Noise suppression of laser jitter in space laser interferometer

In the “Taiji mission”, the laser jitter noise caused by satellite jitter is one of the main noise sources that affect the accuracy of laser interferometer. In order to ensure the measurement accuracy, the noise must be suppressed to 10 nrad/$\sqrt{{\rm{Hz}}} $@10 mHz. Firstly, an angle sensor composed of a four-quadrant photodetector and a phase meter was used to measure the angle signal, and a Mach-Zehnder interferometer combined with proportional-integral-derivative control technology was used to build a ground-based laser jitter noise suppression system. Secondly, the feedback control capability of the system and the effectiveness of the system to suppress laser jitter noise were analyzed. The experimental results showed that the system could effectively suppress the laser jitter noise, and the laser jitter noise was <4 nrad/$\sqrt{{\rm{Hz}}} $@10 mHz. The experiment advanced the study of the “Taiji mission” on the level of laser jitter noise suppression, which laid a physical experimental foundation for laser interferometry.