearly along the fibre link. This result strongly motivates a fundamental paradigm shift in modulation, coding and signal-processing techniques for optical fibre transmission technology.