Optical Fiber Line TEC Connection Loss Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The connection loss between large A eff optical fibers and single-mode optical fibers remains high due to mode field diameter mismatches, which are exacerbated by the diffusion of fluorine in the cladding during thermal expansion connections, as the diffusion coefficient of fluorine is significantly larger than that of germanium, leading to increased MFD mismatch rather than reduction.
Innovation Solution
An optical fiber line is created by connecting a single-mode optical fiber with fluorine-doped cladding and a large A eff optical fiber using thermal expansion connection (TEC) methods, where the transition section's mode field diameter is tapered to minimize the connection loss by carefully controlling the fluorine concentration and refractive index profiles, ensuring the mode field diameter fluctuation is minimal and the connection loss is reduced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If thermal expansion connection (TEC) is used to reduce connection loss between large A eff optical fiber and single-mode optical fiber, then mode field diameter mismatch is reduced, but fluorine diffusion in cladding increases MFD mismatch
Solution Approach 1:
The patent applies preliminary action by pre-doping the cladding with fluorine before the thermal expansion connection process. This fluorine doping creates a refractive index profile that compensates for the expected fluorine diffusion during TEC, thereby maintaining MFD matching throughout the heating process rather than allowing MFD mismatch to increase
Solution Approach 2:
The patent changes the chemical composition parameter of the cladding by introducing fluorine doping. This parameter change modifies the refractive index distribution to counteract the adverse effects of fluorine diffusion during thermal expansion, transforming the MFD characteristic to remain matched during the connection process
2Loss of energy
If bridge connection is used to reduce connection loss, then MFD mismatch is reduced, but system complexity increases
Solution Approach 1:
The patent extracts the intermediate bridge fiber from the connection structure, eliminating the need for additional connection points. Instead of using a bridge fiber with intermediate A eff, the invention modifies the cladding of the existing fibers through fluorine doping to achieve direct low-loss connection
Solution Approach 2:
The patent makes the cladding material serve multiple functions: it provides mechanical support and simultaneously acts as a diffusion medium for fluorine to control MFD. This eliminates the need for a separate bridge fiber, reducing system complexity while maintaining connection performance
3Loss of energy
If taper connection is used to reduce connection loss, then MFD mismatch is reduced, but mechanical strength decreases
Solution Approach 1:
The patent replaces the mechanical tapering process with a chemical diffusion process. Instead of physically tapering the fiber to reduce MFD mismatch, fluorine diffusion is used to modify the refractive index profile, achieving MFD matching without mechanical deformation that would compromise strength
Solution Approach 2:
The patent changes the chemical composition parameter (fluorine concentration) in the cladding to control MFD, replacing the need for geometric parameter changes (tapering). This chemical approach maintains the fiber's mechanical integrity while achieving the desired optical field matching
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
This approach results in a significant reduction of connection loss between the optical fibers, achieving a connection loss of 55% or less of the ideal butt loss, thereby enhancing the transmission efficiency and mechanical strength of the optical fiber line.
Implementation Method 1
the diffusion of fluorine in the cladding during thermal expansion connections, as the diffusion coefficient of fluorine is significantly larger than that of germanium
Implementation Method 2
a core diffusion connection (thermally expanded core (TEC) connection) for heating a connection point to enlarge a core
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present embodiment relates to an optical fiber line or the like by connecting a single-mode optical fiber with a cladding containing fluorine and a large Aeff optical fiber by TEC connection, and a connection state between such two types of optical fibers is set such that a connection loss expressed in dB of a fundamental mode is equal to or less than 55% of an ideal butt loss expressed in dB at a wavelength of 1550 nm.