Conventional metals with high carrier concentrations have served to date as the materials of choice for plasmonic and metamaterial devices. However, typical metals are not well suited for near IR (NIR) plasmonic applications because their associated plasma frequencies correspond to the visible and ultraviolet regions of the spectrum. On the other hand, materials with lower plasma frequencies such as conducting oxides like ZnO and VO2 are capable of more efficiently coupling the electromagnetic radiation for optical metamaterial and plasmonic applications in the NIR. Furthermore, unlike metals, the electrical transport properties of conductive oxides can be modulated intrinsically by doping or extrinsically by applying heat, light or an electrical bias, thus allowing tuning of their electro-optical behavior. At the Naval Research Laboratory (NRL), we have investigated the use of laser processing techniques for the deposition and processing of various types of conducting oxides, such as Al-doped ZnO and W-doped VO2, which can be optimized over a wide range of optical/electrical properties. This paper will describe the laser deposition of these oxide films and their electrical and optical characterization in the NIR.
|