Multistage WDM passive access networks: design and cost issues

The advantages of employing passive optical architectures in the access network have been largely recognized. Particularly, developments in optical technologies have made the realization of wavelength division multiplexing passive optical networks (WDM-PONs) feasible and cost-effective. These networks are more future-proof than conventional PONs, thanks to their intrinsic optical transparency and their extremely high transmission capacity. A very useful optical routing device, called a waveguide grating router, is the basic building-block of new PON architectures capable of connecting a large number of users or to improve the use of the optical bandwidth. In this paper the feasibility of these architectures is discussed by considering the costs and the technological limitations on the optical components.