Broader Impacts

Impact on the development of the principal discipline of the project:

  • This work furthers the development of THz WLANs through the introduction of new capabiltiies and new ideas to the field.
  • The general idea of using transformation optics to design lenses that can balance the competing needs of gain and directionality is novel, and will have important applications throughout the field of millimeter-wave and terahertz wireless. The innovation of rapid prototyping of metasurfaces will enable many researchers in the THz field to study many different structures quickly, leading to more and more rapid breakthroughs. Meanwhile, our work on the characterization of NLOS paths, and the unusual idea that they can be even better than the LOS path when an appropriate antenna is employed, is an exciting result. It offers the curious possibility that a network may ‘choose’ to employ an NLOS path even when the LOS path is available, due to the increased bandwidth. This should cause researchers to rethink the design of LANs, placing more emphasis on the identification and optimization of low-loss NLOS paths in a given environment. It may even be worthwhile to revisit the old idea of designing ‘photonic crystal wallpaper’ which can provide near-ideal reflections to THz signals while not blocking lower frequencies (this idea was first introduced by the PI and his collaborators in 2004 – evidently, an idea that was a bit before its time).
  • Intelligent reflecting surfaces are a critical element to ensure connectivity in wireless communication systems above 100 GHz. While this infrastructure has recently become popular at lower frequency bands, at THz frequencies these are needed to overcome the impact of blockage and non-line-of-sight propagation scenarios. The work developed by the team is the first physics-based and experimentally-driven attempt at developing intelligent reflecting surfaces above 100 GHz.
  • We have performed the first experimental study of an active denial-of-service attack on a terahertz wireless link.
  • We have performed the first study of terahertz backscatter networks employing leaky-wave antennas and multi-user terahertz WLANs with angularly dispersive links. Additionally, we have investigated acute security vulnerabilities of sub-THz wireless backhaul links and demonstrated first-of-its-kind aerial metasurfaces.

Impact on other disciplines:

  • Many researchers outside of THz wireless are interested in metasurfaces. The idea that you can print them for zero cost and in zero time, using common office equipment, should be exciting to people both inside and outside of the discipline.
  • Beyond applications in communications, the developed technology and techniques have direct application in THz sensing, including both nano-bio-sensing as well as non-destructive characterization.
  • Similarly, by focusing on the fundamentals (e.g., very high frequency, very small wavelengths, very large bandwidths), many of the developed solutions are easily extendable to even higher communication systems, including infrared and visible optics.
  • Our research on aerial metasurface not only advances the wireless communications field but also presents exciting opportunities for other disciplines such as robotics.

Impact on teaching and educational experiences:

  • Our research results have been introduced in our newly created Terahertz Communications course, taught in the Department of Electrical and Computer Engineering at Northeastern University.
  • The project is training graduate and undergraduate students who will join the work force in the near future and will ultimately lead the wireless (re) evolution in the years to come, with positions in academia, industry and regularization entities (from FCC to NTIA).
  • The principal investigators of our research have made substantial educational contributions by delivering numerous seminar sessions and tutorials on terahertz communications, sensing, and security at esteemed conferences and workshops. Their expertise and insights have been shared with the wider research community, furthering knowledge and fostering advancements in these critical areas.

Impact on physical resources that form infrastructure:

  • We are maintaining and continuously enhancing the ultra-broadband networking systems testbed, which is the result of two prior NSF CRI awards. Through the combination of resources (from NSF, AFRL and Northeastern), we are committed to advancing and sharing this one-of-a-kind platform in the world.
  • We have released a large dataset containing information-bearing ultra-broadband signals in the 120-140 GHz, 210-240 GHz and 1-1.05 THz (true THz) frequency ranges. The dataset is the first of its kind and is currently accessible through the Northeastern University Library open repository. We adopted the SigMF format as per the NTIA guidelines.
  • Our commitment to open research and knowledge sharing is reflected in our published manuscripts and publicly available resources. As such, we foster a culture of sharing and collaboration, collectively pushing the boundaries of knowledge and driving further innovation in the field we are passionate about.

Impact on knowledge and technique:

  • We are the first research group to explore and propose leaky-wave antennas as a promising transmitter/receiver element in a terahertz network. Although this device architecture has been known based on prior work, but it has never previously been considered in the context of multi-user LANs. We have validated that LWAs with broadband transceivers can be used to harvest the sort of link discovery information that will be critical for control-plane functions in future THz networks. More broadly, our studies have pushed the conversation forward – it’s no longer just about hardware, but rather is about the implications of hardware operation for control-plane functionality (and vice versa). This is a critical development in the maturation of THz systems.
  • Our work is the first study of environmental sensing via single antenna in terahertz networks. We propose a novel non-coherent and training-free system that enables nodal and environmental motion tracking with a single leaky-wave antenna. Our research will also explore a first-of-its-kind multi-face leaky waveguide WLAN architecture.

Impact on information resources that form infrastructure:

  • We are maintaining and continuously enhancing the ultra-broadband networking systems testbed, which is the result of two prior NSF CRI awards. Through the combination of resources (from NSF, AFRL and Northeastern), we are committed to advancing and sharing this one-of-a-kind platform in the world.

Impact on technology transfer:

  • This project will impact industry through demonstration of results coupled with the PIs’ extensive collaborative industry network.
  • At Northeastern University, a provisional patent application for the proposed hybrid reflect-array design has been filled.

Impact on the development of human resources:

  • At Rice University, Several PhD students and undergraduates have participated in our research during the past year.  Chia-Yi Yeh, a lead researcher on THz link security from Knightly’s group, defended her PhD and will continue her research on THz networks and security as a PostDoc at MIT in August. Another graduate student Mohammad Furqan Ahmad successfully defended his MS with results described in the report, and will continue working on THz network design integrating LWAs and metasurfaces.  We recruited two new PhD students, Bin Zhao and Burak Bilgin, in the past year, and they have started working on new functionalities of metasurfaces for THz networks.
  • At Northeastern University, this project has provided support for PhD students Ms. Duschia Bodet, Arjun Singh, and Sherif Badran. Arjun Singh graduated in December 2022 and has since then joined SUNY Polytechnic Institute in Utica, New York, as a tenure-track assistant professor, where he is continuing the work on terahertz communications, with a focus on antenna arrays, reflect-arrays and wavefront engineering.
  • MS student Mr. Jacob Hall contributed to the development of the THz MIMO setup at Northeatsern University, as part of his MS thesis. Mr. Jacob is an AFRL employee sponsored through the SMART program to attend Northeastern University. He has graduated and returned to the AFRL, where he continues the work on THz communications with Dr. Ngwe Thawdar, the program director of the AFRL THz portfolio.
  • Several PhD students and undergraduates have participated in our research during the past year. Yasaman Ghasempour, a PhD student from Knightly’s group at Rice and the lead researcher on the APL Photonics paper, has successfully defended her PhD with significant fraction of her work being devoted to the results described here. She has started in a new position as an Assistant Professor at Princeton University since January 2021. Other PhD students (Chia-Yi Yeh, Shreya Gupta, Zhambyl Shaikhanov, Tarence Rice, Fahid Hassan, Maryam Khalid, and Furqan Ahmad at Rice) continue to work on different aspects of the research.
  • Meanwhile, the lead researcher on the Scientific Reports paper, Yasith Amarasinghe advised by PI Mittleman is about to finish his PhD and will become a post-doctoral researcher at A-Star in Singapore (still working on THz wireless, which is very good news indeed).
  • Finally, the project includes a plan for broadening participation in computing via internships, visiting students, and Ph.D. positions for students from under-represented. In summer 2020, we have broadened participation in computing via summer internships at Rice University for underrepresented groups including Michael Angino, Helena Hu, and Nikhita Gangla, Rice undergraduates and Jelena Lalić, an undergraduate at University of Belgrade.
  • Our research program at Rice University has engaged multiple Ph.D. students and undergraduates, with notable accomplishments such as Keerthi Priya Dasala defending her Ph.D. in Multi-user terahertz WLANs and joining Qualcomm as a senior research engineer. Additionally, new Ph.D. students Dora Zivanovic and Lucy Liao have been welcomed and started new research projects on THz sensing security and THz programmable metasurfaces, respectively. Moreover, graduate students Bin Zhao and Burak Bilging continue their research in THz Airy Networks and multi-function configurable THz metasurfaces around an Access Point (AP), respectively.

Impact on society beyond science and technology:

  • We envision THz communications to be one of the core wireless technologies for beyond 5G systems. The THz band opens the door to a plethora of applications in very diverse domains, ranging from Terabit Wireless Personal and Local Area Networks for pervasive ultra-broadband wireless connectivity, to wireless nanosensor networks or the Internet of Nano-Things with applications in smart healthcare, to name a few. In fact, THz technology has been identified by DARPA as one of the four major research areas that could eventually have an impact on our society larger than that of the Internet itself. Similarly, the development of a new communication and networking technology to support networks with “billions of connected nanosystems” has been recently identified as one of the four essential components of the next IT revolution by the Semiconductor Research Consortium and NSF. While Europe, Japan and Korea have many efforts in place for the development of this field, this is not fully the case in USA. Our team will continue to catalyze development of the field in the USA, not only by technically advancing the state of the art, but also by organizing workshops, conferences, and special issues in renowned journals, thereby increasing the visibility of the field and expanding the community.
  • We have participated in the IEEE 802.15 Standing Committee (SC) Terahertz quarterly meetings. Moreover, we have made a proposal for three physical layer enhancements to the current standard, which have been positively received and now we are working towards how these will be incorporated in a new amendment.
  • We have participated in the biweekly meetings of the mmWave Coalition, an industry group aimed at removing the regulatory barriers to technologies and using the frequencies between 95 GHz and 450 GHz.
  • We have joined and actively participated in the NextG Alliance Spectrum and Technology Working Groups. We have contributed to the 6G Roadmap developed by the same, and are now working on thematic roadmap papers on “spectrum needs for 6G” as well as “sub-THz and THz communications”.
  • With a forward-looking approach, our research focuses on designing and experimentally demonstrating novel THz devices and structures. These technologies not only offer unique functionalities in communications but also have functionalities in sensing and security. By exploring the potential of THz technology, we envision a wide range of applications in various fields, including healthcare, automation, and agriculture.