Introduction to Integrated Optics: Characterisation and Modelling of Optical Waveguides

The first demonstration of the laser in 1960 opened the way to the development of lightwave technology; then the production of low-loss optical fibers in the 70s made guided-wave optical communication systems become a reality. One of the problems associated with the development of long-haul systems was obviously related to the introduction in the transmission line of a number of repeaters, able to recondition and to reamplify the optical signal. The solution offered by conventional optics was unsatisfactory, due to the size and electrical power consumption, as well as to the critical dependence on temperature variations, mechanical vibrations, and the presence of moisture. The alternative first suggested by S.E. Miller, a researcher at Bell Laboratories, was to miniaturise the repeater, integrating all the components onto a single chip and interconnecting them via optical waveguides: the concept of integrated optics was born. More than two decades have passed since then: innovative research has been carried out on a vast spectrum of waveguide devices, and in recent years the goal of performing useful optoelectronic functions in a number of commercial applications has eventually come to fruition.