Dual recycling for GEO 600

Abstract
Dual recycling is the combination of power recycling and signal recycling. GEO 600, a German-British interferometric gravitational wave detector being built in Germany, has no arm cavities and needs to use dual recycling from the beginning, while the other interferometric detectors may use it at a later stage to enhance their sensitivity. The control scheme to be used in GEO 600 has been demonstrated at the Garching 30 m prototype. This paper summarizes those results and the adaptions necessary in order to apply the scheme for GEO 600.