Multimode fibers (MMF) are generally used in short and medium haul optical networks owing to the availability of low cost devices and inexpensive packaging solutions. However, the performance of conventional multimode fibers is limited primarily by the presence of high modal dispersion owing to large core diameters. While electronic dispersion compensation methods improve the bandwidth-distance product of MMFs, they do not utilize the fundamental diversity present in the different modes of the multimode fiber. In this paper, we draw from developments in wireless communication theory and signal processing to motivate the use of vector intensity modulation and signal processing to enable high-data rates over MMFs. Further, we discuss the implementation of a closed-loop system with limited channel state feedback to enable the use of precoding at the transmitter, and show that this technique enhances the performance in a 10 Gb/s MMF link, consisting of 3 km of conventional multimode fiber. Experimental results indicate that vector intensity modulation and direct detection with with two modulators and detectors, along with the use of limited feedback results in a 50% increase over the single laser and detector case.

Multimode fibers (MMFs) offer a cost-effective connection solution for small and medium length networks. However, data rates through multimode fibers are traditionally limited by modal dispersion. Signal processing and Multiple-Input Multiple-Output (MIMO) have been shown to be effective at combating these limitations, but device design for the specific purpose of MIMO in MMFs is still an open issue. This paper utilizes a statistical field propagation model for MMFs to aid the analysis and designs of MMF laser and detector arrays, and aims to improve data rates of the fiber. Simulations reveal that optimal device designs could possess 2-3 times the data carrying capacity of suboptimal ones.