Toward remote sensing with broadband terahertz waves

Abstract

This paper studies laser air-photonics used for remote sensing of short pulses of electromagnetic radiation at terahertz frequency. Through the laser ionization process, the air is capable of generating terahertz field strengths greater than 1 MV/cm, useful bandwidths over 100 terahertz, and highly directional emission patterns. Following ionization and plasma formation, the emitted plasma acoustic or fluorescence can be modulated by an external terahertz field to serve as omnidirectional, broadband, electromagnetic sensor. These results help to close the “terahertz gap” once existing between electronic and optical frequencies, and the acoustic and fluorescence detection methodologies developed provide promising new avenues for extending the useful range of terahertz wave technology. Our experimental results indicate that by hearing the sound or seeing the fluorescence, coherent detection of broadband terahertz wave at remote distance is feasible.

Graphical abstract

Keywords

terahertz / air / plasma / fluorescence / acoustic

Benjamin Clough–graduated from the University of New Mexico with a B.S. degree in Electrical Engineering in Dec. 2006. He received his Ph.D degree in Electrical, Computer, and Systems Engineering in May of 2012 from Rensselaer Polytechnic Institute, Troy NY. He is the author or coauthor of more than 8 journal publications, 16 conference publications and presentations, 1 US patent disclosure, and a contributor to 2 book chapters. He has been involved in a variety of interdisciplinary projects including electronics design, embedded control, ultrafast optics, software development, and terahertz science and technology. He has over 10 years of combined laboratory experience and has worked in several different environments including Sandia National Labs, Honeywell, Rensselaer, and now the Department of Defense. He was awarded the RPI Founder’s Award of Excellence and the NSF IGERT Fellowship in 2009, the DOD SMART scholarship in 2011, and was the winner of the $30000 Lemelson-MIT Student Prize in 2011 for his research developing alternative methods for terahertz detection using laser plasma-induced acoustic waves. He currently works for the Department of Defense, where he provides subject matter expertise and manages technical programs developing technology to counter improvised explosive devices.

Xi-Cheng Zhang–Parker Givens Chair of Optics, assumes Directorship of The Institute of Optics, University of Rochester (UR), NY, a foremost institution in optics and optical physics research and education, on 1/1/2012. Prior to joining UR, he pioneered world-leading research in the field of ultrafast laser-based terahertz technology and optical physics at Rensselaer Polytechnic Institute (RPI), Troy NY (1992–2012). At RPI, he is the Eric Jonsson Professor of Science; Acting Head at the Department of Physics, Applied Physics & Astronomy; Professor of Electrical, Computer & System; and Founding Director of the Center for THz Research. He is co-founder of Zomega Terahertz Corp. With a B.S. (1982) from Peking University, he earned the M.S. (1983) and Ph.D. degree (1985) in Physics from Brown University, RI.

Previous positions included Visiting Scientist at MIT (1985), Physical Tech. Division of Amoco Research Center (1987), EE Dept. at Columbia University (1987–1991); Distinguished Visiting Scientist at Jet Propulsion Lab, Caltech (2006). He holds 27 U.S. patents, and is a prolific author and speaker. He is a Fellow of AAAS, APS (lifetime), IEEE, OSA (lifetime), and SPIE (lifetime). Dr. Zhang is serving as Editor-in-Chief of Optics Letters (2014−2016).

His honors and awards include: IRMMW-THz Kenneth Button Prize (2014); OSA William F. Meggers Award (2012); IEEE Photonics Society William Streifer Scientific Achievement Award (2011); Rensselaer William H. Wiley 1866 Award (2009); Japan Society for the Promotion of Science Fellowship & NRC-CIAR Distinguished Visiting Scientist, Ottawa, Canada (2004); and First Heinrich Rudolf Hertz Lecturer, RWTH, Aachen, Germany (2003). He also served two years as a Distinguished Lecturer of IEEE/LEOS. He received Rensselaer Early Career Award (1996), Research Corporation Cottrell Scholar Award (1995), NSF Early Career Award (1995), K. C. Wong Prize, K. C. Wong Foundation, Hong Kong (1995), NSF Research Initiation Award (1992). In 1993−1994, he was an AFOSR-SRPF Fellow at Hanscom Air Force Base.

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Acknowledgements

This work is supported in part by the Army Research Office-Multidisciplinary University Research Initiative (ARO-MURI), the Defense Threat Reduction Agency (DTRA), National Science Foundation (NSF), and the U.S. Department of Homeland Security through the DHS-ALERT Center under Award 2008-ST-061-ED0001. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Department of Homeland Security.

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