CONTROLLING LIGHT ON THE NANOSCALE (Invited Review)

In many ways light and nanoscience do not mix well.By convention light can be focussed to a spot no smaller than about a micron whereas nano structures by definition are three orders of magnitude smaller in scale.However recent theoretical advances show how to control light at the nanoscale, provided we can find the correct materials for our devices.I shall describe these new theories, and how they enable us to concentrate light to better than a nanometre.In this way light can detect single molecules, and the huge concentrations of optical energy can force photons to interact with one another which they normally do not do.