Abstract
LISA is a proposed space-based laser interferometer detecting gravitational waves by measuring distances between free-floating test masses housed in three satellites in a triangular constellation with laser links in-between. Each satellite contains two optical benches that are articulated by moving optical subassemblies for compensating the breathing angle in the constellation. The phase reference distribution system, also known as backlink, forms an optical bi-directional path between the intra-satellite benches.In this work we discuss phase reference implementations with a target non-reciprocity of at most μrad , equivalent to 1 pm for a wavelength of 1064 nm in the frequency band from 0.1 mHz to 1 Hz. One phase reference uses a steered free beam connection, the other one a fiber together with additional laser frequencies. The noise characteristics of these implementations will be compared in a single interferometric set-up with a previously successfully tested direct fiber connection. We show the design of this interferometer created by optical simulations including ghost beam analysis, component alignment and noise estimation. First experimental results of a free beam laser link between two optical set-ups that are co-rotating by ±1° are presented. This experiment demonstrates sufficient thermal stability during rotation of less than 10−4 K at 1 mHz and operation of the free beam steering mirror control over more than 1 week.
Highlights
The laser interferometer space antenna (LISA) has recently been chosen by the European space agency (ESA) as L3 mission and will consist of three spacecraft (S/C) forming a cartwheel formation following the Earth around the sun [1,2,3]
Taking into account a suppression factor of two orders of magnitude for the polarization components which are not included in the IfoCAD simulation, we find that only the interferometer with the direct fiber link scheme will be limited by ghost beams
LthIaStAharseqauniroens-arenciopprtoicciatlypbhealsoewre1feprmen√ceHbze−tw1.eFenorththeestwe ophoapsteicraelfbereennccheess in the each satellite ghost beams generated by fiber back scatter are critical, as is the case for the performance of all local interferometers
Summary
The laser interferometer space antenna (LISA) has recently been chosen by the European space agency (ESA) as L3 mission and will consist of three spacecraft (S/C) forming a cartwheel formation following the Earth around the sun [1,2,3]. Laser frequency noise limits the readout of the S/C separations in LISA because it enters the phase measurement due to the arm length mismatches of up to 25 000 km This effect is suppressed in data post-processing by time-delay interferometry (TDI) [12, 13], which forms linear combinations of the local and the inter-S/C phase measurements from different arms with time-delayed versions of themselves. The direct optical connection between the fiber injector optical subassembly (FIOS [19]), delivering the transmitted (TX) beam and the local oscillator (LO) beam, leads to back scatter in both fibers and this, in turn, to collinear ghost beams interfering at the critical heterodyne frequencies These parasitic beats couple into all local interferometers, requiring balanced detection to reduce more than two orders of magnitude of phase noise in each one
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
