VCSEL Double Oxide Aperture Red Wavelength Emission
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Solution Overview
Problem
Current VCSELs, particularly those emitting in the red spectrum, face challenges in achieving expanded wavelength coverage, improved performance, reliability, and manufacturability, which limits their applications in optically based medical sensors and plastic optical-fiber links due to high absorption at 850 nm and limited packaging options.
Innovation Solution
The development of VCSELs with a double oxide aperture structure, where one aperture provides optical confinement and the other electrical confinement, allowing for enhanced current and optical mode control, and the use of a multiple-quantum-well structure between conductive mirrors to achieve efficient light emission in the red wavelength range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If VCSELs use standard 850-nm multi-mode design, then they achieve good performance for glass optical-fiber data communication, but they suffer from high absorption losses in plastic optical-fiber links and limited wavelength coverage
Solution Approach 1:
The patent changes the emission wavelength parameter from the standard 850 nm to red wavelengths (650-750 nm) by modifying the VCSEL structure to include multiple quantum well active regions with specific bandgap energies. This wavelength shift reduces absorption losses in plastic optical-fiber links while maintaining compatibility with existing VCSEL fabrication processes
Solution Approach 2:
The VCSEL design achieves multi-functionality by enabling operation across multiple wavelength bands (red and near-infrared) within a single device structure. This allows the same VCSEL to serve both plastic optical-fiber communication (red) and glass optical-fiber communication (near-infrared) applications
2Adaptability or versatility
If VCSELs are designed for red wavelength emission, then they enable plastic optical-fiber links and medical sensor applications, but they face challenges in achieving sufficient output power and reliability
Solution Approach 1:
The patent employs composite material structures including multiple quantum well active regions composed of different semiconductor materials (e.g., AlGaInP, GaInP) with tailored bandgap energies. These composite structures enable efficient red wavelength emission while maintaining high reliability through optimized material composition and layer design
Solution Approach 2:
The VCSEL active region is segmented into multiple quantum well layers, each contributing to the overall light emission. This segmentation allows for distributed current injection and heat dissipation across multiple interfaces, improving device reliability and output power stability
3Device complexity
If VCSELs use single oxide aperture for both optical and electrical confinement, then the structure is simpler, but the control over current and optical mode is insufficient
Solution Approach 1:
The single oxide aperture is segmented into two distinct apertures: an optical aperture that defines the laser mode and an electrical aperture that confines the current injection. This segmentation allows independent optimization of optical and electrical performance, achieving precise control over both current distribution and optical mode while maintaining a relatively simple fabrication process
Solution Approach 2:
The dual aperture structure implements local quality by creating different aperture characteristics in different regions: the optical aperture is optimized for mode confinement with specific dimensions and positioning, while the electrical aperture is optimized for current injection with different dimensions and positioning. Each aperture performs its specific function with high precision
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 approach enables VCSELs to operate with increased output power, extended temperature range, and improved reliability, achieving single-mode power up to 1 mW from 0°C to 60°C and multi-mode power up to 10 mW at 40°C, with extended wavelength coverage beyond 720 nm, making them suitable for diverse applications.
Implementation Method 1
electrical current that flows between the first electrical contact and the second electrical contact provides pump energy to the VCSEL
Implementation Method 2
vertical-cavity surface-emitting lasers (VCSELs)... achieving single-mode power up to 1 mW from 0°C to 60°C and multi-mode power up to 10 mW at 40°C
Data Source
AI summary
VCSELs and methods having improved characteristics. In some embodiments, these include a semiconductor substrate; a vertical-cavity surface-emitting laser (VCSEL) on the substrate; a first electrical contact formed on the VCSEL; a second electrical contact formed on the substrate, wherein the VCSEL includes: a first resonating cavity having first and second mirrors, at least one of which partially transmits light incident on that mirror, wherein the first second mirrors are electrically conductive. A first layer is between the first mirror and the second mirror and has a first aperture that restricts the path of current flow. A second layer is between the first layer and the second mirror and also restricts the electrical current path. A multiple-quantum-well (MQW) structure is between the first mirror and the second mirror, wherein the first and second apertures act together to define a path geometry of the current through the MQW structure.