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Terahertz Science and Technology, IEEE Transactions on

Issue 4 • Date July 2012

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  • Table of contents

    Publication Year: 2012 , Page(s): C1
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  • IEEE Transactions on Terahertz Science and Technology publication information

    Publication Year: 2012 , Page(s): C2
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  • Editorial

    Publication Year: 2012 , Page(s): 373 - 376
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  • Terahertz Pioneers A Series of Interviews With Significant Contributors to Terahertz Science and Technology

    Publication Year: 2012 , Page(s): 377
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  • Terahertz Pioneer: Daniel R. Grischkowsky “We Search for Truth and Beauty”

    Publication Year: 2012 , Page(s): 378 - 382
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    Presents a biographical interview with Daniel R. Grischkowsky. View full abstract»

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  • Early Science Results From the Heterodyne Instrument for the Far Infrared (HIFI) on the Herschel Space Observatory

    Publication Year: 2012 , Page(s): 383 - 392
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1577 KB) |  | HTML iconHTML  

    The Heterodyne Instrument for the Far Infrared (HIFI) on the Herschel Space Observatory covers 480 to 1250 GHz and 1410 to 1910 GHz for high spectral resolution astronomical spectroscopy. Herschel was launched on 14 May 2009, and following cooldown and commissioning, HIFI has been used along with the other two focal plane instruments for a wide variety of astronomical observations. These have ranged from studies of the structure of the interstellar medium in nearby galaxies to detailed studies of the chemistry in star-forming regions of the Milky Way. Observations of the solar system have yielded new results about water in comets and its relationship to the Earth's oceans. In this paper, following a brief review of the instrument and its performance, we give an overview of the most important HIFI discoveries to date. This is necessarily very selective, but is intended to give a hint of the results obtained with this instrument that has really opened submillimeter wavelengths for high-sensitivity/high-resolution spectroscopy. View full abstract»

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  • First In-Field Application of a Full Photonic Local Oscillator to Terahertz Astronomy

    Publication Year: 2012 , Page(s): 393 - 399
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1219 KB) |  | HTML iconHTML  

    This letter reports on our recent improvements in photomixing technology for the realization of a photonic local oscillator (LO) at 1.05 THz for the Atacama Pathfinder Experiment (APEX) radio telescope. Experiments with state-of-the-art photomixers, operated at room temperature and in cryogenic environment demonstrate successful operation of an astronomical heterodyne receiver at 1050 GHz with a superconductor-insulator-superconductor (SIS) mixer. The system noise temperature of the heterodyne receiver pumped by the photonic LO was at least as low as that using a conventional solid-state LO in the same receiver system. An optical comb generator served as a relative frequency reference to which both lasers were phase-locked. Under the phase lock condition, the 3 dB linewidth of the THz signal was below 3 kHz and could be continuously tuned within a range of 500 MHz-the overall tunability of the system was determined by the photomixer antenna resonance bandwidth, which was roughly 200 GHz. We installed the laser system in the telescope pedestal, from there, the frequency-stabilized laser signal, was fed into the photomixer, installed in the Nasmyth cabin of the telescope, through a 20 meters long single-mode fiber optic. View full abstract»

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  • Input Bandwidth of Hot Electron Bolometer With Spiral Antenna

    Publication Year: 2012 , Page(s): 400 - 405
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1144 KB) |  | HTML iconHTML  

    We report the results of our study of the input bandwidth of hot electron bolometers (HEB) embedded into the planar log-spiral antenna. The sensitive element is made of the ultrathin superconducting NbN film patterned as a bridge at the feed of the antenna. The contacts between the antenna and a sensitive element are made from in situ deposited gold (i.e., deposited over NbN film without breaking vacuum), which gives high quality contacts and makes the response of the HEB at higher frequencies less affected by the RF loss. An accurate experimental spectroscopic procedure is demonstrated that leads to the confirmation of the wide ( 8 THz) bandwidth in this antenna coupled device. View full abstract»

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  • Understanding THz Pulse Propagation in the Atmosphere

    Publication Year: 2012 , Page(s): 406 - 415
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2053 KB) |  | HTML iconHTML  

    In this paper, we have extracted the THz refractivity of water vapor (n(ω)-1) from the complex spectra of the precise coherent THz-TDS absorption measurement with a 6.18 m long sample path . We fit the new refractivity and the previous absorption measurements to the sum of the contributions from all of the water vapor lines (with the same van-Vleck Weisskopf lineshape) in the JPL, Pasadena, CA, database from 0 to 10 THz. The precision of the resulting theoretical absorption and refractivity is demonstrated by the good agreement between the calculated THz output pulse and the measured output pulse, both having the same THz input pulse. Using this capability, we have calculated the transmitted THz pulses through the atmosphere at specified humidity and temperature for a variety of input pulses for the distances of 500, 1000, and 2000 m. We have also tested the predicted stable propagation of the proposed “ideal THz bit pulse” [2], and showed that this pulse evolves into two overlapping pulses after 2000 m of propagation. We showed these two new pulses I and II to be transform-limited THz bit pulses with stable propagation to 2000 m. THz bit pulses I and II span the spectral ranges of 0.13-0.18 THz and 0.18-0.33 THz, respectively, and can support the bit rate distance products of 20 and 40 (Gb/s) km, respectively. View full abstract»

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  • THz Time-Domain Sensing: The Antenna Dispersion Problem and a Possible Solution

    Publication Year: 2012 , Page(s): 416 - 423
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1662 KB) |  | HTML iconHTML  

    Optically pumped THz sources generate power in GaAs semiconductors via photoconductive interaction mechanisms over very large bandwidths. However, they are typically affected by low efficiencies, also because of the poor radiation efficiency of the wide band antennas that are used to radiate the THz power in free space. This paper compares the gain performances of systems based on state of the art linearly polarized lens antennas with the ones, proposed here for the first time, that could be obtained by printing these same antennas on micrometric membranes kept at small distance from the lens. The advantages in terms of efficiency and useful bandwidth (BW) intrinsic in these designs are shown to be important, especially in the higher frequency ranges. Among these enhanced designs, the best performing feed is shown to be the recently introduced leaky lens antenna, which outperforms other geometrical options in terms of pattern symmetry and polarization purity for time domain based THz power generation systems. View full abstract»

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  • Scaled Bistatic Radar Cross Section Measurements of Aircraft With a Fiber-Coupled THz Time-Domain Spectrometer

    Publication Year: 2012 , Page(s): 424 - 431
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1240 KB) |  | HTML iconHTML  

    The knowledge of the radar cross section (RCS) of aircraft and other objects is of great interest both for civil and military applications. Scaled setups are often used in order to facilitate RCS measurements in a well-defined laboratory environment. As radar frequencies steadily increase, for high scaling factors these measurements have to be carried out in the THz regime. In this paper, we propose an experimental setup consisting of a fiber-coupled THz time-domain spectrometer integrated with a two circle goniometer, which enables bistatic scaled RCS measurements. To assess the accuracy of the setup, measurements on reference objects as well as on scale model aircraft are performed. The measured data of the reference objects is compared to the theoretical predictions. As for the aircraft, the comparison between a Panavia 200 Tornado and a Lockheed F117 Nighthawk is made and the influence of individual components like bombs on the overall RCS is evaluated. View full abstract»

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  • Towards Three-Dimensional Millimeter-Wave Radar With the Bistatic Fast-Factorized Back-Projection Algorithm—Potential and Limitations

    Publication Year: 2012 , Page(s): 432 - 440
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (986 KB) |  | HTML iconHTML  

    In this paper, we report on a time-domain approach for 3-D synthetic image reconstruction at stand-off distances called the bistatic fast-factorized back-projection (BiFFBP) algorithm. Although the algorithm is suited for multiple purposes, it is applied in this paper to a millimeter-wave radar system that operates in a frequency-modulated continuous-wave mode between 234 and 306 GHz. After initially mapping the bistatic to a quasi-monostatic configuration, the algorithm recursively factorizes both, the aperture positions and the target area. Three-dimensional reconstructions are shown for a simulated point-target in order to evaluate the point-spread-function of the system. In addition, 2-D-imaging is performed on real objects at stand-off distances using a scanner system that consists of 8 transmitters and 16 receivers. Reconstructions with the BiFFBP-algorithm are compared with the global back-projection (GBP) algorithm that serves as a benchmark. The results show that the BiFFBP-approach yields similar results to the GBP with respect to dynamic range in the image and the overall image quality. It is also shown that a resolution of 2 cm can be achieved with relatively few elements, no scanning, and over a large field-of-view. View full abstract»

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  • Terahertz Two-Layer Frequency Selective Surfaces With Improved Transmission Characteristics

    Publication Year: 2012 , Page(s): 441 - 448
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1159 KB) |  | HTML iconHTML  

    In this paper, a cascaded configuration for two-layer frequency selective surfaces (FSSs) at terahertz (THz) frequencies with improved filtering characteristics is realized for electrically thick substrates. At THz frequencies, the thicknesses of commercially available substrates are comparable to the free-space wavelength. As a result, the substrate plays a critical role in determining the transmission characteristics of THz multilayer FSS structures. Proper coupling method between FSS structures should be chosen to avoid unwanted substrate resonances or Fabry-Pérot resonances, which otherwise degrade the transmission characteristics of the cascaded FSS structure. In this paper, a cascaded structure to avoid multiple reflections within the substrate is presented and the same is used to realize two double-layered FSS structures to improve the transmission response. The transmission response is improved by introducing an extra transmission zero at a frequency location lower than the resonant frequency, thereby achieving high roll-off rate for the lower side of the stop band, and to suppress unwanted resonances, thereby increasing the rejection bandwidth of the filter. The proposed cascaded FSS structures were fabricated and tested using THz time-domain spectroscopy. Good agreement between simulations and experiments were obtained. View full abstract»

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  • A High-Q Terahertz Resonator for the Measurement of Electronic Properties of Conductors and Low-Loss Dielectrics

    Publication Year: 2012 , Page(s): 449 - 459
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1167 KB) |  | HTML iconHTML  

    The successful engineering of sources and components in the terahertz (THz) regime benefits from good characterization of materials properties. Previous research reports have shown that calculations of material parameters that are valid at radio frequencies are no longer accurate at THz frequencies. A high-quality-factor quasi-optical hemispherical resonator operating between 300 GHz-1 THz has been designed and implemented for the measurement of electronic properties of conductors as well as low-loss dielectrics. This apparatus is the first quasi-optical resonator to achieve Q≈ 4×105 at frequencies greater than 400 GHz in the THz regime. It is also the first open resonator designed to measure effective conductivity at these frequencies. This paper discusses the techniques that enabled high-Q operation in the THz regime. It also includes measurements of silicon with different doping densities and conductors of various surface roughness values with comparison to theoretical predictions. View full abstract»

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  • Bio-Sensing by Mach–Zehnder Interferometer Comprising Doubly-Corrugated Spoofed Surface Plasmon Polariton (DC-SSPP) Waveguide

    Publication Year: 2012 , Page(s): 460 - 466
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1130 KB) |  | HTML iconHTML  

    The paper describes the design and analysis of a Mach-Zehnder interferometer (MZI) structure consisting of doubly-corrugated spoofed surface plasmon polariton (DC-SSPP) waveguide. The dependence of phase change on the dielectric loading of the DC-SSPP structure causes the output from both arms to interfere and enhances features on the transmission spectrum of the MZI. The paper uses a mathematical model to predict the phase accumulation of THz signals travelling through each arm of the MZI with various sample loadings. HFSS simulation has been performed to verify the theoretical modeling and produce more sophisticated results. The paper demonstrates that compared with single-armed SSPP waveguide, the proposed MZI structure shows significant shift of the transmission maxima and minima with high quality factors for the transmission peaks when different materials are loaded. The paper also demonstrates that the proposed DC-SSPP MZI structure can be potentially used in tag-free bio-molecular sensing. The highly localized E-M field at frequencies close to SSPP resonance is shown to reduce the sample amount needed to produce interference patterns without affecting the selectivity of the sensing structure. View full abstract»

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  • 2012 IEEE membership form

    Publication Year: 2012 , Page(s): 467 - 468
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  • The 37th International Conference on Infared, Millimeter and Terahertz Waves

    Publication Year: 2012 , Page(s): 469
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  • Terahertz Spectroscopic Techniques and Applications

    Publication Year: 2012 , Page(s): 470
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  • Terahertz Imaging and Spectroscopy for Biology and Biomedicine joint special issue

    Publication Year: 2012 , Page(s): 471
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  • IEEE Transactions on Terahertz Science and Technology Information for Authors

    Publication Year: 2012 , Page(s): 472
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  • IEEE Transactions on Terahertz Science and Technology Editorial Board

    Publication Year: 2012 , Page(s): C3
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  • [Blank pages - Back Covers]

    Publication Year: 2012 , Page(s): C4
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Aims & Scope

IEEE Transactions on Terahertz Science and Technology is specifically aimed at the frequency range between 300 GHz and 10 THz – "Expanding the use of the Electromagnetic Spectrum.''

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Peter H. Siegel
California Institute of Technology
Jet Propulsion Laboratory