Tuning Plasma Frequency of Nested Wire Media

We study nested wire media possessing $C_6$ and $C_4$ rotational symmetries whose plasma frequencies can be controlled through breathing deformation. Numerical simulations reveal tunability exceeding $80\%$ and $60\%$ for the considered $C_6$ and $C_4$ breathing geometries, respectively. To describe these structures, we develop an analytical model based on the local field approach within the thin-wire approximation, which confirms the high tunability of the studied wire structures. We also propose an approximation for dense wire media. The developed framework is applicable to the general case of nested wire structures -- wire media with an arbitrary parallelogram lattice and multiple wires per unit cell.