Sensor noise in LISA Pathfinder: laser frequency noise and its coupling to the optical test mass readout

Armano, M. et al. (2024) Sensor noise in LISA Pathfinder: laser frequency noise and its coupling to the optical test mass readout. Physical Review D, 109(4), 042003. (doi: 10.1103/PhysRevD.109.042003)

Abstract

The LISA Pathfinder (LPF) mission successfully demonstrated the feasibility of the technology needed for the future space borne gravitational wave observatory LISA. A key subsystem under study was the laser interferometer, which measured the changes in relative distance in between two test masses (TMs). It achieved a sensitivity of 32.0 + 2.4 − 1.7     fm / √ Hz , which was significantly better than the prelaunch tests. This improved performance allowed direct observation of the influence of laser frequency noise in the readout. The differences in optical path lengths between the measurement and reference beams in the individual interferometers of our setup determined the level of this undesired readout noise. Here, we discuss the dedicated experiments performed on LPF to measure these differences with high precision. We reached differences in path length difference between ( 368 ± 5 )     μm and ( 329.6 ± 0.9 )     μm which are significantly below the required level of 1 mm or 1000     μm . These results are an important contribution to our understanding of the overall sensor performance. Moreover, we observed varying levels of laser frequency noise over the course of the mission. We provide evidence that these do not originate from the laser frequency stabilization scheme which worked as expected. Therefore, this frequency stabilization would be applicable to other missions with similar laser frequency stability requirements.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Robertson, Dr David and Korsakova, Dr Natalia and Ward, Professor Henry and Perreur-Lloyd, Mr Michael and Killow, Dr Christian
• Authors: Armano, M., Audley, H., Baird, J., Binetruy, P., Born, M., Bortoluzzi, D., Brandt, N., Castelli, E., Cavalleri, A., Cesarini, A., Cruise, A. M., Danzmann, K., de Deus Silva, M., Diepholz, I., Dixon, G., Dolesi, R., Ferraioli, L., Ferroni, V., Fitzsimons, E. D., Flatscher, R., Freschi, M., García, A., Gerndt, R., Gesa, L., Giardini, D., Gibert, F., Giusteri, R., Grimani, C., Grzymisch, J., Guzman, F., Harrison, I., Hartig, M.-S., Hechenblaikner, G., Heinzel, G., Hewitson, M., Hollington, D., Hoyland, D., Hueller, M., Inchauspé, H., Jennrich, O., Jetzer, P., Johann, U., Johlander, B., Karnesis, N., Kaune, B., Killow, C. J., Korsakova, N., Lobo, J. A., López-Zaragoza, J. P., Maarschalkerweerd, R., Mance, D., Martín, V., Martin-Polo, L., Martin-Porqueras, F., Martino, J., McNamara, P. W., Mendes, J., Mendes, L., Meshksar, N., Monsky, A., Nofrarias, M., Paczkowski, S., Perreur-Lloyd, M., Petiteau, A., Plagnol, E., Ramos-Castro, J., Reiche, J., Rivas, F., Robertson, D. I., Russano, G., Sanjuan, J., Slutsky, J., Sopuerta, C. F., Steier, F., Sumner, T., Texier, D., Thorpe, J. I., Vetrugno, D., Vitale, S., Wand, V., Wanner, G., Ward, H., Wass, P. J., Weber, W. J., Wissel, L., Wittchen, A., and Zweifel, P.
• 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: 2470-0010
• ISSN (Online): 2470-0029
• Published Online: 15 February 2024
• Copyright Holders: Copyright © 2024 American Physical Society
• First Published: First published in Physical Review D 109(4): 042003
• Publisher Policy: Reproduced under a Creative Commons License