Controlling light at the subwavelength scale

This contribution describes a general strategy, based on transformation optics, to investigate a broad variety of plasmonic nanostructures. We exploit the fact that a finite nanoparticle with sharp geometrical features can behave like an infinite plasmonic system and can exhibit a continuous light absorption property over a broadband spectrum. Comprehensive discussions are provided on how the effects of nonlocality and edge rounding affect the local field enhancement as well as the energy and bandwidth of each plasmonic resonance. Generalization of this method to three dimensional situations will also be discussed. The largely analytic approach gives physical insights into the processes involved and suggests the way forward to study a wide variety of plasmonic nanostructures.