Nonreciprocal Control of Photonic Crystal Structures via Wave Matter Interactions in Weyl Semimetal Platforms.

Abstract

  In this study, a one-dimensional photonic crystal incorporating a Weyl semimetal defect layer is employed to achieve high optical non reciprocity a property of significant interest in modern research due to its geometric implications. This behavior stems from pronounced geometric anisotropy evident in measured transmission and transmission-change (ΔT) maps as well as the topological and gyrotropic responses inherent to the Weyl material.                                                                                                              

The results confirm that, at resonance modes induced by the defect layer, non reciprocal behavior is strongly realized, with the interaction between electromagnetic waves and the Weyl layer becoming the dominant factor. Furthermore, the observed enhancement in transmission contrast arises from strong field localization and improved light-matter interaction, facilitated by "epsilon-near-zero" (ENZ) regions. A comparison of forward and backward propagation reveals a significant spectral shift and a change in intensity, highlighting the structure's effectiveness in breaking the reciprocity principle without the need for external influences. Furthermore, 2D and 3D maps provide a comprehensive understanding of the system's operation by identifying the optimal frequency and angle combinations that yield the best non-reciprocal performance. This design paves the way for a flexible, efficient platform to implement compact, magnet-free non-reciprocal optical devices such as optical isolators and directional filters suitable for use in complex optical communication systems and integrated optical circuits.