Special issue - next generation of optical access [Editorial}

Optical access networks based on Time Division Multiplexed-Passive Optical Network (TDM-PON) technologies are becoming the ubiquitous deployment for major carriers' access networks. However, the sizable investment required to install the customer fibre dictates that this infrastructure must support generations of technologies for years to come. These papers consider the evolution of the TDM-PON and address the changes that long reach and Wavelength Division Multiplexing (WDM) bring.