Plasmonics and Metamaterials with Transparent Conducting Oxides
Here, I will present our recent results on the use of highly conductive metal oxides such as indium-tin-oxide (ITO) and aluminium-doped ZnO (AZO) in active plasmonics and metamaterials [1-4]. We can define three windows of operation for these materials, corresponding to the regimes of dielectric [1,2], metallic , and epsilon-near zero  response. By combining metal oxides with plasmonic materials such as gold and silver, we explore new types of hybrid response with the potential of electrical and picosecond optical control of plasmon resonances . This includes combination of lithographically defined plasmonic nanostructures with coatings obtained using atomic layer deposition (ALD) .
Further in the mid infrared spectral range, the plasmonic response of highly doped metal oxides can be used for spectroscopic characterization of molecular species using Surface Enhanced Infrared Absorption . We have developed new methods for the fabrication of metal oxide antennas and have demonstrated their use as plasmonic devices for infrared molecular fingerprinting. Finally, an intermediate regime is explored where the ITO permittivity approaches zero and the optical response is governed by superluminal group velocity enabling new plasmonic modes with large nonlinearity .
 M. Abb, Y. Wang, P. Albella, C. H. de Groot, J. Aizpurua, O. L. Muskens, ACS Nano 6, 6462 (2012)
 M. Abb, B. Sepulveda, H. M. H. Chong, O. L. Muskens, J. Opt. 14, 114007 (2012)
 D. Traviss, R. Bruck, B. Mills, M. Abb, O. L. Muskens, Appl. Phys. Lett. 102, 121112 (2013)