Fundamentals and applications of phasar demultiplexers

Phased-array demultiplexers (phasars, AWGs or WGRs) are key components in WDM networks. A review is given of the operation principles and the performance of phasar demultiplexers. These components can be realised in almost any waveguide technology and are, therefore, very suitable for integration with other devices. Examples are discussed of integration with switches in optical add-drop multiplexers and crossconnects and with optical amplifiers in devices like wavelength selectors and multiwavelength lasers. Although development costs of devices like these are still high, the present acceleration of InP technology development, driven by the WDM-laser market, will pave the way for integration processes which will provide compact and cost-effective solutions for many functions in WDM applications.