Jena 2013 – wissenschaftliches Programm
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GR: Fachverband Gravitation und Relativitätstheorie
GR 23: Poster (permanent)
GR 23.5: Poster
Freitag, 1. März 2013, 14:45–14:45, HS 6
Monolithic silicon grating reflectors - Current status, chances and challenges for future gravitational wave detection — •Stefanie Kroker, Thomas Käsebier, Stefan Steiner, Ernst-Bernhard Kley, and Andreas Tünnermann — Friedrich-Schiller-Universität Jena Institut für Angewandte Physik, Abbe Center of Photonics, Max-Wien-Platz 1, 07743 Jena, Germany
In order to enhance the sensitivity of future gravitational wave detectors (GWDs), particularly the Brownian coating thermal noise of the optical components in the GWD has to be reduced. Besides an improvement of well-established highly reflective amorphous multilayer stacks two alternative approaches are under investigation: crystalline coatings based on AlxGa1−xAs or AlxGa1−xP and monolithic resonant high-contrast gratings made of crystalline silicon. We discuss possibilities and current achievements of silicon reflectors with respect to feasible reflectance, spectral, angular bandwidth and thermal noise. To optimize the optical performance of the gratings we evaluate the impact of structure deviations on the maximum specular reflectance. It is distinguished between an enhanced transmittance and scattered light. Both result from fabrication processes, whereas the latter might severely disturb the signal in a GWD. It is found, that different parts of the grating structure exhibit significant differences in their sensitivity concerning structural imperfections. These results allow the optimization of fabrication for an improved optical performance. Concluding we compare the current status of crystalline coatings and silicon reflectors for applications in future gravitational wave detectors.