Fast Coatings for DWDM Filters

Des Gibson

Current and forecast market requirements for dense wavelength division multiplexing (DWDM) filters are driving the need for ever-increasing production throughput. Manufacturers are calling for larger substrate diameters, enhanced uniformity and reduced process times.

To meet these requirements, the theoretical design of DWDM filters - the layer thicknesses and sequence - necessitates manufacture with 100 times more precision than conventional thin films. For example, four-cavity DWDM filters demand layer-thickness accuracy less than the interatomic spacing...