The Physics & Astronomy Colloquium Series presents Jason Valentine of Mechanical Engineering, Vanderbilt University on “Harnessing, and Avoiding, Loss in Optical Metamaterials” on Friday, Nov. 04, at 4:10 p.m. in Walter 245.
Jason Valentine
Abstract: Optical metamaterials are man-made materials in which structuring is used to control the effective optical properties. Metamaterials have traditionally been made from metals and absorption loss has long been one of the primary impediments to their adoption in practical applications. Over the past several years researchers have come to realize that loss can not only be harnessed for certain applications but also completely avoided when transparency of the material is critical. In this talk, I will start by discussing how absorption loss in plasmonic materials can be utilized in energy conversion devices by harvesting hot electrons within the metal. In this case, the use of metamaterials provides the freedom to engineer the optical absorption while also optimizing the geometry of the metal for efficient capture of the hot electrons. In the second half of the talk I will discuss all-dielectric metasurfaces in which metal, and the accompanying absorption, is completely avoided. As with their plasmonic counterparts, manipulation of the unit cell structure of all-dielectric metasurfaces offers a means to engineer a wide variety of optical properties. This freedom, combined with the reduction in absorption loss, could lead to ultra-thin optical elements and assemblies. Along these lines, I will discuss several implementations of all-dielectric metasurfaces with functionalities that include polarization control, wavefront tailoring, near-unity reflection, and sharp Fano resonances.
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