Edge-Emitting Laser Facets With Split Reflectivity for Mode Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing edge-emitting semiconductor laser diodes face challenges in achieving homogeneous beam quality, increased efficiency, and high reliability, particularly in manufacturing processes that are simplified at the wafer level.
Innovation Solution
The semiconductor laser diode features an epitaxial semiconductor layer stack with facets having partial surfaces with different reflectivities, which form a resonator to selectively amplify desired electromagnetic laser radiation modes and attenuate undesired modes, improving beam quality and efficiency by adjusting reflectivity through surface roughness and tilt angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional facets with uniform reflectivity are used, then manufacturing is simpler, but beam quality is non-homogeneous and efficiency is reduced
Solution Approach 1:
The facet is divided into multiple partial surfaces (first, second, third partial surfaces) with different reflectivities. The first partial surface has high reflectivity for fundamental modes, the second partial surface has low reflectivity for fundamental modes but high reflectivity for filamentation modes, and the third partial surface has intermediate reflectivity. This local differentiation of optical properties across the facet surface enables selective mode control to achieve homogeneous beam quality.
2Productivity
If all modes are amplified equally, then manufacturing is simpler, but efficiency decreases due to undesired modes and filamentation
Solution Approach 1:
Different regions of the facet are assigned different reflectivity characteristics to selectively amplify or suppress specific modes. The first partial surface amplifies fundamental modes while the second partial surface suppresses fundamental modes but reflects filamentation modes, creating a distributed feedback mechanism that enhances efficiency by preventing unwanted mode growth.
Solution Approach 2:
The facet structures provide optical feedback to the active zone through stimulated emission. The differentiated reflectivities create a feedback mechanism where fundamental modes receive constructive feedback from the first partial surface while filamentation modes are suppressed by the second partial surface, enabling mode-selective amplification that improves laser efficiency.
3Reliability
If uniform facet surfaces are used, then manufacturing is easier, but reliability is reduced due to filamentation
Solution Approach 1:
The facet is structured with distinct partial surfaces having different optical properties. The second partial surface specifically addresses filamentation by providing low reflectivity for fundamental modes and high reflectivity for filamentation modes, thereby suppressing filamentation-induced reliability issues while maintaining manufacturability through defined surface regions.
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 enhances the beam quality, reliability, and efficiency of the semiconductor laser diode by ensuring only desired modes are amplified, reducing undesired modes and filamentation, thereby improving overall performance.
Implementation Method 1
the facet has at least a first partial surface and at least a second partial surface which have different reflectivities from each other for the electromagnetic radiation generated in the active zone
Implementation Method 2
the electromagnetic radiation is generated in the active zone by stimulated emission, which leads to the formation of electromagnetic laser radiation in the resonator
Data Source
AI summary
The invention relates to an edge-emitting semiconductor laser diode, including the following features: an epitaxial semiconductor layer stack including an active one, in which during operation electromagnetic radiation is generated, wherein the epitaxial semiconductor layer stack has at least one facet which laterally delimits the epitaxial semiconductor layer stack, and the facet has at least one first partial surface and at least one second partial surface which have reflectivities differing from one another for the electromagnetic radiation generated in the active zone. The invention also relates to methods for producing a plurality of edge-emitting semiconductor laser diodes.