Implementation of Eigenvalue Multiplex Transmission with a real Fiber Link using the Discrete Nonlinear Fourier Spectrum

The capacity of fiber optic transmission links is limited by nonlinearities due to the Kerr effect. Recently a new type of communication based on the Nonlinear Fourier Transform, which is offering the use of two types of spectra, a continuous one and a discrete one, was proposed. Coherent optical receivers are the enabler for this communication scheme. A prerequisite of the theory is a lossless fiber channel. To cope with varying power along the real fiber link the path average method was introduced. Using the average gain along the fiber and its local deviation a correction coefficient for the nonlinear effects in the fiber is calculated. Few experimental results using continuous or discrete spectrum are reported. These experiments are partly using distributed Raman amplification, while the path average method was only applied to the transmission of the continuous spectrum so far. An experimental setup using the eigenvalue's related discrete spectra for transmission over a lossy link is established. The previous phase shift keying with purely imaginary eigenvalues is extended by modulation of the eigenvalue's real component leading to a frequency offset between the solitonic components of the different eigenvalues and potentially paving the way for a multiuser scenario. Experimental results using this lossy link are provided and compared to theoretical expectations and simulation results for lossless and path averaged transmissions.