Diffraction gratings WDM components

Abstract

Diffraction grating WDM components have tremendous capability in number of channels (160 channel components and more with bi-directionality are commercially available and components with two times more channels have been demonstrated experimentally). They have a high free spectral range (typically 775 nm with gratings working in the first order). Small spacing such as 25 GHz is commercially available and 5 GHz feasibility has been demonstrated. Athermal glass components down to 25 GHz spacing are manufactured with uncontrolled drifts as low as 0.35 pm/° using commonly available glasses. These solutions are based on the traditional and mature optics technology used to manufacture millions of diffractionlimited reliable optics at low cost. The unique three-dimensional nature of these components can be exploited for advanced features requested by network designers such as add/drops, crossconnects, and routing devices. Cyclic passive routers accurately matched to the ITU frequencies in DWDM or to ITU wavelengths in CWDM have been proposed for advanced networks. Diffraction grating components can be used for high quality bidirectional links. For mono-directional or bi-directional links they have virtually unlimited numbers of channels and provide the lowest crosstalk for the higher number of channels. For low cost mass production the problems of fibre handling, that are the same with any solution, remain to be solved. © Springer-Verlag Berlin Heidelberg 2006.