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Articles 1 - 13 of 13
Full-Text Articles in Physics
Chaotic Free-Space Laser Communication Over Turbulent Channel, N. F. Rulkov, Mikhail Vorontsov, L. Illing
Chaotic Free-Space Laser Communication Over Turbulent Channel, N. F. Rulkov, Mikhail Vorontsov, L. Illing
Electro-Optics and Photonics Faculty Publications
The dynamics of errors caused by atmospheric turbulence in a self-synchronizing chaos-based communication system that stably transmits information over a ∼5 km free-space laser link is studied experimentally. Binary information is transmitted using a chaotic sequence of short-term pulses as a carrier. The information signal slightly shifts the chaotic time position of each pulse depending on the information bit. We report the results of an experimental analysis of the atmospheric turbulence in the channel and the impact of turbulence on the bit-error-rate performance of this chaos-based communication system.
Ion Contribution To The Astrophysical Important 447.15, 587.56 And 667.82 Nm He I Spectral Lines Broadening, Vladimir Milosavljevic, Stevan Djenize
Ion Contribution To The Astrophysical Important 447.15, 587.56 And 667.82 Nm He I Spectral Lines Broadening, Vladimir Milosavljevic, Stevan Djenize
Articles
Characteristics of the astrophysical important Stark broadened 447.15 nm, 587.56 nm and 667.82 nm spectral line profiles have been measured at electron densities between 0.3 10 and 8.2 10 m and electron temperatures between 8000 and 33 000 K in plasmas created in five various discharge conditions using a linear, low-pressure, pulsed arc as an optically thin plasma source operated in a helium-nitrogen-oxygen gas mixture. On the basis of the observed asymmetry of the line profiles we have obtained their ion broadening parameters ( A) caused by influence of the ion microfield on the line broadening mechanism and also …
Sensitivity Comparison Of Ladar Receivers Designed To Detect Glint Targets, Christopher D. Brewer, Bradley D. Duncan, Edward A. Watson
Sensitivity Comparison Of Ladar Receivers Designed To Detect Glint Targets, Christopher D. Brewer, Bradley D. Duncan, Edward A. Watson
Electro-Optics and Photonics Faculty Publications
We present four receiver designs for a ladar system, based on an optical parametric amplifier, that is designed to collect returns from glint targets. After coupling the return energy into periodically poled lithium niobate, the target backscatter is detected with either an infrared camera or a CCD array. Assuming reasonable detector and system characteristics, the sensitivity of each design is then evaluated by setting the receiver SNR detection threshold equal to one and using the minimum transmitted energy as the figure of merit. Through numerical analysis, we show that an upconversion receiver followed by a visible CCD array offers the …
Experimental Quantum Cloning Of Single Photons, Antia Lamas-Linares, Christoph Simon, John C. Howell, Dik Bouwmeester
Experimental Quantum Cloning Of Single Photons, Antia Lamas-Linares, Christoph Simon, John C. Howell, Dik Bouwmeester
Mathematics, Physics, and Computer Science Faculty Articles and Research
Although perfect copying of unknown quantum systems is forbidden by the laws of quantum mechanics, approximate cloning is possible. A natural way of realizing quantum cloning of photons is by stimulated emission. In this context, the fundamental quantum limit to the quality of the clones is imposed by the unavoidable presence of spontaneous emission. In our experiment, a single input photon stimulates the emission of additional photons from a source on the basis of parametric down-conversion. This leads to the production of quantum clones with near-optimal fidelity. We also demonstrate universality of the copying procedure by showing that the same …
Experimental Violation Of A Spin-1 Bell Inequality Using Maximally Entangled Four-Photon States, John C. Howell, Antia Lamas-Linares, Dik Bouwmeester
Experimental Violation Of A Spin-1 Bell Inequality Using Maximally Entangled Four-Photon States, John C. Howell, Antia Lamas-Linares, Dik Bouwmeester
Mathematics, Physics, and Computer Science Faculty Articles and Research
We demonstrate the experimental violation of a spin-1 Bell inequality. The spin-1 inequality is based on the Clauser, Horne, Shimony, and Holt formalism. For entangled spin-1 particles, the maximum quantum-mechanical prediction is 2.55 as opposed to a maximum of 2, predicted using local hidden variables. We obtained an experimental value of 2.27±0.02 using the four-photon state generated by pulsed, type-II, stimulated parametric down-conversion. This is a violation of the spin-1 Bell inequality by more than 13 standard deviations.
Cooling Atoms In An Optical Trap By Selective Parametric Excitation, Nicola Poli, Robert J. Brecha, Giacomo Roati, Giovanni Modugno
Cooling Atoms In An Optical Trap By Selective Parametric Excitation, Nicola Poli, Robert J. Brecha, Giacomo Roati, Giovanni Modugno
Physics Faculty Publications
We demonstrate the possibility of energy-selective removal of cold atoms from a tight optical trap by means of parametric excitation of the trap vibrational modes. Taking advantage of the anharmonicity of the trap potential, we either selectively remove the most energetic trapped atoms or excite those at the bottom of the trap by tuning the parametric modulation frequency. This process, which had been previously identified as a possible source of heating, also appears to be a robust way for forcing evaporative cooling in anharmonic traps.
A 0.5 Μm Thick Polysilicon Schottky Diode With Rectification Ratio Of 10^6, Elena A. Guliants, Chunhai Ji, Young J. Song, Wayne A. Anderson
A 0.5 Μm Thick Polysilicon Schottky Diode With Rectification Ratio Of 10^6, Elena A. Guliants, Chunhai Ji, Young J. Song, Wayne A. Anderson
Electrical and Computer Engineering Faculty Publications
Polycrystalline Si films, 0.5-mm thick, were obtained as a result of metal-induced growth by sputtering from a Si target on 25 nm thick Ni prelayers at 525 °C. Silicon grew heteroepitaxially on the NiSi2 layer formed due to the reaction between the sputtered Si atoms and Ni. Schottky diodes were fabricated on the Si films by deposition of a Schottky metal on the front surface of the film while Ni disilicide provided an intimate ohmic contact at the back. A Pd/n-Si diode using an n-Si film annealed for 2 h at 700 °C in forming gas demonstrated a rectification ratio …
Self-Assembly Of Spatially Separated Silicon Structures By Si Heteroepitaxy On Ni Disilicide, Elena A. Guliants, Chunhai Ji, Wayne A. Anderson
Self-Assembly Of Spatially Separated Silicon Structures By Si Heteroepitaxy On Ni Disilicide, Elena A. Guliants, Chunhai Ji, Wayne A. Anderson
Electrical and Computer Engineering Faculty Publications
A nonlithographic approach to produce self-assembled spatially separated Si structures for nanoelectronic applications was developed, employing the metal-induced silicon growth. Densely packed Si whiskers, 500–800 nm thick and up to 2500 nm long, were obtained by magnetron sputtering of Si on a 25 nm thick Ni prelayer at 575 °C. The nucleation of the NiSi2 compound at the Ni–Si interface followed by the Si heteroepitaxy on the lattice-matched NiSi2 is suggested to be the driving force for the whisker formation.
Implementation Of A Si/Sic Hybrid Optically Controlled High-Power Switching Device, Prashant Bhadri, Kuntao Ye, Elena A. Guliants, Fred R. Beyette Jr.
Implementation Of A Si/Sic Hybrid Optically Controlled High-Power Switching Device, Prashant Bhadri, Kuntao Ye, Elena A. Guliants, Fred R. Beyette Jr.
Electrical and Computer Engineering Faculty Publications
The ever-increasing performance and economy of operation requirements placed on commercial and military transport aircraft are resulting in very complex systems. As a result, the use of fiber optic component technology has lead to high data throughput, immunity to EMI, reduced certification and maintenance costs and reduced weight features. In particular, in avionic systems, data integrity and high data rates are necessary for stable flight control. Fly-by-Light systems that use optical signals to actuate the flight control surfaces of an aircraft have been suggested as a solution to the EMI problem in avionic systems. Current fly-by-light systems are limited by …
Translation Of 'Balika Badhu: A Selected Anthology Of Bengali Short Stories', Monish Ranjan Chatterjee
Translation Of 'Balika Badhu: A Selected Anthology Of Bengali Short Stories', Monish Ranjan Chatterjee
Electrical and Computer Engineering Faculty Publications
This project, which began with the desire to render into English a rather long tale by Bimal Kar about five years ago, eventually grew into a considerably more extended compilation of Bengali short stories by 10 of the most well-known practitioners of that art since the heyday of Rabindranath Tagore. The collection is limited in many ways, not the least of which being that no woman writer has been included, and that it contains only a baker's dozen stories (if we count Bonophool's micro-stories collectively as one ) — a number pitifully small considering the vast and prolific field of …
Angular Range For Reflection Of P-Polarized Light At The Surface Of An Absorbing Medium With Reflectance Below That At Normal Incidence, R. M.A. Azzam, Ericson E. Ugbo
Angular Range For Reflection Of P-Polarized Light At The Surface Of An Absorbing Medium With Reflectance Below That At Normal Incidence, R. M.A. Azzam, Ericson E. Ugbo
Electrical Engineering Faculty Publications
The range of incidence angle, 0 < φ < φe, over which p-polarized light is reflected at interfaces between transparent and absorbing media with reflectance below that at normal incidence is determined. Contours of constant φe in the complex plane of the relative dielectric constant ε are presented. A method for determining the real and imaginary parts of the complex refractive index, ε1/2 = n + jk, which is based on measuring φe and the pseudo-Brewster angle φpB, is viable in the domain of fractional optical constants, n, k < 1.
Acceleration Element For Femtosecond Electron Pulse Compression, Bao-Liang Qian, Hani E. Elsayed-Ali
Acceleration Element For Femtosecond Electron Pulse Compression, Bao-Liang Qian, Hani E. Elsayed-Ali
Electrical & Computer Engineering Faculty Publications
An acceleration element is proposed for compressing the electron pulse duration in a femtosecond photoelectron gun. The element is a compact metal cavity with curved-shaped walls. An external voltage is applied to the cavity where a special electric field forms in such a way that the slow electrons in the electron pulse front are accelerated more than the fast electrons, and consequently the electron pulse duration will be compressed. The distribution of the electric field inside the acceleration cavity is analyzed for the geometry of the cavity. The electron dynamics in this acceleration cavity is also investigated numerically. Numerical results …
Fiber Optic Sensor Response To High Levels Of Fat In Cream, Czarena L. Crofcheck, Frederick A. Payne, Clair L. Hicks, M. Pinar Mengüç, Sue E. Nokes
Fiber Optic Sensor Response To High Levels Of Fat In Cream, Czarena L. Crofcheck, Frederick A. Payne, Clair L. Hicks, M. Pinar Mengüç, Sue E. Nokes
Biosystems and Agricultural Engineering Faculty Publications
A light backscatter technique using optical fibers to deliver and receive light was investigated for measuring the milkfat content of unhomogenized cream. Light backscatter through cream at wavelengths of 450 to 900 nm was measured for fiber separation distances from 2 to 6.5 mm and for cream containing 10 to ~40 weight percent (wt%) milkfat. Unhomogenized cream (~40 wt% milkfat) was mixed with skim milk (~0.05 wt% milkfat) to yield samples with five different milkfat levels. Three optical response models were tested for correlation with milkfat content: one using the light intensity measurement at a single separation distance, the second …