Glasses for integrated optics: recent advances and perspectives

The aim of integrated optics is to develop optical chips where passive and active functions, in particular those related to telecom systems (power splitting, signal tapping and addressing, signal modulation, signal generation and detection), are performed. So far, however, only an hybrid integration has been possible, thus reducing the functional capabilities of an integrated optical chip. Thus, an important class of materials for IO circuits is that of advanced glasses (or, better, composite glassy materials), such as silicate waveguides onto silicon substrates (for the integration of passive components with detectors and for the optical interconnection of electronic chips), glasses with nonlinear properties (for frequency conversion and optical switching), glasses doped with rare earths (for optical amplification and laser action), nanostructured glasses (for advanced performance). An overview of current developments in this area will be provided, together with a mention of some important processing techniques, especially for direct writing of channel waveguides and components by using laser irradiation or ion implantation.