Bound and leaky modes in PT-symmetric epsilon-near-zero metamaterial slabs

We show that a judicious combination of balanced gain and loss, inspired by parity-time symmetry concept, can be exploited in epsilon-near-zero metamaterials to support exponentially-localized bound modes that propagate without attenuation. We study the dispersion relationship of these modes for moderate levels of gain/loss, and the exponentially-localized bound modes that propagate without attenuation. We study the dispersion relationship of these modes for moderate levels of gain/loss, and their eventual transition to leaky modes below a gain/loss threshold. These waveguiding/radiation mechanisms may open up intriguing venues for novel nanophotonics platforms.