  Dual recycling is the combination of signal recycling and power recycling;
both optical techniques improve the shot-noise-limited sensitivity of
interferometric gravitational-wave detectors. In addition, signal recycling can
reduce the loss of light power due to imperfect interference and allows, in
principle, to beat the standard quantum limit. The interferometric
gravitational-wave detector GEO600 is the first detector to use signal
recycling. We have recently equipped the detector with a signal-recycling
mirror with a transmittance of 1%. In this paper, we present details of the
detector commissioning and the first locks of the dual- recycled
interferometer.
