Multiplexed Fiber-Coupled Fabry-Perot Sensors for Interference Reduction
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Solution Overview
Problem
Existing optical sensor networks face limitations in dynamic range and inter-sensor interference, particularly in fiber-Bragg grating and Fabry-Perot cavity-based sensors, which restrict their deployment in various applications.
Innovation Solution
The implementation of Fabry-Perot sensors operatively coupled with wavelength-selective filters in a single-fiber network, where each sensor operates within a unique wavelength band to prevent interference, allowing multiple sensors to be multiplexed without degrading the signal-to-noise ratio, and using a light source to launch a range of wavelengths onto an optical fiber bus for reflection-based measurand measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple Fabry-Perot sensors are multiplexed in a single-fiber network, then the quantity of sensors increases, but inter-sensor interference degrades the signal-to-noise ratio
Solution Approach 1:
The optical spectrum is segmented into distinct wavelength bands, with each Fabry-Perot sensor assigned to a specific wavelength band. Wavelength-selective filters (such as FBGs or thin-film filters) are used to separate the reflected signals from different sensors by their wavelength, preventing inter-sensor interference and maintaining signal-to-noise ratio while enabling multiplexing of multiple sensors on a single fiber.
2Measurement precision
If Fabry-Perot sensors are used for high dynamic range measurements, then measurement precision improves, but device complexity increases due to inter-sensor interference issues
Solution Approach 1:
Wavelength-selective filters act as intermediaries between the Fabry-Perot sensors and the interrogation system. These filters (such as fiber-Bragg gratings or thin-film filters) selectively reflect or transmit specific wavelength bands, enabling the system to distinguish signals from different sensors without direct interference, thus maintaining high dynamic range while managing system complexity through wavelength division multiplexing.
3Ease of operation
If fiber-Bragg grating sensors are used for easy multiplexing, then ease of operation improves, but dynamic range is limited
Solution Approach 1:
The patent combines Fabry-Perot cavity sensors with wavelength-selective filters (such as FBGs) to create a hybrid sensor system. The Fabry-Perot cavity provides high dynamic range measurement capability, while the wavelength-selective filter enables easy multiplexing by assigning each sensor a unique wavelength band. This merging of two sensor types leverages the advantages of both approaches.
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 a high dynamic range optical sensor network with reduced interference, allowing for accurate and efficient measurement of multiple measurands without the limitations of prior art, enhancing the deployment of sensor networks in diverse applications.
Implementation Method 1
Each sensor includes a Fabry-Perot cavity that is optically coupled with a reflective wavelength filter
Implementation Method 2
Each sensor operates in reflection mode to reflect a signal back into the fiber bus, where the reflected signal from each sensor is within a different wavelength band that is uniquely identified with that sensor
Implementation Method 3
a light source that launches a range of wavelengths, comprising a plurality of wavelength bands, onto an optical fiber bus
Implementation Method 4
Each sensor operates in reflection mode to reflect a signal back into the fiber bus
Data Source
AI summary
A sensor network having a series arrangement of fiber-coupled, reflective sensors is disclosed. In operation, a first light signal having multiple wavelength bands is launched in an upstream direction on a fiber bus. Each sensor includes a wavelength filter and an FP sensor that is sensitive to a parameter. Each wavelength filter (1) selectively passes a different one of the wavelength bands to its FP sensor and (2) reflects the remaining wavelength bands back into the fiber bus to continue upstream. The FP sensor imprints a signal based on the parameter onto its received light and reflects it as a second light signal. The collimator, wavelength filter, and FP sensor of each sensor are arranged such that each second light signal is returned to the fiber bus, which conveys them in a downstream direction to a processor that measures them and estimates the parameter at each sensor.