Jena 2013 – scientific programme

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GR: Fachverband Gravitation und Relativitätstheorie

GR 23: Poster (permanent)

GR 23.3: Poster

Friday, March 1, 2013, 14:45–14:45, HS 6

Optical absorption of silicon around the fundamental band gap at low temperatures — •Philip Pastrik, Julius Komma, Gerd Hofmann, Christian Schwarz, Daniel Heinert, Paul Seidel, and Ronny Nawrodt — Institut für Festkörperphysik, FSU Jena, Helmholtzweg 5, D-07743 Jena

Silicon is a promising candidate material for the test masses of future gravitational wave detectors operated at cryogenic temperatures. Any optical absorption will introduce heat into the detector’s substrates and, thus, should be minimized. For this reason a laser wavelength of 1550 nm is used with an energy well below the fundamental band gap of silicon. Nevertheless, multiple phonon processes will even lead to an absorption at 1550 nm and can influence the working temperature of the detector.

We studied the optical absorption of silicon near its band gap in a wide temperature range from 5 K to 300 K. In their fine structure these measurements reveal information on the emission and absorption of phonons. We also report a strong temperature dependence of these effects. Thus our results will be valuable for a systematic understanding of the absorption in silicon at 1550 nm.

This work is supported by the German science foundation DFG under contract SFB TR7.