Ladder Fiber Mode Coupling via Uniform Refractive Index
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Solution Overview
Problem
In optical fiber systems, mode-division multiplexing faces challenges due to unequal effective refractive indices between mode groups, leading to modal dispersion and crosstalk, which increase system complexity and cost, and require multiple long period optical gratings for coupling, resulting in signal loss and complexity.
Innovation Solution
An optical fiber system with equally spaced effective refractive indices between mode groups, utilizing a single long period optical grating with a period inversely proportional to the difference in refractive indices to couple all adjacent mode groups, reducing modal dispersion and signal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional optical fiber systems with unequal effective refractive indices are used, then mode coupling requires multiple long period optical gratings, but this increases device complexity and signal loss
Solution Approach 1:
The patent changes the refractive index distribution parameter from unequal to equal spacing between mode groups. This parameter change enables a single optical grating to couple all mode groups effectively, eliminating the need for multiple gratings and reducing device complexity while maintaining signal integrity
Solution Approach 2:
The patent creates a universal optical grating design that can couple all mode groups simultaneously. The single grating with period inversely proportional to the equal refractive index difference serves multiple coupling functions that previously required separate gratings for each mode group pair
2Adaptability or versatility
If multiple long period optical gratings are used for mode coupling, then all mode groups can be coupled, but this increases system complexity and cost
Solution Approach 1:
The patent merges the function of multiple optical gratings into a single grating structure. By combining all mode coupling functions into one grating with appropriately designed period, the system achieves full mode coupling capability with reduced complexity and lower cost
3Quantity of substance
If traditional fibers with unequal refractive index differences are used, then mode groups are supported, but modal dispersion increases
Solution Approach 1:
The patent changes the refractive index distribution to achieve equal spacing between mode groups. This parameter change equalizes the propagation characteristics of different mode groups, reducing modal dispersion while maintaining the ability to support multiple mode groups for high-capacity communication
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 approach simplifies the system by reducing the need for multiple gratings, lowering complexity and cost, while maintaining effective mode coupling across a broad wavelength range, thereby improving signal integrity and reducing modal dispersion.
Implementation Method 1
an optical grating optically coupled to the optical fiber, the optical grating having a period inversely proportional to the difference in effective refractive index between adjacent mode groups and configured to couple adjacent mode groups in the optical fiber
Data Source
AI summary
An optical fiber system including an optical fiber and an optical grating is provided. The optical fiber is configured to support M mode groups, where differences in effective refractive index between adjacent mode groups are substantially equal. The optical grating is optically coupled to the optical fiber, and has a period inversely proportional to the difference in effective refractive index between adjacent mode groups. The optical grating is configured to couple all adjacent mode groups in the optical fiber.