Ultra-low loss optical fiber with segmented cladding for long haul
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Solution Overview
Problem
Current single mode optical fibers, such as those in the G652D and G657 categories, face challenges in 400G transmission due to non-linear effects, higher attenuation, and limited spectral range, making them unsuitable for long haul communication systems.
Innovation Solution
An ultra-low loss optical fiber design featuring a core region with a relative refractive index between -0.06% and +0.06% and a cladding region with specific refractive index profiles and doping, including fluorination, to achieve reduced attenuation and increased effective area, thereby enhancing transmission capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional single mode optical fibers (G652D, G657) are used, then the fiber structure is simple and manufacturing is easy, but the attenuation is high and non-linear effects occur due to small effective area
Solution Approach 1:
The optical fiber is divided into multiple distinct regions: core region, inner cladding region, and outer cladding region, each with specific refractive index profiles and doping concentrations. This segmentation allows optimization of light confinement and attenuation characteristics in each region independently, achieving ultra-low loss while managing complexity through functional division.
Solution Approach 2:
Different regions of the optical fiber are assigned different local properties: the core region has specific refractive index for light guidance, the inner cladding region has optimized doping for reduced attenuation, and the outer cladding region provides mechanical protection and additional optical isolation. This local quality differentiation enables simultaneous achievement of low attenuation and controlled complexity.
2Area of moving object
If conventional single mode fibers are used, then the manufacturing process is straightforward, but the effective area is small causing non-linear effects in 400G transmission
Solution Approach 1:
The patent extends the traditional two-region fiber structure (core and cladding) to a three-region structure by adding the inner cladding region between the core and outer cladding. This dimensional expansion in the radial profile allows increased effective area for reducing non-linear effects while maintaining compatibility with existing manufacturing processes through controlled doping profiles.
Solution Approach 2:
The patent optimizes specific parameters including refractive index differences (Δ1, Δ2, Δ3), doping concentrations (GeO2, F), and region dimensions (core radius a, inner cladding radius b, outer cladding radius c) to achieve the desired effective area while ensuring manufacturability through standardized parameter ranges that align with current production capabilities.
3Adaptability or versatility
If conventional single mode fibers are used, then the fiber design is simple, but the spectral range is limited and attenuation increases at certain wavelengths
Solution Approach 1:
The optical fiber employs a composite structure with multiple materials: silica base glass, germanium oxide (GeO2) for refractive index enhancement, and fluorine (F) for refractive index reduction. This composite material approach enables tailored refractive index profiles across different regions, extending the operational spectral range while managing design complexity through systematic material selection.
4Reliability
If conventional single mode fibers are used, then the structure is straightforward, but the signal-to-noise ratio is low due to higher attenuation
Solution Approach 1:
The patent implements preliminary optimization of the refractive index profiles and doping concentrations during the fiber design phase to minimize attenuation before signal transmission occurs. By pre-configuring the core, inner cladding, and outer cladding regions with specific optical properties, the fiber achieves ultra-low loss characteristics that inherently improve signal-to-noise ratio without requiring additional signal processing or complex post-processing.
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 optical fiber achieves attenuation of less than 0.17 dB/km at 1550 nm, low macro-bend loss, and high Optical Signal to Noise Ratio (OSNR), supporting efficient long haul communications with reduced non-linear effects and extended spectral range.
Implementation Method 1
Optical fibers are strands of glass fiber processed so that light beams transmitted through the glass fiber are subject to total internal reflection wherein a large fraction of the incident intensity of light directed into the fiber is received at the other end of the fiber
Data Source
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AI summary
The present disclosure relates to an ultra-low loss optical fiber for long haul communications (100) comprising a core region (102) defined by a core relative refractive index and a cladding region surrounding the core region, defined by a cladding relative refractive index. In particular, the core region comprises a relative refractive index in a range of -0.06% to +0.06% and the cladding region is down-doped for entire radial cladding thickness. Moreover, the cladding region further comprises an inner cladding region (104) defined by an inner cladding relative refractive index and an outer cladding region (106) defined by an outer cladding relative refractive index. The inner cladding relative refractive index is less than the outer cladding relative refractive index.