What's coming next in the near future for optical networks?

With the fast development of various applications, the demand for network bandwidth has been increasing significantly during the past decade. Although the WDM (wavelength-division multiplexing) technology has already provided high bandwidth using parallel wavelength channels, the overall network spectrum efficiency is however severely discounted by the fixed grid definition and standard rate transmission. The short-term solution to increase capacity is by introducing hardware enabling elastic optical networking (EON), which is intrinsically related to flexible-grid channel allocation; and the longer-term solution involves extending the fiber capacity by space division multiplexing (SDM) based on new types of fibers supporting multiple cores, multiple elements, few LP modes or even modes carrying Orbital Angular Momentum (OAM). Moreover, for short-term evolution, it may not be economically viable to make a one-time complete upgrade to full flexible-grid technology on the entire network, which means, before the current optical transport network capacity is exhausted, the current fixed-grid network could be maximally kept operational during the migration to preserve the already-made investment. In this talk, a series of topics will be discussed, such as the network architecture with co-existing fixed-grid and flexible-grid technologies, migration strategies evolving from fixed-grid to flexible-grid, SDM based Reconfigurable Optical Add/Drop Multiplexers (ROADMs), as well as networking aspects of routing and spectrum resource allocation when considering spectral/spatial switching.