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Course: Optics of thin films

Department/Abbreviation: SLO/TV

Year: 2020

Guarantee: 'Ing. Jaromír Křepelka, CSc.'

Annotation: The aim is to familiarize students with the basic optical characteristics of systems composed from thin isotropic, homogeneous (and inhomogeneos) layers designed from dielectric and also metal materials including their applications. The attention is also paid to the propertiesof ideal thick layers and their combinations with thin film systems, and anisotropic layers too. The theory is based on the solution of Maxwell equations for plane waves, from which the formulae for transformation of tangential components of electric and magnetic field are derived and measurable macroscopic parameters (reflectivity, transparency, absorbtion) are defined. There are discussed theoretically interesting problems, for instance the reversibility principle, principle of equivalence for symetrical system of layers, the thin film behaviour in partly coherent light field, colour effects within thin films, the relation of thin films to the wave guided structures and the relation of periodical structures to photonic crystals. The examples of practical design problems are solved especially using anisotropic structures, highly reflecting systems, narrow band filters and polarising beam splitters.

Course review:
1. Introduction - properties of thin layers, methods of creation of thin layers and their controls, properties of materials 2. Electromagnetic field in isotropic non-homogeneous medium - solution of Maxwell equations in homogeneous isotropic medium, matrix description of systems of thin layers (properties of transmission matrix, transformation of the field and transmission of energy in the systems of thin layers), principle of reversibility 3. Examples - interface of two media, properties of one thin layer, thick layer, systems of thin and thick layers, explicit dependence of parameters on phase thickness of the layer, layer in partially coherent light, colour effects on thin layers, distribution of field inside the system of thin layers 4. Construction methods - half-wave layer, buffer layer, symmetric three-layered structure, approximation expressions for parameters of systems of thin layers (Furman approximation)m methods of numerical computation of differentiations of parameters, optimization problems 5. Construction examples - periodic structures and their applications (reflection in cardinal point, analysis of the bandwidth of suppressed transmittance), antireflective structures (antireflection by one layer and two layers, maximum-flat antireflections), MacNeill polarizer, interference Fabry-Perot filters, backlighting of metal layer (induced transmission) 6. Basics of evaluation of ellipsometric measurement - measurement of ellipsometric parameters, determination of refractive index of substrate, determination of refractive index and thickness of one dielectric layer, influence of roughness of the surface, complicated inverse problems of ellipsometry, estimation of errors of measurement 7. Anisotropic layered media - Maxwell-Berreman equation for plane waves in anisotropic medium, transformation of tangential field components and normal component of the Poynting vector in the anisotropic system of thin films, combination of thin and thick anisotropic layers, reversibility theorem, examples of usage