Electromagnetic radiation focusing lens based on phase transition all-dielectric microstructure

Metasurface can adjust the polarization, amplitude, phase, polarization mode, and propagation mode of electromagnetic waves flexibly and efficiently. Based on Pancharatnam-Berry phase theory, an all-medium geometric phase element structure was proposed to construct a transmission-coded metasurface metalens. In the mid-infrared band, a phase change material (GST) is used to regulate the unit structure in order to achieve the tunability of lens focus. In order to prove that the designed hyperlens has a good focusing effect, we numerically simulate the focusing electromagnetic field distribution characteristics, and the results show that the designed geometric phase hyperlens has a good focusing effect. Using the crystal and amorphous states of phase change materials, we can dynamically control the focus of the superlens.