The chapter reviews filters (to be) used in fibre optic communication: Fibre coupler filters, diffraction gratings, arrayed waveguide gratings, fibre Bragg gratings, Fabry-Pérot interferometers, thin-film and microring filters, interleavers, and acousto-optic filters. The presentations include the underlying basic physics, implementations of filters and modules, and typical performance data in the wavelength domain, but relevant phase properties are discussed as well. Attention is also given to system implications of the various device characteristics.
