Asynchronous digital optical networks

An 'emerging reality' in broadband optical networks is that the existing approaches to photonic networking have significant and fundamental limitations. This paper will explore these limitations, and will describe how they could be overcome by using a radically different approach based on asynchronous digital optical processing. The device technologies needed for photonic networking based on WDM (wavelength division multiplexing) are becoming well established, and several network trials are in progress. In contrast, photonic networking based on OTDM (optical time-division multiplexing) requires special devices and sub-systems that are available currently only in a few research laboratories. Whilst there have been several demonstrations of OTDM point-to-point transmission, so far there have been only a very few experiments to demonstrate the feasibility of OTDM networking.