Zero-fringe demodulation method based on location-dependent birefringence dispersion in polarized low-coherence...

Area of Science:

• Optics and Photonics
• Metrology and Measurement Science
• Sensor Technology

Background:

• Polarized low-coherence interferometry is crucial for high-resolution measurements.
• Location-dependent birefringence dispersion presents challenges in accurate signal demodulation.
• Existing methods often involve complex computations, limiting real-time applications.

Purpose of the Study:

• To develop a high-precision and fast-speed demodulation method for polarized low-coherence interferometers.
• To address the issue of location-dependent birefringence dispersion.
• To reduce computational load and avoid fringe order ambiguity.

Main Methods:

• Utilizing the characteristics of location-dependent birefringence dispersion.
• Implementing a five-step phase-shifting technique.
• Processing data solely in the spatial domain, avoiding Fourier transforms.

Main Results:

• Accurate retrieval of the zero-fringe peak position at the central wavelength.
• Successful demonstration in an optical fiber Fabry-Perot barometric pressure sensing system.
• Achieved measurement precision of 0.091 kPa over a 160 kPa range.
• Reduced computation time by 10 times compared to traditional methods.

Conclusions:

• The proposed method offers a significant improvement in speed and precision for low-coherence interferometry.
• It effectively resolves fringe order ambiguity caused by birefringence dispersion.
• The spatial domain processing approach greatly reduces computational complexity for practical sensing applications.