DC-readout of a signal-recycled gravitational wave detector

S. Hild, H. Grote, J. Degallaix, S. Chelkowski, K. Danzmann, A. Freise, M. Hewitson, J. Hough, H. Lück, M. Prijatelj, K.A. Strain, J.R. Smith, B. Willke

Research output: Contribution to JournalArticleAcademicpeer-review


All first-generation large-scale gravitational wave detectors are operated at the dark fringe and use a heterodyne readout employing radio frequency (RF) modulation-demodulation techniques. However, the experience in the currently running interferometers reveals several problems connected with a heterodyne readout, of which phase noise of the RF modulation is the most serious one. A homodyne detection scheme (DC-readout), using the highly stabilized and filtered carrier light as a local oscillator for the readout, is considered to be a favourable alternative. Recently a DC-readout scheme has been implemented on the GEO 600 detector. We describe the results of first measurements and give a comparison of the performance achieved with homodyne and heterodyne readout. The implications of the combined use of DC-readout and signal recycling are considered. © 2009 IOP Publishing Ltd.
Original languageEnglish
JournalClassical and Quantum Gravity
Issue number5
Publication statusPublished - 2009
Externally publishedYes


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