Photonics originated as a research discipline during the 1960s, with the invention and production of the first lasers. The development of these optical sources was followed in the 1970s by the large-scale deployment of optical fibers, as a medium for information transmission by means of light beams. In the years that followed, scientific research and constant technological development fostered a revolution in the telecommunications field. The association of photonics with other disciplines opened new horizons, unimaginable just a few decades ago. This volume, as it contains material intended for prospective telecommunications and electronic engineers who are going to professionally design optics-based devices and subsystems, it also presents the basic notions to approach further disciplines with which photonics may pro tably interact.