Phase noise suppression technique based on an improved reference interferometer scheme

Area of Science:

• Optical Engineering
• Signal Processing
• Interferometry

Background:

• Reference interferometer schemes are effective for noise reduction but require strictly equal optical path length differences (OPDs), limiting practical applications.
• Phase noise and nonlinear distortions are significant challenges in interferometric measurements, especially when OPDs vary.

Purpose of the Study:

• To propose and validate an improved reference interferometer demodulation technique that eliminates the strict requirement for equal OPDs.
• To suppress phase noise and mitigate nonlinear distortions in interferometric measurements.

Main Methods:

• Introduction of a reference interferometer to remove phase noise from demodulation results.
• Combination of a differential self-multiplication algorithm and a fitted phase modulation depth calculation formula.
• Real-time evaluation of phase modulation depth for both interferometers and simultaneous elimination of nonlinear distortion and OPD effects.

Main Results:

• The technique achieves highly stable and accurate demodulation results even with different OPDs between interferometers.
• Phase modulation depth calculation error is less than 0.57%.
• Maximum phase noise reduction reaches 15 dB (average 9 dB), with minimum total harmonic distortion of 0.17% and SINAD reaching 35.90 dB.

Conclusions:

• The proposed technique effectively removes phase noise and compensates for unequal OPDs in reference interferometer schemes.
• This method offers a robust solution for accurate and stable interferometric measurements in diverse practical environments.
• The technique significantly improves signal quality by reducing noise and harmonic distortion.