Suspended-Core Fiber Air Pressure Sensor with Vernier Effect
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Solution Overview
Problem
Existing optical fiber air pressure sensors based on Fabry-Perot interferometers face issues with fragile structures, easy breakage, and low sensitivity due to large incident light loss and low contrast of interference spectra, especially in double-cavity cascade configurations.
Innovation Solution
A high-sensitivity air pressure sensor is developed using a suspended-core fiber and a side-hole fiber, connected through a multimode fiber, which creates a parallel double-cavity structure that enhances the vernier effect and improves the contrast of interference spectra, allowing for higher sensitivity without the need for adhesive or expensive equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If double-cavity cascade vernier effect is used to improve air pressure sensitivity, then sensitivity is improved by 1-2 orders of magnitude, but incident light loss increases and interference spectrum contrast decreases
Solution Approach 1:
The sensing head is segmented into multiple functional sections: single mode fiber section, multimode fiber section, suspended-core fiber section, and side-hole fiber section. Each section serves a specific function in guiding light and forming cavities, allowing optimized light path management to reduce overall light loss while maintaining high sensitivity.
Solution Approach 2:
The multimode fiber acts as an intermediary component connecting the single mode fiber to the suspended-core fiber. This intermediary section facilitates efficient light coupling between different fiber types and helps manage the light path through the complex sensing structure, reducing incident light loss.
2Measurement precision
If double-cavity cascade vernier effect is used to improve air pressure sensitivity, then sensitivity is improved by 1-2 orders of magnitude, but interference spectrum contrast decreases
Solution Approach 1:
Different sections of the sensing head are designed with specific local qualities: the single mode fiber provides low loss transmission, the multimode fiber provides mode coupling, the suspended-core fiber creates the first cavity with specific refractive index contrast, and the side-hole fiber creates the second cavity. This local optimization ensures high interference spectrum contrast while maintaining high sensitivity.
Solution Approach 2:
The sensing head uses a composite structure combining different fiber types (single mode fiber, multimode fiber, suspended-core fiber, side-hole fiber) with different optical properties. This composite material approach allows simultaneous achievement of high sensitivity and high contrast interference spectrum by leveraging the complementary characteristics of each fiber type.
3Measurement precision
If traditional thin-film type sensors or fiber bubble type sensors are used, then air pressure measurement is achieved, but structure becomes fragile and easy to break
Solution Approach 1:
The patent replaces traditional mechanical cavity structures (thin-film bubbles, fiber bubbles) with an all-optical fiber-based sensing head. The cavities are formed by refractive index differences in the fiber structure itself rather than by physical bubbles or thin films, eliminating fragile mechanical components while maintaining air pressure measurement capability.
Solution Approach 2:
The sensing head uses the flexible fiber structure itself to form the cavities, eliminating the need for separate fragile thin-film or bubble structures. The fiber's inherent flexibility and structural integrity provide both the cavity formation and mechanical strength, preventing breakage while maintaining measurement capability.
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 improved sensitivity by 1-2 orders of magnitude compared to single open-air cavities, with a compact and stable design that simplifies fabrication and operation, and provides a high-contrast interference spectrum.
Implementation Method 1
The optical fiber air pressure sensor based on Fabry-Perot interferometer (FPI) has the advantages that electronic air pressure sensors do not have
Implementation Method 2
The double-cavity cascade vernier effect can further improve the sensitivity of air pressure measurement, which can be improved by 1-2 orders of magnitude
Implementation Method 3
The optical fiber circulator is connected with the broadband light source, the sensing head and the spectrometer
Implementation Method 4
a broadband light source, an optical fiber circulator, a sensing head and a spectrometer; the wave band of the broadband light source is 1200 nanometers (nm) to 1600 nm
Data Source
AI summary
An air pressure sensor based on a suspended-core fiber and a side-hole fiber is provided and includes a broadband light source, an optical fiber circulator, a sensing head and a spectrometer; the optical fiber circulator is connected with the broadband light source, the sensing head and the spectrometer; the sensing head includes a single mode fiber, a multimode fiber, the suspended-core fiber and the side-hole fiber; the single mode fiber is connected with the suspended-core fiber through the multimode fiber; and the multimode fiber is connected with the side-hole fiber through the suspended-core fiber. The sensor uses a fabrication method of fiber fusion, and the operation is simple; the sensor has advantages of small volume, compact structure and convenient use; the sensor has good stability without adhesive; additionally, parallel connection of double cavities could produce vernier effects, so the sensor has good contrast of interference spectrum and high sensitivity.