Strip-loaded sol-gel waveguides for optical amplifiers

Among the various possible production techniques of silica-on-silicon integrated optical devices, sol-gel is the one which combines low cost with a great flexibility and the ease of doping the silica matrix with nonlinear and active compounds. In the frame of an European project, we have investigated the application of the sol-gel technique to the realization of an erbium-doped optical amplifier, operating in the third telecommunication window. Here, in particular, we refer to the development of an optimum fabrication strategy for the guiding structure. A strip-loaded configuration was chosen. Design optimization was carried out by means of a MATLAB software code, mainly based on the Effective Index Method (EIM). For what concerns the technical side, two different routes were followed: that of the Low Index Load (LIL) and that of the High Index Load (HIL). Pros and cons of both structures were carefully evaluated through numerical simulation as well as experimental analysis, in order to choose the best performing one. Results of the design procedure and the characterization of the fabricated waveguides are described here.