Proposal for phase-sensitive heterodyne detection in large-scale passive resonant gyroscopes

Area of Science:

• Physics
• Geophysics
• Optical Engineering

Background:

• Large-scale passive resonant gyroscopes (PRGs) are crucial for measuring Earth's rotation.
• Traditional methods face limitations in sensitivity and noise reduction.

Purpose of the Study:

• To develop an advanced phase-sensitive heterodyne detection scheme for large-scale PRGs.
• To enhance the measurement accuracy of Earth's rotation and explore new applications.

Main Methods:

• Injecting three separated beams into different longitudinal modes of the ring cavity.
• Implementing self-demodulation of detected signals to isolate disturbances.
• Utilizing a novel detection scheme to double the Sagnac frequency.

Main Results:

• Successfully isolated backscattering disturbance and cavity length fluctuation effects.
• Achieved a doubled Sagnac frequency, enhancing the equivalent scale factor.
• Significantly improved signal-to-noise ratio, suppressing quantum noise limits.

Conclusions:

• The new scheme offers a theoretical rotational sensitivity of 10⁻¹² rad/s/Hz for a 3m x 3m PRG.
• Enables precise measurement of the length of day.
• Provides a platform for testing general relativity with unprecedented accuracy.