Collaborative Research: U.S.-Ireland R&D Partnership: HERCULES: pHotonically-drivEn ReConfigUrabLe terahertz rEflectarrayS for High Performance Beam Steering and Forming

This project presents a groundbreaking approach to developing a large-scale terahertz (THz) reconfigurable reflectarray (an antenna focusing beams like a parabolic dish antenna but with an array of unit cells on a flat surface) for advanced beam steering capability in next-generation wireless communication networks. The approach can potentially revolutionize how data is transmitted and received, enabling faster, more reliable, and adaptive wireless networks that can meet the fast-growing demands of a digitally connected society. By using innovative optical control methods, the project aims to eliminate traditional limitations in high-frequency communication systems, such as signal loss and integration complexity. The societal and national benefits are substantial: improved wireless infrastructure can support smart cities, enhance connectivity in rural and underserved areas, and drive economic growth through new technology platforms. Beyond communications, the research has broad impacts across multiple scientific and engineering fields by offering new tools for medical imaging, security screening, and chemical/biological sensing, enabling new discoveries and new applications. The project also contributes to education and outreach by integrating its research findings into university courses, involving students at all levels in research, and promoting STEM engagement in local schools, thereby fostering the next generation of innovators and engineers. The research of this project aims to investigate and demonstrate a novel method for achieving extremely large-scale THz reflectarrays using photonically-driven unit cells based on enhanced spatially resolved photoconductivity modulation. The innovative approach utilizes a closely coupled micro-LED array to modulate the phase of each unit cell in a hybrid Au-Ge mesa-array semiconductor structure. By adjusting computer-generated light patterns, the system enables pseudo-continuous phase modulation across a full 360-degree range, allowing for real-time synthesis of arbitrary two-dimensional phase profiles to control reflected THz beams. This eliminates the need of electrical wires for biasing or control, mitigating parasitic effects and enabling highly scalable, dense array implementations. The project scope includes device-level design, fabrication, and characterization, as well as system/network-level analysis, simulations, and prototype demonstrations of adaptive high-speed THz wireless links. The approach overcomes limitations of conventional methods, which have been constrained by signal losses and design complexity at frequencies above 100 GHz, and enables advanced functionalities such as beam bending, curving, and multiple-input multiple-output (MIMO) operation. The international collaboration team consists of experts in semiconductor physics, THz technology, electromagnetics, antenna design, and wireless communications to carry out the research tasks and advance knowledge in both semiconductors and wireless technologies. This project was submitted under the United States-Ireland-Northern Ireland R&D Partnership and is a collaboration between researchers at the University of Notre Dame, University of Massachusetts Lowell, Tyndall National Institute, and Queen's University Belfast. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2607654 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Hualiang Zhang | Institution: University of Massachusetts Lowell, LOWELL, MA | Award Amount: $301,350 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2607654 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2607654.html