Two papers authored by Professor Alexandra Boltasseva and her group have been the top downloads over the past two years in OSA's (The Optical Society) Optical Materials Express.

These research articles address one of the key challenges in the field of plasmonics and metamaterials. Current plasmonic and metamaterial devices suffer from many limitations arising from the undesirable properties of their material building blocks. In these papers, Boltasseva and colleagues propose unconventional materials that can overcome many of these limitations and pave way towards technologies based on plasmonics and metamaterials.

"Ceramic materials such as metal nitrides and oxides can be designed to exhibit metallic property, an essential property of any plasmonic material. Replacing metals such as gold and silver with these "designer metals" offers many advantages to the performance, ease of nanofabrication and integration of plasmonic devices," says Gururaj Naik from Boltasseva’s group, a lead author of these articles.

"Titanium nitride as a plasmonic material for visible and near-infrared wavelengths".

Abstract:
The search for alternative plasmonic materials with improved optical properties, easier fabrication and integration capabilities over those of the traditional materials such as silver and gold could ultimately lead to real-life applications for plasmonics and metamaterials. In this work, we show that titanium nitride could perform as an alternative plasmonic material in the visible and near-infrared regions. We demonstrate the excitation of surface-plasmon-polaritons on titanium nitride thin films and discuss the performance of various plasmonic and metamaterial structures with titanium nitride as the plasmonic component. We also show that titanium nitride could provide performance that is comparable to that of gold for plasmonic applications and can significantly outperform gold and silver for transformation-optics and some metamaterial applications in the visible and near-infrared regions.

"Oxides and nitrides as alternative plasmonic materials in the optical range".

Abstract:
As alternatives to conventional metals, new plasmonic materials offer many advantages in the rapidly growing fields of plasmonics and metamaterials. These advantages include low intrinsic loss, semiconductor-based design, compatibility with standard nanofabrication processes, tunability, and others. Transparent conducting oxides such as Al:ZnO, Ga:ZnO and indium-tin-oxide (ITO) enable many high-performance metamaterial devices operating in the near-IR. Transition-metal nitrides such as TiN or ZrN can be substitutes for conventional metals in the visible frequencies. In this paper we provide the details of fabrication and characterization of these new materials and discuss their suitability for a number of metamaterial and plasmonic applications.