Stress-Managed Optical Fiber for Pressure and Micro-Bending Sensing
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Solution Overview
Problem
Existing single mode optical fibers are less sensitive to pressure and weight, and specialty fibers required for specific sensing applications have complex designs and are difficult to manufacture.
Innovation Solution
An optical fiber design with a core and two cladding layers, where the first cladding layer has low residual stress and the second cladding layer has high compressive stress, enhancing sensitivity to geometrical deformations and micro-bending loss, while maintaining a simple structure and ease of manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If specialty fibers are used to enhance sensitivity to pressure and weight, then sensing performance is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The cladding is segmented into multiple layers with different stress characteristics. The first cladding layer has low residual stress while the second cladding layer has high compressive stress, allowing each layer to contribute differently to the overall sensing performance and mechanical properties without requiring complex specialty fiber designs
Solution Approach 2:
Different regions of the fiber structure are assigned different stress properties. The core region has high compressive stress for enhanced sensing sensitivity, while the first cladding layer has low residual stress and the second cladding layer has high compressive stress, creating localized quality variations that improve overall performance without increasing overall complexity
2Ease of manufacture
If single mode optical fiber is used, then manufacturing is simplified, but sensitivity to pressure and weight decreases
Solution Approach 1:
The stress parameters in the fiber structure are changed to enhance sensitivity. By introducing high compressive stress in the second cladding layer and maintaining low residual stress in the first cladding layer, the fiber becomes more sensitive to external pressure and weight while maintaining a standard single mode core structure that is easy to manufacture
3Measurement precision
If high compressive stress is applied to enhance sensitivity, then sensing performance is improved, but tensile strength may be compromised
Solution Approach 1:
The cladding is divided into two layers with different stress characteristics. The first cladding layer has low residual stress to maintain structural integrity and tensile strength, while the second cladding layer has high compressive stress to enhance sensing sensitivity. This segmentation allows both requirements to be satisfied simultaneously
Solution Approach 2:
The fiber structure uses a composite approach with multiple cladding layers having different stress properties. This composite structure combines the benefits of high compressive stress for sensitivity with the mechanical strength provided by the low residual stress layer, achieving both sensing performance and structural integrity
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 optical fiber achieves enhanced sensitivity to parameters like temperature, pressure, and micro-bending, with reduced attenuation and improved tensile strength, making it suitable for sensing applications with ease of installation and cost-effectiveness.
Implementation Method 1
Micro-bending loss induces attenuation in the optical fibers. In addition, micro-bending induces mode coupling, causing light to couple from a propagating mode to a radiation or cladding mode.
Implementation Method 2
micro-bending induces mode coupling, causing light to couple from a propagating mode to a radiation or cladding mode
Data Source
Figure 1~2
AI summary
The present disclosure provides an optical fiber (100). The optical fiber (100) includes a core (106). The core (106) has high compressive stress. The compressive stress of the core (106) is in a range of about 20 to 60 MPa. The optical fiber (100) includes a cladding (112). The cladding (112) is divided into a first cladding layer (108) and a second cladding layer (110). The second cladding layer (110) has a high residual stress. The high residual stress of the second cladding layer (110) is in a range of about 20 to 60 MPa. The optical fiber (100) enables reduction of particle related breaks. Further, the optical fiber (100) has elevated LLT strength. The LLT strength is about 6 Kg. The optical fiber (100) has high proof test yield. Furthermore, the optical fiber (100) is highly sensitive to micro-bending of the optical fiber (100).