Long-haul communications is presently performed by microwave systems which have evolved over 40 years towards a theoretical bandwidth limit of around 1 TBPS. Modern military, industrial and commercial requirements each will exceed this limit within a decade.
Optical communications systems promise to deliver improved bandwidth (up to 20 TBPS) with high security in all domains, and over all distances.
In addition to an inherently high bandwidth, optical communications systems offer very high security through their amenability to quantum encryption as well as the extreme physical difficulties they present for signal detection or intercept.