Quantum Optics Seminar by Christoffer Møller – Niels Bohr Institute - University of Copenhagen

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Quantum Optics Seminar by Christoffer Møller

This talk will outline how the use of a common-path photo-thermal
deflection set-up allows the measurement of a few ppm/cm absorption levels
in Silicon at 1550nm. Methods by which the thermal expansion coefficient
and young's modulus of thin films can be determined are also addressed as
well as their use in quantifying the thermo-elastic loss of thin film
mirror coatings.
These material characteristics are of great interest to next generation
gravitational wave detectors as a switch to either silicon or sapphire
mirror substrates have been suggested.  The proposed change comes as a
result of the thermal noise associated with a mechanical loss peak in
fused silica (currently used substrate) at cryogenic temperatures.