Time-delay interferometry with onboard optical delays

TL;DR

This paper investigates the impact of onboard optical delays on time-delay interferometry for space-based gravitational-wave detectors, deriving models and compensation schemes to improve noise reduction accuracy.

Contribution

It introduces analytical models for onboard optical path lengths in TDI and proposes a compensation scheme validated through numerical simulations.

Findings

Onboard optical delays significantly affect TDI performance.

The derived models accurately predict the coupling of optical delays.

The proposed compensation scheme effectively mitigates onboard optical path length effects.

Abstract

Time-delay interferometry (TDI) is a data processing technique for space-based gravitational-wave detectors to create laser-noise-free equal-optical-path-length interferometers virtually on the ground. It relies on the interspacecraft signal propagation delays, which are delivered by intersatellite ranging monitors. Also delays due to onboard signal propagation and processing have a nonnegligible impact on the TDI combinations. However, these onboard delays were only partially considered in previous TDI-related research; onboard optical path lengths have been neglected so far. In this paper, we study onboard optical path lengths in TDI. We derive analytical models for their coupling to the second-generation TDI Michelson combinations and verify these models numerically. Furthermore, we derive a compensation scheme for onboard optical path lengths in TDI and validate its performance via numerical simulations.