Dynamic Optical Metamaterials Based on Vanadium Dioxide
The development of dynamically reconfigurable materials has long been a goal of the metamaterial community. Vanadium dioxide, a first-order phase change material, is a prime candidate for an actively tunable element as its phase transition occurs near room temperature and is accompanied by a large change in both its electrical and optical properties. The majority of past demonstrations of active metamaterials have utilized continuous films of active media and have suffered from limited on/off ratios, high power consumption per bit, and poor temporal response. In this work, I will present my efforts to address these problems by employing nanostructured vanadium dioxide combined with metamaterial field concentrators. Due to the decreased thermal mass, complete control over the optical reflection and absorption can be realized using plasmonic bowtie antennas, with dramatically improved recovering time and energy efficiency. An all-dielectric Huygens metasurface is implemented to achieve dynamic control over the transmission. By introducing an epsilon-near-zero mode we have explored the use of the device as a self-adaptive optical limiter. We envision that these types of active metamaterials could be potentially utilized for applications including tunable color displays, holography, adaptive optics, and anti-forgery devices.