Edge-Emitting Semiconductor Laser Stress Layer Index Guidance
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Solution Overview
Problem
Conventional edge-emitting semiconductor lasers face challenges in achieving high-efficiency radiation emission within a specific region due to limitations in beam quality and brilliance, particularly in gain-guided lasers, where the light-emitting surface is unstable and broad, leading to increased beam parameter product and reduced reliability in applications like fiber coupling.
Innovation Solution
The introduction of a stress layer in the semiconductor laser, which induces targeted material stress perpendicular to the growth direction, creating refractive index gradients that provide index guidance without etching the semiconductor layer sequence, resulting in a narrower light emission surface and improved beam quality by reducing the beam parameter product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If gain-guided laser structure is used, then ease of manufacture is improved, but beam quality deteriorates due to unstable and broad light-emitting surface
Solution Approach 1:
The patent changes the physical parameter of the semiconductor layer by introducing a stress layer that modifies the refractive index through stress-induced effects. This allows the light-emitting surface width to be controlled by material properties rather than geometric etching, improving beam quality while maintaining ease of manufacture
Solution Approach 2:
The patent replaces the mechanical/geometric approach of defining the light-emitting surface through etching with an optical approach using stress-induced refractive index changes. This substitution allows for better beam quality control without compromising manufacturing simplicity
2Manufacturing precision
If light-emitting surface is reduced to improve beam quality, then beam parameter product is reduced, but reliability deteriorates due to increased sensitivity to manufacturing variations
Solution Approach 1:
The patent uses stress layer thickness and material composition as controllable parameters to achieve the desired refractive index profile. This provides a reliable manufacturing approach where the light-emitting surface characteristics are determined by material properties that can be precisely controlled during deposition, reducing sensitivity to geometric variations
3Manufacturing precision
If stress layer is introduced to achieve index guidance, then beam quality is improved through lateral guidance, but device complexity increases
Solution Approach 1:
The patent segments the semiconductor structure into distinct functional layers, with the stress layer being a separate component that can be independently optimized. This segmentation allows the complex function of index guidance to be achieved through a dedicated layer rather than complicating the entire structure
Solution Approach 2:
The patent uses composite material structure combining the semiconductor active layers with a stress-inducing layer. This composite approach enables the stress layer to provide refractive index guidance while the semiconductor layers provide lasing functionality, achieving beam quality improvement without significantly increasing overall device 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 stress layer achieves strong lateral guidance of the electro-optical field, leading to a more defined light emission surface and improved beam quality, specifically reducing the beam parameter product, thus enhancing the semiconductor laser's performance in applications requiring focused optical output.
Implementation Method 1
the at least one stress layer (6) is configured for achieving targeted material stress in the semiconductor layer sequence (3)... as a result of the stress layer a refractive index of the semiconductor layer sequence is reduced... slight index guidance of laser radiation generated during operation is obtained
Data Source
AI summary
An edge-emitting semiconductor laser and a method for operating a semiconductor laser are disclosed. The edge-emitting semiconductor laser includes an active zone within a semiconductor layer sequence and a stress layer. The active zone is configured for being energized only in a longitudinal strip perpendicular to a growth direction of the semiconductor layer sequence. The semiconductor layer sequence has a constant thickness throughout in the region of the longitudinal strip so that the semiconductor laser is gain-guided. The stress layer may locally stress the semiconductor layer sequence in a direction perpendicular to the longitudinal strip and in a direction perpendicular to the growth direction. A refractive index of the semiconductor layer sequence, in regions which, seen in plan view, are located next to the longitudinal strip, for the laser radiation generated during operation is reduced by at least 2×10−4 and by at most 5×10−3.