His past research has included the study of the electronic and optical properties of semiconductor nanostructures, in particular providing insight through Raman spectroscopy into the properties of plasmons and spin excitations in low-dimensional electron gases. Research in nanophotonics has also included the development, theory and application of scanning near-field optical microscopy, including the development of 'tip-enhanced' Raman and fluorescence microscopy, leading in turn to a focus on surface-enhanced Raman scattering (SERS) and the manipulation of fluorescence using plasmonic nanostructures. This has previously included application in fluorescence biological cell imaging for novel cellular screening assays, while other interests in biophotonics have included the development of ultra-broadband coherent anti-Stokes Raman scattering (CARS) imaging.