FBG Measurement Device Using SOA Lasing and Timing Discrimination
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Solution Overview
Problem
Conventional optical fiber measurement systems using fiber Bragg gratings (FBGs) are limited by the narrow wavelength range, leading to a restricted number of sensing locations that can be accurately analyzed, and require complex and costly systems for distinguishing responses from different FBGs.
Innovation Solution
A measurement device incorporating a semiconductor optical amplifier (SOA) and a filter element with a wavelength-dependent transmission coefficient, which enables lasing at unique wavelengths for each FBG, allowing for accurate measurement of local parameters like temperature and strain without the need for expensive spectral analysis equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional spectral analysis systems are used to measure local parameters at multiple sensing locations, then measurement precision is maintained, but device complexity and cost increase significantly
Solution Approach 1:
The patent extracts only the essential function needed for measurement by using a simple photodetector to detect intensity changes at a fixed wavelength, eliminating the need for complex spectral analysis equipment while maintaining the ability to distinguish signals from different FBGs through timing measurements
Solution Approach 2:
The patent uses timing information as a copy or alternative representation of spectral information, where the arrival time of reflected pulses from different FBGs serves as a unique identifier for each sensing location, replacing the need for full spectral analysis
2Measurement precision
If the C-band wavelength range is used for FBG sensing, then measurement precision is maintained, but the number of distinguishable sensing locations is limited
Solution Approach 1:
The patent transitions from using only wavelength as the distinguishing dimension to adding time as a second dimension, where sensing locations are distinguished by both their reflected wavelength and their timing in the pulse sequence, dramatically increasing the number of distinguishable locations
Solution Approach 2:
The patent employs periodic pulsed illumination of the FBG array, where each pulse illuminates all FBGs simultaneously and the reflected pulses return at different times based on their positions, enabling time-based discrimination of multiple sensing locations
3Quantity of substance
If wavelength reuse with timing separation is implemented to increase the number of sensing locations, then the number of sensing locations increases, but system complexity and cost increase due to requirements for both spectral analysis and timing measurements
Solution Approach 1:
The patent extracts only the timing information from the reflected pulses using a simple photodetector and timing circuitry, discarding the need for complex spectral analysis while maintaining the ability to distinguish and count multiple sensing locations based on their temporal separation
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
Enables accurate and cost-effective measurement of local parameters at multiple sensing locations by distinguishing unique lasing wavelengths, improving spectral resolution and reducing system complexity.
Implementation Method 1
a semiconductor optical amplifier, SOA, comprising: a control input for receiving electrical current pulses to control the repetition rate of said SOA, an optical input for receiving light pulses to be amplified, and an optical output for emitting light pulses
Implementation Method 2
an optical fiber element incorporating an array of fiber Bragg gratings, FBGs... Each FBG typically reflects one wavelength and allows transmission of all other wavelengths
Implementation Method 3
a filter element configured with a wavelength dependent transmission coefficient so that the filter element is able to filter the intensity of light transmitted from the respective optical cavities
Data Source
AI summary
The present disclosure relates to a measurement device (1) for measuring a local parameter using an optical fiber element incorporating an array (100) of fiber Bragg gratings, FBGs, (101, 102, 103, 104), the measurement device (1) comprising: a semiconductor optical amplifier, SOA, (10), wherein the measurement device (1) is configured to be able to cause lasing at a respective lasing wavelength of said FBG (101, 102, 103, 104) of the FBG array (100); wherein the measurement device (1) further comprising: a filter element (40) configured with a wavelength dependent transmission coefficient; an output light sensing element (50) configured to detect said intensity of filtered light pulses from the filter element (40) and emit a corresponding electrical signal; processing means (60) for converting the electrical signal to the local parameter being measured for said one of the FBGs (101, 102, 103, 104) of the FBG array (100), and for providing the local parameter being measured. A measurement method (S100) is also disclosed.