Pump-Wavelength Sensitive Terahertz Spatiotemporal Metasurface

Terahertz (THz) technologies hold great promise for nondestructive precision imaging and wireless communication. Active tailoring of the THz field is highly desired for enhancing the resolution of imaging and increasing communication capacity. However, most THz field manipulation devices are limited by passive modulation and single-dimensional external triggers. In this study, an innovative spatiotemporally tunable metasurface is proposed for the multidimensional dynamic manipulation of the THz field. The device combines a metasurface and two-dimensional perovskite materials: the metasurface is responsible for modulation of the THz field in the spatial dimension, while the perovskite is responsible for modulation of the THz field in the temporal dimension. The pumping wavelength is an extra dimension for selectively switching the transmission of the THz field owing to the bandgap tunability of the perovskite. Accordingly, the functions of the metadevice can be multistage-switched utilizing the pump-wavelength sensitive control scheme. Based on this platform, dynamic switching of a THz multifocal lens and a dynamic display of holographic characters are experimentally demonstrated. The proposed metasurface provides a new pathway for multiple orders to manipulate the THz field dynamically, which can be used to realize more multifunctional dynamic meta-devices.