Browsing by Subject "Thin films -- Optical properties"
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Item Dielectric optical notch filter at 1.55 micrometers(Texas Tech University, 1999-05) Geng, CunfangAll-dielectric optical notch filters centered at 1.55 µm has been constructed, tested and analyzed. Optical notch filter design considerations such as choice of dielectric material pair, best structure of filters will be discussed. The actual optical notch filters show some absorption at 1.55 µm. Special single Si and Si02 layers have been deposited in the same deposition condition as that for the construction of optical notch filters. Material analysis including absorption analysis has been done to figure out why optical notch filters show absorption and where absorption come from.Item Optical constants of a system consisting of transparent film on an absorbing substrate(Texas Tech University, 1977-05) Sloan, Mark L.New methods are evaluated for experimentally obtaining the optical constants of a system composed of an absorbing substrate overlaid by a transparent film. The methods require the use of two samples having the same substrate and film materials but differing film thicknesses. The constants which are determined are the refractive index and the respective thicknesses of the two films and the refractive index and extinction coefficient of the substrates. Analysis is based on relations derived at crossing points of the reflectance versus incident angle curves for the two samples. The film thicknesses and refractive index may be obtained solely from crossing point data. In order to determine the substrate constants, an additional measurement must be made of the reflectance of the film - substrate system at Brewster's angle. The sensitivity of the optical constant determinations to errors in experimentally obtained reflectance and angle measurements is explored by numerical analysis.Item Reflection Polarization by a System Consisting of Two Transparent Films on An Absorbing Substrate(Texas Tech University, 1972-12) Parikh, Prashant DThe conditions under which a system consisting of two transparent films on an absorbing substrate functions as a polarizer are analyzed. The analysis yields that for given optical constants of the films and substrate there exists a range of polarizing angles at which either component of polarization can be suppressed. At any angle in this range any one of an infinite number of discrete film thicknesses can be employed to obtain polarized light. The performance of this polarizer is measured by numerically calculating the sensitivity of the suppressed component to small departures of the theoretical polarizing angle, thicknesses and wavelength, and by calculating the magnitude of the unsuppressed component. A variety of films substrate combinations have been studied. The substrates-aluminum, rhodium and gold are selected as they span the range of excellent to intermediate reflectors. The refractive indices of the films do not correspond to any specific material but are varied over a realistic range of practical interest. The advantages of this system with respect to the single film - substrate are enumerated.