Silicon Pillar Fabry-Pérot Fiber Sensor
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Solution Overview
Problem
Fiber-optic temperature sensors based on fused silica have limitations in sensitivity and response time due to their low thermo-optic coefficient and thermal diffusivity, making them less effective for high-resolution and high-speed temperature sensing.
Innovation Solution
A fiber optic sensor is developed by attaching a double-side-polished silicon pillar to the optical fiber tip to form a Fabry-Pérot cavity, utilizing a silicon layer on the optical fiber end face to enhance temperature sensitivity and response time, with a process involving a light source, spectrometer, and controller for noise reduction and resolution enhancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fused silica fiber-optic sensors are used, then the sensor structure is simple and easy to manufacture, but the temperature sensitivity and response time are limited due to low thermo-optic coefficient and thermal diffusivity
Solution Approach 1:
The patent employs a composite structure combining fused silica optical fiber with a silicon sensing tip. The silica fiber provides ease of manufacturing and optical transmission, while the silicon tip contributes high thermal diffusivity and thermo-optic coefficient. This composite approach resolves the contradiction by integrating materials with complementary properties, achieving both manufacturability and high measurement precision (6×10−4° C. resolution).
Solution Approach 2:
The invention applies local quality by concentrating the sensing function in a specific region (the silicon tip) rather than using the entire fiber. The silicon tip is specifically engineered with optimized dimensions and material properties to maximize temperature sensitivity, while the rest of the fiber maintains its simple silica structure for easy manufacturing. This localized enhancement achieves high precision without compromising manufacturability.
2Device complexity
If fused silica fiber-optic sensors are used, then the sensor structure is simple, but the response time is slow due to low thermal diffusivity
Solution Approach 1:
The composite silica-silicon structure resolves the speed-complexity contradiction by combining materials with different thermal properties. The silicon tip's high thermal diffusivity enables rapid heat conduction and fast response (0.51 ms), while the silica fiber maintains structural simplicity and optical functionality. This material combination achieves high-speed sensing without excessive structural complexity.
Solution Approach 2:
The sensor is segmented into distinct functional regions: the silica fiber for optical transmission and the silicon tip for rapid thermal sensing. This segmentation allows each component to be optimized for its specific function—the silicon tip for fast thermal response and the silica fiber for simple, easy-to-manufacture optical guidance—achieving high speed without overall structural complexity.
3Measurement precision
If a silicon layer is attached to the optical fiber tip to form a Fabry-Pérot cavity, then temperature sensitivity and response time improve, but the manufacturing process becomes more complex
Solution Approach 1:
The Fabry-Pérot cavity is implemented locally at the fiber tip using a silicon layer, concentrating the enhanced sensing functionality in the critical measurement region. This localized implementation improves temperature resolution where it is most needed while minimizing the overall structural complexity. The rest of the fiber remains simple and unchanged, balancing performance enhancement with manageable device complexity.
4Speed
If a silicon layer is attached to the optical fiber tip to form a Fabry-Pérot cavity, then response time improves, but the manufacturing process becomes more complex
Solution Approach 1:
The sensor is divided into functional segments with the silicon layer confined to the tip region. This segmentation enables the silicon component to provide fast response characteristics independently, while the silica fiber maintains its simple structure for ease of handling and integration. The segmented approach achieves improved response time with controlled complexity by assigning specific functions to specific regions.
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 sensor achieves a high temperature resolution of 6×10−4° C. and a short response time of 0.51 ms, significantly improving measurement precision and speed, especially in dynamic environments.
Implementation Method 1
a double-side-polished silicon pillar is attached to an optical fiber tip and forms a Fabry-Pérot (FP) cavity
Implementation Method 2
each of the silicon layer(s) defines a Fabry-Pérot interferometer
Implementation Method 3
the flow can include various flowing substances (e.g., water, liquid metal, air, other gasses, etc.) that provide cooling effects to the heated sensor head
Implementation Method 4
An optical fiber can include a flexible, transparent fiber made of extruded glass (silica) or plastic. Light can be transmitted between two ends of the optical fiber
Data Source
AI summary
A fiber optic sensor, a process for utilizing a fiber optic sensor, and a process for fabricating a fiber optic sensor are described, where a double-side-polished silicon pillar is attached to an optical fiber tip and forms a Fabry-Pérot cavity. In an implementation, a fiber optic sensor in accordance with an exemplary embodiment includes an optical fiber configured to be coupled to a light source and a spectrometer; and a single silicon layer or multiple silicon layers disposed on an end face of the optical fiber, where each of the silicon layer(s) defines a Fabry-Pérot interferometer, and where the sensor head reflects light from the light source to the spectrometer. In some implementations, the fiber optic sensor may include the light source coupled to the optical fiber; a spectrometer coupled to the optical fiber; and a controller coupled to the high speed spectrometer.