Frauke Modugno

Frauke joined the group in 2020 as a Bachelor’s student of mechanical engineering. In her Bachelor’s thesis, she worked on the design and development of an OPO with a large round trip length.

During her Master’s thesis for the Optical Technologies and Biomedical Engineering degrees, she worked on optical metrology in the ‘Applied Photonics’ group at the Hannover Centre for Optical Technologies.

Frauke rejoined the ‘QuantumControl’ group in April 2024 as a PhD student in physics. Her research focus is the development of large, heavy interferometer mirrors for next-generation gravitational wave detectors (GWDs), e.g. the Einstein Telescope (ET), made of high-purity monocrystalline silicon.

In the low-frequency part of the planned ET, cryogenic temperatures will be used to reduce thermal noise and thus increase detection sensitivity. At low temperatures, silicon has significantly lower mechanical loss (lower thermal noise) than fused silica, which is used in current, 2nd-generation GWDs.
The ET test mass mirror parameters are bounded by quantum radiation pressure noise (mirror mass ≈ 200 kg), thermal noise, and the interferometer (laser beam size → mirror diameter ≥ 45 cm). Currently, silicon of this size and purity cannot be produced.

The scientific approach involves the development and upscaling of composite test mass mirrors, which are realized through ‘direct bonding’ and characterized with optical measurement methods. The development of bonding parameters involves work in Hannover (e.g. at the LNQE) and in the laboratories of the DZA in Görlitz.
A critical influence for the test masses comes from optical absorption, which gives rise to different noise contributions in ET, limiting the sensitivity. Therefore, a low absorption is targeted. In addition, transmittance, reflectance, and scattering are planned to be characterized.