Interferometry with nano-structured optics

	Nano-structured beam splitter on the basis of a diffraction grating.

We research and develop nano-structured diffraction gratings to split and recombine laser beams in advanced gravitational wave detectors. These all-reflective components can replace the partly transmissive mirrors used in today's detectors. The sensitivity limiting problem of heat absorption in transmissive elements can be solved with this technology.

A new low-loss interferometer concept was demonstrated with custom fabricated gratings [1]. Optimization of the grating design and improvements of the lithographic manufacturing process led to gratings with unprecedented optical quality. A world record diffraction efficiency of 99.62 % has been achieved [2].

Bibliography:

[1] A. Bunkowski, O. Burmeister, P. Beyersdorf, K. Danzmann, and R. Schnabel, T. Clausnitzer, E.-B. Kley, A. Tünnermann, "Low-loss grating for coupling to a high-finesse cavity", Optics Lett. 29, 2342 (2004).

[2] A. Bunkowski, O. Burmeister, T. Clausnitzer, E.-B. Kley, A. Tünnermann, K. Danzmann, R. Schnabel, "Optical Characterization of ultra-high efficiency gratings", Appl. Opt. 45, 5795 (2006).

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