Switchable Dual-Channel Metasurface for Beam Directional Deflection Using Ge₂Sb₂Te₅

A cross-shaped metasurface using the phase-change material Ge2Sb2Te5 (GST) is proposed to satisfy the requirement of high-efficiency dynamic control. The transmission spectrum and phase distribution of the proposed metasurface are characterized. High transmittance and complete phase coverage in the amorphous state are achieved, allowing us to design a switchable beam deflection switch based on the high contrast in the crystalline state. Using multipole decomposition theory, we analyze the high contrast of the metasurface element, which results from the disappearance of the coupling between the electric quadrupole and magnetic quadrupole. Furthermore, the parametric scanning of the metasurface element in two channels is conducted and a switchable metasurface with dual-direction coding is designed. Based on the presented results, it is verified that the proposed switchable dual-channel metasurface can promote the design and application of reconfigurable and multifunctional micro–nano devices as well as optical encryption.