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Articles 1 - 22 of 22
Full-Text Articles in Physics
Vanadium Oxide Thin-Film Variable Resistor-Based Rf Switches, Kuanchang Pan, Weisong Wang, Eunsung Shin, Kelvin Freeman, Guru Subramanyam
Vanadium Oxide Thin-Film Variable Resistor-Based Rf Switches, Kuanchang Pan, Weisong Wang, Eunsung Shin, Kelvin Freeman, Guru Subramanyam
Guru Subramanyam
Vanadium dioxide (VO2) is a unique phase change material (PCM) that possesses a metal-to-insulator transition property. Pristine VO2 has a negative temperature coefficient of resistance, and it undergoes an insulator-to-metal phase change at a transition temperature of 68°C. Such a property makes the VO2 thin-film-based variable resistor (varistor) a good candidate in reconfigurable electronics to be integrated with different RF devices such as inductors, varactors, and antennas. Series single-pole single-throw (SPST) switches with integrated VO2 thin films were designed, fabricated, and tested. The overall size of the device is 380 μm × 600 μm. The SPST switches were fabricated on …
A High Performance Ceramic-Polymer Separator For Lithium Batteries, Jitendra Kumar, Padmakar Kichambare, Amarendra K. Rai, Rabi Bhattacharya, Stanley J. Rodrigues, Guru Subramanyam
A High Performance Ceramic-Polymer Separator For Lithium Batteries, Jitendra Kumar, Padmakar Kichambare, Amarendra K. Rai, Rabi Bhattacharya, Stanley J. Rodrigues, Guru Subramanyam
Guru Subramanyam
A three-layered (ceramic-polymer-ceramic) hybrid separator was prepared by coating ceramic electrolyte [lithium aluminum germanium phosphate (LAGP)] over both sides of polyethylene (PE) polymer membrane using electron beam physical vapor deposition (EB-PVD) technique. Ionic conductivities of membranes were evaluated after soaking PE and LAGP/PE/LAGP membranes in a 1 Molar (1M) lithium hexafluroarsenate (LiAsF6) electrolyte in ethylene carbonate (EC), dimethyl carbonate (DMC) and ethylmethyl carbonate (EMC) in volume ratio (1:1:1). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were employed to evaluate morphology and structure of the separators before and after cycling performance tests to better understand structure-property correlation. As compared …
Industry-University Collaboration: A University Of Dayton Model, Guru Subramanyam
Industry-University Collaboration: A University Of Dayton Model, Guru Subramanyam
Guru Subramanyam
This paper introduces industry-university collaboration activities currently in place at the University of Dayton's School of Engineering. These collaborations are important to prepare industry-ready graduates who excel in technical, entrepreneurial, and leadership skills. One of the key curricular components is the industry-sponsored multidisciplinary projects. Industry involvement in advisory committee, strategic research partnerships, and other forms are discussed.
Sensitivity Improvement Of A 1-Μm Ladar System Incorporating An Active Optical Fiber Preamplifier, Michael S. Salisbury, Paul F. Mcmanamon, Bradley D. Duncan
Sensitivity Improvement Of A 1-Μm Ladar System Incorporating An Active Optical Fiber Preamplifier, Michael S. Salisbury, Paul F. Mcmanamon, Bradley D. Duncan
Bradley D. Duncan
In an effort to increase the SNR of a continuous wave, 1-μm all solid state ladar system, a rare-earth-doped optical fiber amplifier is investigated as a preamplifier for ladar return signals. The experimental system is detailed and a theoretical analysis of the fiber amplifier's effect on both heterodyne and direct detection schemes is provided. Beginning with the optical powers incident on the detector, the signal and noises are analyzed, through the detector electronics, to predict the SNR. The SNR is then plotted as a function of the return signal power, and a SNR threshold is defined to determine a minimum …
Adaptive Beam Director For A Tiled Fiber Array, Mikhail Vorontsov, Jim F. Riker, Ernst Polnau, Svetlana Lachinova, Venkata S. Rao Gudimetla
Adaptive Beam Director For A Tiled Fiber Array, Mikhail Vorontsov, Jim F. Riker, Ernst Polnau, Svetlana Lachinova, Venkata S. Rao Gudimetla
Mikhail Vorontsov
We present the concept development of a novel atmospheric compensation system based on adaptive tiled fiber array architecture operating with target-in-the-loop scenarios for directed beam applications. The adaptive tiled fiber array system is integrated with adaptive beam director (ABD). Wavefront control and sensing functions are performed directly on the beam director telescope primary mirror. The beam control of the adaptive tiled fiber array aims to compensate atmospheric turbulence-induced dynamic phase aberrations and results in a corresponding brightness increase on the illuminated extended object. The system is specifically designed for tiled fiber system architectures operating in strong intensity scintillation and speckle-modulation …
Characterization Of Atmospheric Turbulence Effects Over 149 Km Propagation Path Using Multi-Wavelength Laser Beacons, Mikhail Vorontsov, Gary W. Carhart, Venkata S. Rao Gudimetla, Thomas Weyrauch, Eric Stevenson, Svetlana Lachinova, Leonid A. Beresnev, Jony Jiang Liu, Karl Rehder, Jim F. Riker
Characterization Of Atmospheric Turbulence Effects Over 149 Km Propagation Path Using Multi-Wavelength Laser Beacons, Mikhail Vorontsov, Gary W. Carhart, Venkata S. Rao Gudimetla, Thomas Weyrauch, Eric Stevenson, Svetlana Lachinova, Leonid A. Beresnev, Jony Jiang Liu, Karl Rehder, Jim F. Riker
Mikhail Vorontsov
We describe preliminary results of a set of laser beam propagation experiments performed over a long (149 km) near-horizontal propagation path between Mauna Loa (Hawaii Island) and Haleakala (Island of Maui) mountains in February 2010. The distinctive feature of the experimental campaign referred to here as the Coherent Multi-Beam Atmospheric Transceiver (COMBAT) experiments is that the measurements of the atmospheric-turbulence induced laser beam intensity scintillations at the receiver telescope aperture were obtained simultaneously using three laser sources (laser beacons) with different wavelengths (λ1 = 0.53 μm, λ2 = 1.06 μm, and λ3 = 1.55 μm). The presented experimental results on …
Comparison Of Turbulence-Induced Scintillations For Multi-Wavelength Laser Beacons Over Tactical (7 Km) And Long (149 Km) Atmospheric Propagation Paths, Mikhail Vorontsov, Venkata S. Rao Gudimetla, Gary W. Carhart, Thomas Weyrauch, Svetlana Lachinova, Ernst Polnau, Joseph Rierson, Leonid A. Beresnev, Jony Jiang Liu, Jim F. Riker
Comparison Of Turbulence-Induced Scintillations For Multi-Wavelength Laser Beacons Over Tactical (7 Km) And Long (149 Km) Atmospheric Propagation Paths, Mikhail Vorontsov, Venkata S. Rao Gudimetla, Gary W. Carhart, Thomas Weyrauch, Svetlana Lachinova, Ernst Polnau, Joseph Rierson, Leonid A. Beresnev, Jony Jiang Liu, Jim F. Riker
Mikhail Vorontsov
We report results of the experimental analysis of atmospheric effects on laser beam propagation over two distinctive propagation paths: a long-range (149 km) propagation path between Mauna Loa (Island of Hawaii) and Haleakala (Island of Maui) mountains, and a tactical-range (7 km) propagation path between the roof of the Dayton Veterans Administration Medical Center (VAMC) and the Intelligent Optics Laboratory (IOL/UD) located on the 5th floor of the University of Dayton College Park Center building. Both testbeds include three laser beacons operating at wavelengths 532 nm, 1064 nm, and 1550 nm and a set of identical optical receiver systems with …
Atmospheric Turbulence Compensation Of Point Source Images Using Asynchronous Stochastic Parallel Gradient Descent Technique On Amos 3.6 M Telescope, Mikhail Vorontsov, Jim F. Riker, Gary W. Carhart, Venkata S. Rao Gudimetla, Leonid A. Beresnev, Thomas Weyrauch
Atmospheric Turbulence Compensation Of Point Source Images Using Asynchronous Stochastic Parallel Gradient Descent Technique On Amos 3.6 M Telescope, Mikhail Vorontsov, Jim F. Riker, Gary W. Carhart, Venkata S. Rao Gudimetla, Leonid A. Beresnev, Thomas Weyrauch
Mikhail Vorontsov
The Stochastic Parallel Gradient Descent Technique-based Adaptive Optics (SPGD-AO) system described in this presentation does not use a conventional wavefront sensor. It uses a metric signal collected by a single pixel detector placed behind a pinhole in the image plane to drive three deformable mirrors (DMs). The system is designed to compensate the image for turbulence effects. The theory behind this method is described in detail in [1]. However this technique, while widely simulated and tested in the laboratory, was not yet verified in astronomical field site experiments. During the month of May 2007, a series of experiments with SPGD-AO …
Pocket Deformable Mirror For Adaptive Optics Applications, Leonid A. Beresnev, Mikhail Vorontsov, Peter Wangsness
Pocket Deformable Mirror For Adaptive Optics Applications, Leonid A. Beresnev, Mikhail Vorontsov, Peter Wangsness
Mikhail Vorontsov
Adaptive/active optical elements are designed to improve optical system performance in the presence of phase aberrations. For atmospheric optics and astronomical applications, an ideal deformable mirror should have sufficient frequency bandwidth for compensation of fast changing wave front aberrations induced by either atmospheric turbulences or by turbulent air flows surrounding a flying object (air optical effects). In many applications, such as atmospheric target tracking, remote sensing from flying aircraft, boundary layer imaging, laser communication and laser beam projection over near horizontal propagation paths the phase aberration frequency bandwidth can exceed several kHz. These fast-changing aberrations are currently compensated using relatively …
Adaptive Optics Performance Over Long Horizontal Paths: Aperture Effects In Multi-Conjugate Adaptive Optical Systems, Miao Yu, Mikhail Vorontsov, Svetlana Lachinova, Jim F. Riker, Venkata S. Rao Gudimetla
Adaptive Optics Performance Over Long Horizontal Paths: Aperture Effects In Multi-Conjugate Adaptive Optical Systems, Miao Yu, Mikhail Vorontsov, Svetlana Lachinova, Jim F. Riker, Venkata S. Rao Gudimetla
Mikhail Vorontsov
We analyze various scenarios of the aperture effects in adaptive optical receiver-type systems when inhomogeneities of the wave propagation medium are distributed over long horizontal propagation path, or localized in a few thin layers remotely located from the receiver telescope pupil. Phase aberration compensation is performed using closed-loop control architectures based on phase conjugation and decoupled stochastic parallel gradient descent (DSPGD) control algorithms. Both receiver system aperture diffraction effects and the impact of wave-front corrector position on phase aberration compensation efficiency are analyzed for adaptive systems with single or multiple wave-front correctors.
Monoclinic Optical Constants, Birefringence, And Dichroism Of Slanted Titanium Nanocolumns Determined By Generalized Ellipsometry, Daniel Schmidt, Benjamin Booso, Tino Hofmann, Eva Schubert, Andrew Sarangan, Mathias Schubert
Monoclinic Optical Constants, Birefringence, And Dichroism Of Slanted Titanium Nanocolumns Determined By Generalized Ellipsometry, Daniel Schmidt, Benjamin Booso, Tino Hofmann, Eva Schubert, Andrew Sarangan, Mathias Schubert
Andrew Sarangan
Generalized spectroscopic ellipsometry determines the principal monoclinic optical constants of thin films consisting of slanted titanium nanocolumns deposited by glancing angle deposition under 85° incidence and tilted from the surface normal by 47°. Form birefringence measured for wavelengths from 500 to 1000 nm renders the Ti nanocolumns monoclinic absorbing crystals with c-axis along the nanocolumns, b-axis parallel to the film interface, and 67.5° monoclinic angle between the aand c-axes. The columnar thin film reveals anomalous optical dispersion, extreme birefringence, strong dichroism, and differs completely from bulk titanium. Characteristic bulk interband transitions are absent in the spectral range investigated.
Optical Down-Conversion In Doped Znse:Tb3+ Nanocrystals, Sandip Das, K. C. Mandal
Optical Down-Conversion In Doped Znse:Tb3+ Nanocrystals, Sandip Das, K. C. Mandal
Krishna C. Mandal
No abstract provided.
Investigation Of Cdznte Crystal Defects Using Scanning Probe Microscopy, Goutam Koley, J. Liu, K. C. Mandal
Investigation Of Cdznte Crystal Defects Using Scanning Probe Microscopy, Goutam Koley, J. Liu, K. C. Mandal
Krishna C. Mandal
No abstract provided.
Terahertz Studies Of The Dielectric Response And Second-Order Phonons In A Gase Crystal, B. L. Yu, F. Zeng, V. Kartazayev, R. R. Alfano, K. C. Mandal
Terahertz Studies Of The Dielectric Response And Second-Order Phonons In A Gase Crystal, B. L. Yu, F. Zeng, V. Kartazayev, R. R. Alfano, K. C. Mandal
Krishna C. Mandal
No abstract provided.
Erratum: “Terahertz Studies Of The Dielectric Response And Second-Order Phonons In A Gase Crystal” [Appl. Phys. Lett.87, 182104 (2005)], B. L. Yu, F. Zeng, V. Kartazayev, R. R. Alfano, K. C. Mandal
Erratum: “Terahertz Studies Of The Dielectric Response And Second-Order Phonons In A Gase Crystal” [Appl. Phys. Lett.87, 182104 (2005)], B. L. Yu, F. Zeng, V. Kartazayev, R. R. Alfano, K. C. Mandal
Krishna C. Mandal
No abstract provided.
Investigation Of Cdznte Crystal Defects Using Scanning Probe Microscopy, Goutam Koley, J. Liu, K. C. Mandal
Investigation Of Cdznte Crystal Defects Using Scanning Probe Microscopy, Goutam Koley, J. Liu, K. C. Mandal
Krishna C. Mandal
No abstract provided.
Tb3+-Doped K Pb2Br5: Low-Energy Phonon Mid-Infrared Laser Crystal, U. N. Roy, R. H. Hawrami, Y. Cui, S. Morgan, A. Burger, K. C. Mandal, C. C. Noblitt, S. A. Speakman, K. Rademaker, S. A. Payne
Tb3+-Doped K Pb2Br5: Low-Energy Phonon Mid-Infrared Laser Crystal, U. N. Roy, R. H. Hawrami, Y. Cui, S. Morgan, A. Burger, K. C. Mandal, C. C. Noblitt, S. A. Speakman, K. Rademaker, S. A. Payne
Krishna C. Mandal
No abstract provided.
Doping Dependence Of Electronic And Mechanical Properties Of Gase1−XTeX And Ga1−XInXSe From First Principles, Zs. Rak, S. D. Mahanti, K. C. Mandal, N. C. Fernelius
Doping Dependence Of Electronic And Mechanical Properties Of Gase1−XTeX And Ga1−XInXSe From First Principles, Zs. Rak, S. D. Mahanti, K. C. Mandal, N. C. Fernelius
Krishna C. Mandal
No abstract provided.
Terahertz Studies Of The Dielectric Response And Second-Order Phonons In A Gase Crystal, B. L. Yu, F. Zeng, V. Kartazayev, R. R. Alfano, K. C. Mandal
Terahertz Studies Of The Dielectric Response And Second-Order Phonons In A Gase Crystal, B. L. Yu, F. Zeng, V. Kartazayev, R. R. Alfano, K. C. Mandal
Krishna C. Mandal
No abstract provided.
Optical Down-Conversion In Doped Znse:Tb3+ Nanocrystals, Sandip Das, K. C. Mandal
Optical Down-Conversion In Doped Znse:Tb3+ Nanocrystals, Sandip Das, K. C. Mandal
Krishna C. Mandal
No abstract provided.
Investigation Of Cdznte Crystal Defects Using Scanning Probe Microscopy, Goutam Koley, J. Liu, K. C. Mandal
Investigation Of Cdznte Crystal Defects Using Scanning Probe Microscopy, Goutam Koley, J. Liu, K. C. Mandal
Krishna C. Mandal
No abstract provided.
Joint Map Registration And High Resolution Image Estimation Using A Sequence Of Undersampled Images, Russell C. Hardie, Kenneth J. Barnard, Ernest E. Armstrong
Joint Map Registration And High Resolution Image Estimation Using A Sequence Of Undersampled Images, Russell C. Hardie, Kenneth J. Barnard, Ernest E. Armstrong
Russell C. Hardie
n many imaging systems, the detector array is not sufficiently dense to adequately sample the scene with the desired field of view. This is particularly true for many infrared focal plane arrays. Thus, the resulting images may be severely aliased. This paper examines a technique for estimating a high-resolution image, with reduced aliasing, from a sequence of undersampled frames. Several approaches to this problem have been investigated previously. However, in this paper a maximum a posteriori (MAP) framework for jointly estimating image registration parameters and the high-resolution image is presented. Several previous approaches have relied on knowing the registration parameters …