This paper outlines the concept of the asynchronous digital optical network, which is aimed to combine the advantages, and overcome the drawbacks, of existing approaches to photonic networking. The network is based on digital optical transmission and processing, which offers the prospect of almost infinite scalability. Optical transmission throughout the network is in burst mode, using a standard digital optical signal format. The main defining feature of the asynchronous network is that the network nodes (in which the optical processing and routing take place) do not share global synchronization at the bit level. Instead, the nodes each operate with independent bit-level clocks. This approach removes the architectural constraints found in synchronous networks. An essential component of the network is the asynchronous digital optical regenerator. Various design and performance aspects of this new type of regenerator are analyzed.
David Cotter and Andrew D. Ellis, "Asynchronous Digital Optical Regeneration and Networks," J. Lightwave Technol. 16, 2068- (1998)