The Center for Metamaterials (CfM) designs, fabricates, and tests a wide range of metamaterials. Its mission is to advance fundamental and applied metamaterials research, development, and technology transfer through strong collaborations between industry and universities. There is strong industry interest in metamaterials, as they are being used to develop new or higher-performing optical, electronic, and acoustic devices.
Metamaterials are patterned and/or composite materials that exhibit effective permittivity, permeability, or refractive index properties not found in nature. Their properties are commonly the result of resonant phenomena arising from the subwavelength-scaled elements forming those patterns or composites. The smaller these elements are with respect to the wavelength of the electromagnetic radiation, the better the metamaterial satisfies effective medium criteria and the more accurately they can be treated as a genuinely new material. Such materials have the potential to provide index values - very large, less than unity, or negative - with broad applications.
CfM explores this rich area of fundamental research of metamaterial, which is characteristically defined by its active composition of the host material. "Active" refers to the material properties that exhibit either optical gain under pumping, strong material nonlinear properties, or both.
Metamaterials researchers have developed novel metallic feature structures, metasurfaces, that allow for local control of the phase as an optical beam is transmitted through a surface. This project is investigating these metasurfaces using a low-cost, rapid-development approach to increase the efficiency of the refraction, develop designs that allow for pixilated arrays of flat lenses, and investigate tuning concepts that would allow for the steering of microwave and infrared beams.
Design and fabrication of low-loss low-index optical metamaterials
A new and rigorous theory that goes well beyond well-known mixing rules has been used to predict specific particle properties that would lead to a composite metamaterial having a desired refractive index, such as less than unity. Modeling based on this method and the development of processes and procedures to make and characterize coated nanoparticles are in progress.
Infrared Mueller matrix imaging of dielectric metamaterials
Recent advances in three-dimensional laser direct writing enable the fabrication of dielectric metamaterials composed of constituents with virtually arbitrary geometry at the nanometer scale. But analysis of such metamaterials in the infrared spectral range is still lacking. In this project, CfM uses variable angle of incidence ellipsometry and near normal incidence ellipsometry to characterize infrared metamaterials composed of subwavelength dielectric structures.
This project is developing and validating a design tool for bulk metamaterials that considers coupling effects between nanostructures. It is based on a building block of resonators for each nanostructure referenced in a database to compile the desired design structure.
Orbital angular momentum (OAM) fiber
This project focuses on generating, detecting, and sorting OAM modes. In this project, CfM takes what it has learned in past projects combined with knowledge in the field of fiber gratings and aims to develop a fiber grating that filters for OAM mode.
Sorting uniquely identical spherical resonators by light forces
CfM is developing a disruptive technology of sorting microspheres with extraordinary high level of uniformity of their whispering gallery mode resonances. The proposed method is based on work done by CfM showing that a focused laser beam exerts optical force on microspheres traversing the beam.
Terahertz (THz) metamaterials
CfM has discovered that THz form-birefringence can be induced in subwavelength structures fabricated from methacrylates using stereolithographic fabrication. These results provide a new avenue for the fabrication of highly anisotropic THz metamaterials and their use for THz sensing and imaging applications.