Feedback based Compensation of Second Order Modal Dispersion in Principal Mode based Multiplexed MMF Links

Multiplexing using principal modes (PMs) of mul-timode fibers is known to be effective at enhancing data rates for channel variations that are up to first order in modulation bandwidth $\Omega$. However, for large $\Omega$, the second order group delay terms (dependent on $\Omega{2}$) diminish the effectiveness of PMs. In this paper, we show that simultaneously feeding back PMs as well as second order group delay matrices permits transmission that overcomes the higher order modal dispersion. In addition, using manifold based quantization of PMs minimizes feedback overheads. Simulations reveal that modal dispersion is effectively eliminated with very little additional feedback overhead.