Recent Development of the Laser Interferometer for Taiji Space Gravitational Wave Detection

In this study, we have designed a full-function interferometer OB (optical bench) for the Taiji program and, for the first time, provided detailed parameter specifications for its interferometer system. Additionally, we constructed a first-generation Taiji interferometer OB and ground test system and conducted preliminary testing and calibration. A comprehensive analysis was carried out on the various noise sources impacting the interferometer system, including laser frequency noise, laser power noise, thermal drift noise, and angular jitter noise. The results revealed that the noise level of the interferometer system reached 1.1 pm/Hz 1/2 at 1 Hz, 5 pm/Hz 1/2 at 0.1 Hz, and 8 pm/Hz 1/2 at 0.01 Hz; these levels satisfied the requirements of the Taiji-2 mission. This work marks the first step in transitioning the Taiji program’s interferometer system from a principle prototype to an engineering prototype, playing a critical role in its future development.