Diode Laser Wavelength Stabilization via Segmented Epitaxial Growth
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional GaAs-based broad area laser diodes with aluminum-containing layers face challenges in achieving high power and efficiency due to the introduction of Bragg gratings, which result in spectral instability and defect-rich crystal growth caused by oxidation, leading to reduced performance.
Innovation Solution
A two-stage epitaxial growth process is employed, where a continuous aluminum-free layer and mask layer are used to separate and structure the aluminum-containing layer within a reactor, minimizing oxygen incorporation and preventing oxidation, allowing for the formation of a Bragg grating with reduced oxygen concentration at the interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a Bragg grating is integrated in conventional laser diodes with aluminum-containing layers, then the emission wavelength stability is improved, but the power and efficiency are severely reduced due to oxidation and defect-rich crystal growth
Solution Approach 1:
The patent segments the growth process into two distinct stages: first growing the aluminum-containing layer with the Bragg grating in a nitrogen atmosphere to prevent oxidation, then growing subsequent aluminum-containing layers in a separate step. This segmentation allows the Bragg grating to be formed with minimal oxygen incorporation while maintaining high laser power and efficiency.
Solution Approach 2:
The patent employs an inert nitrogen atmosphere during the growth of the aluminum-containing layer and Bragg grating. By replacing the conventional oxygen-containing atmosphere with nitrogen, oxidation of the aluminum-containing layer is prevented, avoiding defect-rich crystal growth and maintaining high laser power and efficiency while still achieving wavelength stabilization.
2Stability of the object's composition
If a Bragg grating is integrated in conventional laser diodes with aluminum-containing layers, then the emission wavelength stability is improved, but the efficiency is severely reduced due to oxidation and defect-rich crystal growth
Solution Approach 1:
The patent segments the growth process into two distinct stages: first growing the aluminum-containing layer with the Bragg grating in a nitrogen atmosphere to prevent oxidation, then growing subsequent aluminum-containing layers in a separate step. This segmentation allows the Bragg grating to be formed with minimal oxygen incorporation while maintaining high laser power and efficiency.
Solution Approach 2:
The patent employs an inert nitrogen atmosphere during the growth of the aluminum-containing layer and Bragg grating. By replacing the conventional oxygen-containing atmosphere with nitrogen, oxidation of the aluminum-containing layer is prevented, avoiding defect-rich crystal growth and maintaining high laser power and efficiency while still achieving wavelength stabilization.
3Ease of manufacture
If the aluminum-containing layer is exposed during Bragg grating formation outside the reactor, then the Bragg grating can be structured, but the aluminum-containing layer is oxidized leading to defect-rich crystal growth
Solution Approach 1:
The patent employs an inert nitrogen atmosphere during the growth of the aluminum-containing layer and Bragg grating. By replacing the conventional oxygen-containing atmosphere with nitrogen, oxidation of the aluminum-containing layer is prevented, avoiding defect-rich crystal growth and maintaining high laser power and efficiency while still achieving wavelength stabilization.
Solution Approach 2:
The patent performs preliminary protection by growing the aluminum-containing layer completely covering the substrate before any structuring operations. The Bragg grating is then formed by selective etching of this pre-grown layer, eliminating the need to expose the aluminum-containing layer to oxidation during subsequent growth steps.
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 stabilizes the emission wavelength with minimal reduction in power or efficiency, achieving spectral widths less than 1 nm and temperature sensitivity less than 0.1 nm/K, while maintaining high power and efficiency comparable to or exceeding conventional laser diodes.
Implementation Method 1
a continuous aluminum-free layer and an aluminum-free mask layer are applied in a first growth process
Implementation Method 2
the aluminum-free layer and in the underlying aluminum-containing layer that a Bragg grating is formed
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present invention relates to a high-efficiency diode laser and a method for its fabrication. The object of the present invention is to describe a diode laser with aluminum-containing layers and a Bragg grating implemented for stabilizing the emission wavelength, which exhibits higher power and/or higher efficiency compared to conventional laser diodes. The idea of the present invention is that the growth process for introducing the Bragg grating is divided into two steps, wherein a continuous aluminum-free layer and an aluminum-free mask layer are continuously applied after the first growth process such that the aluminum-containing layer is completely covered by the continuous aluminum-free layer.Therefore, structuring can be performed outside a reactor without causing unwanted oxidation of the aluminum-containing semiconductor layer. Subsequently, the pre-structured semiconductor surface can be further etched within the reactor, so that the structuring is imprinted down to the aluminum-containing layer. In this process, so little oxygen is incorporated into the semiconductor crystal of the aluminum-containing layers in the vicinity of the lattice that the power and efficiency of a diode laser according to the invention are not reduced compared to a diode laser without the lattice layers, which was fabricated in an epitaxial step.