Effects of static and dynamic higher-order optical modes in balanced homodyne readout for future gravitational waves detectors

Zhang, T. et al. (2017) Effects of static and dynamic higher-order optical modes in balanced homodyne readout for future gravitational waves detectors. Physical Review D, 95(6), 062001. (doi: 10.1103/PhysRevD.95.062001)

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With the recent detection of Gravitational waves (GW), marking the start of the new field of GW astronomy, the push for building more sensitive laser-interferometric gravitational wave detectors (GWD) has never been stronger. Balanced homodyne detection (BHD) allows for a quantum noise (QN) limited readout of arbitrary light field quadratures, and has therefore been suggested as a vital building block for upgrades to Advanced LIGO and third generation observatories. In terms of the practical implementation of BHD, we develop a full framework for analyzing the static optical high order modes (HOMs) occurring in the BHD paths related to the misalignment or mode matching at the input and output ports of the laser interferometer. We find the effects of HOMs on the quantum noise limited sensitivity is independent of the actual interferometer configuration, e.g. Michelson and Sagnac interferometers are effected in the same way. We show that misalignment of the output ports of the interferometer (output misalignment) only effects the high frequency part of the quantum noise limited sensitivity (detection noise). However, at low frequencies, HOMs reduce the interferometer response and the radiation pressure noise (back action noise) by the same amount and hence the quantum noise limited sensitivity is not negatively effected in that frequency range. We show that the misalignment of laser into the interferometer (input misalignment) produces the same effect as output misalignment and additionally decreases the power inside the interferometer. We also analyze dynamic HOM effects, such as beam jitter created by the suspended mirrors of the BHD. Our analyses can be directly applied to any BHD implementation in a future GWD. Moreover, we apply our analytical techniques to the example of the speed meter proof of concept experiment under construction in Glasgow. We find that for our experimental parameters, the performance of our seismic isolation system in the BHD paths is compatible with the design sensitivity of the experiment.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Spencer, Dr Andrew and Pascucci, Daniela and Danilishin, Dr Stefan and Bell, Dr Angus and Hild, Professor Stefan and Barr, Dr Bryan and Sorazu Lucio, Dr Borja and Dupej, Mr Peter and Leavey, Mr Sean and Hennig, Mr Jan-Simon and Steinlechner, Dr Sebastian and Wright, Ms Jennifer and Houston, Mr Ewan and Huttner, Dr Sabina and Strain, Professor Kenneth and Zhang, Mr Teng
Authors: Zhang, T., Danilishin, S. L., Steinlechner, S., Barr, B. W., Bell, A. S., Dupej, P., Gräf, C., Hennig, J.-S., Houston, E. A., Huttner, S. H., Leavey, S. S., Pascucci, D., Sorazu, B., Spencer, A., Wright, J., Strain, K. A., and Hild, S.
College/School:College of Science and Engineering > School of Physics and Astronomy
Research Centre:College of Science and Engineering > School of Physics and Astronomy > Institute for Gravitational Research
Journal Name:Physical Review D
Publisher:American Physical Society
ISSN (Online):1550-7998
Published Online:06 March 2017
Copyright Holders:Copyright © 2017 American Physical Society
First Published:First published in Physical Review D 95(6): 062001
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
624341Investigations in Gravitational Radiation / Particle Astrophysics Capital equipmentSheila RowanScience & Technologies Facilities Council (STFC)ST/L000946/1S&E P&A - PHYSICS & ASTRONOMY
683761AQUIREStefan HildEuropean Commission (EC)658366S&E P&A - PHYSICS & ASTRONOMY