Guided-wave phenomena and devices: From microwaves to optical frequencies

Several research projects on microwave optics were carried out since the early Fifties at IROE (then "Centro Microonde") under the guidance of Giuliano Toraldo di Francia. These projects were anticipating the development, some twenty years later, of integrated optical components and devices exploiting the same physical phenomena. Here a brief review is presented of IROE's researches in these two fields, from earlier microwave investigations to later achievements in integrated optics. Mention is also made of some recent results in nonlinear and active integrated optics: even if these results are not directly linked to previous researches at microwaves, that microwave activity has in some way indicated the route to broader and original researches in the area of optical guided waves.