Multiplexed Exceptional Point Operation in a Single Metasurface for WDM Phase Control

Abstract

Metasurfaces operating at exceptional points (EPs) provide a phase control mechanism via topological protection. Most existing EP-based designs, however, remain constrained to single-wavelength operation. In this work, we propose a multiplexed-EP strategy in a single metasurface with quick response (QR)-code meta-atoms for multi-wavelength phase engineering. Using the direct binary search algorithm, we optimized a singular meta-atom geometry supporting EPs simultaneously at three wavelengths. By exploiting the inherent $2\pi $ topological phase, we designed a wavelength-division-multiplexing (WDM) holographic metasurface, numerically validated via full-wave simulations. This work establishes a generalized framework for WDM metasurfaces, with promising applications in high-capacity and multifunctional photonic devices.