Optical Metasurfaces with Electric, Magnetic, and Magneto-electric Responses
Abstract
PROJECT SUMMARY We propose an innovative approach to devising metasurfaces (metamaterial surfaces) that will allow complex optical responses using planar nanofabrication processes. The proposed metasurfaces will consist of patterned, plasmonic (optically anisotropic) sheets separated by optically-thin (subwavelength) dielectric layers. The metasurfaces can exhibit electric, magnetic and magneto-electric responses, which will allow arbitrary control of polarization, reflection and transmission phases, and reflection/transmission magnitude. In contrast to earlier efforts, complex 3D geometries such as spirals or omega particles are not required to achieve desired bianisotropic surface properties. The mesoscale characteristics of metasurfaces will be explored, in particular tailored bianisotropic properties, to demonstrate compact optical systems with unprecedented wavefront and polarization control. Polarization control is typically achieved with combinations of linear polarizers and standard waveplates, while phase control is achieved using dielectric lenses and spatial light modulators. However, these conventional systems are bulky and do not lend themselves to nanophotonic system integration. The proposed metasurfaces promise an ultracompact alternative to conventional optical components since they allow abrupt phase changes and extreme polarization control. In addition to making optical components thinner, the metasurfaces will also allow the closer integration of sources with optics, since even complicated field polarizations that occur close to light sources (i.e. radial polarization) can be converted to polarizations of interest (linear, circular, etc.). Several different devices will be realized to establish the broad applicability of bianisotropic metasurfaces for optical design. First, homogeneous, reflectionless metasurfaces will be explored. Unprecedented polarization control will be demonstrated with the first ultrathin, isotropic polarization rotator at optical wavelengths. Next, inhomogeneous, reflectionless metasurfaces that can spatially tailor the phase and polarization of a wavefront will be investigated. Metasurfaces will be developed that convert commonplace Gaussian beams to vector Bessel beams of mixed polarization. The metasurfaces will excite beams that exert either push or pull forces on microparticles, depending upon the incident polarization. This work will demonstrate the extraordinary light-matter interaction that bianisotropic metasurfaces can enable. Finally, inhomogeneous, semi-transparent metasurfaces with bianisotropic properties will be pursued that can be integrated with active optical devices for added functionality and unprecedented performance. Metasurfaces will be pursued that control both guidance and radiation. Such metasurfaces could be used to control a laser’s cavity Q, while simultaneously shaping an emitted beam. The proposed metasurfaces will be of interest to the Navy’s specific missions. Controlling the phase, amplitude, and polarization of light within a small form factor will allow optical systems to be placed on arbitrary platforms. For example, metasurface-based cameras/imagers and sensors could be integrated into manned/unmanned vehicles to allow for enhanced imaging/reconnaissance capabilities. The polarization control that is enabled by bianisotropic metasurfaces will provide additional polarimetric information of the scene. Further, metasurfaces derive their properties from their subwavelength texture rather than simply their shape. Therefore, metasurfaces can take on specific form factors for hydrodynamic/aerodynamic reasons while maintaining a desired optical performance. In contrast, the properties of conventional dielectric lenses are directly related to their shape.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 12, 2016
- Source ID
- N000141512390
Entities
People
- Anthony Grbic
Organizations
- Board of Regents of the University of Michigan
- Office of Naval Research
- United States Navy