Very-large-scale reconfigurable intelligent surfaces for dynamic control of terahertz and millimeter waves

Unlocking the potential of terahertz (THz) and millimeter (mm) waves for next generation communications and imaging applications requires reconfigurable intelligent surfaces (RIS) with programmable elements that can manipulate the waves in real-time. Realization of this technology has been hindered by the lack of efficient THz electro-optical materials and scalable THz semiconductor platform. Here, by merging graphene-based THz modulators and the thin-film transistor (TFT) technology, we demonstrate very-large-scale (>300000 pixels) spatial light modulator with individually addressable subwavelength pixels. We demonstrate electronically programmable reflection and transmission patterns of THz light over a large area with unprecedent levels of uniformity and reproducibility. To highlight the potential of these devices, we demonstrate a single pixel mm-wave camera capable of imaging metallic objects. Furthermore, we demonstrate dynamic beam steering with reconfigurable direction pattern. We anticipate that these results will provide realistic pathways to structure THz waves for applications in non-invasive THz imaging and next generation THz communications.