Optical Fiber Grating L-Band Transmission Loss Reduction
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Solution Overview
Problem
Conventional optical fiber gratings experience a gradual increase in transmission loss, particularly at the long-wavelength end of the L-band, due to reduced orthogonality between the LP01 mode and higher-order modes, which is not suitable for high-capacity transmission in wide wavelength bands.
Innovation Solution
An optical fiber with a single-peaked and graded refractive index profile, co-doped with GeO2 and B2O3 as photosensitive materials, is used to create a refractive index modulated region that maintains orthogonality across the fiber cross-section, reducing transmission loss and enabling efficient high-capacity transmission in the L-band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional optical fiber structure is used to manufacture an optical fiber grating, then the manufacturing process is simple, but transmission loss gradually increases particularly at the long-wavelength end of the L-band
Solution Approach 1:
The patent applies local quality by creating a photosensitive region with specific GeO2 and B2O3 doping concentrations in the core and inner cladding, while the outer cladding has different properties. This localized modification of the fiber structure in the photosensitive region enables reduced transmission loss at the long-wavelength end without complicating the entire fiber structure.
Solution Approach 2:
The patent uses composite materials by co-doping GeO2 and B2O3 in the core and inner cladding regions. This composite doping approach creates a photosensitive region with enhanced properties that reduce transmission loss while maintaining manufacturing feasibility through standard optical fiber manufacturing processes.
2Reliability
If the optical fiber grating length is increased to improve filtering performance, then the filtering performance improves, but transmission loss increases due to mode coupling
Solution Approach 1:
The patent maintains orthogonality between LP01 mode and higher-order modes throughout the grating length by having the photosensitive region extend through the entire core and inner cladding. This localized quality control prevents mode coupling and transmission loss even as the grating length increases to improve filtering performance.
Solution Approach 2:
The patent creates equipotentiality by ensuring uniform photosensitive material distribution and consistent refractive index modulation across the entire grating length. This uniformity maintains mode orthogonality and prevents gradual transmission loss accumulation that would otherwise occur with increased grating length.
3Productivity
If GeO2 and B2O3 are co-doped in the core and inner cladding, then transmission loss is reduced and manufacturing efficiency is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for GeO2 (0.1-1.0 wt%) and B2O3 (0.05-0.5 wt%) doping concentrations to optimize the balance between manufacturing efficiency and precision requirements. These parameter changes enable standard manufacturing processes to achieve the desired performance without excessive complexity.
Data Source
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AI summary
An optical fiber according to an embodiment includes a core having a single-peaked and graded refractive index profile, an inner cladding surrounding the core, and an outer cladding surrounding the inner cladding. The inner and outer claddings have refractive indices lower than the maximum refractive index of the core. A photosensitive region constituted by the core and the inner cladding contains a photosensitive material. The inner cladding has an outer diameter one time or more and two times or less the MFD of an LP01 mode in a 1310-nm wavelength band.