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arXiv · 0811.3242

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. Lueck·M. Prijatelj·K. A. Strain·J. R. Smith·B. Willke
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Abstract

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 local oscillator for the readout, is considered to be a favourable alternative. Recently a DC-readout scheme was 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.

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S. Hild, H. Grote, J. Degallaix, S. Chelkowski, K. Danzmann, A. Freise, M. Hewitson, J. Hough, H. Lueck, M. Prijatelj, K. A. Strain, J. R. Smith, B. Willke. 2008-11-19. DC-readout of a signal-recycled gravitational wave detector. https://doi.org/10.1088/0264-9381/26/5/055012

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