Herstellung, Charakterisierung und Anwendung von ionenstrahlgesputterten optischen Schichten (English shop)

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This thesis describes the fabrication of optical coatings by means of reactive ion beam sputter deposition. The thin films produced by this process are of high quality with minimal absorption and can therefore also be used at high optical power densities and intracavity. The use of various oxides (SiO2, Al2O3, Y2O3, Ta2O5 and TiO2) opens up, owing to the wide range of refractive indices, a multitude of optoelectronic applications. For the characterisation of the fabricated films, ellipsometry is used above all to determine the layer thickness and the refractive index. The photothermal deflection method allows the determination of the very low absorptions. Measurements of the spectral reflection and the surface roughness as well as etching experiments complement the film investigations. The applications of the optical coatings are examined primarily on edge-emitting semiconductor lasers. Anti-reflection (AR), high-reflection (HR) and far-field-modifying coatings thereby influence the optical properties of the lasers. The facet reflectivity is determined by measuring the threshold current shift and by the Hakki–Paoli modulation measurement. Passivation of the coated laser facets increases the catastrophic optical mirror damage (COMD) threshold and the lifetime. The dielectric films are moreover also applied to semiconductor disk lasers, vertical emitters, light-emitting diodes, detectors as well as to sensor and electronic devices, in order to illustrate their wide field of application.