Reflection-type transparent metamaterial polarization rotator with ultra-wide bandwidth

Polarization is the most fundamental property of electromagnetic waves and the key to control its propagation, while conventional methods can only achieve polarization conversion in narrowband and lack of optical transparency. In this paper, we design an ultra-broadband transparent polarization converter consisting of a surface-etched indium tin oxide (ITO)-polyethylene terephthalate (PET) resonator, a laser-cut polymethyl methacrylate layer, and an ITO-PET substrate bonded together. The structure simulation can achieve the co-polarization reflection coefficient less than -10 dB in 13.1-32.3 GHz. Then, we analyze the conversion mechanism from electric field, magnetic field, and surface current distribution. Moreover, the actual test performance achieves polarization conversion over 90% at 11.5-25.2 GHz with wide-angle incidence performance and visible light transmittance up to 53%. The excellent performance of this structure provides a new idea for the future design of ultra-broadband transparent polarization converters and expands the application of polarization converters in optical fields such as RF.