Valliyakalayil, Jobin ThomasWade, AndrewRabeling, DavidZhang, JueShaddock, DanielMcKenzie, Kirk2025-05-232025-05-232470-0010ORCID:/0000-0002-1463-4595/work/184100088http://www.scopus.com/inward/record.url?scp=85204706691&partnerID=8YFLogxKhttps://hdl.handle.net/1885/733751333Laser frequency noise suppression is a critical requirement for the Laser Interferometer Space Antenna (LISA) mission to detect gravitational waves. The baseline laser stabilization is achieved using cavity prestabilization and a postprocessing technique called Time-Delay Interferometry (TDI). To enhance the margins for TDI, alternate laser-locking schemes should be investigated. A novel stabilization blending the excellent stability of the arm with the existing cavity reference has been shown theoretically to meet the first-generation TDI margins. This locking system was designed to be implemented as a firmware change and have minimal or no changes to the LISA hardware. This paper experimentally verifies the hybrid laser-locking technique by utilizing two references - an optical cavity and an interferometer with delay imparted using 10 km of optical fiber. The results indicate the viability of the combination of the arm-cavity-locking system for LISA. They show the key benefits envisioned by this technique: suppression of the cavity fluctuations by the arm sensor (by 21 dB in this demonstration) and reduction of Doppler pulling of the laser frequency, a key technical challenge for arm locking.The authors acknowledge that this research was conducted with support from the Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav), through Project No. CE170100004.enPublisher Copyright: © 2024 American Physical Society.2024-09-1510.1103/PhysRevD.110.06200485204706691