Surface Emitting Laser Composition Gradient Oxidation Control
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Solution Overview
Problem
Conventional surface emitting lasers with oxide-confined structures face challenges in achieving high output power and single-mode operation due to refractive index differences, which lead to manufacturing complexities and cost increases, while also experiencing degradation issues from oxidized layers.
Innovation Solution
Incorporating a composition gradient layer between refractive index layers in the semiconductor DBR, where the composition gradually changes, allowing for more control over oxidation rates and reducing variations in oxidized layer thickness, thereby improving manufacturing yield and extending service lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a selective oxidation process is performed to form an oxide-confined structure, then current influx efficiency is enhanced and light confinement is improved, but manufacturing complexity increases and service lifetime decreases due to degradation from oxidized layers
Solution Approach 1:
The patent applies parameter changes by modifying the Al composition gradient in the semiconductor layers. By controlling the aluminum composition to gradually decrease from the substrate side toward the light-emitting surface, the oxidation rate is naturally regulated without requiring complex selective oxidation processes. This composition parameter change enables both simplified manufacturing and improved service lifetime by reducing oxidized layer degradation.
Solution Approach 2:
The patent employs composite materials by creating a multi-layer semiconductor structure with varying Al compositions (e.g., AlGaAs layers with different aluminum contents). This composite structure allows different regions to have optimized properties: higher Al content near the substrate for better oxidation control and lower Al content near the surface for reduced degradation, thereby extending service lifetime while maintaining manufacturing feasibility.
2Reliability
If the area of the confined region is reduced to achieve single-mode oscillation, then higher-order lateral modes are suppressed, but output power decreases
Solution Approach 1:
The patent applies local quality by creating spatial variation in Al composition within the semiconductor layers. The composition is locally optimized at different positions: higher Al content in regions requiring strong confinement to suppress higher-order modes, and lower Al content in regions where output power needs to be maintained. This local compositional quality enables simultaneous achievement of single-mode stability and high output power.
Solution Approach 2:
The patent utilizes parameter changes by continuously varying the aluminum composition gradient across the semiconductor structure. This gradual parameter change allows the refractive index and confinement characteristics to be tuned spatially, enabling single-mode operation while maintaining sufficient active region area for high output power through optimized carrier and light distribution.
3Productivity
If Al content in semiconductor layers is increased to enhance light confinement, then refractive index difference increases and emission efficiency improves, but oxidation rate increases leading to thicker oxidized layers and potential degradation
Solution Approach 1:
The patent applies parameter changes by implementing a controlled Al composition gradient rather than using uniform high Al content. The aluminum composition parameter is varied systematically: higher values where light confinement is needed for efficiency, and lower values where oxidation control is critical for reliability. This dynamic parameter adjustment resolves the contradiction between emission efficiency and service lifetime.
Solution Approach 2:
The patent uses composite materials with different Al compositions to balance conflicting requirements. Layers with higher Al content provide the refractive index contrast needed for efficient light confinement and high emission efficiency, while adjacent layers with lower Al content exhibit reduced oxidation rates, forming thinner oxidized layers and improving service lifetime. This composite approach allows both high productivity and reliability.
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 enables the production of surface emitting lasers with high single-mode output without increasing costs, while reducing the negative impact on the active layer and improving the stability and longevity of the devices.
Implementation Method 1
a composition gradient layer in which composition is gradually changed from one side to the other is interposed between the refractive index layers
Implementation Method 2
a selective oxidation process is usually performed with respect to an AlAs (Al: aluminum, As: arsenic) layer
Implementation Method 3
The refractive index of the aluminum-oxidized layer (Al x O y ) (hereinafter referred to as an 'oxidized layer') in the oxide-confined structure is about 1.6, which is lower than that of semiconductor layers
Data Source
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AI summary
A disclosed surface emitting laser is capable of being manufactured easily, having a higher yield and a longer service lifetime. In the surface emitting laser, a selectively-oxidized layer is included as a part of a low refractive index layer of an upper semiconductor distribution Bragg reflector; the low refractive index layer including the selectively- oxidized layer includes two intermediate layers adjoining the selectively-oxidized layer and two low refractive index layers adjoining the intermediate layers. Al content rate in the intermediate layers is lower than that in the selectively-oxidized layer, and Al content rate in the low refractive index layers is lower than that in the selectively-oxidized layer. This configuration enables providing more control over the thickness and oxidation rate of the oxidized layer, thereby enabling reducing the variation of the thickness of the oxidized layer.