Optical Fiber Tapered Core Beam Quality Scaling
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Solution Overview
Problem
Existing high-power laser systems face challenges in achieving high beam quality and power scalability due to increased beam parameter product (BPP) during beam combining, which degrades the beam quality and requires costly production.
Innovation Solution
The use of an optical fiber combiner with pre-formed tapers in the core, independent of the cladding diameter, allows for decoupling of the clad-to-core diameter ratio (CCDR) from the taper ratio, enabling adiabatic tapers and preserving beam quality during power scaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional beam combining is used to scale power, then output power increases, but beam parameter product (BPP) increases significantly degrading beam quality
Solution Approach 1:
The patent applies parameter changes by modifying the core diameter along the propagation direction through a pre-formed taper, transforming the waveguide from a uniform structure to a graded structure. This gradual change in core diameter enables adiabatic mode evolution, allowing power scaling while maintaining beam quality by keeping BPP increase minimal.
Solution Approach 2:
The pre-formed taper is created before the fiber is assembled into the combiner system. This preliminary action of creating the tapered core structure in advance allows the fiber to be optimized for adiabatic mode evolution before integration, ensuring beam quality is preserved from the outset during power scaling operations.
2Ease of manufacture
If the core and cladding are tapered together, then manufacturing is simpler, but the clad-to-core diameter ratio (CCDR) cannot be independently optimized from the taper ratio
Solution Approach 1:
The patent segments the tapering process into two independent stages: first, the core is pre-formed with a specific taper profile; second, the cladding is tapered separately during combiner assembly. This segmentation allows independent optimization of the core taper ratio and the clad-to-core diameter ratio, providing versatility in designing for specific application requirements.
Solution Approach 2:
The core taper is formed in advance before cladding tapering occurs. This preliminary action of pre-forming the core with its optimal taper profile allows subsequent independent adjustment of the cladding dimensions, enabling separate optimization of both the taper ratio and CCDR without compromising manufacturing feasibility.
3Device complexity
If non-ideal optics are used in beam combining, then device complexity increases, but beam quality deteriorates with significant BPP increase
Solution Approach 1:
The tapered core fiber performs the beam quality preservation function inherently through its graded structure, eliminating the need for additional corrective optics. The fiber itself provides the adiabatic mode evolution that maintains beam quality, making the system self-sufficient and reducing overall device complexity while preserving reliability.
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 improves taper adiabaticity, maintains high beam quality with low BPP, and enables high-power, high-brightness laser systems, even in applications with large core diameter fibers or short taper lengths.
Implementation Method 1
The pre-formed taper may be described as an adiabatic taper, and the term 'adiabatic' is well-understood in the field of optical waveguides to refer to a gradual change in the waveguide dimensions
Implementation Method 2
the core and the cladding providing light guidance along the optical fiber in a light propagation direction
Data Source
AI summary
In some implementations, an optical fiber may include a core and a cladding surrounding the core. The core and the cladding may provide light guidance along the optical fiber in a light propagation direction. The core may have a taper in the light propagation direction in a section of the optical fiber. A diameter of the core may decrease independently of a diameter of the cladding in the section of the optical fiber.