Diode-like asymmetric transmission in ultrathin hyperbolic epsilon-near-zero slabs: extreme anisotropy mimicking chirality

TL;DR

This paper demonstrates that ultrathin epsilon-near-zero hyperbolic slabs can support strong asymmetric transmission of circular polarized light purely due to anisotropy, enabling ultra-compact polarization devices without breaking reciprocity.

Contribution

It reveals that anisotropy alone can induce asymmetric transmission in hyperbolic epsilon-near-zero slabs, with enhanced effects near epsilon-near-zero points, advancing polarization device design.

Findings

Asymmetric transmission is supported without breaking reciprocity.

Hyperbolic epsilon-near-zero slabs exhibit enhanced effects near epsilon-near-zero points.

Etalon resonances activate in ultrathin slabs, enabling strong polarization control.

Abstract

We demonstrate that a strong asymmetric transmission for forward and backward propagation of tilted circular polarized optical waves is supported by ultrathin epsilon-near-zero hyperbolic slabs. We find that, remarkably, this effect is solely triggered by anisotropy without resorting to any breaking of reciprocity and chiral symmetries or spatial nonlocal effects. In addition, we show that the asymmetric transmission undergoes a dramatic enhancement if the slab is hyperbolic in the epsilon-near-zero regime. This happens since, close to epsilon-near-zero point, the hyperbolic dispersion activates etalon resonances where extraordinary waves accumulate propagation phase even though the slab is ultrathin. The proposed strategy holds promise for realizing ultra-compact and efficient polarization devices at different frequency bands.