Center for Terahertz Research

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Director: Xi-Cheng Zhang

Center Home Page: www.rpi.edu/terahertz

The Center for Terahertz Research at Rensselaer Polytechnic Insitute is one of the most active centers in exploring the unique advantages of terahertz (THz) radiation. Using the relatively unexplored terahertz portion of the electromagnetic spectrum, the center is creating innovative sensing and imaging technologies that hold enormous potential in fields such as non-destructive testing, genetics diagnostics, microelectronics, and chemical and biological materials identification that support homeland defense initiatives.

Spaced along the electromagnetic spectrum are microwaves, infrared, visible light, and X-rays. Between microwaves and infrared, at a frequency of more than a trillion cycles per second, lies terahertz radiation. In the same way that visible light can create a photograph, radio waves can transmit sound, and X-rays can see shapes within the human body, T-rays can create images or carry information.

The promise of terahertz wave radiation, known as “T-rays”, is being realized through ongoing research projects at the THz Center’s state-of-the-art laboratories: The W. M. Keck Laboratory for THz Science, Dr. Michael Shur’s THz Electronics laboratory, Dr. Masashi Yamaguchi’s THz Optoelectronics laboratory, Dr. Ingrid Wilke’s THz Spectroscopic laboratory, Dr. Gwo-Ching Wang’s NSF-IGERT THz-GHz laboratory, and Dr. Xi-Cheng Zhang’s THz Photonics laboratory. Together, these core researchers are overcoming significant challenges posed by the fundamental physics that underlie this large—and historically inaccessible—portion of the electromagnetic spectrum.

Rensselaer’s THz research team has established itself as a leader in the development and application of terahertz technology. Their breakthroughs in microscopy, imaging, and development of THz emitters and detectors have opened the door to tremendous opportunities for THz radiation throughout major industries. For example, Dr. Shur’s group reported the use of novel semiconductor devices to generate and detect CW THz wave at room temperature; Dr. Wilke reported the use of InN as a new THz material for intense THz wave emission; Dr. Yamaguchi uses tunable GHz-THz acoustic spectroscopy for non-contact direct acoustic transport measurement and Impulsive Stimulated Thermal Scattering (ISTS) for non-contact thermal transport measurement in nanomaterials; and Dr. Zhang’s and Dr. Yamaguchi’s groups have demonstrated the generation, manipulation, amplification, and detection of THz waves in ambient air with amplified laser beams (THz air photonics).

The THz Center has also designed and built portable THz wave imaging systems, which were tested and approved by NASA for the nondestructive testing of foam insulation used on space shuttles. One compact THz imaging system was installed in NASA’s George Marshall Space Flight Center and another at Lockheed Martin. In the Center’s Compact THz Applications lab, Mr. Brian Schulkin, NSF-IGERT Fellow and IMRA Fellow (and winner of the inaugural 2007 Lemelson-Rensselaer Student Prize, one of the 2007 Scientific American 50) designed and fabricated a portable handheld THz spectrometer for defense applications. Mr. Ben Clough, another NSF-IGERT Fellow, is one of three Lemelson-Rensselaer Student Prize Finalists in 2011. His invention is Terahertz Enhanced Acoustics (TEA). The final winner of the award will be announced on March 7, 2011. The THz Center has more than 20 US patents with graduate students as co-inventors.

One of the research activities at the center is currently focused on the generation and detection of free-space THz beams using air as THz wave emitter and THz wave sensor. A primary goal is to develop and refine the instrumentation—finding higher dynamic ranges, achieving faster data acquisition, and increasing sensitivities to enable the remote detection—that will move THz technology beyond its current niche applications to support wider use in nondestructive analysis, homeland security, and biomedicine. Center researchers demonstrated strong THz wave generation with air photonics. An intense THz field greater than 1.5 MV/cm has been demonstrated. Remote THz wave generation, up to 30 meters, has been reported.

Recently, the center researchers also demonstrated the use of radiation-enhanced-emission-of-fluorescence (REEF) to coherently measure free-space THz radiation. This newly developed remote sensing method at Rensselaer provides a new way to measure a pulsed THz signal at standoff application. Remote pulsed THz sensing was previously considered impossible, due to the water attenuation in atmosphere. REEF, for the first time, made it possible to perform pulsed remote THz sensing. The work was highlighted by Nature Photonics in a September issue, 2010. Early REEF work was published in Phys. Rev. Lett.   Our THz research news was featured on Media: ABC News, BBC, Reuters, Discovery News, USA Today, MSNBC, Yahoo, International Business Times, News Blaze, Physics Today, SmartPlanet, etc. The center’s work was also featured in magazines: Nature, Science, Laser Focus World, Nature Photonics, Photonic Spectra, Popular Science, Optics & Photonics News, Wired Magazine, Gizmodo and etc. (over 100 news media).

During the last several years, scientists and engineers from more than 100 universities and 300 companies have visited our center, and Rensselaer’s THz team has helped scientists from 22 different countries learn to use THz technology.

Rensselaer’s terahertz research group has received grants from the National Science Foundation, Army Research Office, Army Research Laboratory, Air Force Office of Scientific Research, Department of Energy, Defense Advanced Research Projects Agency, Department of Homeland Security, Navy, NASA, and the W.M. Keck Foundation. Currently, seven companies support the THz Center.

The center’s labs are equipped with the most advanced photonic and opto-electronic instrumentation for generating, measuring, and recording picosecond and femtosecond terahertz radiation waves. Rensselaer’s Center for Terahertz Research stands at the forefront of terahertz technology, a science still in its infancy yet expected to become one of the most promising research areas for transformational imaging in the 21st century.

Affiliated Faculty

Jianming Dai, Research Associate Professor of Physics.

Albert Redo, Research Assistant Professor of Physics.

Michael Shur, Patricia W. and C. Sheldon Roberts Professor, Professor of ECSE & Physics.

Gwo-Ching Wang, Professor of Physics.

Ingrid Wilke, Associate Professor of Physics.

Masashi Yamaguchi, Associate Professor of Physics.

X.-C. Zhang, J. Erik Jonsson Distinguished Professor of Science, Professor of Physics and ECSE.

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