4-Channel incoherent MIMO transmission over MM fiber with different offset light launch

The paper presents realization of 4 channel incoherent MIMO system operating over 4.4 km of 50 μm core silica GI MM fiber. At the transmitter side, there were generated four uncorrelated pseudorandom binary sequences (PRBS) of lengths 2^7-1 that modeled short length line codes. These binary signals independently drove four QPSK modulators and 4 transmitter lasers. RML launches with different offsets were used to couple light into the MM fiber core. After transmisson along the fiber the channel signals at the receiver were recovered by an optimization algorithm that maximized the Q-parameter value. The quality of the received signals varied among channels and in time but in general it was better than in the case when central launches were employed in all channels.