Lab experiments for interferometry on Earth
A good fraction of the more than 2000 square meter large laboratory space of the AEI is devoted to the experiments in the area of ground based interferometry.
The large floor space and the availability of a crane makes a high bay an ideal location for the AEI 10 m prototype. A second large area is occupied by a copy of the pre-stabilized Advanced LIGO 200 W laser. Furthermore several experiments are devoted to high power lasers and their stabilization:
The Advanced LIGO laser provides a highly stable 165 W laser beam in a clean spatial mode. This beam is used
- to optimize the power and frequency stabilization of the Advanced LIGO light source [Kwee et al. Opt. Lett. (2011)]
- in a second-harmonic-generation (SHG) experiment to generate a 130 W laser beam at 532nm [Meier et al. Opt. Lett. (2010)]
- to illuminate a diffractive optical element generating a 83W beam in the Laguerre-Gauss LAG33 mode spatially filtered by a ring resonator (in collaboration with University of Birmingham) [Carbone, L. et al. Phys. Rev. Lett. (2013)]
- measure the thermal lens in several optical components as Faraday Isolators, electro-optical modulators and other non-linear optical material that develops under high power illumination (in collaboration with University of Glasgow) [Bogan et al., in prep. (2013)]
Interferometric measurements often require an extraordinary high power stability of the light source. The crucial part of power stabilization experiments is the sensing of the power fluctuations. AEI physicists were able to achieve the world-wide best power stability of a laser which is equivalent to the shot noise of 200 mA of photocurrent [Kwee et al. Opt. Lett. (2009)].
A small table-top experiment is used to test and optimize the length and alignment control of two cavities used in a particle-physics experiment called ALPS in collaboration with DESY Hamburg. The main challenge of this experiment is, to stabilize an optical resonator to an imaginary gaussian beam without using any light with the same properties as this fictive beam.