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Articles 1 - 6 of 6
Full-Text Articles in Engineering
Beam Propagation In Parabolically Tapered Graded-Index Waveguides, Anthony A. Tovar, Lee W. Casperson
Beam Propagation In Parabolically Tapered Graded-Index Waveguides, Anthony A. Tovar, Lee W. Casperson
Electrical and Computer Engineering Faculty Publications and Presentations
To a good approximation, the electromagnetic-propagation characteristics of graded-index waveguides can be written in terms of polynomial-Gaussian modes. For uniform quadratic-index waveguides the behavior of these modes is well known. However, there are sometimes practical reasons for using tapered waveguides, but detailed propagation solutions are known for only a few specific taper functions. The parabolic taper is perhaps the most important special case, and the solution-generating techniques that we generalize are used to obtain analytic solutions for this case.
Generalized Reverse Theorems For Multipass Applications In Matrix Optics, Lee W. Casperson, Anthony A. Tovar
Generalized Reverse Theorems For Multipass Applications In Matrix Optics, Lee W. Casperson, Anthony A. Tovar
Electrical and Computer Engineering Faculty Publications and Presentations
The reverse theorem that governs backward propagation through optical systems represented by transfer matrices is examined for various matrix theories. We extend several reverse theorems to allow for optical systems represented by matrices that may or may not be unimodular and that may be 2 × 2 or take on an augmented 3 × 3 form. As an example, we use the 3 × 3 form of the reverse theorem to study a laser with intracavity misaligned optics. It is shown that, by tilting one of the laser's mirrors, we can align the laser output arbitrarily, and the mirror tilt …
Fluttering Fountains: Stability Criteria, Lee W. Casperson
Fluttering Fountains: Stability Criteria, Lee W. Casperson
Electrical and Computer Engineering Faculty Publications and Presentations
The fluttering oscillations that have long been seen in falling sheets of water have recently been subjected to detailed theoretical analysis. In this study stability criteria for these oscillations are derived and discussed. These criteria provide insight into the physical mechanisms of the instability and may be employed in the design of fluttering waterfall systems.
Transform Method Of Processing For Speckle Strain-Rate Measurements, Donald D. Duncan, Sean J. Kirkpatrick, F. Fausten Mark, Lawrence W. Hunter
Transform Method Of Processing For Speckle Strain-Rate Measurements, Donald D. Duncan, Sean J. Kirkpatrick, F. Fausten Mark, Lawrence W. Hunter
Electrical and Computer Engineering Faculty Publications and Presentations
We have developed a highly sensitive method for measuring thermal expansion, mechanical strain, and creep rates. We use the well-known technique of observing laser speckle with a pair of linear array cameras, but we employ a data-processing approach based on a two-dimensional transform of the speckle histories from each camera. This technique can effect large gauge sizes, which are important in the assessment of the spatial statistics of creep. Further, the algorithm provides simultaneous global estimates of the strain rates at both small- and large-scale sizes. This feature may be of value in the investigation of materials with different short- …
Programmable Analog Array Circuit, Marek Perkowski, Edmund Pierzchala
Programmable Analog Array Circuit, Marek Perkowski, Edmund Pierzchala
Electrical and Computer Engineering Faculty Publications and Presentations
There is disclosed a programmable analog or mixed analog/ digital circuit. More particularly, this invention provides a circuit architecture that is ?exible for a programmable electronic hardWare device or for an analog circuit Whose input and output signals are analog or multi-valued in nature, and primarily continuous in time. There is further disclosed a design for a current-mode integrator and sample-and-hold circuit, based upon Miller effect.
Threshold Characteristics Of Multimode Semiconductor Lasers, Lee W. Casperson, Mehdi Khoshnevissan
Threshold Characteristics Of Multimode Semiconductor Lasers, Lee W. Casperson, Mehdi Khoshnevissan
Electrical and Computer Engineering Faculty Publications and Presentations
The effects of spontaneous emission on the threshold characteristics of multimode laser oscillators with mixed line broadening are considered in detail. Most previous studies of multimode laser operation have emphasized the two limits of homogeneous and inhomogeneous broadening. With homogeneous broadening there is a tendency for oscillation in a single longitudinal mode, while in the inhomogeneous limit oscillation over much of the gain spectrum is expected. All practical lasers are somewhere between these limits, and this study explores the mode characteristics of lasers with mixed line broadening. Special attention is given to the important practical case of semiconductor diode lasers, …