ALPS II control system prototype
AEI has built and is operating a miniaturized 1-meter prototype of ALPS II to investigate fundamental concepts of the experiment.
Among the issues investigated are the stability of some optomechanical components and the overall stabilization concept of the system.
The optomechanical components were developed at AEI and their required stability was demonstrated. For the ALPS II experiment, it is also essential that the length of the production cavity and the regeneration cavity are matched. This requires a suitable control system, which was tested with the prototype.
For this experimental demonstration, the frequency of a high-power laser was first stabilized to the length of the production cavity by means of a suitable control loop. In a further step, the frequency of an additional reference laser was stabilized to the length of the regeneration cavity with frequency doubling and a suitable control loop. In the last step, the length of the production cavity was tuned to the length of the regeneration cavity by means of phase stabilization.