Following the successful on-orbit verification of the "Taiji-1" interferometer in 2019, the gravitational wave experimental center team at the Institute of Mechanics, Chinese Academy of Sciences (hereinafter referred to as the Institute), addressing the ultra-high-precision laser interferometry requirements of the Taiji Program, designed and implemented for the first time a full-function optical bench interferometer platform suitable for the Taiji Program, and completed ground-based performance testing and noise assessment of the system, paving the way for the engineering realization of the interferometer for gravitational wave detection in the Taiji Program. This marks a significant milestone in transitioning the Taiji Program's interferometer system from a principle prototype to an engineering prototype. The related findings were published in the international journal Research, a collaboration between the American Association for the Advancement of Science and the China Association for Science and Technology.
The Taiji Program is a space-based gravitational wave detection initiative proposed by the Chinese Academy of Sciences. The program employs three satellites to form a laser interferometer with an arm length of 3 million kilometers, detecting gravitational wave signals in the frequency range of 0.1 millihertz to 1 hertz. This requires the interferometer to achieve picometer-level ranging precision, posing unprecedented challenges to environmental control, instrument performance, and noise analysis.
To meet the practical demands of million-kilometer-scale arm lengths and picometer-level measurement precision, the research team defined the required functions and corresponding performance specifications for the interferometer model, and accordingly designed a full-function interferometer optical platform. The platform innovatively adopts a three-dimensional layout with "forward and reverse separation," effectively isolating the impact of heat sources on the optical path and significantly enhancing the system's thermal stability in the space environment. Additionally, the design is compatible with vertical beam connections to the telescope and inertial sensor, offering high functional completeness.
Leveraging the picometer-precision laser interferometry platform at the Institute's Beijing Huairou campus, the research team conducted comprehensive stability testing and noise assessment of the interferometer optical platform. Targeting the noise sources, the team developed a data post-processing suppression method. After applying this method, the system stability in the target frequency band improved by an order of magnitude, and the performance now meets the interferometer system specifications required for the Taiji Program's space-based gravitational wave detection mission.