Noise analyses of Vernier-effect-based fiber sensing systems

Area of Science:

• Optical sensing technologies
• Fiber optic interferometry
• Metrology and measurement science

Background:

• Vernier-effect-based fiber sensing systems utilize spectral interferograms for physical parameter measurement.
• Amplitude noise in these systems introduces measurement errors, with limited understanding of its impact.
• Accurate identification of spectral envelope extrema is crucial for precise sensing.

Purpose of the Study:

• To propose a model for amplitude noise distribution in Vernier-effect spectral interferograms.
• To investigate the statistical characteristics of errors in identifying spectral envelope extrema.
• To compare the performance of two distinct extremum identification methods under amplitude noise.

Main Methods:

• Development of a mathematical model for amplitude noise distribution.
• Numerical simulations to analyze error statistics in extremum identification.
• Evaluation of direct fringe extremum locating versus envelope fitting methods.

Main Results:

• The standard variance of extremum deviation using direct fringe locating is bandwidth-limited, improving with signal-to-noise ratio (SNR) and free spectral range (FSR).
• The envelope fitting method demonstrates a consistently small standard variance, independent of envelope bandwidth.
• Amplitude noise significantly affects direct extremum identification but is mitigated by the fitting approach.

Conclusions:

• The envelope fitting method offers superior robustness against amplitude noise for Vernier-effect fiber sensors.
• The proposed noise model and analysis provide a theoretical foundation for enhancing sensor accuracy.
• These findings support the broader application of Vernier-effect-based sensors in various physical parameter measurements.