scispace - formally typeset
Search or ask a question
Author

T. D. Hewitt

Bio: T. D. Hewitt is an academic researcher from Rensselaer Polytechnic Institute. The author has contributed to research in topics: Terahertz radiation & Polarization (waves). The author has an hindex of 3, co-authored 3 publications receiving 540 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: In this article, a novel electro-optic sampling system for real-time terahertz (THz) imaging applications was proposed, which achieved time-resolved images of pulsed far-infrared radiation emitted from an unbiased GaAs wafer.
Abstract: We report on a novel electro‐optic sampling system for real‐time terahertz (THz) imaging applications. By illuminating a 6×8 mm2 ZnTe crystal with a 300 μW optical sampling beam and detecting the beam with a digital CCD camera, we achieved time‐resolved images of pulsed far‐infrared radiation emitted from an unbiased GaAs wafer. At the focal point of the peak far‐infrared field, the THz beam diameter is approximately 0.75 mm (full width at half‐maximum). The temporal and spatial resolutions of this imaging system are mainly limited by the laser pulse duration and the diffraction limit of the THz beam, respectively.

464 citations

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate the use of a magnetic field to switch and control the direction and polarization of a THz beam radiated from a semiconductor emitter, and demonstrate that the magnetic field can also be used to control the polarization of the beam.
Abstract: We demonstrate the use of a magnetic field to switch and to control the direction and polarization of a THz beam radiated from a semiconductor emitter.

101 citations

Book ChapterDOI
01 Jan 1996
TL;DR: In this article, an alternative method for real-time terahertz (THz) imaging applications was proposed by illuminating an electro-optic crystal with a THz beam and an optical readout beam, then detecting the optical beam with a linear diode array or a CCD camera.
Abstract: The use of terahertz (THz) beams for imaging applications was first demonstrated by Hu and Nuss. We report on an alternative method for real-time terahertz (THz) imaging applications. By illuminating an electro-optic crystal with a THz beam and an optical readout beam, then detecting the optical beam with a linear diode array or a CCD camera, we achieved time-resolved ID or 2D images of pulsed far-infrared radiation. The temporal and spatial resolution of this imaging system are mainly limited by the laser pulse duration and the diffraction limit of the THz beam, respectively.

5 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: An overview of the status of the terahertz technology, its uses and its future prospects are presented in this article, with a focus on the use of the waveband in a wide range of applications.
Abstract: Research into terahertz technology is now receiving increasing attention around the world, and devices exploiting this waveband are set to become increasingly important in a very diverse range of applications. Here, an overview of the status of the technology, its uses and its future prospects are presented.

5,512 citations

Journal ArticleDOI
TL;DR: The terahertz time-domain spectroscopy (THz-TDS) as discussed by the authors is a new spectroscopic technique based on coherent and time-resolved detection of the electric field of ultrashort radiation bursts.
Abstract: Over the past three decades a new spectroscopic technique with unique possibilities has emerged. Based on coherent and time-resolved detection of the electric field of ultrashort radiation bursts in the far-infrared, this technique has become known as terahertz time-domain spectroscopy (THz-TDS). In this review article the authors describe the technique in its various implementations for static and time-resolved spectroscopy, and illustrate the performance of the technique with recent examples from solid-state physics and physical chemistry as well as aqueous chemistry. Examples from other fields of research, where THz spectroscopic techniques have proven to be useful research tools, and the potential for industrial applications of THz spectroscopic and imaging techniques are discussed.

1,636 citations

Journal ArticleDOI
TL;DR: In this article, stand-off interferometric imaging and sensing for the detection of explosives, weapons and drugs is emphasized, and future prospects of terahertz technology are discussed.
Abstract: Over the past 5 years, there has been a significant interest in employing terahertz (THz) technology, spectroscopy and imaging for security applications. There are three prime motivations for this interest: (a) THz radiation can detect concealed weapons since many non-metallic, non-polar materials are transparent to THz radiation; (b) target compounds such as explosives and illicit drugs have characteristic THz spectra that can be used to identify these compounds and (c) THz radiation poses no health risk for scanning of people. In this paper, stand-off interferometric imaging and sensing for the detection of explosives, weapons and drugs is emphasized. Future prospects of THz technology are discussed.

1,604 citations

Journal ArticleDOI
TL;DR: A comprehensive review of the various techniques used for terahertz image formation can be found in this paper, as well as numerous examples which illustrate the many exciting potential uses for these emerging technologies.
Abstract: Within the last several years, the field of terahertz science and technology has changed dramatically. Many new advances in the technology for generation, manipulation, and detection of terahertz radiation have revolutionized the field. Much of this interest has been inspired by the promise of valuable new applications for terahertz imaging and sensing. Among a long list of proposed uses, one finds compelling needs such as security screening and quality control, as well as whimsical notions such as counting the almonds in a bar of chocolate. This list has grown in parallel with the development of new technologies and new paradigms for imaging and sensing. Many of these proposed applications exploit the unique capabilities of terahertz radiation to penetrate common packaging materials and provide spectroscopic information about the materials within. Several of the techniques used for terahertz imaging have been borrowed from other, more well established fields such as x-ray computed tomography and synthetic aperture radar. Others have been developed exclusively for the terahertz field, and have no analogies in other portions of the spectrum. This review provides a comprehensive description of the various techniques which have been employed for terahertz image formation, as well as discussing numerous examples which illustrate the many exciting potential uses for these emerging technologies.

962 citations

Journal ArticleDOI
TL;DR: In this paper, the authors describe the technology necessary to perform terahertz "T-ray" imaging, novel imaging techniques, and commercial applications of T-ray imaging.
Abstract: The use of terahertz pulses for imaging has opened new possibilities for scientific and industrial applications in the terahertz frequency range. In this article, we describe the technology necessary to perform terahertz "T-ray" imaging, novel imaging techniques, and commercial applications of T-ray imaging.

874 citations