Our information society relies to an unprecedented extent on broadband communication solutions such as high-speed Internet access, mobile voice and data services, multimedia broadcast systems, etc. In order to fulfill the steadily growing volume and bandwidth demand of those data services while simultaneously reducing the cost per transported information bit, communication systems have been continuously improved in terms of reach and aggregate transport capacity. However, it is now recognized that communication systems are rapidly approaching the fundamental information capacity of current technology, a trend with potential negative impact on the economy and social progress. In order to meet future demands with prospective cost and energy savings, the most promising solution is the emerging technology of mode-division multiplexing (MDM). MDM technology enables much wider conduits of information by offering an additional dimension for transporting optical channels. This book reports the investigation performed by the authors on high capacity optical fiber transmission systems based on MDM over few-mode fibers.