Optical Semiconductor Mesa Layout for Low-Reflection Light Output
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Solution Overview
Problem
Current optical semiconductor elements face challenges in enhancing output, particularly in achieving high light output while minimizing reflection and light emission from the end surface.
Innovation Solution
The optical semiconductor element incorporates a substrate with a {100} plane orientation, featuring a mesa with specific surface orientations and inclinations for the laser and optical amplifier portions, where the optical axis of the amplifier is inclined to reduce reflectivity and the second semiconductor layer confines light, preventing external radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the optical semiconductor element uses a conventional mesa structure with vertical surfaces, then the manufacturing process is simple, but the light output is limited and reflection from the end surface is high
Solution Approach 1:
The patent applies asymmetry by inclining the optical axis of the optical amplifier portion at a specific angle (α) relative to the normal direction of the end surface, rather than using a symmetric vertical configuration. This asymmetric inclination reduces reflectivity from the end surface and improves light output performance while maintaining manufacturing feasibility through controlled epitaxial growth and etching processes
Solution Approach 2:
The patent transitions from a conventional two-dimensional vertical mesa structure to a three-dimensional configuration by inclining the optical axis in a specific direction. The mesa structure includes surfaces with different orientations (first surface, second surface, third surface, fourth surface) that are inclined at different angles, creating a multi-dimensional geometric configuration that optimizes light extraction while managing reflectivity
2Productivity
If the end surface is perpendicular to the optical axis, then light extraction is maximized, but reflection from the end surface increases
Solution Approach 1:
The patent deliberately introduces asymmetry by setting the optical axis of the optical amplifier at an inclination angle α (0° < α ≤ 10°) relative to the normal of the end surface. This asymmetric configuration reduces the reflectivity from the end surface by preventing coherent reflection, while the light extraction efficiency is maintained through optimized coupling between the laser portion and optical amplifier portion
Solution Approach 2:
The patent converts the potentially harmful reflection effect into a beneficial configuration by carefully controlling the inclination angle. The inclined optical axis reduces harmful coherent reflection while the geometric configuration of the mesa surfaces (with specific inclination angles) ensures that light is still effectively extracted and coupled into the optical amplifier, turning the reflection reduction into a performance enhancement
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 results in suppressed reflection and enhanced light output, with low reflectivity at the end surface and improved light coupling efficiency, leading to a higher output performance.
Implementation Method 1
the optical axis of the amplifier is inclined to reduce reflectivity
Implementation Method 2
the second semiconductor layer confines light, preventing external radiation
Data Source
AI summary
An optical semiconductor element includes a substrate having a first main surface whose plane orientation is {100}, a first semiconductor layer provided on the first main surface and in which a mesa is formed, and a second semiconductor layer. The mesa has a laser portion and an optical amplifier portion. The laser portion has a first surface and a second surface. The optical amplifier portion has a third surface, a fourth surface, a fifth surface, a sixth surface, and an end surface. A first distance is smaller than a second distance. The first surface and the second surface are parallel to a {01-1} plane of the substrate. The end surface is perpendicular to the {01-1} plane. In a plane parallel to the first main surface, the third surface and the fourth surface are inclined from the {01-1} plane in directions identical to each other.