Experimental validation of time-delay interferometry for space-borne gravitational-wave detectors using electro-optic modulation

Abstract Laser frequency noise is the primary noise source in space gravitational wave detection, and the main method for its suppression is to construct equal-arm interferometers using time-delay interferometry (TDI) technology. However, how to simulate the million-kilometer-level time delays and arm length variations in space is a key challenge for ground-based experimental verification of TDI. In this paper, a simulation method using an electro-optic modulator (EOM) as the core device was proposed, an experimental optical platform was constructed to simulate the time delay and to verify the noise-reduction capability of TDI. The simulation of time-delayed laser noise was implemented by adding frequency noise with a delay of several seconds to the laser beam through EOM-based phase modulation, approximating actual mission conditions. Theoretical modeling and analysis of the system indicate that the TDI algorithm achieves noise suppression down to the fundamental limit set by the experimental setup’s noise floor.