Dr. Dwight L. Woolard Profile

Dr. Dwight L. Woolard

Mgr of Solid-State/High-Frequency Electronics Prgm at US Army Research Office

SPIE Involvement:

Author

Publications (29)

Proceedings Article | 27 March 2013 Paper

Ultra-broadband wavelength conversion sensor using thermochromic liquid crystals

Ichun Anderson Chen, S. W. Park, G. Chen, C. Wang, C. Bethea, R. Martini, D. Woolard

Proceedings Volume 8624, 862415 (2013) https://doi.org/10.1117/12.2012071

KEYWORDS: Sensors, Imaging systems, Liquid crystals, Cameras, Terahertz radiation, Solids, Quantum cascade lasers, RGB color model, Temperature metrology, Thermography

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Proceedings Article | 28 February 2012 Paper

THz lasing in InAs/GaSb broken-gap heterostructure devices and quantum-dot pillar arrays

Dwight Woolard, Weidong Zhang

Proceedings Volume 8261, 82610B (2012) https://doi.org/10.1117/12.915985

KEYWORDS: Terahertz radiation, Doping, Heterojunctions, Indium arsenide, Mirrors, Absorption, Quantum cascade lasers, Diodes, Polarization, Resonators

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Proceedings Article | 13 May 2011 Open Access

Functionalized DNA materials for sensing and medical applications

Dwight Woolard, James Jensen

Proceedings Volume 8031, 80310V (2011) https://doi.org/10.1117/12.884538

KEYWORDS: Molecules, Receptors, Terahertz radiation, Smart materials, Biosensing, Sensors, Molecular biology, Spectroscopy, Chemical elements, Polymers

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Proceedings Article | 18 February 2011 Paper

THz lasing concepts based upon InAs/GaSb broken-gap heterostructures

Dwight Woolard, Weidong Zhang

Proceedings Volume 7938, 79380C (2011) https://doi.org/10.1117/12.881254

KEYWORDS: Terahertz radiation, Heterojunctions, Gallium antimonide, Phonons, Indium arsenide, Semiconductor lasers, Quantum efficiency, Acoustics, Diodes, Doping

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Proceedings Article | 9 September 2010 Open Access

Molecular-level engineering of THz/IR-sensitive materials for future biological sensing application

Dwight Woolard, Gregory Recine, Alexei Bykhovski, Weidong Zhang

Proceedings Volume 7763, 77630D (2010) https://doi.org/10.1117/12.865580

KEYWORDS: Molecules, Biosensing, Switches, Molecular biology, Dielectrics, Absorption, Terahertz radiation, Carbon, Chemical species, Biological and chemical sensing

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Proceedings Article | 12 February 2009 Paper

Advanced nanoelectronic architectures for THz-based biological agent detection

Dwight Woolard, James Jensen

Proceedings Volume 7215, 72150K (2009) https://doi.org/10.1117/12.809127

KEYWORDS: Molecules, Nanoelectronics, Terahertz radiation, Biological detection systems, Sensors, Molecular spectroscopy, Spectroscopy, Absorption, Molecular self-assembly, Biomimetics

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Proceedings Article | 19 May 2006 Paper

Simulations of retinal-based electronic components for application to THz frequency sensing platforms

Ying Luo, Dwight Woolard, Boris Gelmont, Hui Liu

Proceedings Volume 6212, 621202 (2006) https://doi.org/10.1117/12.664562

KEYWORDS: Gold, Molecules, Terahertz radiation, Nanostructures, Molecular electronics, Semiconductors, Optical filters, Sensors, Nanolithography, Far infrared

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Proceedings Article | 19 May 2006 Paper

An analysis of the THz frequency signatures in the cellular components of biological agents

Alexei Bykhovski, Tatiana Globus, Tatyana Khromova, Boris Gelmont, Dwight Woolard, Maria Bykhovskaia

Proceedings Volume 6212, 62120H (2006) https://doi.org/10.1117/12.665272

KEYWORDS: Terahertz radiation, Molecules, Absorption, Biological research, Biological weapons, Water, Chemical species, Computer simulations, Data modeling, Solids

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Proceedings Article | 19 May 2006 Paper

THz resonance spectra of Bacillus Subtilis cells and spores in PE pellets and dilute water solutions

Tatiana Globus, Tatyana Khromova, Dwight Woolard, Alan Samuels

Proceedings Volume 6212, 62120K (2006) https://doi.org/10.1117/12.665246

KEYWORDS: Terahertz radiation, Absorption, Matrices, Infrared spectroscopy, Genetics, Water, Refractive index, Magnesium, Fabry–Perot interferometers, Spectroscopy

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Proceedings Article | 8 May 2006 Paper

An optically triggered I-RTD hybrid device for continous-wave generation of THz oscillations

Dwight Woolard, Weidong Zhang, Elliott Brown, Boris Gelmont, Robert Trew

Proceedings Volume 6212, 621207 (2006) https://doi.org/10.1117/12.665820

KEYWORDS: Gallium, Gallium antimonide, Oscillators, Indium gallium arsenide, Terahertz radiation, Diodes, Semiconductors, Interfaces, Chromium, Hybrid optics

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Proceedings Article | 27 February 2006 Paper

Terahertz characterization of dilute solutions of DNA

Tatiana Globus, Tatyana Khromova, Boris Gelmont, Dwight Woolard, Lukas Tamm

Proceedings Volume 6093, 609308 (2006) https://doi.org/10.1117/12.646529

KEYWORDS: Terahertz radiation, Absorption, Spectroscopy, Absorbance, Molecules, Proteins, Molecular interactions, FT-IR spectroscopy, Liquids, Fourier transforms

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Only few studies have attempted to characterize biological materials by THz spectroscopy. Most of these used either solid samples or biological tissues. In this work, we present results of THz spectroscopic characterization of dilute solutions of DNA samples. Water and heavy water (D₂O) have strong absorbance that overlap significantly with important absorption bands of biomolecules in conventional FTIR spectroscopy. Cumbersome spectral subtractions and highly concentrated samples are therefore required to partially overcome problems of water interference in FTIR spectra of biomolecules. Although liquid water absorbs and contributes to background in the THz spectral range of interest, the level of water absorption in the low THz range is at least 2.5 orders of magnitude less than in the far IR. Here, we demonstrate that reproducible spectra of dilute solutions of DNA in the frequency range 10-24 cm^-1 can be obtained. We show that dilute aqueous samples of DNA produce THz spectra with signals that do not overlap with those of water. This is a significant achievement towards the goal of developing THz resonance spectroscopy as a useful tool for the biological sciences because all biological functions of DNA and proteins take place in aqueous environments. A simple technique for sample preparation and characterization is described. Samples containing as little as 100 ng of DNA in 10 μl of water (0.01 mg/ml or 0.001%) have been prepared and measured. The signal/noise ratios of THz spectra of these samples are sufficient to detect reproducible resonances at several characteristic frequencies. The effect of orientation on different substrates and the mechanism of sensitivity enhancement in these samples is discussed. It should be possible to extend these methods to also study proteins in dilute solutions. Advantages of using dilute samples include small quantities of biological material required, the absence of interference from interactions between neighboring molecules, and the absence of problems with light-scattering that are often encountered with short wave-length optical techniques.

Proceedings Article | 10 February 2006 Paper

Vertical-cavity laser based on interband-tunneling staggered-bandgap heterostructure

Boris Gelmont, Dwight Woolard, Tatiana Globus

Proceedings Volume 6132, 61320E (2006) https://doi.org/10.1117/12.646882

KEYWORDS: Indium arsenide, Mid-IR, Mirrors, Heterojunctions, Quantum wells, Optical simulations, Laser development, Electron transport, Dielectrics, Instrument modeling

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Proceedings Article | 5 November 2005 Paper

A novel I-RTD based optically pulsed hybrid device for generating THz oscillations

Weidong Zhang, Dwight Woolard, Elliott Brown, Boris Gelmont

Proceedings Volume 5995, 59950S (2005) https://doi.org/10.1117/12.630570

KEYWORDS: Diodes, Oscillators, Terahertz radiation, Hybrid optics, Indium arsenide, Electron transport, Rhodium, Photons, Resistance, Transient nonlinear optics

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The double-barrier AlGaSb/InAs/AlGaSb heterostructure with staggered bandgap alignment can admit significant interband tunneling current in addition to the conduction band electron transport. The resulting positive hole-charge accumulation in the right valence-band (VB) well will electrostatically modify the spatial potential profile across the device structure, thereby effectively altering the conduction of conduction-band electron transport. A sequentially triggered optical discharging process can be used to annihilate, or substantially reduce, the trapped holes that are generated from the interband tunneling process. Hence, an artificially induced electro-optic interaction can be used to return the device to its initial state and to produce a two-cycle oscillation process - i.e., one with a interband-induced charging transient followed by a optically-induced discharging transient to the initial state. These charging-discharging cycles obtained from this hybrid type of interband resonant-tunneling-diode (I-RTD) device constitute steady-state oscillatory behavior at very high frequency and produce alternating-current (ac) power as long as very short (i.e., sub-picosecond) and intense far-infrared laser pulses are presented to the diode. Initial studies of non-optimized structures and designs predict impressive figures of merit for oscillation frequencies (e.g., ~ 300-600 GHz) and substantial output powers (e.g., ~ 10 mW) for very modest device areas (i.e., 100 μm²). This paper will present physics-based I-RTD diode simulation results to precisely describe transport dynamics and transient electric current for both charging (initiated by Zener tunneling) and discharging (artificially induced by photons flux) processes. A basic electro-optical design concept and modeling approach for the analysis and synthesis of non-linear hybrid I-RTD circuits will also be presented. The main objectives of this paper are: (1) to perform a detailed assessment of the ac output power and efficiency of an optically-triggered (OT) I-RTD hybrid oscillator in the frequency range approximately 300 to 600 GHz, and (2) to prescribe the general requirements for realizing a diode-laser pair upon a single solid-state platform in the future. Therefore, guidelines for a practical engineering implementation and performance estimates for an OT-I-RTD hybrid oscillator design will be presented.

Proceedings Article | 5 November 2005 Paper

THz absorption signature detection of genetic material of E. coli and B. subtilis

Alexei Bykhovski, Xiaowei Li, Tatiana Globus, Tatyana Khromova, Boris Gelmont, Dwight Woolard, Alan Samuels, James Jensen

Proceedings Volume 5995, 59950N (2005) https://doi.org/10.1117/12.629959

KEYWORDS: Terahertz radiation, Absorption, Genetics, Biological weapons, Proteins, Spectroscopy, Biological research, Computer simulations, Data modeling, Solids

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The development of efficient biological agent detection techniques requires in-depth understanding of THz absorption spectral features of different cell components. Chromosomal DNA, RNAs, proteins, bacterial cell wall, proteinaceous coat might be essential for bacterial cells and spores THz signature. As a first step, the DNA's contribution into entire cell THz spectra was analyzed. The experimental study of cells and DNAs of E. coli and cells/spores and DNA of Bacillus subtilis was conducted. Samples were prepared in the form of water solutions (suspension) with the concentrations in the range 0.01-1 mg/ml. The measurable difference in the THz transmission spectra of E. coli and Bacillus subtilis DNAs was observed. The correlation between chromosomal DNA signature and a corresponding entire spore/cell signature was observed. This correlation was especially pronounced for spores of Bacillus subtilis and their DNA. These experimental results justify our approach to develop a model for THz signatures of biological simulants and agents. In parallel with the experimental study, for the first time, the computer modeling and simulation of chromosome DNAs of E. coli and Bacillus subtilis was performed and their THz signatures were calculated. The DNA structures were optimized using the Amber software package. Also, we developed the initial model of the DNA fragment poly(dAT)-poly(dTA) solvated in water to be used in the simulations of genetic material (DNA and RNA) of spores and cells. Molecular dynamical simulations were conducted using explicit solvent (3-point TIP3P water) and implicit solvent (generalized Born) models. The calculated THz signatures of E. coli and Bacillus subtilis DNAs and poly(dAT)-poly(dTA) reproduce many features of our measured spectra. The results of this study demonstrate that THz Fourier transform infrared spectroscopy is a promising tool in generating spectral data for complex biological objects such as bacterial cells and spores.

Proceedings Article | 5 November 2005 Paper

Multilayered diluted magnetic semiconductor structures and 2DEG

H. Grubin, Dwight Woolard

Proceedings Volume 5995, 59950Q (2005) https://doi.org/10.1117/12.633578

KEYWORDS: Magnetism, Quantum wells, Magnetic semiconductors, Electrons, Semiconductors, Heterojunctions, Multilayers, Manganese, Ions, Gallium

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Proceedings Article | 18 May 2005 Paper

Nitride-based two-terminal oscillators operating in the THz regime

K. Kim, V. Sokolov, V. Kochelap, V. Korotyeyev, D. Woolard

Proceedings Volume 5790, (2005) https://doi.org/10.1117/12.602975

KEYWORDS: Electrons, Microwave radiation, Terahertz radiation, Gallium nitride, Quantum wells, Diodes, Phonons, Heterojunctions, Oscillators, Scattering

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Proceedings Article | 18 May 2005 Paper

Terahertz-frequency quantum oscillator operating in the positive differential resistance region

Peiji Zhao, Dwight Woolard, Matthew Lasater, C. Kelley, Robert Trew

Proceedings Volume 5790, (2005) https://doi.org/10.1117/12.602727

KEYWORDS: Electrons, Oscillators, Resistance, Quantum wells, Gallium arsenide, Scattering, Diodes, Aluminum, Electromagnetism, Terahertz radiation

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Proceedings Article | 18 May 2005 Paper

THz characterization of lysozyme at different conformations

Tatiana Globus, Tatyana Khromova, Rebecca Lobo, Dwight Woolard, Nathan Swami, Erik Fernandez

Proceedings Volume 5790, (2005) https://doi.org/10.1117/12.603581

KEYWORDS: Proteins, Terahertz radiation, Liquids, Spectroscopy, Absorption, Hydrogen, FT-IR spectroscopy, Molecules, Circular dichroism spectroscopy, Solids

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Proceedings Article | 18 May 2005 Paper

A bio-molecular inspired electronic architecture: bio-based device concepts for enhanced sensing

Dwight Woolard, Ying Luo, Boris Gelmont, Tatiana Globus, James Jensen

Proceedings Volume 5790, (2005) https://doi.org/10.1117/12.601029

KEYWORDS: Terahertz radiation, Molecules, Absorption, Biosensing, Phonons, Sensors, Computer architecture, Spectroscopy, Electronic components, Telecommunications

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Proceedings Article | 1 April 2005 Paper

Terahertz spectroscopic characterization of cancer cells

Tatiana Globus, Dan Theodorescu, Henry Frierson, Tatyana Khromova, Dwight Woolard

Proceedings Volume 5692, (2005) https://doi.org/10.1117/12.594391

KEYWORDS: Cancer, Bladder cancer, Tumors, Liquids, Terahertz radiation, Spectroscopy, Absorption, Prostate cancer, Prostate, FT-IR spectroscopy

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Proceedings Article | 14 December 2004 Paper

Enhancement of numerical computations of the Wigner-Poisson equations for application to the simulation of THz-frequency RTD oscillators

Matthew Lasater, Carl Kelley, Andrew Salinger, Dwight Woolard, Peiji Zhao

Proceedings Volume 5584, (2004) https://doi.org/10.1117/12.580669

KEYWORDS: Oscillators, Terahertz radiation, Semiconductors, Computer simulations, Electron transport, Doping, Diodes, Numerical simulations, Electronics, Instrument modeling

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Proceedings Article | 14 December 2004 Paper

Optical characteristics of biological molecules in the terahertz gap

Tatiana Globus, Ramakrishnan Parthasarathy, Tatyana Khromova, Dwight Woolard, Nathan Swami, Andrew Gatesman, Jerry Waldman

Proceedings Volume 5584, (2004) https://doi.org/10.1117/12.580838

KEYWORDS: Absorption, Refractive index, Liquids, Reflection, Molecules, Spectroscopy, Terahertz radiation, Data modeling, Biomedical optics, Molecular biology

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Proceedings Article | 8 September 2004 Paper

Terahertz signatures of biological-warfare-agent simulants

Tatiana Globus, Dwight Woolard, Tatyana Khromova, Ramakrishnan Partasarathy, Alexander Majewski, Rene Abreu, Jeffrey Hesler, Shing-Kuo Pan, Geoff Ediss

Proceedings Volume 5411, (2004) https://doi.org/10.1117/12.549128

KEYWORDS: Spectroscopy, FT-IR spectroscopy, Liquids, Terahertz radiation, Mercury, Lamps, Radio astronomy, Observatories, Bacteria, Error analysis

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Proceedings Article | 27 February 2004 Paper

Terahertz Fourier transform characterization of biological materials in solid and liquid phases

Tatiana Globus, Tatiana Khromova, Dwight Woolard, Boris Gelmont

Proceedings Volume 5268, (2004) https://doi.org/10.1117/12.519172

KEYWORDS: Liquids, Solids, Absorption, Molecules, Spectroscopy, Terahertz radiation, Molecular biology, Fourier transforms, Macromolecules, Proteins

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Proceedings Article | 7 February 2002 Paper

Far-infrared phonon modes of selected RNA molecules

Tatiana Globus, Maria Bykhovskaia, Boris Gelmont, Dwight Woolard

Proceedings Volume 4574, (2002) https://doi.org/10.1117/12.455149

KEYWORDS: Molecules, Absorption, Phonons, Oscillators, FT-IR spectroscopy, Spectroscopy, Macromolecules, Hydrogen, Far infrared, Potassium

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Proceedings Article | 7 February 2002 Paper

Millimeter wave absorption spectroscopy of biopolymers

Jing Ju, Hongliang Cui, Alan Samuels, James Jensen, Dwight Woolard

Proceedings Volume 4574, (2002) https://doi.org/10.1117/12.455150

KEYWORDS: Biopolymers, Extremely high frequency, Absorption spectroscopy, Absorption, Air contamination, Environmental monitoring, Atmospheric sciences, Absorbance, Biological weapons

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Proceedings Article | 18 December 2000 Paper

Rapid self-matching modeling and optimization technique for submillimeter-wave Schottky-diode harmonic multipliers

Chih-Chen Lee, Boris Gelmont, Dwight Woolard

Proceedings Volume 4111, (2000) https://doi.org/10.1117/12.422152

KEYWORDS: Diodes, Instrument modeling, Optimization (mathematics), Device simulation, Semiconductors, Metals, Analytical research, Circuit switching, Physics, Computer simulations

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Proceedings Article | 14 July 1999 Paper

Microwave spectroscopy of chemical warfare agents: prospects for remote sensing

Alan Samuels, James Jensen, Richard Suenram, Angela Hight Walker, Dwight Woolard

Proceedings Volume 3703, (1999) https://doi.org/10.1117/12.352997

KEYWORDS: Microwave radiation, Molecules, Spectroscopy, Extremely high frequency, Remote sensing, Molecular beams, Nerve agents, Millimeter wave sensors, Molecular spectroscopy

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