Some ideas for non-hermitian doping of epsilon-near-zero media

We put forward some ideas to extend the recently introduced concept of photonic doping of epsilon-near-zero media to non-Hermitian scenarios featuring mixtures of gain and loss in dopants. In particular, we show that cylindrical core-shell inclusions (with loss in the core and gain in the shell, or vice versa) can exhibit resonant phenomena that enable the tailoring of the effective permeability over broad regions of the complex plane. Within this framework, we envision possible applications to reconfigurable nanophotonic platforms.