S Hild et al 2009 Class. Quantum Grav. 26 055012 doi:10.1088/0264-9381/26/5/055012
S Hild1, H Grote2, J Degallaix2, S Chelkowski1, K Danzmann2, A Freise1, M Hewitson2, J Hough3, H Lück2, M Prijatelj2, K A Strain3, J R Smith4 and B Willke2
Show affiliationsAll 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.
Issue 5 (7 March 2009)
Received 19 November 2008, in final form 8 January 2009
Published 17 February 2009
S Hild et al 2009 Class. Quantum Grav. 26 055012
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