An Optically Transparent, Lightweight, High-Efficiency, and Ultra-Broadband Polarization Converter Based on a Low-Filling-Factor Metallic Frame Metasurface

Abstract

Realizing high efficiency and ultra-wideband polarization conversion while maintaining optical transparency and lightweight characteristics is a critical challenge for integrated electromagnetic systems. In this study, we present a novel transparent metasurface based on a low-filling-factor metallic frame integrated with an air-cavity architecture. Numerical simulations demonstrate that the device achieves highly efficient linear-to-cross polarization conversion with an average polarization conversion ratio (PCR) exceeding 97% across an ultra-wide bandwidth of 9.0-32.5 GHz, corresponding to a relative bandwidth (RBW) of 113.3%. Simultaneously, the structure preserves an optical transparency of approximately 62.86% and achieves an exceptionally low weight factor of 0.002. Beyond polarization control, the metasurface functions as a high-performance refractive index sensor, exhibiting a high sensitivity of 13.13 GHz/RIU. With its multifunctional capabilities and compact profile, the proposed design is highly suitable for advanced transparent surfaces and non-destructive biomedical diagnostics.