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.