TST, Vol. 2, No. 4, PP. 120-130

Terahertz Quantum Cascade Lasers and Real-time T-rays Imaging at video rate

Qing Hu
Department of Electrical Engineering and Computer Science,
Massachusetts Institute of Technology, Cambridge, MA 02139, U.S.A.
Email: qhu@mit.edu

Abstract: We report our development of terahertz (THz) quantum-cascade lasers with record performance. Using those high-power lasers as the illumination sources and a focal-plane array camera, we are able to perform real-time THz imaging at video rate.

Keywords: Terahertz, quantum-cascade lasers, imaging

doi: 10.11906/TST.120-130.2009.12.13

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TST, Vol. 2, No. 4, PP. 131-143

Remote THz Wave Sensing in Ambient Atmosphere

J.M. Dai, X.F. Lu, J. Liu, I.C. Ho, N. Karpowicz, and X.-C. Zhang^*
Center for Terahertz Research
CII 9009, Rensselaer Polytechnic Institute, Troy, NY 12180-3590 USA
Phone/Fax: (518) 276-3079/3292; web: http://www.rpi.edu/terahertz/
^*Email: zhangxc@rpi.edu

Abstract: Historically, THz technologies were mainly used within the astronomy community for studying cosmic far-infrared radiation background, and by the laser fusion community for the diagnostics of plasmas. Since the first demonstration of THz wave time-domain spectroscopy in the late 80¡¯s, there has been a series of significant advances (particularly in recent years) as more intense THz sources and more sensitive detectors provide new opportunities for understanding the basic science in the THz frequency range. Now, the region of the electromagnetic spectrum from 0.3 to 10 THz (1 mm ¨C 30 ¦Ìm wavelength) is a frontier for research in physics, chemistry, biology, materials science and medicine. Ambient air, when excited with intense femtosecond laser beams, exhibits a remarkable ability to generate and detect pulsed THz waves through an optical nonlinear process. The use of air (or selected gases) as a broadband THz wave emitter and THz wave sensor provides superior bandwidth (0.5 - 20 THz at 10% bandwidth), sensitivity (heterodyne), resolution (<MHz), and the standoff sensing capability in atmosphere which was heretofore considered impossible due to water vapor attenuation. However, research into the basic science and engineering of THz waves in laser-induced air plasma, especially the application of wide-band and high-field THz waves with standoff capability, is just beginning. Our proposed instrumentation development explores this new area, with an emphasis on broadband spectroscopy, remote sensing and nonlinear effect.

Keywords: Terahertz generation, THz detection, THz spectroscopy, nonlinear optics, air photonics, remote sensing

doi: 10.11906/TST.131-143.2009.12.14

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TST, Vol. 2, No. 4, PP. 144-149

Terahertz energy confinement in finite-width parallel-plate waveguides

Hui Zhan, Rajind Mendis, and Daniel M. Mittleman^*
Rice University, Department of Electrical and Computer Engineering, MS-366
6100 Main Street, Houston, TX 77005, USA

Abstract: We experimentally investigate the terahertz energy confinement in finite-width parallel-plate waveguides. Although there is some apparent energy confinement parallel to the plates due to the narrowing of the width, this does not result in actual energy conservation, when the plate separation is as large as 1 cm. However, these findings indicate that by reducing the plate separation, it may be possible to achieve real energy confinement along with energy conservation in these waveguides.

Keywords: Terahertz, waveguides

doi: 10.11906/TST.144-149.2009.12.15

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TST, Vol. 2, No. 4, PP. 150-155

Powerful terahertz gyrotrons based on pulsed magnets

Mikhail Yu. Glyavin^*, Alexey G.Luchinin
Institute of Applied Physics Russian Academy of Science,
603950, 46 Ul'yanov St., Nizhny Novgorod, Russia
^*Email: glyavin@appl.sci-nnov.ru

Abstract: The terahertz radiation has been demonstrated in pulse gyrotrons. Pulsed coils with field intensity up to 50T have been developed and tested. After more than 3500 shorts no any variation at solenoid operation observed. The repetition rate one short per minute was limited by coil cooling. The output power 5 kW at 1 THz and 0.5 kW at 1.3 THz has been obtained with pulse duration 40 microseconds at the fundamental harmonic with 30 kV/5A electron beam. The design of a sub-THz sub-MW gyrotron has been presented.

Keywords: Terahertz, gyrotron, pulsed solenoid

doi: 10.11906/TST.150-155.2009.12.16