Engineering Commons^™

Constraint On The Optical Constants Of A Transparent Film On An Absorbing Substrate For Inversion Of The Ratio Of Complex P And S Reflection Coefficients At A Given Angle Of Incidence, R. M.A. Azzam, M. A. Habli

Electrical Engineering Faculty Publications

An absorbing substrate of complex refractive index n₂-jk₂ can be coated by a transparent thin film of refractive index n₁ and normalized thickness ζ so that the ratio of complex reflection coefficients for the pand s polarizations of the film-covered substrate ρ is the inverse of that of the film-free substrate ρ¯ at a given angle of incidence φ. A pair of parallel (metallic) mirrors, one uncoated and the other coated with a ρ-inverting layer, causes a beam displacement without change of polarization and with a certain net reflectance (insertion loss) ℜ. In this …

Angular Sensitivity Of Brewster-Angle Reflection Polarizers: An Analytical Treatment, R. M.A. Azzam

Electrical Engineering Faculty Publications

The angular sensitivity of Brewster-angle reflection polarizers (BARP) is first studied approximately by determining the Taylor series expansion of the parallel reflectance R_p as a function of angle of incidence ø near the Brewster angle ø_B. Subsequently, exact and explicit equations are derived that determine the lower and upper limits, ø_l and ø_u, of the range of ø, that includes ø_B, over which R_p or the extinction ratioER is below a stated limit L. Examples are given of Ge and Si IR BARP for which ø_l and ø …

An Investigation Of Electrical And Optical Properties Of Sputtered Amorphous Silicon Nitride And Germanium Thin Films, Rajendra S. Khandelwal

Theses

Low temperature preparation of thin amorphous Silicon Nitride and Germanium Films by direct RF sputter deposition was investigated. Influence of various sputtering parameters on film properties was studied. Infrared transmission spectrophotometry was used to evaluate optical properties of the films whereas electrical characteristics of the films were determined from current-voltage measurements of MIS structures. For Silicon Nitride films it was observed that the stoichiometry, as indicated by the IR transmission, dielectric constant and current density versus square root of electric field measurements, was a strong function of the sputtering gas composition and particularly the Ar/N ratio in the sputtering gas. …

Time Series Analysis Of Respiration Component In Heart Rate Variability, Anuradha Ramaswamy Iyengar

Theses

Time series signal processing techniques (Fourier based) were applied to analyze the relationship between heart rate and respiration. This analysis takes advantage of the different timing charecteristics of the autonomic nervous system inputs to analyze their influence on the heart rate.

Data from three experiments were analyzed. The first set of data was from helicopter pilots of the US Army. They injected atropine into themselves on certain days. The effect of atropine on the heart rate spectrum and the relationship between heart rate and respiration was studied. It was found that atropine abolishes the respiration peak in the heart rate …

Properties Of Sputtered A-Ge And A-Ge : H Thin Films, Hanjin Cho

Theses

The effect of the amorphous and glassy structure of amorphous germanium films on their electrical characteristics was investigated experimentally. The films were deposited onto silicon substrates using a modified MRC 8800 triode sputtering system. The Poole-Frenkel and Schottky mechanisms are discussed in detail and the shortcomings of the accepted picture of the former in amorphous materials are dealt with. It was concluded on the basis available evidence that the current flow in amorphous germanium favors the Poole-Frenkel mechanism at high fields.

Amorphous hydrogenated germanium films which were deposited by bias sputtering were characterized by measuring the infrared absorption. The films …

Antireflection Of An Absorbing Substrate By An Absorbing Thin Film At Normal Incidence, R. M.A. Azzam, E. Bu-Habib, J. Casset, G. Chassaing, P. Gravier

Electrical Engineering Faculty Publications

An absorbing substrate of complex refractive index n₂ - jk₂ at wavelength λ can be coated by an absorbing thin film of complex refractive index n₁ - jk₁ and thickness d to achieve zero reflection at normal incidence. For given n₂,k₂ multiple solutions (n₁,k₁,d/λ) are found that correspond to infinitely many distinct antireflection layers. This is demonstrated for a Si substrate at two wavelengths (6328 and 4420 Å). The response of these absorbing antireflection layers to changes of the angle of incidence from 0 …