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arXiv · 1504.06503

Birefringence Measurements on Crystalline Silicon

Christoph Krüger·Daniel Heinert·Alexander Khalaidovski·Jessica Steinlechner·Ronny Nawrodt·Roman Schnabel·Harald Lück
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Abstract

Crystalline silicon has been proposed as a new test mass material in third generation gravitational wave detectors such as the Einstein Telescope (ET). Birefringence can reduce the interferometric contrast and can produce dynamical disturbances in interferometers. In this work we use the method of polarisation-dependent resonance frequency analysis of Fabry-Perot-cavities containing silicon as a birefringent medium. Our measurements show a birefringence of silicon along the (111) axis of the order of $\Delta\, n \approx 10^{-7}$ at a laser wavelength of 1550nm and room temperature. A model is presented that explains the results of different settings of our measurements as a superposition of elastic strains caused by external stresses in the sample and plastic strains possibly generated during the production process. An application of our theory on the proposed ET test mass geometry suggests no critical effect on birefringence due to elastic strains.

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Christoph Krüger, Daniel Heinert, Alexander Khalaidovski, Jessica Steinlechner, Ronny Nawrodt, Roman Schnabel, Harald Lück. 2015-04-24. Birefringence Measurements on Crystalline Silicon. https://doi.org/10.1088/0264-9381/33/1/015012

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