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Full-Text Articles in Engineering
Nanosecond Transient Electroluminescene From Polymer Light-Emitting Diodes, David Braun, D. Moses, C. Zhang, A. J. Heeger
Nanosecond Transient Electroluminescene From Polymer Light-Emitting Diodes, David Braun, D. Moses, C. Zhang, A. J. Heeger
Electrical Engineering
The transient electroluminescence from polymer light-emitting diodes is reported. When the devices are mounted on a microstrip transmission line, the temporal response is limited by the electrode geometry, with rise and fall times below 50 ns. With low duty-cycle pulses (0.5%) the electroluminescence intensity remains proportional to the current at values up to 10 A/cm2, two orders of magnitude greater than possible under direct current operation. Since the spectral blue-shift observed at high current levels (with power dissipation above 1 W/cm2) indicates significant sample heating, still higher levels should be possible with proper thermal management.
Stabilization Of Passively Mode-Locked Semiconductor Laser Repetition Frequency, Roger Helkey, Dennis J. Derickson, Alan Mar, John Wasserbauer, Robert L. Thornton
Stabilization Of Passively Mode-Locked Semiconductor Laser Repetition Frequency, Roger Helkey, Dennis J. Derickson, Alan Mar, John Wasserbauer, Robert L. Thornton
Electrical Engineering
No abstract provided.
Nsf Sponsored Innovation In Engineering And Cornputer Science, Jacob Abel, Patricia Daniels, James G. Harris, Harry Hedges
Nsf Sponsored Innovation In Engineering And Cornputer Science, Jacob Abel, Patricia Daniels, James G. Harris, Harry Hedges
Electrical Engineering
No abstract provided.
Model For The Infrastructure Of Engineering Education, James G. Harris, Karen Frair, Win Aung, Susan T. Hill
Model For The Infrastructure Of Engineering Education, James G. Harris, Karen Frair, Win Aung, Susan T. Hill
Electrical Engineering
There are many ways to describe and model physical systems. The infrastructure of engineering education in the United States is an example of such a system, and it is the intent of this report to describe and model this infratructure. The means for doing this starts with the graduation statistics for the year 1989 given by the Computer Aided Science Policy Analysis & Research Database System (CASPAR) developed for the National Science Foundation by Quantum Research Corporation [1], and uses a simple categorization for the institutions that contribute to those statistics. This categorization sorts the post -secondary institutions in the …
Waste-Surface Mapping Of The Fernald K-65 Silos Using A Structured Light Measurement System, B. L. Burks, Fred W. Depiero, M. A. Dinkins, J. C. Rowe, C. B. Selleck, D. L. Jacoboski
Waste-Surface Mapping Of The Fernald K-65 Silos Using A Structured Light Measurement System, B. L. Burks, Fred W. Depiero, M. A. Dinkins, J. C. Rowe, C. B. Selleck, D. L. Jacoboski
Electrical Engineering
During FY 1991, a remotely operated surface-mapping measurement system was developed by the Robotics & Process Systems Division at Oak Ridge National Laboratory for use in the K-65 waste-storage silos at Fernald, Ohio. The mapping system used three infrared line-generating laser diodes as illumination sources and three high-resolution, low-lux, calibrated, black-and-white, chargecoupled- device video cameras as receivers. These components were combined to form structured light source range and direction sensors with six different possible emitter-receiver pairs. A technology demonstration and predeployment tests were performed at Fernald during July and August 1991, using the empty Silo 4 into which was placed …
Short Pulse Generation Using Multisegment Mode-Locked Semiconductor Lasers, Dennis J. Derickson, R. J. Helkey, A. Mar, Judy R. Karin, J. G. Wasserbauer, J. E. Bowers
Short Pulse Generation Using Multisegment Mode-Locked Semiconductor Lasers, Dennis J. Derickson, R. J. Helkey, A. Mar, Judy R. Karin, J. G. Wasserbauer, J. E. Bowers
Electrical Engineering
No abstract provided.
Repetition Frequency Stabilisation Of Passively Mode-Locked Semiconductor Lasers, R. J. Helkey, Dennis J. Derickson, A. Mar, J. G. Wasserbauer, J. E. Bowers, R. L. Thornton
Repetition Frequency Stabilisation Of Passively Mode-Locked Semiconductor Lasers, R. J. Helkey, Dennis J. Derickson, A. Mar, J. G. Wasserbauer, J. E. Bowers, R. L. Thornton
Electrical Engineering
The repetition frequency of an external cavity mode-locked GaAs semiconductor diode laser has been stabilized by voltage controlled electrical feedback. The phase noise has been reduced by 40dB at 1 kHz offset from the carrier and timing jitter reduced from more than 30ps to 4ps. This technique can be used to stabilize millimetre-wave mode-locked lasers.
Mode-Locking Of High-Power Resonant-Optical-Waveguide Diode Laser Arrays, Alan Mar, Dennis J. Derickson, Roger Helkey, John Bowers, Dan Botez
Mode-Locking Of High-Power Resonant-Optical-Waveguide Diode Laser Arrays, Alan Mar, Dennis J. Derickson, Roger Helkey, John Bowers, Dan Botez
Electrical Engineering
We report the first mode-locked operation of a resonant optical waveguide (ROW semiconductor laser array. Pulsewidths as short as 23 ps and peak powers of over 1W are generated in a single-lobed beam.
Remote Driving With Reduced Bandwidth Communication, Fred W. Depiero, Timothy E. Noell, Timothy F. Gee
Remote Driving With Reduced Bandwidth Communication, Fred W. Depiero, Timothy E. Noell, Timothy F. Gee
Electrical Engineering
Oak Ridge National Laboratory has developed a real-time video transmission system for low-bandwidth remote operations. The system supports both continuous transmission of video for remote driving and progressive transmission of still images. Inherent in the system design is a spatiotemporal limitation to the effects of channel errors. The average data rate of the system is 64,000 bits/s, a compression of approximately 1000:1 for the black and white National Television Standard Code video. The image quality of the transmissions is maintained at a level that supports teleoperation of a high-mobility multipurpose wheeled vehicle at speeds up to 15 mph on a …
Integrated Optical Transmitters And Receivers Using Multi-Segment Laser Processes, J. G. Wasserbauer, Dennis J. Derickson, K. Giboney, R. J. Helkey, J. R. Karin, A. Mar, J. E. Bowers
Integrated Optical Transmitters And Receivers Using Multi-Segment Laser Processes, J. G. Wasserbauer, Dennis J. Derickson, K. Giboney, R. J. Helkey, J. R. Karin, A. Mar, J. E. Bowers
Electrical Engineering
No abstract provided.
Electroluminescence And Electrical Transport In Poly(3-Octylthiophene) Diodes, David Braun, G. Gustafsson, D. Mcbranch, A. J. Heeger
Electroluminescence And Electrical Transport In Poly(3-Octylthiophene) Diodes, David Braun, G. Gustafsson, D. Mcbranch, A. J. Heeger
Electrical Engineering
We report visible light emission from diodes made from poly(3-octylthiophene). Use of a soluble derivative of polythiophene allows fabrication of the light emitting diodes by casting the polymer film from solution with no subsequent processing or heat treatment required. The devices emit dim red-orange light with relatively low external quantum efficiencies, below 2.5×10−5 photons per electron at room temperature. Electrical characterization reveals diode behavior with rectification ratios greater than 102. The temperature dependence indicates that tunneling phenomena dominate the charge injection.
Microwave And Millimeter Wave Signal Generation Using Mode-Locked Semiconductor Lasers With Intra-Waveguide Saturable Absorbers, Dennis J. Derickson, R. J. Helkey, A. Mar, J. G. Wasserbauer, Y. G. Wey, J. E. Bowers
Microwave And Millimeter Wave Signal Generation Using Mode-Locked Semiconductor Lasers With Intra-Waveguide Saturable Absorbers, Dennis J. Derickson, R. J. Helkey, A. Mar, J. G. Wasserbauer, Y. G. Wey, J. E. Bowers
Electrical Engineering
Microwave and millimeter wave signals can be generated using mode-locked semiconductor lasers with intra-waveguide saturable absorbers. Monolithic and external cavity devices optimized for electrical and optical signal generation are discussed along with measurements of amplitude noise, phase noise, output power, and repetition rate tunability.
Suppression Of Multiple Pulse Formation In External-Cavity Mode-Locked Semiconductor Lasers Using Intrawaveguide Saturable Absorbers, Dennis J. Derickson, R. J. Helkey, A. Mar, Judy R. Karin, J. E. Bowers, R. L. Thornton
Suppression Of Multiple Pulse Formation In External-Cavity Mode-Locked Semiconductor Lasers Using Intrawaveguide Saturable Absorbers, Dennis J. Derickson, R. J. Helkey, A. Mar, Judy R. Karin, J. E. Bowers, R. L. Thornton
Electrical Engineering
Imperfect antireflection coatings in external-cavity mode-locked semiconductor lasers can cause multiple output pulse generation. The incorporation of an intrawaveguide saturable absorber segment into the laser suppresses this problem. Single pulse outputs of less than 2.8 ps and 0.7 pJ of energy are obtained using such devices with both quantum well and bulk active regions