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Dissertation Defense

Advances in Manipulating Electromagnetic Waves Using Paired-Metasurface Devices

Brian Raeker

Passcode: 1301


Metasurfaces are two-dimensional arrays of subwavelength elements, which aggregately manipulate electromagnetic waves to perform desired functions. These elements impart a local field manipulation on the amplitude, phase, or polarization of an incident wave. Metasurfaces have demonstrated a wide variety of functions, such as focusing, polarization conversion, radiation pattern control, and holography, with substantially more compact devices than traditional components. However, individual metasurfaces have relied on loss-based methods to control the transmitted wave amplitude, significantly lowering the achievable efficiency. Many applications require high efficiency, so alternative approaches are necessary to realize the full application space of metasurface-based devices.

In this work, metasurface devices are demonstrated for amplitude and phase control with high efficiency. By spatially separating multiple metasurfaces along a common axis, wave propagation is harnessed to achieve lossless amplitude control. First, a novel design approach is developed for paired-metasurface devices. Converting simple field profiles to custom radiation patterns is shown at microwave frequencies. Next, the design approach is extended to all-dielectric optical metasurfaces, where combined beam forming and splitting, and high-quality three-dimensional holograms are demonstrated with measured efficiencies near 80%. Finally, aspects of microwave and optical metasurface design are combined for dual-band mechanical beam-steering applications. Simulation and experimental validation reinforce the applicability of paired-metasurface devices to functions requiring high-efficiency performance.

Chair: Professor Anthony Grbic