Latest Advances in Magnetless Nonreciprocal Metasurfaces
Magnetless Nonreciprocal Metasurfaces represents one of the most vibrant fields of modern electromagnetic science and technology. This talk will present the latest advances of our research group in this area. First, it will introduce nonreciprocity by recalling its engineering and physics definitions, historical milestones and ferrite-technology principles. Motivated by the drawbacks of that technology, it will then establish the key conditions for nonreciprocity in terms of time-reversal symmetry breaking, and deduce from them three routes for magnetless that have been recently explored, namely asymmetric nonlinearity, spacetime modulation and transistor loading. Third, it will show that the most promising of these routes is the transistor-loaded particle one that it will describe in some details. Fourth, it will note that metasurfaces represent ideal embodiments of metamaterials for magnetless nonreciprocity, and subsequently describes the Generalized-Sheet Transition Condition (GSTC) synthesis allowing to design efficient bianisotropic metasurfaces [1]. Finally, it will overview several examples of metamaterial magnetless nonreciprocity applications recently developed in the speaker’s group, including nongyrotropic/gyrotropic rotators and isolators, nonreciprocal refractive and birefringent systems, nonreciprocal specular transformers, energy sinking cavities and angle-independent absorbers/amplifiers.
[1] K. Achouri and C. Caloz, Electromagnetic Metasurfaces: Theory and Applications. Wiley - IEEE Press, 2020.
