Multicore Fiber Amplifier Combiner With Pump Spot Size Conversion
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Solution Overview
Problem
The challenge in SDM optical fiber amplifiers is the mismatch between the spot size of pumping light from a pumping light source and the cladding diameter of the amplification optical fiber, leading to loss of pumping light and reduced amplification efficiency.
Innovation Solution
A core size conversion unit is introduced to narrow the core diameter of the optical fiber before the pumping light combiner, ensuring the spot size matches the cladding diameter of the amplification optical fiber, thereby reducing light loss and increasing amplification efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a small cladding diameter optical fiber is used to increase Rcc ratio, then amplification efficiency is improved, but spot size mismatch with multimode fiber increases causing pumping light loss
Solution Approach 1:
The patent introduces a spot size conversion unit as an intermediary component between the multimode optical fiber and the amplification optical fiber. This unit converts the spot size of pumping light from the larger multimode fiber to match the smaller cladding diameter of the amplification fiber, enabling efficient light transfer without direct connection. The converter acts as a mediator that resolves the size mismatch problem while maintaining high amplification efficiency.
Solution Approach 2:
The patent segments the optical fiber system into distinct functional sections: a multimode optical fiber section for light source connection, a spot size conversion unit for dimension transformation, and a small cladding diameter amplification fiber section for signal amplification. This segmentation allows each component to be optimized for its specific function while working together as an integrated system.
2Productivity
If core diameter is reduced to match small cladding diameter, then Rcc ratio increases improving amplification efficiency, but connection compatibility with standard multimode fiber deteriorates
Solution Approach 1:
The optical fiber system is divided into separate sections with different core diameters. The first section maintains standard core diameter for compatibility with conventional multimode fibers and light sources, while the second section has reduced core diameter to achieve high Rcc ratio. The spot size conversion unit bridges these two segments, allowing standard components to interface with optimized amplification sections.
Solution Approach 2:
The spot size conversion unit serves as an intermediary that enables connection between standard multimode fibers and optimized small-core amplification fibers. It transforms the optical mode dimensions to be compatible between the two different fiber types, allowing the system to simultaneously achieve standard interface compatibility and optimized amplification performance.
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 solution effectively reduces pumping light loss in the combiner and enhances amplification efficiency by aligning the spot size with the cladding diameter, improving the Rcc ratio.
Implementation Method 1
signal light and pumping light for exciting a rare earth element are injected into an amplification optical fiber in which a core region doped with the rare earth element, and the signal light is amplified
Implementation Method 2
a core size conversion unit that reduces a diameter of a core of the multimode optical fiber to a diameter of the cladding of the amplification optical fiber
Data Source
AI summary
An object is to provide an optical fiber amplifier in which loss of pumping light in a pumping light combiner is reduced to increase amplification efficiency.An optical fiber amplifier according to the present invention includes: an amplification optical fiber 13 having a plurality of cores doped with a rare earth element in a cladding; a pumping light source 11 that outputs pumping light for pumping the rare earth element to a multimode optical fiber 16-1; a core size conversion unit 14 that reduces a diameter of a core of the multimode optical fiber 16-1 to a diameter of the cladding of the amplification optical fiber 13; and a pumping light combiner 12 that causes signal light Ls propagated through each core of a multicore optical fiber 15 to enter each core of the amplification optical fiber 13, and causes pumping light Le output from the pumping light source 11 and passing through the core size conversion unit 14 to enter the cladding including the cores of the amplification optical fiber 13.