Realization of a photoswitchable anapole metasurface based on phase change material Ge2Sb2Te5

Abstract

The electromagnetic anapole mode originates from the phase cancellation interference between the far-field radiation of an oscillating electric dipole moment and toroidal dipole moment, which presents a radiation-free state of light while enhancing the near-field, and has potential applications in micro- and nanophotonics. The active control of the anapole is crucial for the design and realization of tunable photonic devices. In this paper, we realize dynamic tuning of an anapole metasurface and metasurface optical switching based on the phase change material Ge2Sb2Te5 (GST). By utilizing the destructive interference of the electric dipole moment and ring dipole moment, we design the non-radiative anapole mode. At the same time, we introduce the phase change material GST to dynamically regulate the intensity and position of the far-field scattering, electric field, and transmission spectra, and to realize the transition from anapole mode to electric dipole mode. At the same time, the modulation of the transmission spectrum by the metasurface after the addition of GST film is achieved. A relative transmission modulation of 640.62% is achieved. Our study provides ideas for realizing effective active modulation of active micro- and nanophotonic devices, and promotes active modulation of active micro- and nanophotonic devices in lasers and filters and potential applications in dynamic near-field imaging.