Bend-Insensitive Multimode Fiber Core Cladding Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional multimode fibers face limitations in bandwidth and wavelength sensitivity, leading to reduced transmission capacity and increased signal loss due to high chromatic dispersion and sensitivity to bending, which restricts their ability to support high-speed networks and multiple wavelength windows.
Innovation Solution
A high-bandwidth bend-insensitive multimode fiber is designed with a core layer co-doped with germanium, phosphorus, and fluorine, featuring a parabolic refractive index profile and a structured cladding with specific refractive index differences and doping concentrations to minimize chromatic dispersion and enhance bend-insensitivity, allowing for improved bandwidth performance across multiple wavelength windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional multimode fiber is bent at a small radius, then the fiber can be installed in compact spaces, but high-order modes transmitted near the edge of the fiber core leak out causing signal loss
Solution Approach 1:
The patent introduces a low refractive index area in the fiber cladding at specific locations to locally address mode leakage. This localized modification creates a refractive index profile that guides high-order modes away from the core-cladding interface, preventing their leakage while maintaining compact bending radius for space-efficient installation.
2Length of moving object
If the refractive index profile is designed to reduce intermodal dispersion, then transmission distance is improved, but the fiber becomes sensitive to bending and macrobending loss increases
Solution Approach 1:
The patent modifies the refractive index profile parameters by introducing a specific low refractive index area in the cladding. This parameter change creates a dual-function profile: the graded index in the core reduces intermodal dispersion for long transmission distances, while the low index area in the cladding compensates for bending effects, reducing macrobending loss and making the fiber less sensitive to bending.
3Productivity
If the bandwidth of the multimode fiber is increased to support higher transmission speeds, then transmission capacity is improved, but the fiber can only support limited wavelength windows
Solution Approach 1:
The patent designs a refractive index profile with a low refractive index area in the cladding that provides universal performance across multiple wavelength windows. This profile structure simultaneously supports high bandwidth for short-distance high-speed transmission and maintains low macrobending loss across different wavelengths, enabling the fiber to serve multiple functions including 2.5Gbps, 10Gbps, and future higher speed transmissions across various wavelength ranges.
4Manufacturing precision
If dopant concentration is increased to adjust refractive index, then refractive index control is improved, but chromatic dispersion increases and bandwidth performance deteriorates
Solution Approach 1:
The patent applies localized dopant distribution rather than uniform doping throughout the fiber. A specific low refractive index area is created in the cladding through controlled dopant placement, allowing precise refractive index control in the critical region where mode leakage occurs, while maintaining overall fiber quality and bandwidth performance by avoiding excessive dopant concentration in the core.
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 fiber achieves enhanced bandwidth performance with reduced wavelength sensitivity and improved bend-insensitivity, supporting high-speed transmission over longer distances and multiple wavelength windows, making it suitable for advanced network applications and compatible with existing OM3/OM4 fibers.
Implementation Method 1
The core layer has a refractive index profile in a shape of a parabola... A center of the core layer has a maximum relative refractive index difference Δ1max in a range of 0.9% to 1.2%
Implementation Method 2
high chromatic dispersion and sensitivity to bending, which restricts their ability to support high-speed networks
Implementation Method 3
a low refractive index area can be added in a fiber cladding to limit leakage of the high-order modes so as to minimize the signal loss
Data Source
AI summary
A high-bandwidth bend-insensitive multimode fiber includes a core laver and a cladding including an inner cladding, a depressed cladding, and an outer cladding arranged sequentially from inside to outside. The core layer is a silicon dioxide glass layer co-doped with germanium, phosphorus (P), and fluorine (F) and has a refractive index profile in a shape of a parabola, a distribution index in a range of 2.0-2.3, a radius in a range of 23-27 μm, and a maximum relative refractive index difference in a range of 0.9-1.2% at its center. A contribution amount of P at the center is in a range of 0.01-0.30%. A doping amount of F increases from the center to the edge of the core layer. A contribution amount of F at the center and edge of the core layer is in range of 0.0% to −0.1%, and −0.40% to −0.20%, respectively.