Double Mode Adapter for Two-Ended Pumping in Fiber Amplifiers
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Solution Overview
Problem
Current all-fiber semiconductor-pumped fiber lasers struggle to produce narrow linewidth amplified signals at multi-kW power levels with near-diffraction-limited beam quality, as existing pump combiners are limited by low input bundle diameters and inability to handle multi-kW power levels, and fail to seamlessly integrate pump light in both co- and counter-pumped directions.
Innovation Solution
The development of a fiber optic amplifier system with a double mode adapter that seamlessly integrates multi-kW pump light in both co- and counter-pumped directions, utilizing etched taper all-fiber pump combiner technology and double mode adapter technology to efficiently transition between different core and cladding sizes, allowing for high-power capable fiber-laser integration with low loss and efficient mode matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If existing pump combiners are used, then device complexity is reduced, but power handling capability and beam quality deteriorate at multi-kW levels
Solution Approach 1:
The system is divided into multiple gain stages (first stage with first core fiber, second stage with second core fiber) connected by a double mode adapter. This segmentation allows each stage to be optimized for specific power levels and pump configurations, enabling multi-kW operation while maintaining manageable device complexity through modular architecture.
Solution Approach 2:
The double mode adapter provides transitions for both cores and claddings simultaneously, adding a dimensional aspect to the mode matching process. This enables efficient pump light integration in both co- and counter-pumped directions by matching both the signal core modes and the pump cladding modes across stage interfaces.
2Manufacturing precision
If single-stage amplification is used, then device complexity is minimized, but beam quality and narrow linewidth performance deteriorate at high power levels
Solution Approach 1:
The amplifier is segmented into multiple stages with different core fiber types and pump configurations. The first stage uses one core fiber configuration while the second stage uses another, allowing each stage to be optimized for specific beam quality requirements. This multi-stage approach maintains near-diffraction-limited beam quality at multi-kW power levels by distributing the amplification function across optimized segments.
3Productivity
If pump light integration in both co- and counter-pumped directions is implemented, then power and efficiency are improved, but device complexity and alignment requirements increase
Solution Approach 1:
The double mode adapter is designed to provide mode matching for both co- and counter-pumped directions simultaneously. This multi-functional component enables efficient pump light integration from both directions without requiring separate adapter configurations, thereby improving energy transfer efficiency while managing device complexity through a universal interface design.
4Power
If large pump cladding diameters are used, then power handling capability is improved, but pump fiber bundle input diameter and device complexity increase
Solution Approach 1:
The system uses different core fiber types in different stages, with the first stage potentially using smaller pump cladding diameters and the second stage using larger pump cladding diameters. This segmentation allows the pump fiber bundle input diameter to be optimized for each stage's power requirements, enabling progressive power scaling without requiring all components to accommodate the largest diameter from the outset.
Data Source
AI summary
Exemplary embodiments of the disclosure include a fiber optic amplifier system and a fiber optic oscillator system having a first stage, comprising a first core fiber having a first core diameter and a first cladding size; a second stage, comprising a second core fiber having a second core diameter and a second cladding size; and a double mode adapter connecting the first stage to the second stage, wherein the double mode adapter is configured to provide transitions for the cores and the claddings of the first and second core fibers.