Double-Clad Fiber Laser Coupling via Polarization Beam Splitting
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Solution Overview
Problem
Existing methods for coupling a laser beam into a double-clad fiber are mechanically complex and require significant adjustment efforts to change laser beam parameters such as focus diameter, intensity distribution, and beam profile, which is challenging for different machining processes.
Innovation Solution
A device comprising a first birefringent optical element to split the laser beam into sub-laser beams, a polarization rotation device to adjust the polarization of these sub-laser beams, and a second birefringent optical element to further split the sub-laser beams into sub-sub-laser beams, which are then coupled into the inner and annular cores of the double-clad fiber, allowing for adjustable beam quality and reduced mechanical complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wedge switch is used to adjust beam quality by coupling laser beam components into different cores, then beam profile characteristics and beam quality can be adjusted, but the device becomes mechanically complex and requires extensive adjustment
Solution Approach 1:
The patent replaces the mechanical wedge switch system with a polarization-based optical system using birefringent elements and polarization controllers. This substitution eliminates mechanical moving parts while achieving the same function of directing laser components to different cores through polarization manipulation rather than mechanical switching
Solution Approach 2:
The invention changes the control parameter from mechanical position (wedge switch position) to polarization state (controlled by birefringent elements and polarization controllers). By adjusting polarization parameters rather than mechanical positions, the system achieves beam quality adjustment with reduced mechanical complexity
2Adaptability or versatility
If polarization splitting with birefringent elements is used to couple sub-laser beams into different cores, then beam quality can be adjusted, but the device requires significant refitting effort when changing machining processes
Solution Approach 1:
The patent creates a universal optical system where the same birefringent elements and polarization controllers can produce different beam profiles (Gaussian, top-hat, annular) by adjusting polarization states. This multi-functional capability allows the system to adapt to different machining processes without physical refitting, as the optical components serve multiple beam shaping functions through parameter adjustment alone
3Adaptability or versatility
If mechanical adjustment systems are used to change laser beam parameters for different machining processes, then beam parameters can be modified, but the refitting effort and adjustment time increase significantly
Solution Approach 1:
The patent replaces mechanical adjustment systems with polarization-based control using birefringent elements and polarization controllers. This allows rapid, non-mechanical adjustment of beam parameters by changing polarization states, eliminating the time-consuming mechanical refitting process while maintaining adaptability to different machining processes
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 enables efficient coupling of laser beams into double-clad fibers with adjustable beam quality, reducing the mechanical complexity and refitting efforts required for different machining processes, thus enhancing the stability and efficiency of laser material machining systems.
Implementation Method 1
a first birefringent optical element configured to split the laser beam incident on a beam entry surface into two sub-laser beams, wherein the two sub-laser beams have first exit angles and/or first beam displacements with respect to a beam exit surface normal, wherein the two sub-laser beams are polarized along base polarization components of the first birefringent optical element
Implementation Method 2
a polarization rotation device configured to adjust a polarization of the sub-laser beams to provide polarization-adjusted sub-laser beams
Implementation Method 3
a second birefringent optical element wherein the beam exit surface of the second birefringent optical element is first passed through by the polarization-adjusted sub-laser beams, wherein the first exit angles and/or the first beam displacements of the sub-laser beams from the first birefringent optical element are second angles of impingement and/or second beam displacements of the polarization-adjusted sub-laser beams relative to a beam exit surface normal of the second birefringent optical element, wherein the second birefringent optical element is configured to split each of the polarization-adjusted sub-laser beams into two sub-sub-laser beams
Data Source
AI summary
A device for coupling a laser beam into a double-clad fiber includes a first birefringent optical element configured to split the laser beam into two sub-laser beams polarized along base polarization components of the first birefringent optical element, a polarization rotation device configured to adjust a polarization of the sub-laser beams to provide polarization-adjusted sub-laser beams, a second birefringent optical element configured to split each of the polarization-adjusted sub-laser beams into two sub-sub-laser beams polarized along base polarization components of the second birefringent optical element, and an in-coupling optical unit configured to couple the sub-sub-laser beams with compensated first exit angles and/or first beam displacements into an inner core of the double-clad fiber, and to couple other sub-sub-laser beams into an annular core of the double-clad fiber.