A hitless reconfigurable add-drop multiplexer for WDM networks utilizing planar waveguides, thermo-optic switches and UV-induced gratings

Summary form only given. We describe a reconfigurable add-drop multiplexer that can insert or remove a single channel per stage without disrupting service on the remaining channels. The device was fabricated in Ge-doped SiO/sub 2/ channel waveguides with a delta of 1.2 percent on silicon substrates. The device design consists of two null path Mach-Zehnder thermo-optic switches on either side of an inner Mach-Zehnder grating filter.