Common-mode phase noise suppression with an open-loop differential phasemeter

Area of Science:

• Optical Physics
• Metrology
• Interferometry

Background:

• Differential optical interferometry is crucial for precise measurements.
• Conventional phasemeters struggle with common-mode signal dynamics and require high dynamic range.
• Tracking optical phase differences can be challenging due to noise and signal instability.

Purpose of the Study:

• To introduce a novel open-loop phasemeter topology for direct differential phase recovery.
• To reduce dynamic range requirements by mitigating common-mode signal dynamics before phase tracking.
• To enhance the performance of differential optical interferometric measurements.

Main Methods:

• Developed an open-loop phasemeter topology for differential phase recovery.
• Implemented a technique to remove common-mode signal dynamics prior to phase tracking.
• Experimentally demonstrated a phase difference measurement using the proposed technique.

Main Results:

• Achieved a phase sensitivity of 1 × 10^-6 rad/√Hz.
• Demonstrated a common-mode noise rejection of 141 dB.
• Successfully measured phase differences even when individual channels experienced cycle slips and were unable to track phase.

Conclusions:

• Direct differential phase recovery offers a robust solution for optical interferometry.
• The proposed technique significantly improves phase sensitivity and noise rejection.
• This method enables accurate phase measurements in challenging conditions with unstable channels.