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Electrical and Computer Engineering

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1999

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Articles 31 - 60 of 124

Full-Text Articles in Engineering

Signal Induced Emi In Fibre Channel Cable-Connector Assemblies, Minjia Xu, S. Radu, James L. Knighten, James L. Drewniak, Todd H. Hubing, L. O. Hoeft, J. T. Dibene Ii Aug 1999

Signal Induced Emi In Fibre Channel Cable-Connector Assemblies, Minjia Xu, S. Radu, James L. Knighten, James L. Drewniak, Todd H. Hubing, L. O. Hoeft, J. T. Dibene Ii

Electrical and Computer Engineering Faculty Research & Creative Works

The EMI performance of cable-connector assemblies designed for FC-0 transmission has been studied. Two types of cable and two connector styles were evaluated. Experimental results show that the dominant radiation mechanism for short cable lengths is the common-mode current caused by source and PCB skew that leaks to the exterior of the shield via the transfer impedance of the connector. However, the cable imbalance becomes a more significant source of common-mode current than the source skew when the cable assembly is tens of meters long.

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Microstrip Coupling Algorithm Validation And Modification Based On Measurements And Numerical Modeling, Theodore M. Zeeff, Chris E. Olsen, Todd H. Hubing, James L. Drewniak, Richard E. Dubroff Aug 1999

Microstrip Coupling Algorithm Validation And Modification Based On Measurements And Numerical Modeling, Theodore M. Zeeff, Chris E. Olsen, Todd H. Hubing, James L. Drewniak, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

In this study, mutual capacitance and inductance between two coupled traces is measured and computed to validate and simplify coupling algorithms used in an expert system software package. The algorithm's applicability to common microstrip configurations is tested through comparisons between FEM based solutions, |S21| measurements and the algorithm solutions under several permutations of a test board. Adjustments to the original algorithm are proposed that reduce computation times with out significantly affecting the accuracy of the result.

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Application Of A Hybrid Fem/Mom Method To A Canonical Pcb Problem, Yun Ji, J. Chen, Todd H. Hubing, James L. Drewniak Aug 1999

Application Of A Hybrid Fem/Mom Method To A Canonical Pcb Problem, Yun Ji, J. Chen, Todd H. Hubing, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

A hybrid FEM/MOM method was used to solve a canonical printed circuit board (PCB) problem. The PCB is populated with three traces. One is a signal line and the other two are I/O lines that extend beyond the boundary of the board. The finite element method (FEM) was used to model the fields in the volume around the on-board trace. The method of moments (MOM) was employed to model the equivalent surface currents on the board and the current on the off-board traces. The FEM and MOM equations were coupled by forcing the continuity of tangential fields on the dielectric …

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Anticipating Emi From Coupling Between High-Speed Digital And I/O Lines, Wei Cui, Min Li, Xiao Luo, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, Richard E. Dubroff Aug 1999

Anticipating Emi From Coupling Between High-Speed Digital And I/O Lines, Wei Cui, Min Li, Xiao Luo, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

The increasing speed of digital circuit design as well as the density of printed circuit board (PCB) layouts often result in more challenging electromagnetic interference (EMI) problems. The coupling between a high-speed digital line and an I/O line can be a primary EMI coupling path, and the attached cable a dominant radiator. This mechanism is studied and modeled herein in a multi-stage modeling fashion. EMI modeling is developed for coupling between the transmission lines, and the attached cable as the EMI antenna. Finally, the EMI is calculated for the coupled noise driving the attached cable. The agreement between the modeled …

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Rf Isolation Using Power Islands In Dc Power Bus Design, Jun Fan, Yong Ren, Juan Chen, David M. Hockanson, Hao Shi, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, Richard E. Dubroff Aug 1999

Rf Isolation Using Power Islands In Dc Power Bus Design, Jun Fan, Yong Ren, Juan Chen, David M. Hockanson, Hao Shi, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

Power island structures are often employed for minimizing the propagation of high-frequency noise on DC power buses. The rationale is based on introducing a series impedance in the power plane to provide isolation of a noise source from the rest of the PCB design. The power island concept is investigated herein experimentally, to determine its noise mitigation attributes and limitations. A modeling approach that is suitable for arbitrary PCB island geometries including lumped SMT decoupling capacitors is also presented. The modeling and measurements indicate that island structures can achieve some degree of isolation under certain conditions.

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Improved Wavelet-Based Multiresolution Edge Detection In Noisy Images, Yunwoo Lee, Samuel Peter Kozaitis Jul 1999

Improved Wavelet-Based Multiresolution Edge Detection In Noisy Images, Yunwoo Lee, Samuel Peter Kozaitis

Electrical Engineering and Computer Science Faculty Publications

We used the multiresolution property of the discrete wavelet transform to detect edges in noisy images. In our approach, we used wavelets corresponding to 1 and 2 derivatives to generate noisy wavelet coefficients. Then, we compared the wavelet COeffiCientS as a function of scale to reduce the effects of noise. In addition, our approach considered the change in edge position as a function of scale. We analyzed l..D experimental results and compar1 2..D results ofnoisy images to a more common edge detection method. Our results lead to improved edge detection resutts in noisy images.

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An Efficient Finite Difference Time Domain (Fdtd) Technique For Modeling A Reflector Antenna System With Partial Circular Symmetry, Dean Arakaki, Wenhua Yu, Raj Mittra Jul 1999

An Efficient Finite Difference Time Domain (Fdtd) Technique For Modeling A Reflector Antenna System With Partial Circular Symmetry, Dean Arakaki, Wenhua Yu, Raj Mittra

Electrical Engineering

This paper presents an efficient method for solving a large body scattering problem, viz., a paraboloidal reflector antenna system with only partial circular symmetry. The asymmetry in the system is introduced by two factors, viz., the microstrip feed and an inhomogeneous radome. The paper presents a novel approach, based on the reciprocity principle and the “equivalent aperture” theory, to handle the asymmetry problem and still take advantage of the circular symmetry of the large paraboloid of revolution to render the problem manageable

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Design And Performance Characterization Of Simultaneous Reflectance And Surface-Mapping Laser Scanner For Application In Underwater Inspection, Frank M. Caimi, Donna M. Kocak, Coy Colquitt Jul 1999

Design And Performance Characterization Of Simultaneous Reflectance And Surface-Mapping Laser Scanner For Application In Underwater Inspection, Frank M. Caimi, Donna M. Kocak, Coy Colquitt

Electrical Engineering and Computer Science Faculty Publications

Considerable advancements have been made in undersea imaging over the past decade enabling long-range detection and observation of underwater objects in clear and turbid (cloudy) water. The image transfer characteristics of the medium (i.e. scattering and absorption) have been primary obstacles in developing high performance systems. However, the application of lasers to the imaging formation process is currently providing a means for acquiring long-range images, over 5-6 attenuation lengths in comparison to 1 -2 attenuation lengths for more conventional methods. In addition, laser technology is now offering the promise of systems capable of forming range maps and depth resolved images. …

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Differential Reflection Phase Shift Under Conditions Of Attenuated Internal Reflection, R. M.A. Azzam Jul 1999

Differential Reflection Phase Shift Under Conditions Of Attenuated Internal Reflection, R. M.A. Azzam

Electrical Engineering Faculty Publications

The angle-of-incidence dependence of the differential reflection phase shift Δ between p and s polarizations is considered a function of the real and imaginary parts of the relative complex dielectric function ε of an interface in the domain of fractional optical constants, i.e., under conditions of internal reflection. The constraint on complex ε such that oscillatory and monotonic angular responses are obtained is determined. A sensitive and stable technique, which is based on attenuated internal reflection ellipsometry between the Brewster angle and the critical angle, is proposed for measuring small induced absorption (εi∼10−5) in the medium …

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Laser Beam Profile Deformation Effect During Bragg Acousto-Optic Interaction: A Non-Paraxial Approximation, Ray S. Huang, Chen-Wen Tarn, Partha P. Banerjee, Doungchin Cao Jul 1999

Laser Beam Profile Deformation Effect During Bragg Acousto-Optic Interaction: A Non-Paraxial Approximation, Ray S. Huang, Chen-Wen Tarn, Partha P. Banerjee, Doungchin Cao

Electrical and Computer Engineering Faculty Publications

It is commonly known that the spatial profiles of the diffracted light beams during Bragg acousto-optic interaction are distorted due to the Bragg angle selection mechanism. All the conventional studies on this effect use the paraxial approximation. But this approximation should be amended when the incident angle of the light is large enough that the diffracted light waves do not propagate closely along the optic axis of the acousto-optic diffraction system. By using a spatial Fourier transform approach, we rigorously study the light beam profile deformation effect of the diffracted light during the Bragg acousto-optic interaction beyond the paraxial approximation. …

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An Analytical Approximation For The Excess Noise Factor Of Avalanche Photodiodes With Dead Space, Majeed M. Hayat, Zikuan Chen, Mohammad Rezaul Karim Jul 1999

An Analytical Approximation For The Excess Noise Factor Of Avalanche Photodiodes With Dead Space, Majeed M. Hayat, Zikuan Chen, Mohammad Rezaul Karim

Electrical and Computer Engineering Faculty Research and Publications

Approximate analytical expressions are derived for the mean gain and the excess noise factor of avalanche photodiodes including the effect of dead space. The analysis is based on undertaking a characteristic-equation approach to obtain an approximate analytical solution to the existing system of recurrence equations which characterize the statistics of the random multiplication gain. The analytical expressions for the excess noise factor and the mean gain are shown to be in good agreement with the exact results obtained from numerical solutions of the recurrence equations for values of the dead space reaching up to 20% of the width of the …

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A Blind Deconvolution Approach For Resolution Enhancement Of Near-Field Microwave Images, Ali Mohammad-Djafari, Nasser N. Qaddoumi, R. Zoughi Jul 1999

A Blind Deconvolution Approach For Resolution Enhancement Of Near-Field Microwave Images, Ali Mohammad-Djafari, Nasser N. Qaddoumi, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper we propose a blind deconvolution method to enhance the resolution of images obtained by near-field microwave nondestructive techniques using an open ended rectangular waveguide probe. In fact, we model such images to be the result of a convolution of the real input images with a point spread function (PSF). This PSF depends mainly on the dimensions of the waveguide, the operating frequency, the nature of the object under test and standoff distance between the waveguide and the object. Unfortunately, it is very difficult to model this PSF from the physical data. For this reason, we consider the …

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Guest Editorial: Special Section On Acousto-Optic Devices And Optical Information Processing: Research And Developments, Partha P. Banerjee, Ting-Chung Poon Jul 1999

Guest Editorial: Special Section On Acousto-Optic Devices And Optical Information Processing: Research And Developments, Partha P. Banerjee, Ting-Chung Poon

Electrical and Computer Engineering Faculty Publications

This guest editorial provides an overview of the topical area and an introduction to the articles featured in the special section.

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Examination Of Beam Propagation In Misaligned Holographic Gratings And Comparison With The Acousto-Optic Transfer Function Model For Profiled Beams, Monish Ranjan Chatterjee, David D. Reagan Jul 1999

Examination Of Beam Propagation In Misaligned Holographic Gratings And Comparison With The Acousto-Optic Transfer Function Model For Profiled Beams, Monish Ranjan Chatterjee, David D. Reagan

Electrical and Computer Engineering Faculty Publications

A transfer function formalism developed earlier for the propagation of profiled optical beams through acousto-optic Bragg cells is revisited and applied to a thick holographic grating. The results based on the holographic coupled wave model and the acousto-optic multiple scattering model are shown to be compatible, and equivalent parameters such as the Q and grating strength are defined for the two systems. Results for a Gaussian spatial profile are numerically computed and compared. For the holographic grating, a profiled beam may be interpreted as an angular misalignment or Bragg-angle mismatch problem. The case of Bragg-wavelength mismatch is also investigated for …

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Electroluminescent Illumination System, Dirk J. Broer, David Braun, Antonius H.J. Venhuizen, Christianne R.M. De Witz Jun 1999

Electroluminescent Illumination System, Dirk J. Broer, David Braun, Antonius H.J. Venhuizen, Christianne R.M. De Witz

Electrical Engineering

An illumination system has an active layer which includes an electroluminescent material, the active layer being located between an optically transparent electrode layer and a reflective electrode layer. A reflective polarizer is present at a side of the transparent electrode layer facing away from the active layer. A sub-beam incident on the polarizer and having an unwanted polarization is reflected back to the active layer, where it is again partially depolarized to recover a component having the desired state of polarization. The invention also relates to a flat-panel picture display device which includes such an illumination system.

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Crosstalk And Image Uniformity In Passive Matrix Polymer Led Displays, David Braun, J. Rowe, G. Yu Jun 1999

Crosstalk And Image Uniformity In Passive Matrix Polymer Led Displays, David Braun, J. Rowe, G. Yu

Electrical Engineering

Passive matrix displays based on polymer and organic light-emitting diodes suffer from crosstalk, when the emission of light from one pixel depends on the operation of another pixel. We use circuit simulation in order to explain the causes of crosstalk and to quantify the consequences. This work analyzes how crosstalk arises from electrode resistance, pixel leakage current, and the location of faulty pixels. All factors influence both image uniformity and the power consumption of the display.

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Resonant Tank Motor Model For Voltage Reflection Simulations With Pwm Drives, Davia W. Schlegel, Glenn T. Wrate, Russ Kerkman, Gary Skibinski May 1999

Resonant Tank Motor Model For Voltage Reflection Simulations With Pwm Drives, Davia W. Schlegel, Glenn T. Wrate, Russ Kerkman, Gary Skibinski

Conference Papers in Published Proceedings

Reflected wave transient voltages that are impressed on drive output cables and low voltage AC induction motors are normally simulated with steep fronted dv/dt pulse waveforms from PWM voltage source inverters. System simulation arises from a need to correlate reflected wave peak voltage and risetime with the dielectric insulation capability of both the motor and cable. To obtain reasonable results, accurate models of each component must be employed. This investigation concentrates on parameter identification for a high frequency resonant tank motor model from fractional to several hundred horsepower.

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Performance Optimization And Light-Beam-Deviation Analysis Of The Parallel-Slab Division-Of-Amplitude Photopolarimeter, Aed M. El-Saba, Rasheed M.A. Azzam, Mustafa A. G. Abushagur May 1999

Performance Optimization And Light-Beam-Deviation Analysis Of The Parallel-Slab Division-Of-Amplitude Photopolarimeter, Aed M. El-Saba, Rasheed M.A. Azzam, Mustafa A. G. Abushagur

Electrical Engineering Faculty Publications

A division-of-amplitude photopolarimeter that uses a parallel-slab multiple-reflection beam splitter was described recently [Opt. Lett. 21, 1709 (1996)]. We provide a general analysis and an optimization of a specific design that uses a fused-silica slab that is uniformly coated with a transparent thin film of ZnS on the front surface and with an opaque Ag or Au reflecting layer on the back. Multiple internal reflections within the slab give rise to a set of parallel, equispaced, reflected beams numbered 0, 1, 2, and 3 that are intercepted by photodetectors D0, D1, D2, and D …

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Variable Angle Of Incidence Analysis Of Magneto-Optic Multilayers, William A. Mcgahan, Liang-Yao Chen, John A. Woollam May 1999

Variable Angle Of Incidence Analysis Of Magneto-Optic Multilayers, William A. Mcgahan, Liang-Yao Chen, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

We have applied the technique of variable angle of incidence spectroscopic ellipsometry (VASE) to the analysis of multilayered magneto-optic structures. With this instrument we measure the complete pseudodielectric tensor (diagonal and off-diagonal elements) for the sample of interest at variable angles of incidence. We have also developed computer software to perform a best-fit analysis of the measured data, providing optical constants, Voigt parameters, and layer thicknesses for the individual layers in the sample. Additionally, given an estimate of the material parameters, this software will provide an estimate of the optimum spectral range and angles of incidence for accurate characterization of …

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Fdtd Modeling Of Emi Antennas, Motoshi Tanaka, Wei Cui, Xiao Luo, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, Richard E. Dubroff May 1999

Fdtd Modeling Of Emi Antennas, Motoshi Tanaka, Wei Cui, Xiao Luo, James L. Drewniak, Todd H. Hubing, Thomas Van Doren, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

The FDTD (finite-difference time-domain) method is used for modeling EMI antenna geometries to anticipate EMI problems in high-speed digital designs. FDTD is well-suited to modeling large-scale geometries such as cables that might be driven against PCB ground planes as a result of a noise voltage that appears at the connector. Three specific cases are addressed herein including a simple cable driven against a PCB ground, coupling between a high-speed digital and I/O line that drives a cable against the PCB, and the finite impedance of the PCB reference plane that results in an effective noise source that drives the PCB …

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Low-Temperature Molecular Beam Epitaxy Of Gaas: A Theoretical Investigation Of Antisite Incorporation And Reflection High-Energy Diffraction Oscillations, K. Natarajan, Rama Venkat, Donald L. Dorsey May 1999

Low-Temperature Molecular Beam Epitaxy Of Gaas: A Theoretical Investigation Of Antisite Incorporation And Reflection High-Energy Diffraction Oscillations, K. Natarajan, Rama Venkat, Donald L. Dorsey

Electrical & Computer Engineering Faculty Research

Surface dynamics dominate the incorporation of charged, As+Ga, and neutral, As0Ga, antisite arsenic, and the temporal variation of reflection high-energy electron diffraction(RHEED) intensity in the low-temperature molecular beam epitaxy of (100) gallium arsenide(GaAs). A rate equation model is proposed which includes the presence and dynamics of a physisorbed arsenic (PA) layer riding the growth surface. The PA layer dictates the incorporation and concentration of As+Ga and As0Ga. Additionally, it influences the RHEED oscillations (ROs) behavior and the RO’s dependence on its coverage through its contribution to the reflected intensity. The model results for the dependence of As+Ga and As0Ga concentrations …

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A Worst-Case Analysis Of Direct-Sequence Spread-Spectrum In Multipath Channels, Murad Hizlan, Xuedong Liu May 1999

A Worst-Case Analysis Of Direct-Sequence Spread-Spectrum In Multipath Channels, Murad Hizlan, Xuedong Liu

Electrical and Computer Engineering Faculty Publications

We consider a direct-sequence spread-spectrum system operating in an indoors environment in the presence of multiaccess and multipath interference, and additive white Gaussian noise. We focus on the worst-case bit error probability of this system with a constraint on signal-to-interference ratio, and derive a Chernoff-type upper bound on this error probability. We evaluate the upper bound for a special case in order to gain understanding of the basic worst-case performance. We also compare the effects of the worst-case multipath interference with those of the worst-case multiuser interference of …

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Cryosphere Applications Of Nscat Data, David G. Long, Mark R. Drinkwater May 1999

Cryosphere Applications Of Nscat Data, David G. Long, Mark R. Drinkwater

Faculty Publications

Though designed to measure vector winds over the ocean, new imaging techniques facilitate the use of NASA scatterometer data (NSCAT) in cryosphere studies. NSCAT provides data of unprecedented coverage, resolution, and quality which, when coupled with the scatterometer image reconstruction with filtering (SIRF) algorithm, enables images of O at resolutions approaching 8 km over stationary targets. Such images are useful in ice mapping and classification, and multidecadal studies are possible by comparison with Seasat Scatterometer (SASS) data. The utility of NSCAT data in polar ice studies is illustrated through a review of two cryosphere applications of NSCAT data: (1) sea-ice …

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Postlaunch Sensor Verification And Calibration Of The Nasa Scatterometer, David G. Long, Wu-Yang Tsai, James E. Graf, Carroll Winn, James N. Huddleston, R. Scott Dunbar, Michael H. Freilich, Frank J. Wentz, W. Linwood Jones May 1999

Postlaunch Sensor Verification And Calibration Of The Nasa Scatterometer, David G. Long, Wu-Yang Tsai, James E. Graf, Carroll Winn, James N. Huddleston, R. Scott Dunbar, Michael H. Freilich, Frank J. Wentz, W. Linwood Jones

Faculty Publications

Scatterometer instruments are active microwave sensors that transmit a series of microwave pulses and measure the returned echo power to determine the normalized radar backscattering cross section (sigma-0) of the ocean surface from which the speed and direction of near-surface ocean winds are derived. The NASA Scatterometer (NSCAT) was launched on board the ADEOS spacecraft in August 1996 and returned ten months of high-quality data before the failure of the ADEOS spacecraft terminated the data stream in June 1997. The purpose of this paper is to provide an overview of the NSCAT instrument and sigma-0 computation and to describe the …

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The Probability Density Of Spectral Estimates Based On Modified Periodogram Averages, David G. Long, Paul E. Johnson May 1999

The Probability Density Of Spectral Estimates Based On Modified Periodogram Averages, David G. Long, Paul E. Johnson

Faculty Publications

Welch's (1967) method for spectral estimation of averaging modified periodograms has been widely used for decades. Because such an estimate relies on random data, the estimate is also a random variable with some probability density function. Here, the PDF of a power estimate is derived for an estimate based on an arbitrary number of frequency bins, overlapping data segments, amount of overlap, and type of data window, given a correlated Gaussian input sequence. The PDFs of several cases are plotted and found to be distinctly non-Gaussian (the asymptotic result of averaging frequency bins and/or data segments), using the Kullback-Leibler distance …

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Integrating Research Results Into A Power Engineering Curriculum, Chanan Singh, Kraig J. Olejniczak, Kevin Tomsovic, Richard D. Christie, Anil Pahwa, Kwang Y. Lee, Mariesa Crow May 1999

Integrating Research Results Into A Power Engineering Curriculum, Chanan Singh, Kraig J. Olejniczak, Kevin Tomsovic, Richard D. Christie, Anil Pahwa, Kwang Y. Lee, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents summaries of the activities of six research active power engineering educators which were presented in a panel session of the same name at the IEEE Power Engineering Society Winter Meeting on February 3, 1997 in New York City, USA. Each of the panelists discusses how research results are incorporated into courses and how students benefit from this approach.

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Power Bus Noise Reduction Using Power Islands In Printed Circuit Board Designs, Todd H. Hubing, Juan Chen, James L. Drewniak, Thomas Van Doren, Y. Ren, Jun Fan, Richard E. Dubroff May 1999

Power Bus Noise Reduction Using Power Islands In Printed Circuit Board Designs, Todd H. Hubing, Juan Chen, James L. Drewniak, Thomas Van Doren, Y. Ren, Jun Fan, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

Power islands are often used to isolate devices that put noise on a power bus from devices that may be susceptible to power bus noise. At high frequencies however, the effectiveness of these islands depends on the implementation. This paper experimentally investigates the effectiveness of different power island structures at frequencies up to 3 GHz.

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Stratified Volume Diffractive Optical Elements As High Efficiency Gratings, Gregory P. Nordin, D. M. Chambers May 1999

Stratified Volume Diffractive Optical Elements As High Efficiency Gratings, Gregory P. Nordin, D. M. Chambers

Faculty Publications

We propose stratified volume diffractive optical elements as a new type of diffractive optical element that is capable of functioning as a high-efficiency grating in applications with requirements not suited to traditional holographic or diffractive optical techniques. In this approach, diffractive optical fabrication methods are used to construct an optical structure that emulates volume grating behavior. We discuss the diffraction properties of stratified volume diffractive optical elements and compare them with those used previously in both volume holographic optical elements and stratified volume holographic optical elements. A systematic design process is then presented for deriving structure parameters. We illustrate this …

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Simulations Of Passive Matrix Polymer Image Sensors, David Braun, G. Yu Apr 1999

Simulations Of Passive Matrix Polymer Image Sensors, David Braun, G. Yu

Electrical Engineering

Two-dimensional passive photodiode matrices are hardly useful for image sensing due to the crosstalk between pixels. This crosstalk makes it difficult to recover information from individual pixels. A switching unit attached to each sensing unit has been the common solution in image sensors (such as in CMOS sensors and in TFT-PiN a-Si photosensors). A novel organic photodiode with voltage-switchable photosensitivity was developed recently. Passive photodiode matrices made with such organic photodiodes can be used for image sensing applications. This circuit simulation study demonstrates an effective scheme to extract images from passive photodiode matrices, concluding that individual photodiode parameters determine the …

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Output Control Of Vertical Microcavity Light Emitting Device, James A. Lott Apr 1999

Output Control Of Vertical Microcavity Light Emitting Device, James A. Lott

AFIT Patents

An improved intracavity sensor based output power control for microcavity light emitting devices. An improved phototransistor transducer is both configured and physically disposed so that it passively transmits the spurious optical energy output of the microcavity light emitting device while simultaneously generating a light determined electrical signal of easily used large magnitude that is nearly free of error. The base-collector region of the transistor is disposed with a quantum well absorbing layer and produces a signal responsive to a selected emission wavelength. The configuration of the optical energy communicating transducer is arranged so that it is improved in sensitivity and …

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