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From tunable metasurfaces to parametric metadevices
December 2, 2022 @ 11:00 am - 11:55 am
Metasurfaces are flat analogues of metamaterials, they are artificial composite materials made of resonant inclusions (also called meta-atoms) that are smaller than the wavelength of electromagnetic waves of interest. If parameters of metasurfaces change in time, such metasurfaces are called parametric. Development of multifunctional devices based on parametric metasurfaces is a promising area of research. There is a range of approaches towards creating metasurfaces whose properties change in time: they can be tuned either electrically, mechanically, optically, or thermally. Nonlinear mechanisms, as well as magnetic and chemical approaches, are also used to control the characteristics of metasurfaces. The choice of tuning technology depends on various features of the metasurface design, such as the required speed of modulation and material compatibility, as well as local access to individual meta-atoms. Parametric metasurfaces give us access to many non-trivial physical effects. They can shift the frequency of the radiation, steer electromagnetic beams, control parametric waves in the scattered field and exhibit nonreciprocity, meaning that electromagnetic waves are transmitted through the metasurface differently depending on the direction of incidence. The higher the modulation rate, the more interesting effects can be achieved in general. When it becomes comparable to the frequency of an electromagnetic wave, it is possible to have complete control over light both in space and time. In this seminar, I will first show how the integration of metasurfaces with a micro-electro-mechanical system can improve spectrally tunable band-pass filters for infrared imaging devices. Then I will present parametric metadevices based on split-ring resonators with embedded varactor diodes that can be used for amplification of electromagnetic waves in the microwave and subterahertz frequency ranges. Co-sponsored by: Morteza Shahpari Speaker(s): Mr Fedor Kovalev, Room: N218, Bldg: Engineering North, The University of Adelaide, Adelaide, South Australia, Australia, Virtual: https://events.vtools.ieee.org/m/334124