A broadband electromagnetic circulator in magnetized plasma

We propose a broadband electromagnetic circulator based on an array of magnetized plasma rods arranged as a triangular lattice. Contrary to ferrite-based circulators, our design leverages the anisotropy of plasma's dielectric tensor to achieve non-reciprocity. By applying the inverse design technique, one can optimize the plasma frequencies of each rod, as well as the cyclotron frequency of the entire array, to achieve a broadband non-reciprocal response of the system. Furthermore, we show that configurations with compound symmetry naturally emerge in optimization without any symmetry constraints, and such compound symmetry can be incorporated into the optimization process to reduce the computational cost. Our design demonstrates the possibility of a broadband non-reciprocal response through the use of an array of plasma rods, taking advantage of the reconfigurability of each individual rod.