Birefringent Multi-Peak Optical Reference Element for Polarization Drift
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Solution Overview
Problem
Birefringent optical fiber sensors face challenges in accurately measuring Bragg wavelengths due to sensitivity to residual polarization and polarization-dependent loss, which cause drift and uncertainty in measurements.
Innovation Solution
A birefringent multi-peak optical reference element is used in an optical sensing system, producing a plurality of wavelength functions with peaks spaced over a range of wavelengths due to orthogonal birefringence axes, allowing for the determination of characteristic wavelengths of optical sensing elements by comparing sensor and reference electrical signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard optical fiber sensor is used to measure Bragg wavelengths, then the sensor can detect physical parameters such as pressure and temperature, but the measurement accuracy deteriorates due to sensitivity to residual polarization and polarization-dependent loss causing drift and uncertainty
Solution Approach 1:
The invention segments the single peak reference spectrum into multiple peaks by introducing birefringence through geometric asymmetry or anisotropic stress. This creates multiple resolvable wavelength functions (at least three) that can be individually tracked, eliminating the drift and uncertainty issues associated with single-peak polarization-sensitive measurements.
Solution Approach 2:
The invention deliberately introduces geometric asymmetry or anisotropic stress into the optical waveguide to create birefringence. This asymmetry causes the single peak to split into multiple peaks corresponding to different polarization modes, providing a reference spectrum that is insensitive to residual polarization effects while maintaining measurement accuracy.
2Measurement precision
If a birefringent multi-peak optical reference element is used to eliminate polarization sensitivity, then measurement stability and accuracy improve, but the device complexity increases due to the need to introduce and control birefringence
Solution Approach 1:
The invention applies birefringence locally within a specific section of the optical waveguide rather than throughout the entire system. This is achieved by introducing geometric asymmetry or anisotropic stress only in the reference element region, keeping the rest of the sensing system simple while achieving the desired multi-peak reference spectrum.
Solution Approach 2:
The invention changes the physical parameters of the optical waveguide (geometric asymmetry or stress state) to induce birefringence. By controlling these parameters, the single peak is transformed into multiple resolvable peaks, providing a stable reference that eliminates polarization sensitivity without requiring complex additional components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach eliminates drift issues associated with residual polarization and polarization-dependent loss, providing stable and accurate measurements of Bragg wavelengths, independent of input light polarization state.
Implementation Method 1
A birefringent multi-peak optical reference element is used in an optical sensing system, producing a plurality of wavelength functions with peaks spaced over a range of wavelengths due to orthogonal birefringence axes
Implementation Method 2
allowing for the determination of characteristic wavelengths of optical sensing elements by comparing sensor and reference electrical signals
Data Source
AI summary
Certain aspects of the present disclosure generally relate to an optical reference element having a wavelength spectrum comprising a plurality of wavelength functions having wavelength peaks spaced over a range of wavelengths, wherein adjacent wavelength functions are due to two orthogonal birefringence axes in the optical reference element. Aspects of the present disclosure may eliminate the drift issues associated with residual polarization and polarization dependent loss (PDL) with respect to grating-based sensor and reference element measurements.