Optoelectronic Semiconductor Laser Light Blocking Layer
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Solution Overview
Problem
Existing optoelectronic semiconductor lasers face issues with substrate modes causing undesirable radiation emission, which degrades beam quality and leads to imaging aberrations, especially when using transparent substrates like GaN for UV or blue/green emission.
Innovation Solution
A method involving epitaxial growth of semiconductor layers on a growth substrate, shaping a front facet, and applying a directional light blocking layer by shading with the growth substrate or dummy bars to prevent substrate modes from interfering with the main laser radiation exit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transparent growth substrate is used for UV or blue/green emission, then the substrate allows radiation transmission, but substrate modes cause undesirable radiation emission that degrades beam quality
Solution Approach 1:
The harmful substrate mode radiation is extracted and removed from the optical path by applying a light blocking layer to the front facet of the substrate. This layer selectively blocks the unwanted substrate modes while allowing the desired laser radiation to pass through the light exit region.
Solution Approach 2:
The light blocking layer is applied locally to specific regions of the front facet rather than uniformly across the entire surface. The layer is positioned to block substrate modes while leaving the light exit region uncovered, creating different optical properties in different areas of the substrate.
2Object-generated harmful factors
If a light blocking layer is applied to the front facet, then substrate modes are suppressed, but the light exit region must remain uncovered to allow laser radiation emission
Solution Approach 1:
The front facet is segmented into two functional regions: a light blocking region where the light blocking layer is applied to suppress substrate modes, and a light exit region that remains uncovered to allow laser radiation emission. This segmentation resolves the contradiction by assigning different optical functions to different areas.
3Ease of manufacture
If conventional coating methods are used, then the front facet can be coated, but precise control of light blocking regions is difficult
Solution Approach 1:
A mask layer is introduced as an intermediary element during the coating process. This mask layer defines the light exit region and protects it from the light blocking material deposition. The mask layer enables precise positioning of the light blocking regions while using conventional coating methods, resolving the contradiction between ease of manufacture and manufacturing precision.
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 light blocking layer effectively suppresses substrate modes, enhancing the beam quality of the semiconductor laser by ensuring radiation emission occurs from a single point-like region, reducing halo effects and improving imaging accuracy.
Implementation Method 1
the second partial layers include a material absorbent for the emission wavelength λ
Implementation Method 2
the first partial layers include a material transmissive for the emission wavelength λ
Implementation Method 3
the light blocking layer is produced by a directional coating method
Data Source
AI summary
An optoelectronic semiconductor laser includes a growth substrate; a semiconductor layer sequence that generates laser radiation; a front facet at the growth substrate and at the semiconductor layer sequence, wherein the front facet constitutes a main light exit side for the laser radiation generated in the semiconductor laser and has a light exit region at the semiconductor layer sequence; a light blocking layer for the laser radiation, which partly covers at least the growth substrate at the front facet such that the light exit region is not covered by the light blocking layer; and a bonding pad at a side of the semiconductor layer sequence facing away from the growth substrate, wherein a distance between the bonding pad and the light blocking layer at least at the light exit region is 0.1 μm to 100 μm.