Giant and reversible circular dichroism based on phase change materials for near-field image display

Switchable circular dichroism (CD) is in high demand in wireless communication, real-time imaging, etc. At present, the active switching range of CD magnitudes in a nanostructure is relatively narrow. Herein, the giant and reversible CD with large-range modulation is realized by controlling the phase transition of GST (Ge₂Sb₂Te₅) in a double Z-shape array. The demonstrated CD undergoes the large range from −0.85 to 0.85, which is a major advance. The giant CD arises from the polarization-dependent excitations of electric and magnetic dipole resonances. Utilizing the giant and reversible CD, the application for dynamic near-field image display is demonstrated. The reconfiguration capability of our metasurface for large-range switchable CD will promote the prosperity of active chiro-optical devices.