Reduced-Diameter Multimode Fiber Composite Coating Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current multimode optical fibers with reduced diameters face challenges in maintaining high modal bandwidth, low attenuation, low microbending sensitivity, and puncture resistance, making them unsuitable for high-density data center applications.
Innovation Solution
A reduced-diameter multimode optical fiber design featuring a graded-index core with a specific refractive index profile and optimized coatings to minimize microbending and enhance mechanical integrity, allowing for high modal bandwidth and puncture resistance while maintaining a compact form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the cladding diameter is reduced to decrease fiber diameter, then cable size and footprint are reduced, but microbending sensitivity increases and attenuation increases
Solution Approach 1:
The patent employs a composite coating structure with a soft primary coating layer (modulus 1-10 MPa) and a hard secondary coating layer (modulus 1-10 GPa). This composite structure allows the soft layer to absorb microbending stresses while the hard layer provides mechanical protection, enabling reduced cladding diameters (62.5 μm or 50 μm) without excessive microbending sensitivity
Solution Approach 2:
The patent modifies the physical parameters of the coating layers, specifically controlling the modulus of elasticity of the primary coating to be 1-10 MPa and the secondary coating to be 1-10 GPa. It also optimizes the thickness ratios (primary coating 2-10 μm, secondary coating 10-20 μm) to balance microbending protection with puncture resistance, enabling reduced fiber diameter while maintaining reliability
2Volume of moving object
If the primary coating thickness is reduced to decrease fiber diameter, then cable size is reduced, but susceptibility to shear-induced defects increases
Solution Approach 1:
The patent uses a composite coating system where the soft primary layer (2-10 μm thick) provides shear resistance through its viscoelastic properties, while the hard secondary layer (10-20 μm thick) provides puncture resistance. This composite structure allows overall diameter reduction while maintaining strength characteristics
Solution Approach 2:
The patent optimizes the thickness and modulus parameters of the primary coating to 2-10 μm and 1-10 MPa respectively, which provides sufficient shear resistance even at reduced overall fiber diameters (125 μm or 100 μm cladding diameter)
3Volume of moving object
If the secondary coating thickness is reduced to decrease fiber diameter, then cable size is reduced, but puncture resistance decreases
Solution Approach 1:
The patent employs a hard secondary coating layer with modulus 1-10 GPa and thickness 10-20 μm that provides puncture resistance. This hard layer compensates for the reduced overall fiber diameter by providing a dedicated protective barrier against punctures while allowing the soft primary layer to handle microbending stresses
Solution Approach 2:
The patent controls the secondary coating thickness to be 10-20 μm with high modulus (1-10 GPa), which maintains puncture resistance even when the overall fiber diameter is reduced to 100 μm or smaller
4Quantity of substance
If the fiber diameter is reduced to increase fiber count in cables, then bandwidth density increases, but maintaining high modal bandwidth becomes more difficult
Solution Approach 1:
The patent implements a graded-index profile with optimized relative index difference (Δ) parameters and core/cladding radius ratios that maintain high modal bandwidth even at reduced diameters. The refractive index profile is specifically tailored to compensate for the reduced geometric dimensions, enabling 100 μm diameter fibers to achieve bandwidths comparable to or exceeding traditional 125 μm fibers
Solution Approach 2:
The optimized coating structure with specific modulus ratios between primary and secondary layers provides mechanical stability that maintains the graded-index profile integrity, thereby preserving high modal bandwidth characteristics in reduced-diameter fibers
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 achieves high modal bandwidth, low attenuation, and improved mechanical properties, enabling the use of reduced-diameter multimode optical fibers in high-density data center applications with increased fiber count and connector density.
Implementation Method 1
The glass fiber includes a higher index core region surrounded by a lower index cladding region
Implementation Method 2
The glass fiber includes a higher index core region surrounded by a lower index cladding region
Implementation Method 3
the primary coating acts to dissipate external forces to prevent them from being transferred to the glass fiber. By dampening external forces, the primary coating prevents damage to the glass fiber and minimizes attenuation of optical signals caused by microbending
Implementation Method 4
The primary coating has a modulus in the range from 1 MPa to 10 MPa, and the secondary coating has a modulus in the range from 1 GPa to 10 GPa
Implementation Method 5
the secondary coating provides mechanical integrity and allows the optical fiber to be handled for processing and installation in cables
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present description provides reduced-diameter multimode optical fibers. The optical fibers include a reduced-diameter glass fiber and/or reduced-thickness coatings. The overall diameter of the optical fibers is less than 210 µm and examples with diameters less than 160 µm are presented. Puncture resistant secondary coatings enable thinning of the secondary coating without compromising protection of the glass fiber. The optical fibers are suitable for data center applications and features high modal bandwidth, low attenuation, low microbending sensitivity, and puncture resistance in a compact form factor.