Laser Interferometry and Nano-Structured Optics

Mirrors and beam splitters with nano-structured surfaces have applications in high-precision interferometry. A reflection grating can be used to couple a laser beam into a high-finesse resonator without transmitting the light through an optical material. Nano-structured surfaces can also replace multilayer dielectric anti- or high-reflectivity coatings.

The Quantum Interferometry Group researches the application of nano-structured optics in high-precision laser interferometry. This work is performed in collaboration with the University of Jena in the framework of the SFB TR7 “Gravitational Wave Astronomy”.

The QI-Group has demonstrated ultra-high diffraction efficiency (>99.6%) reflection gratings.

All-reflectively coupled optical cavities with finesse values of several thousands were demonstrated and an all-reflected Michelson interferometer with power-recycling resonator was realized.

A recent success was the realization of a high-reflectivity mirror from a pure silicon crystal [Brückner et al.,Phys. Rev. Lett. 104, 163903 (2010)]. No material was added to the crystal but a surface nano-structure etched into it. This structure established a wave-guide which provided a reflectivity of 99.8% for laser light at 1550 nm for normal incidence.

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