The constant development of optical transmission technologies nowadays allows having large bandwidths and transmission velocities, which is used for high quality and increased user subscription. To go one step forward in the field of optical communications, it is needed the development of photonic devices capable of processing optically without the need for optical-electrical-optical conversion which limits the final capacity. One of the alternatives to achieve this kind of optical processing devices is using periodic structures such as photonic crystals.
In this doctoral thesis, the use of periodic structures to perform processing functions directly in the optical domain has been studied: guiding, ultra-compact delay lines and dispersion compensation elements, or XOR logic-gates with slow-wave elements. Besides these functionalities, other issues of interest of this kind of periodic structures have also been studied: the influence of finite length in photonic crystal waveguides, the use of slow-wave structures to enhance the non-linear effects of the materials, or the increase of propagation losses for waves with low group velocity. Also a new configuration of photonic crystal made of Silicon rods in a silica core, which presents several advantages when comparing to the traditional configurations of holes in a high index core, is proposed.
Several samples with some of the structures theoretically studied have been fabricated and characterized, confirming that their real behavior matches with the results obtained in the design step. It is worth to mention that, both in the design and the fabrication-characterization steps, only materials compatible with CMOS fabrication technology have been considered (Silicon, Silicon oxide and Cadmium telluride). This is a basic requirement to have a simple and cheap fabrication process, which allows the mass-manufacturing of these photonic devices and their entry into the telecommunications market.