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. Luck, M. Prijatelj, K.A. Strain, J.R. Smith, B. Willke

*Corresponding author for this work

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.
Original languageEnglish
Article number055012
Number of pages10
JournalClassical and Quantum Gravity
Issue number5
Publication statusPublished - 7 Mar 2009
Externally publishedYes



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