Despite its potential to enhance communications, sensing, imaging, and other technologies, the terahertz region of the spectrum remains underutilized. To realize the promise of terahertz and millimeter waves for next-generation applications, reconfigurable intelligent surfaces (RIS) with programmable elements, that can manipulate the waves in real-time, are needed. In response to this need, researchers at The University of Manchester developed a new class of RIS capable of dynamically shaping terahertz and millimeter waves. The very-large-scale RIS demonstrated by the team could offer a practical pathway to structuring terahertz waves for applications in noninvasive imaging and 6G communications. The researchers integrated graphene-based terahertz spatial light modulators with large-area thin-film transistor (TFT) arrays to create a very-large-scale spatial light modulator, with a surface of more than 300,000 subwavelength pixels, capable of manipulating terahertz light in both transmission and reflection in real time. Researchers at the University of Manchester’s National Graphene Institute developed a new class of reconfigurable intelligent surfaces capable of dynamically shaping terahertz and millimeter waves. Courtesy of University of Manchester/Coskun Kocabas. The pixels have three key functional layers — graphene, electrolyte, and back-plane electronics. In this architecture, the terahertz active layer consists of bilayer graphene, produced by chemical vapor deposition on copper foils, and then transferred onto a thin polymer sheet. A 5 µm-thick, porous membrane infused with an ionic liquid electrolyte is laminated between the graphene layer and the partially transparent indium tin oxide (ITO) pixel electrode. The thickness of the electrolyte layer is critical to minimize electrostatic crosstalk between pixels. The charge accumulated on the pixel capacitor, which is formed between the middle electrode and ground plane, determines the local hole/electron density on the graphene layer through electrolyte gating, thereby modulating terahertz reflection and transmission. “Our devices operate by adjusting local charge densities on a continuous graphene sheet, allowing for pixel-level control without the need for graphene patterning,” researcher M. Said Ergoktas said. “This architecture allows for scalable fabrication using commercial display backplanes.” The device architecture supports dynamic beam steering and the generation of structured terahertz beams carrying orbital angular momentum — capabilities that are critical for advanced terahertz communication systems. The researchers demonstrated several of the platform’s capabilities, including programmable terahertz transmission patterns, beam steering, grayscale holography, and a single-pixel terahertz camera. They showed dynamic beam steering with a reconfigurable direction pattern, demonstrating how a binary “fork” diffraction pattern could generate donut-shaped beams with tunable vortex order. This functionality could be used for multiplexed data transmission and beam shaping. They also demonstrated a single-pixel millimeter-wave camera capable of imaging concealed metallic objects. The camera, which uses compressive sensing algorithms to reconstruct images from modulated terahertz patterns, highlights the flexibility of the programmable RIS platform. The single-pixel terahertz camera could be used for noninvasive inspection in security, industrial monitoring, and medical diagnostics. “Until now, terahertz modulators have struggled with scale and speed,” professor Coskun Kocabas said. “By leveraging display technology, we demonstrate that it’s possible to bring this field from lab-scale demonstrations to real-world applications.” The functionality of the platform is made possible through the fine-tuned, electrostatic gating of graphene, a material known for its electrical and optical properties at terahertz frequencies. The next steps for the research team will include enhancing the platform’s modulation speeds and extending the system to operate in reflection mode for full spectroscopic imaging. In the future, the researchers may integrate the platform with advanced beamforming systems and next-generation 6G wireless technologies. The very-large-scale RIS demonstrated electronically programmable reflection and transmission patterns of terahertz light over a large area with exceptional levels of uniformity and reproducibility. The integration of graphene-based terahertz modulators with large-area TFT arrays enabled the device to provide high-speed, programmable control over the amplitude and phase of terahertz light across such expansive areas. “We have developed a new method to dynamically control terahertz waves at an unprecedented scale and speed,” Kocabas said. “By integrating graphene optoelectronics with advanced TFT display technologies, we can now reconfigure complex terahertz wavefronts in real time.” The research was published in Nature Communications (www.doi.org/10.1038/s41467-025-58256-w).