SLM-Based Mode Division Multiplexing System With $6 \times 6$ Sparse Equalization

We demonstrate a mode division multiplexing (MDM) system over an 8 km conventional graded index multimode fiber. Spatial light modulators (SLMs) are used to multiplex and demultiplex three linearly polarized (LP) modes (LP01, LP11a, and LP11b) in two polarizations. A 6
$ {\times }$
6 sparse frequency domain equalizer (FDE) is used as the channel impulse response of the SLM-based MDM system is found to be sparse due to the large crosstalk at the mode MUX/DEMUX and small coupling in the fiber. The signal transmitted on each mode is recovered with improved performance over conventional FDEs. The results indicate that this system can be used in short reach transmission applications to increase the system capacity.