VECSEL Strain Compensation Layers for Quantum Well Gain
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Solution Overview
Problem
Conventional VECSEL devices with strain compensation layers offset strains around quantum well layers, leading to reduced maximum gain, necessitating a structural improvement to enhance the gain of quantum well layers in a periodic gain structure.
Innovation Solution
A VECSEL device with a multiple quantum well layer having first and second strain compensation layers formed of GaAsP and GaNAs, respectively, to gradually relieve strain, along with a capping layer of AlxGa(1−x)As, and barrier layers of AlyGa(1−y)As, to maximize quantum well layer gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If strain compensation layers are formed to completely offset strains around quantum well layers, then structural defects are suppressed, but the maximum gain of the quantum well layers is lowered
Solution Approach 1:
The patent applies local quality by creating different strain compensation conditions in different regions. The first strain compensation layer (GaAsP) and second strain compensation layer (GaNAs) have different material compositions and strain compensation capabilities, allowing localized optimization where complete strain offset is not uniformly applied, thus preserving quantum well gain while preventing structural defects.
Solution Approach 2:
The patent uses composite materials by combining GaAsP and GaNAs in a layered structure. These composite strain compensation layers have different bandgap energies and strain characteristics, enabling them to work together to manage strain distribution without completely offsetting it, thereby maintaining quantum well layer gain while ensuring structural reliability.
2Power
If a periodic gain structure with quantum wells is used to increase gain volume, then laser output power can be increased to 100 mW or more, but strain accumulation causes structural defects
Solution Approach 1:
The patent segments the strain compensation function into multiple distinct layers: a first strain compensation layer (GaAsP) and a second strain compensation layer (GaNAs). This segmentation allows each layer to handle different aspects of strain management in the periodic quantum well structure, preventing strain accumulation that would lead to structural defects while maintaining high laser output power.
Solution Approach 2:
The strain compensation layers act as intermediary structures between the quantum well layers. These intermediate layers (GaAsP and GaNAs) mediate the strain stress generated by the periodic quantum well structure, distributing and relieving strain without completely offsetting it, thus preventing structural defects while preserving the high gain necessary for 100 mW or more laser output.
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 effectively maximizes the gain of quantum well layers, preventing structural defects and ensuring improved operating characteristics and reliability of the VECSEL device.
Implementation Method 1
first and second strain compensation layers sequentially formed above and below each of the quantum well layers to gradually relieve the strain of the quantum well layers
Implementation Method 2
multiple quantum well layer having a periodic gain structure
Data Source
AI summary
An improved VECSEL device is provided in which the gain of each of the quantum well layers can be increased in a periodic gain structure. A vertical external cavity surface emitting laser (VECSEL) device comprising: a substrate; a bottom DBR mirror formed on the substrate; a multiple quantum well layer formed on the bottom DBR mirror and comprising: a plurality of quantum well layers; first and second strain compensation layers sequentially formed above and below each of the quantum well layers to gradually relieve the strain of the quantum well layers; a capping layer formed on the multiple quantum well layer; an optical pump radiating a pump beam to the surface of the capping layer; and an external cavity mirror separated from and facing the bottom DBR mirror.