Physics is fascinating because of the intellectual excitement it provides and because of the applications it offers. In the Group of Applied Physics (GAP) at Geneva University we get our inspiration from both of these motivations. Optics, in this respect, has a privileged place. Indeed, in modern optics, experiments and theory progress hand-in-hand, and practical applications are close behind. Consequently, we can work both on conceptual issues and on applications. Moreover, it is a very good time for optics! The fascinating new insight about quantum mechanics brought about by recent quantum optics experiments on one side, and the tremendous development of optical communications on the other, illustrates our privileged position.