Elliptical Multi-Mesa VCSEL Structure for Heat and Current Uniformity
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Solution Overview
Problem
Conventional VCSELs face issues with poor heat dissipation, non-uniform current injection, large spectral line width, and low monochromaticity and thermal stability of light extraction, leading to inefficient current injection and output power.
Innovation Solution
An elliptical multi-mesa laser structure is introduced, featuring a substrate layer, N-DBR, functional layer, and P-DBR with space layers inserted into the DBRs, forming coaxial elliptical cylinders for improved heat dissipation and current injection efficiency, and including oxidation confinement layers for enhanced light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer circular or square mesa with single oxide layer and reflector layer is used, then the VCSEL structure is simple, but heat dissipation performance is poor
Solution Approach 1:
The patent divides the single mesa structure into multiple mesas arranged in an array. Each mesa is independently structured with its own oxide confinement layer and active region, allowing heat to be distributed across multiple discrete heat dissipation paths rather than concentrated in a single structure, thereby improving overall heat dissipation performance.
Solution Approach 2:
The patent transitions from a planar single-layer mesa to a three-dimensional multi-mesa array structure with vertical stacking and horizontal arrangement. This dimensional expansion creates additional heat dissipation surfaces and pathways, enabling more effective thermal management through increased surface area and distributed heat flow paths.
2Ease of manufacture
If a single-layer mesa structure is used, then manufacturing is simple, but current injection uniformity is poor due to high free carrier absorption
Solution Approach 1:
The patent segments the current injection path by creating multiple independent mesas with separate oxide confinement layers. This segmentation divides the high free carrier absorption region into smaller, manageable units, allowing more uniform current distribution across each individual mesa while maintaining manufacturing simplicity through replicated structures.
Solution Approach 2:
The patent introduces oxide confinement layers as intermediary structures between the current injection path and the active region. These oxide layers act as mediators that guide and distribute current more uniformly across the mesa structure, reducing the impact of free carrier absorption and improving current injection uniformity without complicating the overall fabrication process.
3Device complexity
If conventional VCSEL structure is used, then device simplicity is maintained, but spectral line width is large and monochromaticity is poor
Solution Approach 1:
The patent segments the optical cavity into multiple discrete mesas, each with its own confined active region. This segmentation creates multiple independent optical modes that can be controlled individually, allowing for narrower spectral line widths and improved monochromaticity while maintaining a relatively simple overall device structure through the use of identical replicated units.
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 elliptical multi-mesa laser structure enhances monochromaticity, thermal stability, and current injection efficiency, resulting in improved output power and conversion efficiency.
Implementation Method 1
replace a high AL component AlxGal-xAs material in BDR with the space layers to reduce DBR logarithm and increase a contrast refractive index
Implementation Method 2
an upper oxidation confinement layer group and a lower oxidation confinement layer group respectively fixedly connected on upper and lower end faces of the active layer
Data Source
AI summary
Provided is an elliptical multi-mesa laser structure, including a substrate layer, an N-DBR, a functional layer and a P-DBR sequentially arranged from bottom to top. The substrate layer is fixedly connected with an N contact layer. The N-DBR is fixedly connected to a top of the substrate layer, and the N contact layer is arranged around the N-DBR. A space layer is inserted in the N-DBR. The functional layer is fixedly connected to a top of the N-DBR. The P-DBR is fixedly connected to a top of the functional layer, and a top of the P-DBR is fixedly connected with a P contact layer. Another space layer is inserted into the P-DBR.