Fiber Bragg Grating Temperature Compensation Spring Jacket
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Solution Overview
Problem
Existing fiber Bragg grating (FBG) devices face challenges in maintaining accurate wavelength filtration due to temperature-induced refractive index changes, leading to information loss in optical fiber communication, and current temperature compensation methods result in large, costly structures that occupy valuable space.
Innovation Solution
A precision wavelength filter device is developed using a fiber Bragg grating jacketed and pre-stressed by springs, combining high-expansion and low-expansion coefficient materials to create a self-spring-jacketed structure that compensates for thermal effects through pre-tensioning and pre-twisting, reducing the size and cost of the mechanical structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional temperature compensation structures (double-metal strip, C-shape clamp, axial rod) are used to compensate for wavelength shift, then temperature compensation effect is achieved, but device size and structural complexity increase significantly
Solution Approach 1:
The patent combines the temperature compensation function and the protective jacketing function into a single spring structure. The spring jacket directly contacts and pre-stresses the FBG while simultaneously providing temperature compensation through its thermal expansion properties, eliminating the need for separate compensation mechanisms like double-metal strips or C-shape clamps.
Solution Approach 2:
The spring jacket serves multiple functions simultaneously: it acts as a protective covering for the optical fiber, applies pre-stress to the FBG for wavelength tuning, and provides temperature compensation through differential thermal expansion. This multi-functional design reduces overall device complexity while maintaining compensation effectiveness.
2Reliability
If conventional temperature compensation structures are implemented, then wavelength stability under temperature variation is improved, but manufacturing cost increases
Solution Approach 1:
By merging the protective jacketing and temperature compensation functions into a single spring component, the patent reduces the number of parts that need to be manufactured and assembled. This simplification directly lowers manufacturing costs while maintaining wavelength stability through the spring's inherent thermal expansion properties.
3Measurement precision
If FBG is pre-stressed by spring jacket to achieve wavelength accuracy, then filtration precision is improved, but device size increases
Solution Approach 1:
The patent uses a flexible spring jacket that closely conforms to the optical fiber diameter. The spring's coiled structure provides the necessary pre-stress and temperature compensation while occupying minimal radial space, maintaining a compact device footprint comparable to the original fiber diameter.
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 solution effectively compensates for temperature-induced wavelength shifts, maintaining accurate filtration and reducing the size and cost of the FBG device, while preventing moisture and dust ingress, thus enhancing the reliability and efficiency of optical fiber communication systems.
Implementation Method 1
a first spring jacket made of a high-expansion coefficient spring material is concentrically combined in a loose jacketing manner on the periphery of a fiber Bragg's grating (FBG) 103, and then a second spring jacket made of a low-expansion coefficient spring material is concentrically combined in a loose jacketing manner on the periphery of the first spring jacket
Implementation Method 2
as the density of glass molecules in a light guide core of the optical fiber changes due to temperature change, the refractive index n changes; and as a result, even though the FBG does not receive any force, the original preset Bragg feedback wavelength λB will still shift
Implementation Method 3
The FBG can reflect the wavelength as reception of light waves according to a default Bragg's feedback wavelength λB engendered by a default grating period Λ of the fiber grating
Data Source
AI summary
The present invention provides a filter composed of two layers of materials with different expansion coefficients. The difference between a length added to a whole section length of an outer low-expansion coefficient metal sleeve by a temperature change and a length added to a length of a whole section of high-expansion coefficient cylindrical coil spring arranged therein by the temperature change causes a stress-releasing or stress-increasing effect on the whole section of pre-tensioned high-expansion coefficient cylindrical coil spring arranged therein, so that a structure capable of compensating the wavelength shift of the fiber Bragg's grating filter caused by temperature by increasing or decreasing the refractive index is achieved.