Multicore Optical Fiber With Tapered Inner-Outer Core Structure
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Solution Overview
Problem
Existing optical devices for multicore fiber communications face challenges in efficiently transmitting LP01 and LP11 mode light beams with high bending losses and crosstalk, requiring complex configurations to manage refractive index differences and core diameters effectively.
Innovation Solution
An optical device with a simple configuration featuring a plurality of cores with an inner and outer core, where the outer core has a lower refractive index than the inner core, and a cladding with a refractive index lower than the outer core, with a tapered portion to reduce pitch between cores, achieving specific refractive index volume ratios and lengths to minimize bending losses and crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multicore fiber is used to transmit multiple signals with light propagating through each core, then the transmission capacity is increased, but the pitch between cores is decreased leading to increased crosstalk and bending losses
Solution Approach 1:
The core is segmented into multiple cores within a single fiber, allowing multiple signals to be transmitted simultaneously through different cores, thereby increasing transmission capacity while maintaining signal integrity through proper core spacing and refractive index design
Solution Approach 2:
The refractive index is locally optimized in different regions of the core structure. The inner core has a higher refractive index than the outer core, creating localized refractive index differences that guide light propagation and reduce crosstalk between adjacent cores, thus maintaining signal integrity
2Productivity
If the pitch between cores is decreased to increase transmission capacity, then more cores can be packed, but bending losses and crosstalk increase
Solution Approach 1:
The refractive index is locally optimized in different regions of the core structure. The inner core has a higher refractive index than the outer core, creating localized refractive index differences that guide light propagation and reduce crosstalk between adjacent cores, thus maintaining signal integrity
Solution Approach 2:
The core structure uses composite material design with different refractive indices for the inner core and outer core. This composite structure creates effective optical isolation between adjacent cores, reducing crosstalk and bending losses even when cores are closely packed
3Reliability
If a complex configuration with multiple refractive index layers is used to reduce crosstalk, then signal integrity is maintained, but device complexity increases
Solution Approach 1:
The refractive index is locally optimized in different regions of the core structure. The inner core has a higher refractive index than the outer core, creating localized refractive index differences that guide light propagation and reduce crosstalk between adjacent cores, thus maintaining signal integrity
Solution Approach 2:
The core structure uses a nested configuration where the inner core is surrounded by the outer core, which is in turn surrounded by the cladding. This nested structure efficiently manages light confinement and crosstalk reduction with a relatively simple geometric arrangement
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 device effectively transmits LP01 and LP11 mode light beams with reduced coupling losses and crosstalk, enabling efficient few-mode communications in the C and L bands, while maintaining a simpler core configuration compared to previous devices.
Implementation Method 1
The refractive index of the inner core is set higher than the refractive index of the outer core. The refractive index of the cladding is set lower than the refractive index of the outer core.
Data Source
AI summary
0.5377×r2−7.7≦V2/V1≦0.5377×r2−5.7, 3≦r2/r1≦5 are satisfied, where a radius of the inner core before tapered in diameter is defined as r1, a radius of the outer core before tapered in diameter is defined as r2, a refractive index volume formed of a product of a cross sectional area of the inner core and a relative refractive index difference of the inner core to the cladding before tapered in diameter is defined as V1, and a refractive index volume formed of a product of a cross sectional area of the outer core and a relative refractive index difference of the outer core to the cladding before tapered in diameter is defined as V2.