VCSEL Reflector With AlN-GaN Lamination For Thermal Management
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Solution Overview
Problem
Vertical cavity surface emitting lasers (VCSELs) face challenges with heat dissipation due to the poor thermal conductivity of traditional distributed Bragg reflectors (DBR) made from laminated InGaN and AlGaN layers, which limits their reflectance and performance.
Innovation Solution
A reflector structure is developed with a low refractive index layer of alternately laminated AlN and GaN layers and a high refractive index layer containing InGaN, optimizing the refractive index difference and film thickness to achieve high reflectance while improving thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a DBR is made from laminated InGaN and AlGaN layers, then the reflectance can be improved, but the heat dissipation deteriorates
Solution Approach 1:
The patent uses a composite reflector structure combining AlN/GaN laminated layers (low refractive index) with InGaN layers (high refractive index). This composite structure achieves high reflectance through refractive index contrast while improving heat dissipation by incorporating GaN and InGaN materials with better thermal conductivity compared to traditional AlGaN-based DBRs
Solution Approach 2:
The patent applies local quality by creating distinct regions with different material compositions and thermal properties. The AlN/GaN laminated structure provides one set of properties (low refractive index, good thermal conductivity) while the InGaN layers provide complementary properties (high refractive index, good thermal conductivity), allowing each region to contribute optimally to both reflectance and heat dissipation
2Illumination intensity
If the refractive index difference is increased to improve reflectance, then the reflectance is improved, but the crystal quality may deteriorate
Solution Approach 1:
The patent carefully controls parameters including the thickness of each layer (AlN, GaN, InGaN), the composition ratio of InGaN, and the lamination structure to achieve the desired refractive index difference. By optimizing these parameters, the patent maintains high reflectance while preventing crystal defects that would arise from excessive refractive index contrast or improper layer dimensions
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 proposed reflector structure achieves reflectance of 99.9% or more and enhances heat dissipation, addressing the limitations of traditional DBR materials by maintaining high crystal quality and reducing defects.
Implementation Method 1
a low refractive index layer having a laminated structure in which an AlN layer and a GaN layer are alternately laminated
Implementation Method 2
The low refractive index layer has a first average refractive index and has a laminated structure in which an AlN layer and a GaN layer are alternately laminated. The high refractive index layer has a second average refractive index higher than the first average refractive index
Data Source
AI summary
A reflector includes a low refractive index layer and a high refractive index layer. The low refractive index layer has a first average refractive index and has a laminated structure in which an AlN layer and a GaN layer are alternately laminated. The high refractive index layer has a second average refractive index higher than the first average refractive index and includes an InGaN layer.