A terahertz reconfigurable photo-induced fresnel-zone-plate antenna for dynamic two-dimensional beam steering and forming

We report a novel and simple approach to realize terahertz (THz) dynamic two-dimensional (2D) beam steering and forming antennas, based on reconfigurable photo-induced Fresnel zone plates (PI-FZPs). The FZPs are formed by directly illuminating a high-resistivity silicon wafer with the desired patterns using a digital light processing (DLP) projector, without any circuit or device fabrication. At 750 GHz, the THz beam from a diagonal horn antenna has been steered two dimensionally over a range from approximately -12° to +12° from the antenna boresight, by projecting different PI-FZP patterns. In addition, using PI-FZPs with different focal lengths, the THz beam size can be dynamically tuned. Both the beam steering and forming can be performed simultaneously without affecting the antenna performance, making this an enabling technology for emerging THz applications such as sensing, imaging, tracking, adaptive wireless communications and short-range high-speed interconnections.