Semiconductor Laser Waveguide Refractive Index Gradient
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Solution Overview
Problem
Laser diodes face challenges in achieving high efficiency and independent adjustment of electrical series resistance and beam divergence due to the interdependence of these parameters in their layer structure, especially at high temperatures and operating currents.
Innovation Solution
A semiconductor laser design featuring a waveguide with a subregion made from compound semiconductor material, where the material proportion gradually increases towards the active zone, allowing for independent adjustment of series resistance and beam divergence by varying the aluminum or phosphorus proportion, thereby reducing series resistance while maintaining wave guidance quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the layer structure of the laser diode is modified to reduce series resistance, then electrical efficiency is improved, but vertical beam divergence and beam parameter product cannot be independently adjusted
Solution Approach 1:
The waveguide is divided into multiple subregions (first subregion, second subregion, third subregion) with different material compositions and refractive index profiles. Each subregion can be independently optimized: the first subregion controls series resistance through its material composition, while the second and third subregions control vertical and lateral beam divergence through their respective refractive index gradients. This segmentation allows independent adjustment of electrical and optical parameters without mutual interference.
Solution Approach 2:
Different portions of the waveguide are assigned different material properties tailored to specific functions. The first subregion has material composition optimized for low series resistance, while the second subregion has a refractive index gradient optimized for vertical beam divergence control, and the third subregion has properties optimized for lateral beam divergence control. This local differentiation enables each region to perform its specific function optimally without compromising other parameters.
2Shape
If the material composition is changed to adjust beam divergence, then radiation characteristics are improved, but series resistance increases
Solution Approach 1:
The waveguide is segmented into functional zones where material composition changes are localized to specific regions. The second subregion contains the refractive index gradient needed for beam divergence control, while the first subregion maintains material composition optimized for low series resistance. This spatial segmentation allows beam divergence adjustment without significantly increasing overall series resistance.
Solution Approach 2:
Material composition is locally optimized for specific functions: the second subregion has a refractive index gradient ( achieved through material composition variation) specifically for controlling vertical beam divergence, while other regions maintain compositions optimized for electrical performance. This local quality differentiation allows beam divergence control with minimal impact on series resistance.
3Stability of the object's composition
If high aluminum or phosphorus proportion is used in the waveguide, then refractive index control for beam guidance is improved, but charge carrier mobility decreases and series resistance increases
Solution Approach 1:
The waveguide is divided into subregions with different aluminum/phosphorus proportions. The first subregion uses lower aluminum/phosphorus content to maintain high charge carrier mobility and low series resistance, while the second subregion uses higher proportions to achieve the desired refractive index gradient for beam guidance. This segmentation allows refractive index control without excessive series resistance penalty.
Solution Approach 2:
High aluminum or phosphorus proportion is localized to the second subregion where refractive index gradient is needed for beam guidance, while the first subregion maintains lower proportions to preserve charge carrier mobility. This local quality differentiation allows refractive index control with minimal impact on overall electrical performance.
4Ease of manufacture
If the waveguide structure is simplified, then manufacturing is easier, but the ability to independently control series resistance and beam divergence is lost
Solution Approach 1:
The waveguide is segmented into subregions that can be fabricated using standard epitaxial growth techniques with controlled material composition gradients. Each subregion's material properties are established during the growth process through controlled variation of aluminum/phosphorus content, avoiding the need for complex post-fabrication processing. This segmentation approach maintains manufacturing simplicity while enabling independent parameter control.
Solution Approach 2:
The material composition parameters (aluminum/phosphorus proportion) are continuously varied during epitaxial growth to create the desired refractive index gradients in different subregions. By controlling composition parameters during a single growth process, the complex multi-functional waveguide structure is created without requiring multiple fabrication steps, thus maintaining ease of manufacture while achieving independent parameter control.
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 design enables targeted adjustment of series resistance and beam divergence, enhancing the efficiency and precision of semiconductor lasers by reducing leakage currents and maintaining beam quality, particularly at high powers and temperatures.
Implementation Method 1
a proportion of a material of the compound semiconductor material gradually increases in the entire subregion along the vertical direction toward the active zone so that a refractive index of the subregion gradually decreases toward the active zone
Data Source
AI summary
A semiconductor laser including an active zone and a waveguide, wherein the active zone includes an active layer configured to generate electromagnetic radiation during operation of the semiconductor laser, the waveguide is configured to guide the electromagnetic radiation generated during operation of the semiconductor laser within the semiconductor laser, the waveguide includes a subregion formed from a compound semiconductor material, wherein a proportion of a material of the compound semiconductor material gradually increases in the entire subregion along the vertical direction toward the active zone so that a refractive index of the subregion gradually decreases toward the active zone, and the proportion is an aluminum proportion or a phosphorus proportion.