Optical Frequency Comb Multiplexing for Precision Ranging and High-Rate Communication in Space-Borne Gravitational Wave Detection

Future space-based gravitational wave observatories, such as LISA and TianQin, require inter-satellite laser links that simultaneously support ultra-precise ranging, low-noise scientific phase measurements, and high-integrity data communication. Traditional pseudo-random noise (PRN) phase modulation on continuous-wave (CW) lasers is limited by phase disruption, bandwidth constraints, and poor spectral utilization. In this paper, we propose a unified inter-satellite ranging and communication architecture based on electro-optically generated optical frequency combs (OFCs). The system employs wavelength-division multiplexing (WDM) to assign distinct comb lines for PRN-based coarse ranging, high-throughput communication, and unmodulated dual-comb interferometry. A hierarchical ranging mechanism combines PRN time-of-flight estimation with dual-comb phase extraction, achieving sub-millimeter accuracy over million-kilometer baselines. System-level simulations based on LISA mission parameters demonstrate nanometric ranging resolution, data rates exceeding 1 Gbps, and minimal phase distortion in the scientific channel. The proposed architecture is compatible with existing EOM-based hardware and scalable to photonic integration, offering a promising solution for precision metrology and data transfer in next-generation space missions.