c © 2012 Peter Kairouz MIMO COMMUNICATIONS OVER MULTI-MODE OPTICAL FIBERS BY

We consider multi-input multi-output (MIMO) communications over multi-mode fibers (MMFs). Current MMF standards, such as OM3 and OM4, use fibers with core radii of 50µm, allowing hundreds of modes to propagate. Unfortunately, due to physical and computational complexity limitations, we cannot couple and detect hundreds of data streams. In order to circumvent this issue, two solutions were presented in the literature. The first is to design new fibers with smaller radii so that they can support a desired number of modes. The second is to design multi-core fibers with a reasonable number of cores. However, both approaches are expensive as they necessitate the re-placement of installed fibers. In our work, we consider input-output coupling schemes that allow the user to couple and extract a reasonable number of signals from a fiber with many modes. This approach is particularly attrac-tive as it is scalable; i.e., the fibers do not have to be replaced every time the number of transmitters or receivers is increased (which is likely to happe