Tapered Laser Diode Beam Shaping Optics
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Solution Overview
Problem
Semiconductor laser diodes face challenges in achieving high power capability while maintaining good beam quality, which is essential for applications like welding and cutting, as their poor beam quality hinders their use in industrial processes compared to optically pumped solid-state lasers.
Innovation Solution
A semiconductor laser module incorporating a tapered laser diode or tapered amplifier diode combined with beam shaping optics, specifically a plano-convex spherical cylindrical lens, is used to adjust the beam divergence in the fast axis direction to match that of the slow axis direction, enabling the production of a high-quality, high-power laser beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high power is increased in semiconductor laser diodes, then power output is improved, but beam quality deteriorates
Solution Approach 1:
The patent segments the beam correction function into two distinct optical components: a cylindrical lens for fast-axis divergence control and a spherical lens for overall beam shaping. This segmentation allows each lens to be optimized for its specific function, enabling high power output while maintaining beam quality through specialized correction of different divergence components.
Solution Approach 2:
The patent introduces beam shaping optics as intermediary elements between the laser diode emitter and the target application. These optics act as mediators that transform the inherently poor beam quality of high-power diodes into acceptable beam profiles, enabling high power semiconductor lasers to compete with solid-state lasers in applications requiring good beam quality.
2Device complexity
If beam divergence in fast axis direction is not corrected, then device complexity is reduced, but beam quality deteriorates
Solution Approach 1:
The patent applies local quality correction by using a cylindrical lens specifically targeted at correcting fast-axis divergence, which is the primary source of beam quality degradation. This localized correction approach addresses the specific problem area without requiring complete redesign of the entire optical system, balancing complexity reduction with beam quality improvement.
Solution Approach 2:
The patent employs asymmetric optical correction by using a cylindrical lens with different optical properties in orthogonal directions. The cylindrical lens corrects fast-axis divergence while leaving slow-axis characteristics largely unchanged, creating an asymmetric correction strategy that efficiently improves beam quality by addressing the direction of greatest divergence without over-complicating the system.
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 configuration allows for the achievement of high-power, high-brightness laser beams that can be efficiently coupled into optical fibers, enabling applications such as deep-penetration welding with improved beam quality and efficiency, comparable to optically pumped solid-state lasers.
Implementation Method 1
The beam-shaping optics comprise a plano-convex spherical cylindrical lens having a planar surface arranged facing the facet and a circular cylindrical surface facing away from the facet
Data Source
AI summary
A semiconductor laser module comprises a tapered laser diode and/or a tapered amplifier diode equipped with beam shaping optics. The tapered laser diode and/or the tapered amplifier diode includes an emission facet for emitting a laser beam along a beam axis. The beam-shaping optics comprise a plano-convex cylindrical lens oriented so as to change divergence of the beam in the fast axis direction, the plano-convex spherical cylindrical lens having a planar surface arranged facing the facet and a circular cylindrical surface facing away from the facet. The refractive index of lens may be uniform throughout the entire lens. Alternatively, the lens may have a refractive index varying in the direction of the slow axis and/or in the direction of the fast axis.