Multifunctional polarization converter via liquid metal-based reconfigurable transmission-reflection-integrated metasurfaces.

Metasurfaces, known for their unique properties such as polarization manipulation, have greatly enhanced wireless systems and optical devices. However, to meet the demand for multi-band functionality and flexibility in wireless systems, there is a need to expand the diversity and integration of polarization conversion devices. Liquid metals, with their excellent electrical conductivity and fluidity, offer a promising opportunity for reconfigurable electromagnetic devices. In this study, we propose an integrated polarization converter based on liquid metal metasurfaces. By adjusting the liquid metal injection, this device can manipulate the polarization state of transmitted or reflected waves, switch between various functions, and adjust the operating frequency. The metasurface consists of four microfluidic layers: the first and third layers contain periodic element arrays, while the second and fourth layers have cavity structures. This design supports multiple functional states, including polarization maintaining, linear-to-left-hand circular polarization, linear-to-right-hand circular polarization, and linear-to-linear polarization conversions. We fabricated a prototype and tested it in a microwave anechoic chamber. The experimental results align with theoretical predictions and simulations, demonstrating the multifunctional capabilities and adaptability of the device, making it ideal for broadband channel multiplexing and integrated antenna systems.