Work Package 3


In this task, we plan to study the fundamental properties of the transmission matrix to improve the efficiency of the telecommunication protocols in multimode fiber systems with moderate to strong mode coupling. Spatial division multiplexing in multimode fibers requires to send signals into different channels. The signals are then measured and reconstructed using MIMO algorithms to compensate for the channel crosstalk and the dispersion. Our goal is to act both on the hardware multiplexing and on the numerical treatment. Instead of directly using the spatial modes of the ideal fiber, we will try to identify the best sets of spatial channels to minimize the detrimental effects of the multimode propagation and to decrease the computational complexity of the MIMO algorithms. This would allow increasing the number of channels to more than 10, which is today the greatest number that can be managed in real time. We will also investigate the use of wavefront shaping techniques to, at least partially, compensate in real time for the temporal fluctuations of the multimode fibers.