Andrew S. Keys
University of Alabama in Huntsville
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Publication
Featured researches published by Andrew S. Keys.
Optics Express | 1999
Richard L. Fork; Spencer T. Cole; Lisa Gamble; William M. Diffey; Andrew S. Keys
We describe an optical amplifier designed to amplify a spatially sampled component of an optical wavefront to kilowatt average power. The goal is means for implementing a strategy of spatially segmenting a large aperture wavefront, amplifying the individual segments, maintaining the phase coherence of the segments by active means, and imaging the resultant amplified coherent field. Applications of interest are the transmission of space solar power over multi-megameter distances, as to distant spacecraft, or to remote sites with no preexisting power grid.
SPIE's International Symposium on Optical Science, Engineering, and Instrumentation | 1999
Andrew S. Keys; Richard L. Fork; Thomas R. Nelson; John P. Loehr
We describe a design for an agile, electronically- configurable, optical beam steering array to be used in directional free-space transmission of optical signals. The proposed device employs a 1D array of tunable resonant transmissive modulators constructed from customized multi- layered stacks of dielectric materials. Each modulator may be individually configured to transmit an optical signal with a known amount of phase and group velocity modulation. Proper configuration of each individual modulator results in diffractive interactions between multiple modulator outputs, providing a method for directional optical signal transmission. Of particular focus within this paper is the design of the individual modulator. We generate custom transmission functions by varying the parameters describing the modulators specific construction, such as number of layers within the multi-layer stack, refractive indices of stack materials, layer thickness, and combinations of periodic versus non-periodic layer repetitions. A computational optimization of the variables describing the stacks construction strives to maximize the amount of optical signal modulation obtainable within defined limits. Our optimization is based largely on maximizing transmitted phase delay. We discuss trade-offs between methods of increasing device performance versus practical limitations of fabrication technologies.
Frontiers in Optics 2004/Laser Science XXII/Diffractive Optics and Micro-Optics/Optical Fabrication and Testing (2004), paper DMC8 | 2004
Andrew S. Keys; Robert W. Crow; Paul R. Ashley; Thomas R. Nelson; Jack H. Parker; Elizabeth A. Beecher
This effort describes the fabrication and testing of binary-phase Fourier gratings designed to generate an incoherent array of output source points with nonuniform user-defined intensities, symmetric about the zeroth order.
Proceedings of SPIE, the International Society for Optical Engineering | 1999
Thomas R. Nelson; John P. Loehr; Qianghua Xie; James E. Ehret; Joseph Van Nostrand; Lisa Gamble; Darryl K. Jones; Spencer T. Cole; Rebecca H. Trimm; William M. Diffey; Richard L. Fork; Andrew S. Keys
We present an optical delay line structure incorporating InxGa1-xAs quantum wells in the GaAs quarter- wave layers of a GaAs/AlAs distributed Bragg reflector. Applying an electric field across the quantum wells shifts and broadens the e1-hh1 exciton peak via the quantum- confined Stark effect. Resultant changes in the index of refraction thereby provide a means for altering the group delay of an incident laser pulse. Theoretical results predict tunable delays on the order of 50 fs for a 30-period structure incorporating 3 quantum wells per GaAs layer. Structure design, growth and fabrication are detailed. Preliminary group delay measurements on large-area samples with no applied bias are presented.
Archive | 1998
Richard L. Fork; Darryl K. Jones; Andrew S. Keys
Archive | 2001
Andrew S. Keys; Richard L. Fork
Physics, Theory, and Applications of Periodic Structures in Optics | 2001
Andrew S. Keys; Richard L. Fork; Thomas R. Nelson; James E. Ehret; Joseph Van Nostrand
Archive | 2004
Andrew S. Keys; Richard L. Fork
Archive | 1999
Richard L. Fork; William M. Diffey; Lisa Gamble; Andrew S. Keys
Archive | 1998
Andrew S. Keys; Darryl K. Jones; Richard L. Fork