Divided Electrode Semiconductor Laser for Beam Quality
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Solution Overview
Problem
High-output semiconductor lasers for laser machining face challenges in maintaining high beam quality and preventing catastrophic optical damage, particularly in wide stripe structures where higher-order transverse modes lead to degraded beam parameter product (BPP).
Innovation Solution
The semiconductor laser device incorporates a divided electrode or current block layer structure, positioned at specific locations where the integrated light intensity of higher-order mode oscillation has local maxima or minima, to favor fundamental mode oscillation by adjusting current distribution and gain differences between modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a wide stripe structure is adopted to prevent catastrophic optical damage, then output power is improved, but beam quality deteriorates due to higher-order mode oscillation
Solution Approach 1:
The electrode is divided into multiple independent electrode sections along the stripe width direction, allowing independent current control to different regions. This segmentation enables selective current suppression in regions where higher-order modes dominate, while maintaining sufficient current in the central region for fundamental mode oscillation, thus achieving both high power and good beam quality
Solution Approach 2:
Different current densities are applied to different regions of the stripe structure. The central region receives higher current density to support fundamental mode oscillation, while edge regions receive lower current density to suppress higher-order modes. This local differentiation of current quality enables the wide stripe structure to maintain good beam quality while achieving high output power
2Manufacturing precision
If current is increased to maintain fundamental mode oscillation in wide stripe structure, then beam quality is improved, but catastrophic optical damage risk increases
Solution Approach 1:
By dividing the electrode into multiple sections, the total current is distributed across different regions. This allows the current density in any single region to be controlled below the threshold for catastrophic optical damage, while the integrated effect across all sections maintains sufficient total power for fundamental mode oscillation
Solution Approach 2:
The current density distribution is optimized by adjusting the division positions of electrode sections. By positioning division points at specific locations (such as intensity minima of higher-order modes), the current parameters are tuned to achieve fundamental mode dominance without exceeding safe current density thresholds that would cause catastrophic optical damage
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 enables stable fundamental transverse mode oscillation with excellent BPP, even in wide stripe structures, maintaining high beam quality and output while reducing the likelihood of catastrophic optical damage.
Implementation Method 1
Almost all semiconductor lasers obtain an optical gain by condensing electrons/positive holes and light to an active layer to perform stimulated emission using a so-called double heterostructure.
Implementation Method 2
Laser machining utilizes high energy obtained by condensing laser beams to an extremely small area to cut or weld materials by heating, melting, evaporating the materials.
Data Source
AI summary
A semiconductor laser device includes: a first semiconductor layer of a first conductivity type; a light emitting layer formed above the first semiconductor layer; a second semiconductor layer of a second conductivity type formed above the light emitting layer; and an electrode formed above a ridge portion formed in the second semiconductor layer. The electrode is divided at positions at which an integrated value of light intensities of higher-order mode oscillation has a local maximum.