Control of the laser frequency in the Virgo interferometer: Dynamic noise budgeting for controller optimization

• Published in: Astroparticle physics 2025-01, Vol.164, p.103028, Article 103028
• Main Authors: van Dael, Mathyn, Casanueva, Julia, Witvoet, Gert, Swinkels, Bas, Bersanetti, Diego, Pinto, Manuel, Ruggi, Paolo, Mantovani, Maddalena, de Rossi, Camilla, Spinicelli, Piernicola, Boldrini, Mattia, Oomen, Tom
• Format: Article
• Language: English
• Subjects: Advanced Virgo Plus; Gravitational Waves; Laser frequency stabilization; Noise budget; Systematic control design; ℋ2 synthesis
• ISSN: 0927-6505
• DOI: 10.1016/j.astropartphys.2024.103028

This paper presents a framework for the derivation of a noise budget and the subsequent utilization in the optimization of the control design, using the laser frequency stabilization loop in the Virgo interferometer, which is a complex nested feedback system, as an experimental case study. First, the system dynamics and noise sources are modeled and experimentally verified to produce the noise budget, after which an optimization problem using the H2 norm is formulated and tailored to the specific design requirements for the detector. The structure of the synthesized controller is then used to produce an improved control design. Experimental verification of the developed controller on the Virgo interferometer shows roughly a factor 3 reduction in root-mean-square error, illustrating the effectiveness of the presented method.