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A Silicon-tipped Fiber-optic Sensing Platform with High Resolution and Fast Response
Published on: January 7, 2019
Phase-demodulation error of a fiber-optic Fabry-Perot sensor with complex reflection coefficients.
J M Kilpatrick1, W N MacPherson, J S Barton
1Department of Physics, Heriot-Watt University, Edinburgh EH14 4AS, UK.
Applied Optics
|March 14, 2008
Summary
Reflector losses in fiber optic Fabry-Perot (FFP) sensors can cause significant phase errors during demodulation. Neglecting reflected fringe asymmetry leads to inaccuracies, particularly in phase-stepped methods.
Area of Science:
- Optics and Photonics
- Sensor Technology
- Interferometry
Background:
- Standard Fabry-Perot interferometer models often overlook reflector losses.
- These losses can be a significant source of error in fiber optic Fabry-Perot (FFP) sensor applications.
- Accurate phase demodulation is critical for reliable sensor performance.
Purpose of the Study:
- To investigate the impact of reflector losses on FFP sensor accuracy.
- To develop a general transfer function accounting for complex reflection coefficients.
- To quantify systematic phase errors introduced by neglecting fringe asymmetry.
Main Methods:
- Developed a general transfer function for FFP sensors incorporating complex reflection coefficients.
- Modeled systematic phase errors arising from neglected reflected fringe asymmetry.
- Measured the asymmetric response of metal-dielectric FFP sensors with varying finesse.
Main Results:
- A model predicting systematic phase errors was developed.
- Measured asymmetric responses corroborated the model's predictions.
- A low-finesse FFP sensor (R=0.05) with 25% internal reflector losses showed a 0.06 rad phase error in three-step demodulation.
Conclusions:
- Reflector losses are a critical, often overlooked, factor in FFP sensor accuracy.
- The developed model accurately predicts phase errors due to fringe asymmetry.
- Accurate FFP sensor demodulation requires considering complex reflection coefficients and reflector losses.
