TDM WDM Fast-Sweep Interrogator for Optical Sensor Multiplexing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional swept-wavelength Bragg grating interrogators are limited in the number of sensors that can be interrogated on a single fiber due to the use of only wavelength division multiplexing, and existing techniques for increasing sensor count, such as swept-wavelength interferometry and time-gated lasers, suffer from limited spatial window range and wavelength resolution.
Innovation Solution
A method and apparatus for fast sweeping a spectral bandwidth to distinguish among wavelength division multiplexed (WDM) and time division multiplexed (TDM) optical components on a single fiber, involving a pulse of light introduced into an optical waveguide with a sweep of wavelengths completed in less than the round-trip time for light to reach a receiver, allowing for effective multiplexing of multiple sensors using both WDM and TDM techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wavelength division multiplexing (WDM) is used to interrogate sensors, then measurement accuracy is maintained, but the number of sensors that can be interrogated on a single fiber is limited
Solution Approach 1:
The patent combines wavelength division multiplexing (WDM) and time division multiplexing (TDM) techniques into a hybrid interrogation system. WDM separates sensors by wavelength while TDM separates them by time of flight, allowing the system to interrogate multiple sensors on a single fiber without compromising measurement accuracy. The optical source sweeps through a wavelength range and detects reflected signals at different times, enabling both multiplexing dimensions to work together.
Solution Approach 2:
The patent adds the time dimension to the traditional wavelength-based sensor interrogation. By measuring the time of flight of reflected optical pulses and correlating it with wavelength information, the system creates a two-dimensional detection space (wavelength × time) that significantly increases the number of distinguishable sensors on a single fiber compared to wavelength-only interrogation.
2Quantity of substance
If swept-wavelength interferometry is used to increase sensor count, then more sensors can be interrogated, but spatial window range and wavelength resolution are limited
Solution Approach 1:
The patent employs continuous wavelength sweeping across the entire spectral range of interest, rather than discrete wavelength steps. This continuous sweep allows for high wavelength resolution by capturing the full spectral profile of each sensor's reflection. The system maintains continuous operation throughout the measurement process, ensuring no useful signal information is lost while achieving both high sensor count and high resolution.
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 enables the interrogation of multiple optical elements on a single fiber with improved accuracy and repeatability by distinguishing signals based on timing and wavelength, increasing the number of sensors that can be multiplexed and measured effectively.
Implementation Method 1
introducing a pulse of light, by an optical source, into an optical waveguide to interrogate at least a first set of optical elements having different characteristic wavelengths by performing a sweep of wavelengths over a period of the pulse, wherein the period is less than a round-trip time for light reflected from an optical element closest to the optical source to reach a receiver
Implementation Method 2
at least a first set of optical elements disposed along the optical waveguide and having different characteristic wavelengths which reflect interrogating light at the characteristic wavelength
Data Source
AI summary
Methods and apparatus for fast sweeping a spectral bandwidth in order to distinguish among signals received from effectively wavelength division multiplexed (WDMed) and time division multiplexed (TDMed) optical components on a single fiber. For some embodiments, a method for interrogating optical elements having characteristic wavelengths spanning a sweep range is provided. The method generally includes introducing a pulse of light, by an optical source, into an optical waveguide to interrogate at least a first set of optical elements having different characteristic wavelengths by performing a sweep of wavelengths over a period of the pulse, wherein the period is less than a round-trip time for light reflected from an optical element closest to the optical source to reach a receiver and processing the reflected light to determine a parameter based on the times at which signals are received.