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GR: Fachverband Gravitation und Relativitätstheorie

GR 5: Experimente

GR 5.1: Vortrag

Dienstag, 26. Februar 2013, 16:30–16:45, HS 6

Optical grating concepts 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

Many experiments in the field of optical high-precision metrology are limited in their sensitivity by the thermal noise of optical components, for example, mirrors or beam splitters. Amorphous coating stacks are known to be a major source for these thermal fluctuations. In this contribution we discuss concepts to realize coating free optical components based on subwavelength resonant high contrast gratings (HCGs). The use of crystalline silicon promises a low level of thermal noise. Beside classical cavity mirrors HCGs can also be used to realize reflective cavity couplers acting as beam splitters for the incident light. Therefore, a large angular tolerance of the HCG reflectors has to be ensured. In order to realize HCGs with such angular broadband reflectivity two approaches are presented. The first makes use of stacking HCGs whereas the second benefits from polarization effects in HCGs with two-dimensional periodicity. For reflective beam splitters these angular broadband reflectors can be combined with either additional superposed lateral (grating duty cycle, ridge positions) or transversal (grating thickness) modulations to provide the subwavelength structures with diffraction orders. The diffraction efficiency can therewith be tuned with the strength of the modulation.