Fiber Bragg Grating Interrogator Tunable Waveguide Sensitivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fiber Bragg grating interrogator systems face challenges in sensitivity due to polarization dependency and difficulty in maintaining the initial Bragg wavelength between the center wavelengths of output ports, leading to suboptimal performance in detecting damage in composite structures.
Innovation Solution
The system splits orthogonal polarization components of incoming light onto non-overlapping spectral ranges, allowing for accurate correction of polarization dependency and improved sensitivity by using an arrayed waveguide grating with tunable waveguides to optimize spectral energy distribution, enabling precise Bragg wavelength determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the initial Bragg wavelength is located precisely between the center wavelengths of two associated output ports of the AWG, then the sensitivity of the system is greatest, but it is rather difficult to effect this condition on installation
Solution Approach 1:
The patent applies parameter changes by making the waveguides tunable, allowing the spectral ranges of the output ports to be adjusted after installation. This enables the system to achieve optimal sensitivity conditions (Bragg wavelength positioned between center wavelengths of output ports) without requiring precise installation, as the parameters can be tuned to compensate for installation variations.
2Adaptability or versatility
If an FBG sensor has a relatively large dynamic range over which its Bragg wavelength may shift during use, then the sensor can accommodate wavelength shifts, but a Bragg wavelength may easily shift outside the spectral range of at least one of the output ports, which may render an accurate wavelength determination impossible
Solution Approach 1:
The patent applies dynamics by making the waveguide spectral ranges tunable and adjustable. This allows the system to adapt to large dynamic ranges of the FBG sensor by dynamically reconfiguring the spectral ranges of the output ports to always encompass the shifted Bragg wavelength, ensuring accurate wavelength determination throughout the entire dynamic range.
Solution Approach 2:
The patent uses parameter changes by adjusting the spectral ranges of the output ports to match the dynamic range of the FBG sensor. This ensures that even when the Bragg wavelength shifts significantly during use, it remains within the measurable spectral range of the appropriate output port.
3Measurement precision
If the spectrally selective device is used to split orthogonal polarization components, then polarization dependency can be corrected, but the device complexity increases due to production variations of optical waveguides
Solution Approach 1:
The patent applies feedback by using the detected polarization components to correct for polarization dependency in the spectrally selective device. The system measures the polarization states and uses this information to compensate for device-induced polarization effects, thereby improving measurement accuracy despite production variations in the optical waveguides.
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 enhances the sensitivity and accuracy of Bragg wavelength measurement, compensating for polarization dependency and allowing for reliable health monitoring of structures over a large wavelength range.
Implementation Method 1
the spectrally selective device is configured to split two orthogonal polarization components of incoming light onto substantially non-overlapping spectral ranges in the spectral energy distribution of said output ports
Implementation Method 2
arrayed waveguide grating with tunable waveguides to optimize spectral energy distribution
Implementation Method 3
fiber Bragg grating (FBG) sensor that is interrogated by an arrayed wave guide (AWG) based interrogator, which system may infer the existence of various kinds of damage to the monitored structure from changes in the Bragg wavelength
Data Source
AI summary
A fiber Bragg grating interrogator assembly, comprising: an optical fiber including a fiber Bragg grating (FBG; 122) having a variable Bragg wavelength (λB) and a dynamic range of interest (Δλdyn,B) over which the Bragg wavelength (λB) can shift during use; —a light source operably connected to the optical fiber, and configured to illuminate the fiber Bragg grating to solicit a response therefrom; and an response analyzer, including: a spectrally selective device having an input port and a plurality of output ports (149-n), wherein the input port is operably connected to the optical fiber and wherein each of the output ports is associated with a respective spectral range (Δλn), said spectrally selective device being configured to provide a spectral energy distribution of a response of the fiber Bragg grating received on the input port onto said output ports.