Zhao Research Group

Metamaterials are artificial media composed of engineered sub-wavelength structures, which cause them to have fascinating new electromagnetic properties that are not usually found in nature. The resonant frequencies associated with the underlying structures are a function of size, shape, composition, and lattice arrangement.  Typical micro/nano structures include but are not limited to, rods, split-ring resonators, omega, and fishnet structures. Although there has been great progress in shifting the resonant response of metamaterials from the microwave frequency regime to the optical frequency regime over the past 10 years, there are still many challenges  that must be overcome in order to make “metamaterials” practical materials for real-life applications. In order to fulfill the requirements of a “real-world” metamaterial, at least three conditions need to be met: Firstly, the materials must operate at optical wavelengths, especially covering the telecommunication to visible wavelengths. Secondly, the structures should be multilayer so that they can be treated as three-dimensional (3D) or bulk materials. Thirdly, the losses should be reasonably low. By making the dimensions of metamaterial unit cell such as a split ring resonator (SRR) on the nanometer scale, or redesigning metamaterial structures such as the fishnet, investigators have already extended the working wavelength of metamaterials to the optical region. The third challenge could be potentially solved by using all-dielectric structures. Due to many advantages of the GLAD technique, I believe that it is a scalable fabrication method to construct 3D optical metamaterials.