Multimode Optical Fiber Graded Index Profile for Broad Wavelength Bandwidth
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Solution Overview
Problem
Current multimode optical fibers optimized for 850 nm wavelengths exhibit limited bandwidth when used with VCSELs operating at wavelengths greater than 900 nm, due to inter-modal chromatic dispersion, making them unsuitable for high-speed applications across a broad wavelength range.
Innovation Solution
Development of multimode optical fibers with a graded index glass core and specific refractive index profiles, including a depressed index cladding region, to achieve high bandwidth across 850 nm to 1060 nm wavelengths, supporting bit rates of 16 Gb/s or higher and reducing chromatic dispersion and attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multimode fibers are optimized for peak modal bandwidth at 850 nm, then bandwidth at 850 nm is improved, but bandwidth in the 900 nm-1200 nm range deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the graded index profile with specific alpha values (2.0-2.5) and controlling the peak modal bandwidth wavelength to be between 860-930 nm. This shifts the optimization from traditional 850 nm peak to a broader wavelength range, enabling high bandwidth performance at both 850 nm and 900 nm-1200 nm wavelengths simultaneously
Solution Approach 2:
The fiber design achieves multi-functionality by creating a universal optical fiber that can support multiple VCSEL wavelengths (850 nm, 900 nm, 910 nm, 920 nm, 930 nm, 980 nm, 1000 nm, 1060 nm) with high bandwidth performance. The graded index profile with alpha=2.0-2.5 creates a universal solution that works across different wavelength ranges without requiring separate fiber optimizations
2Manufacturing precision
If multimode fibers are designed with graded index alpha-profiles to minimize inter-modal chromatic dispersion, then bandwidth is improved, but material dispersion limitation prevents high bandwidth in broad wavelength range
Solution Approach 1:
The patent changes the alpha parameter of the graded index profile to specific values (2.0-2.5) and controls the peak modal bandwidth wavelength (860-930 nm) to compensate for material dispersion. This parameter optimization reduces inter-modal chromatic dispersion while maintaining high bandwidth across broad wavelength ranges including 850 nm, 900 nm, and 1060 nm windows
3Speed
If VCSELs operate at wavelengths greater than 900 nm for high speed operation, then speed is improved, but existing optical fibers cannot support high bandwidth
Solution Approach 1:
The patent optimizes the fiber's graded index profile parameters (alpha=2.0-2.5, peak modal bandwidth wavelength=860-930 nm) to match the operating characteristics of VCSELs at wavelengths greater than 900 nm. This enables the fiber to support high-speed VCSEL operation at 900 nm, 910 nm, 920 nm, 930 nm, 980 nm, 1000 nm, and 1060 nm with bandwidths exceeding 1 GHz·km
Solution Approach 2:
The fiber design provides multi-functionality by being compatible with both traditional 850 nm VCSELs and newer VCSELs operating at 900 nm-1200 nm. The universal graded index profile with alpha=2.0-2.5 creates a single fiber type that supports high-speed applications across multiple wavelength ranges, eliminating the need for separate fiber optimizations
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 enables optical fibers to maintain high bandwidth and reduced chromatic dispersion across a broader wavelength range, supporting high-speed data transmission while meeting Class 1 eye safety specifications and lowering operational costs.
Implementation Method 1
MM fibers are designed with graded index α-profiles. Current high bandwidth (greater than 1 GHz·Km) optical fibers are optimized for use at 850 nm
Implementation Method 2
The bandwidth (BW) of these multimode (MM) fibers is limited mostly by inter-modal chromatic dispersion. To minimize the inter-modal chromatic dispersion, MM fibers are designed with graded index α-profiles
Implementation Method 3
reducing chromatic dispersion and attenuation
Implementation Method 4
Multimode (MM) fibers that operate at the wavelength range centered around 850 nm are known
Data Source
AI summary
According to some embodiments, a multimode optical fiber comprises a graded index glass core with refractive index Δ1, a maximum refractive index delta Δ1MAX, and a core radius between 10 and 40 microns; and cladding region surrounding the core comprising refractive index Δ4, wherein the fiber exhibits an overfilled bandwidth exhibits an overfilled bandwidth of at least 3 GHz-km at a wavelength of 850 nm and an overfilled bandwidth of at least 1.2 GHz-km at one or more wavelengths between 980 and 1060 nm.