Supervised by:

First of all, I wish to express my gratitude to Dr. Miguel Beruete and Dr. Miguel Navarro, who supervised this work, for their continuous support, constant advice and transferring me their knowledge and passion in this fascinating field. They always pushed me in the right way and they never let me lose the motivation during these years. I also thank to Dr. Francisco Falcone for introducing me in the research world and for his priceless advices regarding to research topics and life in general. Moreover, I have had the profound honor of working with the late Prof. Mario Sorolla who taught me the importance of humility and hardworking and who I consider one of the best examples of how a researcher must be. Also to my fellows from the Teralab, Pablo, Pacheco, Unai, and Baha for all moments spent together. I would like to thank to Prof. Nader Engheta from University of Pennsylvania, Prof. Stefan A. Maier from Imperial College London and Prof. Alejandro Martínez from Universitat Politècnica de València for giving me the opportunity of being part of their research groups and so improving my quality as a researcher. Thanks to all people that I met in Philadelphia, London and Valencia, particularly to Pak, Jero