Optical Fiber Trench Cladding for Low Macrobend Loss
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Solution Overview
Problem
Current bend-insensitive optical fibers struggle to maintain low macrobend loss across a wide range of bend diameters, particularly at 30 mm and beyond, leading to inconsistent manufacturing yield and connectivity issues with standard single-mode fibers.
Innovation Solution
The development of optical fibers with a relative refractive index profile featuring a trench cladding region of large width and shallow depth, which minimizes macrobend loss at bend diameters between 10 mm and 40 mm, including a core region with a mode field diameter of 9.0 μm or greater.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mode field diameter is reduced to improve bend insensitivity at small bend diameters, then macrobend loss decreases at 10-20 mm bends, but connectivity loss increases when connecting to standard single-mode fibers
Solution Approach 1:
The patent applies local quality by creating a trench cladding region with distinct refractive index properties (lower than outer cladding) at a specific radial location, while maintaining a mode field diameter matching standard fibers. This localized refractive index modification provides bend insensitivity without requiring overall mode field diameter reduction, thus avoiding connectivity losses.
2Reliability
If the trench width is increased to improve bend insensitivity at large bend diameters, then macrobend loss decreases at 30 mm and beyond, but manufacturing precision requirements become more stringent
Solution Approach 1:
The patent changes the trench parameters to a wider width (10-20 μm) and shallower depth configuration, which provides bend insensitivity at large bend diameters while being more tolerant to manufacturing variations. The larger trench width allows for greater process window compared to narrow, deep trenches, reducing the stringency of manufacturing precision requirements.
3Reliability
If the trench depth is increased to minimize macrobend loss, then bend insensitivity improves, but the complexity of the refractive index profile increases
Solution Approach 1:
Instead of using a deep, narrow trench configuration, the patent inverts the approach by using a wide, shallow trench. This inverted geometry achieves similar or better bend insensitivity performance while simplifying the refractive index profile structure, making it easier to manufacture and control.
4Reliability
If the mode field diameter is reduced to meet ITU-G.657 standard across all bend diameters, then compliance is achieved, but manufacturing yield decreases due to increased sensitivity to variations
Solution Approach 1:
The patent creates a universal refractive index profile with a wide, shallow trench that simultaneously provides bend insensitivity across the full ITU-G.657 bend diameter range (10-40 mm) while maintaining a mode field diameter of 9.0 μm or greater for compatibility with standard fibers. This multi-functional design achieves standard compliance without the manufacturing yield penalties associated with reduced mode field diameter.
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 design achieves low macrobend loss at various bend diameters, enhancing manufacturing yield and ensuring compatibility with standard single-mode fibers by maintaining low connectivity losses.
Implementation Method 1
As the optical fiber bends, a fraction of the optical signal refracts or tunnels out of the core to the cladding and is dissipated in the protective coating surrounding the fiber.
Data Source
AI summary
The disclosure provides optical fibers that exhibit low macrobend loss at 1550 nm at bend diameters between 10 mm and 40 mm. The relative refractive index profile of the fibers includes a trench cladding region with small depth, large width and a trench volume configured to minimize macrobend loss at large and small bend diameters. The optical fiber includes an outer cladding region that surrounds and is directly adjacent to the trench cladding region and an optional offset cladding region between the trench cladding region and the core region. In some embodiments, the trench cladding region has a relative refractive index that decreases monotonically from the inner radius to the outer radius. The monotonic decrease in relative refractive index may have a constant slope. The low macrobend loss at large and small diameters makes the optical fibers well suited for space-constrained deployment environments, such as data centers.