Physics Colloquium Thursday , February 19 th at 3 : 40 PM in SC 234 Featuring

Materials which optical and electrical properties can be dynamically tuned have potential applications in many areas including smart windows, ultrafast switches, spatial light modulators, reconfigurable metamaterials and frequency selective filters. Vanadium dioxide (VO2) has been envisioned as one of the most promising material to realize tunable optical devices for THz and NIR applications. VO2 exhibits a well-known reversible insulator-metal transition (IMT) which is accompanied by change in the electrical conductivity by several orders of magnitude. For photon energies below the bandgap, VO2 exhibits high optical transmittance in the insulating phase and low optical transmittance in the metallic phase, leading to a large optical contrast. This is particularly important at THz and NIR frequencies where transmission amplitude modulation depths as large as 85% has been recently demonstrated using thin film VO2 grown on sapphire substrates.