Survey and Evaluation of Space Division Multiplexing: From Technologies to Optical Networks

Abstract

Single-mode fiber's physical capacity boundaries will soon be reached; hence, alternative solutions are much needed to overcome the multiplying and remarkably large bandwidth requests. Space division multiplexing (SDM) using multicore fibers (MCFs), multielement fibers, multimode fibers, and their combination; few-mode MCFs; or fibers based on orbital angular momentum are considered to be the propitious stepping-stones to overcome the capacity crunch of conventional single-core fibers. We critically review research progress on SDM fibers and network components, and we introduce two figures of merit aiming for quantitative evaluation of technologies such as amplifiers, fan-in/fan-out multiplexers, transmitters, switches, and SDM nodes. Results show that SDM fibers achieve a 1185-fold (18-fold) spectral-spatial efficiency increase compared with the 276-SMF bundle (single-core fiber) currently installed on the ground. In addition, an analysis of crosstalk in MCFs shows how SDM concepts can be further exploited to fit in various optical networks such as core, metro, and especially future intra-data center optical interconnects. Finally, research challenges and future directions are discussed.