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arXiv · 0903.3324

Coupling of lateral grating displacement to the output ports of a diffractive Fabry-Perot cavity

J. Hallam·S. Chelkowski·A. Freise·S. Hild·B. Barr·K. A. Strain·O. Burmeister·R. Schnabel
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Abstract

Diffraction gratings have been proposed as core elements in future laser-interferometric gravitational-wave detectors. In this paper, we use a steady-state technique to derive coupling of lateral grating displacement to the output ports of a diffractive Fabry-Perot cavity. By introducing a signal to noise ratio (SNR) for each of the three cavity output ports the magnitude of the noise sidebands originating from lateral grating displacement are compared to the magnitude of a potential gravitational wave signal. For the example of a 3km long Fabry-Perot cavity featuring parameters similar to the planned Advanced Virgo instrument, we found that the forward-reflecting grating port offers the highest SNR at low frequencies. Furthermore, for this example suspension requirements for lateral isolation were computed, and a factor of twenty relaxation at a frequency of 10Hz can be gained over the transmitted port by observing the forward-reflected port.

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J. Hallam, S. Chelkowski, A. Freise, S. Hild, B. Barr, K. A. Strain, O. Burmeister, R. Schnabel. 2009-03-19. Coupling of lateral grating displacement to the output ports of a diffractive Fabry-Perot cavity. https://doi.org/10.1088/1464-4258/11/8/085502

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