FBG Sensor Interrogation with Tunable Optical Bandpass Filtering
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Solution Overview
Problem
Existing methods for interrogating Fiber Bragg Grating (FBG) sensors are complex, slow, and susceptible to spurious power variations, with limited dynamic performance and high cost, making them unsuitable for applications in harsh environments.
Innovation Solution
A method and system using a tunable optical bandpass filter, specifically an optical micro-ring resonator, to interrogate FBG sensors by detecting optical signals at complementary ports, compensating for power variations and enabling quick, robust measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sequential wavelength scanning is used to interrogate FBG sensors, then measurement accuracy is improved, but response time deteriorates
Solution Approach 1:
The patent uses periodic wavelength scanning with a tunable filter to interrogate FBG sensors. The filter scans through the wavelength range periodically, and the reflected light intensity variations during this periodic scan are used to determine the FBG wavelength shift. This periodic scanning approach enables accurate measurement while maintaining relatively fast response times compared to continuous full-spectrum analysis.
2Adaptability or versatility
If tunable devices are used for wavelength scanning, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent introduces a tunable optical filter as an intermediary device between the broadband light source and the FBG sensor. This filter selectively transmits specific wavelength ranges, enabling wavelength-tuned interrogation of the FBG sensor without requiring the entire system to be complex. The filter acts as a mediator that simplifies the overall system architecture while maintaining measurement capability.
3Productivity
If continuous wavelength scanning is performed, then dynamic performance is improved, but susceptibility to spurious power variations worsens
Solution Approach 1:
The patent employs feedback mechanisms where the reflected light intensity from the FBG sensor during wavelength scanning is continuously monitored and processed. The system uses this feedback information to track the FBG wavelength shift dynamically. By comparing the reflected intensity variations against the known filter transmission characteristics, the system can distinguish between actual FBG wavelength shifts and spurious power variations in the optical path.
4Measurement precision
If broadband reception with tunable receiver is used, then wavelength resolution is improved, but system cost increases
Solution Approach 1:
The patent uses a single tunable optical filter that serves multiple functions: it performs wavelength scanning, provides wavelength selection, and enables dynamic interrogation of FBG sensors. This multi-functional approach eliminates the need for separate expensive components such as spectrometers or multiple fixed wavelength sources, thereby reducing system cost while maintaining wavelength resolution capability.
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
The system provides compact, simple, and cost-effective FBG sensor interrogation with improved dynamic performance and immunity to spurious losses, suitable for measuring strain and temperature in various environments.
Implementation Method 1
tunable optical bandpass filter, specifically an optical micro-ring resonator
Implementation Method 2
tunable optical bandpass filter BPF
Implementation Method 3
Fiber Bragg Grating type, the spectrum reflected or transmitted thereby must be analyzed
Data Source
AI summary
A method for interrogating an FBG sensor includes lighting the FBG sensor with a broadband excitation optical radiation, conveying the optical spectrum transmitted or reflected by the FBG sensor to a tunable optical BPF having a first extraction port and a second transmission port, tuning the optical BPF at a constant operating wavelength, depending on nominal operating wavelength of the FBG sensor, detecting a first optical signal exiting the first extraction port, converting, by a first opto-electronic receiver, the first optical signal into a first electrical signal, representative of a wavelength shift of the spectrum transmitted or reflected by the FBG sensor, detecting a second optical signal exiting the second transmission port, converting the second optical signal, by a second opto-electronic receiver, into a second electrical signal, representative of an optical reference power, and determining the wavelength shift of the spectrum transmitted or reflected by FBG sensor, based on detected first and second electrical signals. A system for interrogating an FBG sensor is also provided.