Integrated optic tunable add-drop filters for WDM ring networks

This paper deals with two types of thermo-optically tunable add-drop filters realized by means of different technologies: fiber-matched low-pressure chemical vapor deposited (LPCVD)-grown SiO/sub 2/ waveguides and plasma-enhanced chemical vapor deposition (PECVD)-grown high-refractive-index-contrast SiON waveguides. Design and technology aspects are outlined. The device characterizations, drawn from laboratory and field trial measurements, are reported. The description focuses on the device applications in a system context. In particular, the usefulness of the components as the basic elements of an optical add-drop multiplexer node, suitable for a ring network, is shown. The key component aspects are presented as strictly related to system requirements and issues.