Transformation optics

When light travels through some transparent materials it behaves almost exactly as if travelling through nothing at all. It turns out that we can completely understand the effect of some transparent materials through forgetting about the material altogether, and instead treat the region of space occupied by the material as being distorted, stretched, or curved in some way.  Transformation optics is the study of electromagnetism in transparent materials through understanding the behaviour of electromagnetism in a general space–time geometry.

The need for such a theory has arisen because of the great freedom in the kinds of optical properties that can be explored with modern manufacturing techniques. Transformation optics was partly developed here at St. Andrews, and has been applied to design devices that can overcome the diffraction limit, as well as an invisibility cloak that can work over a broad spectrum of frequencies.

Yet transformation optics has inspired our work beyond just the design of optical devices. It has been applied to the theory of the Casimir–Lifshitz force to invent a new method for levitating objects, and is the theory underlying our experimental investigation of a fibre–optic analogue of the event horizon.