Design and control of highly spectrally efficient photonic networks enabled by fiber-granular routing on overlaid ring-shaped topologies

We propose an ultradense wavelength-division-multiplexing (WDM) network architecture that dramatically enhances channel accommodation density to achieve extremely high spectral efficiency. The trade-offs between high spectral efficiency and severe signal impairment due to optical filtering are resolved by network optimization of the overlaid subnetworks based on fiber-granular routing and wavelength-granular add/drop operations. The spectrum narrowing induced by node operations is well controlled by the impairment-suppressing routing and wavelength assignment (RWA) method. Numerical simulations on several metro-scale network topologies verify that the proposal enhances the spectral efficiency by up to 31.0% compared to comparable dense WDM networks.