The 2023 terahertz science and technology roadmap
Authors: Leitenstorfer Alfred , Moskalenko Andrey S , Kampfrath Tobias , Kono Junichiro , Castro-Camus Enrique , Peng Kun , Qureshi Naser , Turchinovich Dmitry , Tanaka Koichiro , Markelz Andrea G , Havenith Martina , Hough Cameron , Joyce Hannah J , Padilla Willie J , Zhou Binbin , Kim Ki-Yong , Zhang Xi-Cheng , Jepsen Peter Uhd , Dhillon Sukhdeep , Vitiello Miriam , Linfield Edmund , Davies A Giles , Hoffmann Matthias C , Lewis Roger , Tonouchi Masayoshi , Klarskov Pernille , Seifert Tom S , Gerasimenko Yaroslav A , Mihailovic Dragan , Huber Rupert , Boland Jessica L , Mitrofanov Oleg , Dean Paul , Ellison Brian N , Huggard Peter G , Rea Simon P , Walker Christopher , Leisawitz David T , Gao Jian Rong , Li Chong , Chen Qin , Valušis Gintaras , Wallace Vincent P , Pickwell-MacPherson Emma , Shang Xiaobang , Hesler Jeffrey , Ridler Nick , Renaud Cyril C , Kallfass Ingmar , Nagatsuma Tadao , Zeitler J Axel , Arnone Don , Johnston Michael B , Cunningham John 
Published: February 2023

Abstract
Terahertz (THz) radiation encompasses a wide spectral range within the electromagnetic spectrum that extends from microwaves to the far infrared (100 GHz–∼30 THz). Within its frequency boundaries exist a broad variety of scientific disciplines that have presented, and continue to present, technical challenges to researchers. During the past 50 years, for instance, the demands of the scientific community have substantially evolved and with a need for advanced instrumentation to support radio astronomy, Earth observation, weather forecasting, security imaging, telecommunications, non-destructive device testing and much more. Furthermore, applications have required an emergence of technology from the laboratory environment to production-scale supply and in-the-field deployments ranging from harsh ground-based locations to deep space. In addressing these requirements, the research and development community has advanced related technology and bridged the transition between electronics and photonics that high frequency operation demands. The multidisciplinary nature of THz work was our stimulus for creating the 2017 THz Science and Technology Roadmap (Dhillon et al 2017 J. Phys. D: Appl. Phys.
50 043001). As one might envisage, though, there remains much to explore both scientifically and technically and the field has continued to develop and expand rapidly. It is timely, therefore, to revise our previous roadmap and in this 2023 version we both provide an update on key developments in established technical areas that have important scientific and public benefit, and highlight new and emerging areas that show particular promise. The developments that we describe thus span from fundamental scientific research, such as THz astronomy and the emergent area of THz quantum optics, to highly applied and commercially and societally impactful subjects that include 6G THz communications, medical imaging, and climate monitoring and prediction. Our Roadmap vision draws upon the expertise and perspective of multiple international specialists that together provide an overview of past developments and the likely challenges facing the field of THz science and technology in future decades. The document is written in a form that is accessible to policy makers who wish to gain an overview of the current state of the THz art, and for the non-specialist and curious who wish to understand available technology and challenges. A such, our experts deliver a ‘snapshot’ introduction to the current status of the field and provide suggestions for exciting future technical development directions. Ultimately, we intend the Roadmap to portray the advantages and benefits of the THz domain and to stimulate further exploration of the field in support of scientific research and commercial realisation.