Subwavelength and nanoscale control over electromagnetic fields is one of the major advantages of plasmonics. New materials and techniques for tailoring plasmonic properties allow us to extend the application range and achieve novel functionalities. Recently metal oxides have been introduced as promising plasmonic materials for the infrared. By designing nanoantennas and metamaterials using transparent conducting oxides, we can achieve strong light-matter interactions in the infrared while maintaining high transparency in the visible range [1,2]. We have shown that high-density arrays of indium-tin-oxide antennas provide a useful platform for surface enhanced infrared spectroscopy.
Next to plasmonic nanomaterials with tunable properties by design, efficient and reversible control of plasmonic modes at visible and near-infrared wavelengths will allow new tunable devices for control of local hotspots or plasmonic switches. In recent studies, we have investigated how local field enhancement around a nanoantenna can be used to drive an optical nonlinear material. As the nonlinear medium, indium-tin-oxide can provide a large nonlinear response . An ultrafast hybrid nonlinearity can be designed where the antenna assists the nonlinear substrate through the strong optical near-fields and also enhances the readout of the nonlinear response.
Phase-change materials offer another technologically relevant opportunities as they can provide very large changes in the dielectric response. Compared to chalcogenide phase-change materials which offer slow, rewritable memory functionality at relatively high temperatures, vanadium oxide (VO2) provides an ultrafast, reversible phase transition at only modestly elevated temperatures around 78°C. Most studies so far have reported the effects of a global phase transition of a VO2 layer on the plasmonic response of nanoparticles and metamaterials. We have successfully demonstrated ultrafast phase changes in a plasmonic antenna - VO2 hybrid. The phase change response is fully reversible over >1 million cycles per second, opening new avenues for ultracompact and low energy transistor-type optical switches .
 M. Abb, Y. Wang, N. Papasimakis, C. H. de Groot, O. L. Muskens, Surface-Enhanced Infrared Spectroscopy Using Metal Oxide Plasmonic Antenna Arrays, Nano Lett. 2014, 14, 346 – 352.
 S. Gregory, Y. Wang, C. H. de Groot, O. L. Muskens, Extreme subwavelength metal oxide direct and complementary metamaterials, ACS Photon. 2015, 2, 606 – 614.
 M. Abb, Y. Wang, C. H. de Groot, O. L. Muskens, Hotspot-mediated ultrafast nonlinear control of multifrequency plasmonic nanoantennas, Nature Communications 2014, 5, 4869.
 O.L Muskens, L. Bergamini, Y. Wang, J. M. Gaskell, N. Zabala, C.H. de Groot, D. W. Sheel, J. Aizpurua, Antenna-assisted picosecond control of nanoscale phase-transition in vanadium dioxide, Light: Science