Edge-Emitting Laser Diode Layer Stack for Substrate Mode Suppression
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Solution Overview
Problem
Edge-emitting semiconductor laser diodes face challenges in achieving improved beam quality due to parasitic substrate modes that impair imaging and image quality.
Innovation Solution
The implementation of a matching layer on the substrate's second main surface, in conjunction with an absorption layer, to attenuate substrate modes by adjusting their phase and intensity maxima, thereby enhancing absorption and suppressing parasitic modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a transparent substrate is used for the laser diode, then the substrate allows electromagnetic radiation to pass through, but parasitic substrate modes are generated that impair beam quality
Solution Approach 1:
An absorption layer is introduced as an intermediary between the transparent substrate and the external environment. This absorption layer specifically targets and absorbs parasitic substrate modes while allowing the useful laser radiation to pass through, thus mediating between the transparency requirement and the parasitic mode problem
Solution Approach 2:
The patent converts the harmful parasitic substrate modes into a beneficial situation by using the substrate's transparency as a double-edged sword: the same transparency that allows useful radiation to pass also enables the absorption layer to effectively target and absorb parasitic modes, turning the substrate's property into a solution rather than just a problem
2Object-generated harmful factors
If an absorption layer is added to suppress substrate modes, then parasitic modes are reduced, but the device structure becomes more complex
Solution Approach 1:
The absorption layer is applied selectively only to specific regions of the substrate where parasitic modes are generated, rather than covering the entire device. This localized approach suppresses harmful modes while minimizing the increase in overall device complexity and maintaining manufacturing simplicity
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 significantly improves the beam quality of the edge-emitting laser diode by reducing substrate modes by two orders of magnitude, leading to better imaging and image quality.
Implementation Method 1
an absorption layer disposed directly on the matching layer and configured for absorbing the electromagnetic radiation generated during operation at least partially
Implementation Method 2
the matching layer is configured for increasing the absorption of electromagnetic radiation in the absorption layer
Implementation Method 3
A highly reflective layer is preferably arranged on a facet, which is referred to below as back side facet, which is configured for reflecting electromagnetic radiation generated during operation
Implementation Method 4
An anti-reflective layer is preferably arranged on the light outcoupling facet, which has a lower reflectivity than the highly reflective layer on the back side facet
Data Source
AI summary
The invention relates to an edge-emitting semiconductor laser diode including a substrate having a first main face and a second main face opposite the first main face, an epitaxial semiconductor layer stack on the first main face of the substrate, wherein the epitaxial semiconductor layer stack includes an active layer for generating electromagnetic radiation, a matching layer arranged on the second main face of the substrate, and an absorption layer applied directly to the matching layer and configured to at least partially absorb the electromagnetic radiation, wherein the substrate and the matching layer are transparent to electromagnetic radiation generated during operation, and the matching layer is configured to increase the absorption of electromagnetic radiation in the absorption layer.