Surface-Emitting Laser Current Confinement via Composition Gradient
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Solution Overview
Problem
High-performance printers require surface-emitting semiconductor lasers with long service lives and stable single-mode light output for improved image quality, along with controlled laser beam divergence, which existing technologies have not adequately addressed.
Innovation Solution
A surface-emitting semiconductor laser with a current confinement layer comprising a high-Al content first semiconductor layer, a lower Al content second semiconductor layer, and a composition-gradient layer, formed by selective oxidation, to achieve both current and light confinement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional current confinement layer with uniform composition is used, then the manufacturing process is simple, but the single-mode light output and polarization stability are insufficient
Solution Approach 1:
The current confinement layer is divided into multiple distinct layers: a first semiconductor layer with high Al content (0.7-0.95), a second semiconductor layer with lower Al content (0.3-0.6), and a composition-gradient layer with gradually changing Al content. This segmentation allows each layer to perform specific functions - the high-Al layer provides strong current confinement, the lower-Al layer reduces optical loss, and the gradient layer minimizes dislocation density, collectively achieving stable single-mode output.
Solution Approach 2:
Different regions of the current confinement layer are assigned different Al compositions tailored to local requirements. The high-Al content region near the active layer optimizes current confinement where it is most needed, while the lower-Al content region away from the active layer reduces optical absorption losses. The composition-gradient layer provides transitional properties with gradually varying Al content to manage stress and dislocations locally.
2Reliability
If selective oxidation is applied to achieve current confinement, then current confinement efficiency improves, but control of laser beam divergence angle becomes difficult
Solution Approach 1:
The Al composition parameter is strategically varied across different layers of the current confinement structure. The first semiconductor layer uses high Al content (0.7-0.95) to enhance oxidation resistance and current confinement, while the second layer uses lower Al content (0.3-0.6) to control the oxidation front propagation and influence the oxidized region shape, thereby controlling beam divergence. The gradient layer provides intermediate compositions to balance these effects.
3Reliability
If high Al content semiconductor layer is used in current confinement layer, then current confinement is enhanced, but manufacturing precision requirements increase due to composition gradient control
Solution Approach 1:
The composition-gradient layer is designed with a predetermined Al content profile that transitions from the high-Al first semiconductor layer to the lower-Al second semiconductor layer. This preliminary structuring of the composition gradient before oxidation ensures that the subsequent selective oxidation process proceeds uniformly, reducing variability and easing manufacturing precision requirements while maintaining effective current confinement.
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 solution enables the production of surface-emitting semiconductor lasers with enhanced single-mode light output and stable polarization, improving image quality and controlling laser beam divergence, thus meeting the requirements for high-performance printing applications.
Implementation Method 1
a current confinement layer including an oxidized region formed by selective oxidation
Implementation Method 2
a composition-gradient layer adjacent to the first semiconductor layer... A portion of the composition-gradient layer which faces the first semiconductor layer has a lower Al content than the first semiconductor layer
Data Source
AI summary
A surface-emitting semiconductor laser includes a first semiconductor multilayer film reflector, an active region, a second semiconductor multilayer film reflector, and a current confinement layer including an oxidized region formed by selective oxidation. The current confinement layer includes a first semiconductor layer having a relatively high Al content, a second semiconductor layer that is adjacent to the first semiconductor layer on an active-region side of the first semiconductor layer and has a lower Al content than the first semiconductor layer, and a composition-gradient layer adjacent to the first semiconductor layer on a side of the first semiconductor layer which is opposite to the active-region side. A portion of the composition-gradient layer which faces the first semiconductor layer has a lower Al content than the first semiconductor layer.