Leslie A. Rusch
The use of optical fiber cable to achieve enormous bandwidth expansion has become de rigeur. Communications engineers have been working miracles for decades by weaving together the most appropriate combination of available multiplexing strategies over single mode optical fiber. The price per bit per kilometer in optical communications has plummeted again and again as new components and fibers have stretched the carrying capacity of each multiplexing dimension.
Despite these advances, short-haul requirements continue to grow and are expected to exceed the capacity of simple single mode fiber transmission. Spatial multiplexing is a new technique in fiber communications allowing fiber capacity to grow in another dimension by carrying signals on multiple modes of light.
The short length and high capacity requirements for data center and front-haul links make them well suited for exploitation of orbital angular momentum (OAM) of light in spatial multiplexing, as they hold the promise of low correlation among modes.