Low-Delay Optical Fiber Core With Stable Refractive Index Profile
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Solution Overview
Problem
The manufacturability of optical fibers used in Master-Slave CPE (MS-CPE) systems is compromised due to refractive index distribution deformation during manufacturing, particularly in multicore fibers with reduced group delay times, affecting the effectiveness of phase noise reduction.
Innovation Solution
The optical fiber employs a low delay core with a general-purpose refractive index distribution, specifically designed to meet certain mathematical expressions for refractive index differences and core radii, ensuring improved manufacturability and compatibility with MS-CPE systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a multicore fiber with reduced refractive index distribution (about 1 μm) is used to achieve reduced group delay time for MS-CPE, then the DSP processing delay time is reduced, but the refractive index distribution is easily deformed during manufacturing, compromising manufacturability
Solution Approach 1:
The patent changes the refractive index distribution parameter from a reduced distribution (about 1 μm) to a standard step index distribution. This parameter change maintains the reduced group delay time effect while making the fiber structure more stable during manufacturing, thus improving manufacturability without sacrificing the DSP processing delay reduction benefit
Solution Approach 2:
Instead of reducing the refractive index distribution to achieve reduced group delay (which causes manufacturing problems), the patent inverts the approach by using a standard step index distribution with optimized core radius and refractive index difference parameters. This inverted approach achieves the same functional benefit while avoiding the manufacturing deformation issue
2Speed
If a core with reduced refractive index distribution is used to achieve low group delay time, then communication delay time is reduced, but the refractive index distribution deforms due to spinning tension during manufacturing
Solution Approach 1:
The patent changes the structural parameters from a reduced refractive index distribution to a standard step index distribution with optimized core radius (a) and refractive index difference (Δ). This parameter change maintains the low group delay time characteristic while providing sufficient stability to resist deformation from spinning tension during manufacturing
Solution Approach 2:
The patent designs the fiber structure with adequate mechanical strength and structural stability beforehand to cushion against the spinning tension that occurs during manufacturing. The step index distribution with proper parameter selection provides this preemptive protection, preventing refractive index deformation before it can occur
Data Source
AI summary
An object of the present invention is to achieve a low delay core applicable to a Master channel of a Master-Slave CPE (MS-CPE) transmission method with a general-purpose refractive index distribution structure.An optical fiber according to the present invention is a single-mode optical fiber, and has an SI-type refractive index distribution structure, in which a clad region relative refractive index difference Δ (%) with respect to a core region refractive index, a radius a (μm) of the core region, and a group delay time difference Δτ between the Master channel and the Slave channel satisfy “Mathematical Expression 19” and “Mathematical Expression 20”, orhas a W-type refractive index distribution structure, in which a mode field diameter MFD is 9.5 to 10.1 μm, and a relative refractive index difference Δ1 (%) of a low refractive index layer with respect to a core, a relative refractive index difference Δ2 (%) of the clad region with respect to the core, the core radius a1, and the group delay time difference Δτ between the Master channel and the Slave channel satisfy “Mathematical Expression 41”.