Mode Field Adapter for High-Cladding-Power Fiber Splicing
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Solution Overview
Problem
Existing mode field adapters (MFAs) are limited in handling high-power cladding light and fail to preserve beam quality due to mismatched cladding sizes and core fundamental mode fields, especially when dealing with large-mode-area fibers with low numerical aperture, leading to significant insertion loss and degraded beam quality.
Innovation Solution
A high cladding power MFA design that adiabatically etches and tapers the cladding of input and output fibers to match core fundamental mode fields and cladding sizes, ensuring a constant core-to-cladding ratio, thereby preserving high-power cladding light and maintaining beam quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a standard splice is used between asymmetric fiber geometries, then the connection is simple, but insertion loss increases and beam quality degrades
Solution Approach 1:
The patent introduces a mode field adapter as an intermediary component between asymmetric fibers. The adapter includes a first section with adiabatically etched cladding and a second section with adiabatically tapered core and cladding, serving as a transition element that gradually transforms the mode field from one fiber geometry to another, thereby reducing insertion loss and beam quality degradation while maintaining connection simplicity
Solution Approach 2:
The patent applies parameter changes by adiabatically varying the cladding diameter in the first section and simultaneously varying both core and cladding diameters in the second section. These gradual parameter changes enable smooth mode field transformation between asymmetric fibers, resolving the contradiction between simple connection and low insertion loss
2Reliability
If a mode field adapter is used to match core fundamental mode fields, then beam quality improves, but cladding size mismatch causes high-power cladding light loss
Solution Approach 1:
The patent segments the mode field adapter into two distinct functional sections: a first section with adiabatically etched cladding designed to preserve high-power cladding light, and a second section with adiabatically tapered core and cladding designed to match core fundamental mode fields. This segmentation allows each section to optimize for its specific function, simultaneously achieving beam quality improvement and cladding light preservation
Solution Approach 2:
The patent applies local quality by giving different structural characteristics to different sections of the adapter. The first section has etched cladding with constant core-to-etched cladding ratio optimized for cladding light preservation, while the second section has tapered core and cladding optimized for mode field matching. Each local region is optimized for its specific function, resolving the contradiction between beam quality and cladding light loss
3Loss of energy
If adiabatic etching is applied to match core-to-cladding ratio, then cladding light preservation improves, but manufacturing complexity increases
Solution Approach 1:
The patent uses adiabatic parameter changes where the cladding diameter is gradually reduced along the first section while maintaining a constant core-to-etched cladding ratio. This controlled parameter transformation enables smooth mode field adaptation for cladding light preservation without introducing abrupt discontinuities, achieving improved cladding light preservation with manageable manufacturing complexity
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 MFA effectively matches core and cladding diameters across fibers, allowing high-power cladding light to pass through with minimal loss, improving beam quality and handling a wide range of fiber types, including those with different numerical apertures.
Implementation Method 1
the cladding surrounding the core of the first fiber is adiabatically etched such that a ratio between the core of the first fiber and the cladding surrounding the core changes over a length of the first fiber
Implementation Method 2
the core and the cladding surrounding the core of the second fiber are adiabatically tapered such that a ratio between the core of the second fiber and the cladding surrounding the core of the second fiber is constant over a length of the second fiber
Data Source
AI summary
As described herein, a mode field adapter (MFA) comprises a first fiber including a core associated with a fundamental mode field diameter and a cladding with a diameter that decreases toward a waist. The MFA comprises a second fiber including a core associated with a fundamental mode field diameter that matches the fundamental mode field of the first fiber at the waist and a cladding with a diameter that matches the diameter of the cladding of the first fiber at the waist and increases from the waist of the second fiber. The cladding of the first fiber may be adiabatically etched such that a core-to-cladding ratio of the first fiber changes over a length of the first fiber, and the core and the cladding of the second fiber may be adiabatically tapered such that a core-to-cladding ratio of the second fiber is constant over a length of the second fiber.