Our research focusses on the interaction between light and nanostructured objects and materials. We are interested in light from powerful ultrafast lasers all the way down to single photons. The range of materials we investigate includes artificially-structured chiral meta-materials, plasmonic nanoparticles, two-dimensional materials such as graphene, and molecular nanomaterials.
Often, we use nonlinear techniques to study how light interacts with these materials. When illuminated with a high-power laser some materials generate new wavelengths of light, for example at twice the frequency of the incident beam. The intensity and polarisation of this second harmonic light depends strongly on the properties of the material, in particular its symmetry, and can be used to learn more about how light interacts with novel materials.
One example is our work with chiral materials. Chiral materials have a handedness – that is to say they cannot be superimposed on their own mirror image. We study the nonlinear response of artificial chiral structures – arrays of tiny metal helices or spirals – to left- or right-circularly polarised light. In doing so, we can isolate the optical effects of chirality and determine if these structures might be useful as sensors or in detecting contamination by pharmaceutical drugs of different handedness.
Our techniques include various forms of optical microscopy, linear and nonlinear spectroscopy from the UV to the mid-IR, and a range of in-house and commercial numerical tools for solving Maxwell's equations.