Non-geometric tilt-to-length coupling in precision interferometry: mechanisms and analytical descriptions

Abstract

This paper is the second in a set of two investigating tilt-to-length (TTL) coupling. TTL describes the cross-coupling of angular or translational jitter into an interferometric phase signal and is an important noise source in precision interferometers, including space gravitational wave detectors like LISA. We discussed in 10.1088/2040-8986/ac675e the TTL coupling effects originating from optical path length changes, i.e. geometric TTL coupling. Within this work, we focus on the wavefront and detector geometry dependent TTL coupling, called non-geometric TTL coupling, in the case of two interfering fundamental Gaussian beams. We characterise the coupling originating from the properties of the interfering beams, i.e. their absolute and relative angle at the detector, their relative offset and the individual beam parameters. Furthermore, we discuss the dependency of the TTL coupling on the geometry of the detecting photodiode. Wherever possible, we provide analytical expressions for the expected TTL coupling effects. We investigate the non-geometric coupling effects originating from beam walk due to the angular or translational jitter of a mirror or a receiving system. These effects are directly compared with the corresponding detected optical path length changes in 10.1088/2040-8986/ac675e. Both together provide the total interferometric readout. We discuss in which cases the geometric and non-geometric TTL effects cancel one-another. Additionally, we list linear TTL contributions that can be used to counteract other TTL effects. Altogether, our results provide key knowledge to minimise the total TTL coupling noise in experiments by design or realignment.

References in corpus (7)

• Laser Interferometer Space Antenna
• On orbit performance of the GRACE Follow-On Laser Ranging Interferometer
• LISA technology and instrumentation
• Design and construction of an optical test bed for LISA imaging systems and tilt-to-length coupling
• Vanishing tilt-to-length coupling for a singular case in two-beam laser interferometers with Gaussian beams
• LISA Pathfinder
• Geometric tilt-to-length coupling in precision interferometry: mechanisms and analytical descriptions

Cited by in corpus (7)

• Tilt-to-length coupling in LISA Pathfinder: a data analysis
• Tilt-to-length coupling in LISA Pathfinder: analytical modelling
• Detection and Mitigation of Glitches in LISA Data: A Machine Learning Approach
• Searching for gravitational-wave bursts with space-borne detectors
• Post-processing subtraction of tilt-to-length noise in LISA in the presence of gravitational wave signals
• Tilt-To-Length Coupling in LISA -- Uncertainty and Biases
• Experiment demonstration of tilt-to-length coupling suppression by beam-alignment-mechanism