Axion-like Dark Matter Search with Space-based Gravitational Wave Detectors

Abstract: We propose a novel modification to the optical benches of space-based gravitational wave detectors (SGWDs) to enable the detection of axion-like dark matter (ALDM)-induced birefringence without altering the polarization of inter-spacecraft laser links. Our design introduces an auxiliary interferometer to convert polarization modulation into measurable phase shifts. Analytical expressions for sensitivity to the ALDM-photon coupling are derived for various time-delay interferometry (TDI) combinations. Projected sensitivity curves demonstrate complementary coverage across the ALDM mass range $10^{-19}\sim10^{-14}\mathrm{eV}$. This approach preserves the original interferometric stability while enabling new physics capabilities for SGWDs.