Optical Fiber Ring Interferometer Signal Fading Mitigation
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Solution Overview
Problem
Optical fiber ring interferometers face signal fading issues due to the length dependency of detected signals, making it difficult to detect and characterize disturbances, especially in multi-path and multi-wavelength systems, and are limited by environmental impedance mismatch and inter-wavelength interference.
Innovation Solution
The solution involves relocating the reference coil to the center of the sensing extension in single-path systems, rearranging the interferometer loop topology to position insensitivity points differently in multi-path systems, and using separate light sources and coils for each wavelength in multi-wavelength systems, along with impedance matching techniques and concentrated point sensors to enhance signal detection and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a significantly longer length of optical fiber is used for the reference coil to increase signal gain and bandwidth, then the frequency bandwidth and gain of the detected signal improve, but signal fading occurs which lessens the ring interferometer's ability to detect disturbances
Solution Approach 1:
The patent segments the optical fiber into multiple independent paths (first path, second path, third path) with different lengths and characteristics. Each path contributes differently to the interference signal, allowing the system to maintain high gain while avoiding signal fading by distributing the reference coil functionality across multiple segmented paths rather than using a single long reference coil
Solution Approach 2:
The patent employs asymmetric path lengths among the multiple optical fiber paths, where the first path has a first length, the second path has a second length, and the third path has a third length. This asymmetry ensures that insensitivity points (signal fading locations) occur at different positions in each path, preventing simultaneous fading across all paths and maintaining reliable disturbance detection
2Adaptability or versatility
If multiple topological variants of ring interferometer are used to detect rotational motion and acousto-mechanical disturbances, then the application range and detection capability improve, but inter-wavelength interference occurs in multi-wavelength systems
Solution Approach 1:
The patent segments the optical system into multiple wavelength-specific paths, where each path is configured to handle a specific wavelength range. This segmentation prevents inter-wavelength interference by isolating different wavelength components in separate interference paths that can be processed independently
Solution Approach 2:
The patent applies local quality by optimizing each optical path for specific wavelengths, where the first path, second path, and third path can be tailored with different characteristics suitable for their respective wavelength ranges, allowing the system to maintain high adaptability across multiple applications while eliminating cross-wavelength interference
3Adaptability or versatility
If environmental impedance mismatch is present in the sensing extension, then the ring interferometer can operate in various environmental conditions, but signal detection capability is impeded
Solution Approach 1:
The patent introduces an intermediary mechanism through the multi-path optical fiber configuration that mediates between the sensing extension and the detection system. The multiple paths with different lengths and characteristics act as intermediaries that can adapt to various environmental impedance conditions while maintaining sufficient signal strength for accurate disturbance detection
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 mitigates signal fading, allows for more accurate disturbance location and characterization with lower data sampling rates, increases detected signal strength, and eliminates inter-wavelength interference, enabling effective detection and analysis of disturbances in various optical fiber ring interferometer topologies.
Implementation Method 1
A ring interferometer, as known to a person of ordinary skill in the art (POSITA), is a common path interferometer which uses the Sagnac effect to act as a rate of rotation detector
Implementation Method 2
Additional optical fiber based topologies of a ring interferometer are described
Data Source
AI summary
An optical fiber ring interferometer is provided, which is based on a common light path for two or more light beam pairs preferably originated from two or more light sources of a substantially different spectrum or from a single light source split spectrum and whereas each light beam of a specific pair is propagating in relative opposite directions, wherein at least one pair of light beams is utilized to detect acousto-mechanical events and to provide information regarding location and other characteristics of detected environmental disturbance.