Enhanced Frequency noise suppression for LISA by combining cavity and arm locking control systems

Arm locking in conjunction with time-delay interferometry

“…Such a scheme inherits the delimited laser frequency pulling and low-frequency noise coupling of common arm locking while retaining the advantage of dual-arm locking. More recently, the compatibility between the cavity stabilization and the arm locking was also discussed, and a new type of arm-locking sensor integrated with the Pound-Dever-Hall (PDH) error signals has been proposed [44]. In this scenario, the noise is feedback controlled by the hybrid combination between the arm locking and PDH locking loops, and no additional hardware is required.…”

“…To be more specific, we make the following estimations following [44,48]. The first-generation TDI considers static arm lengths.…”

“…By assuming the worst-case scenario that the relative velocity between spacecraft is ∆v ∼ 10ms −1 , which leads to an armlength mismatch of ∆L TDI1.0 166m. As a result, the upper bound of the laser frequency noise is estimated to be [44,48]…”

“…On the other hand, the arm-locking technique typically provides a suppression in the laser frequency noise of 2-4 orders of magnitude [38,44,48]. Compared to the difference between the first and second-generation TDI, which is approximately two orders of magnitude, it is competent for the task.…”