Self-adaptive demodulation for polarization extinction ratio in distributed polarization coupling

Area of Science:

• Optical Engineering
• Fiber Optics
• Metrology

Background:

• Accurate polarization extinction ratio (PER) measurement is crucial for optical systems.
• Existing methods for distributed PER demodulation can be complex and time-consuming.
• Challenges exist in adapting demodulation techniques to varying coupling conditions in polarizing devices.

Purpose of the Study:

• To demonstrate a novel self-adaptive method for distributed PER demodulation.
• To improve the efficiency and accuracy of PER measurements in polarizing devices.
• To enable automated and selective accumulation of coupling points for precise PER calculation.

Main Methods:

• Development of a self-adaptive algorithm featuring dynamic PER threshold coupling intensity (TCI) and nonuniform PER iteration step length (ISL).
• Adaptive determination of contributing coupling points within polarizing devices based on preset accuracy and original coupling intensity.
• Automated and selective accumulation of identified coupling points for distributed PER calculation.

Main Results:

• The proposed method achieved distributed PER measurements in just 3-5 iterations for two types of polarization-maintaining fibers.
• High consistency was observed when comparing results with a commercial Thorlabs instrument.
• An optimal preset PER calculation accuracy of 0.05 dB was determined through extensive experimentation.

Conclusions:

• The self-adaptive PER demodulation method offers an efficient and accurate approach for optical metrology.
• The dynamic adjustment of TCI and ISL allows for robust performance across different fiber types and coupling conditions.
• This technique provides a reliable and consistent means for distributed PER assessment, validated by experimental comparisons.