A low-noise analog frontend design for the Taiji phasemeter prototype

Area of Science:

• Astrophysics
• Instrumentation

Background:

• The Taiji program requires precise measurement of picometer-level movements between free-floating test masses using laser interferometry.
• Phasemeters are critical for phase readout, needing accuracy of μrad/Hz to detect the beat note.
• Noise from the analog frontend of analog-to-digital converters is a primary limitation in phasemeter performance.

Purpose of the Study:

• To develop and test a self-designed phasemeter prototype for the Taiji program.
• To address the main noise source in phasemeters: the analog frontend.
• To ensure the phasemeter meets the stringent sensitivity requirements for gravitational wave detection.

Main Methods:

• Development of a novel phasemeter prototype incorporating a low-noise analog frontend.
• Implementation of pilot tone correction techniques to mitigate noise.
• Experimental testing of the prototype to evaluate its performance and sensitivity.

Main Results:

• The developed phasemeter prototype demonstrates performance satisfying the Taiji program's sensitivity requirements across the entire frequency range.
• Achieved a sensitivity of 0.5 μrad/Hz within the 0.1-1 Hz frequency band.
• The prototype's successful testing validates its design for future, fully functional Taiji phasemeters.

Conclusions:

• The self-designed phasemeter prototype is a viable and effective solution for the Taiji program's phase readout needs.
• The low-noise analog frontend and pilot tone correction are key to achieving the required sensitivity.
• This prototype serves as a strong foundation for the development of the complete Taiji phasemeter system.