Semipolar GaN Laser Structure for Thermal-Stable Blue-Green Emission
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Solution Overview
Problem
Conventional light sources, such as Edison bulbs and early laser technologies, are inefficient and prone to thermal failure, and high-power diode lasers face challenges in modulating at high speeds due to energy storage properties, limiting their deployment in broad applications.
Innovation Solution
The use of gallium and nitrogen containing substrates configured on specific planes, such as the {20-21} family of planes, for emitting electromagnetic radiation, which enables the development of high-efficiency blue and green lasers with improved material quality and reduced thermal degradation, allowing for higher gain and wall plug efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional light sources like Edison bulbs are used, then they have been in use for over one hundred years with simple design, but they dissipate most power as thermal energy and fail due to thermal expansion and contraction
Solution Approach 1:
The patent changes the fundamental operating parameters by transitioning from thermal radiation (Edison bulb) to electroluminescence (LED). This involves changing the energy conversion mechanism from resistive heating to electron-hole recombination in semiconductor quantum wells, achieving wavelength-specific light emission with minimal thermal loss and dramatically improved efficiency
Solution Approach 2:
The patent replaces the mechanical/thermal system of Edison bulbs (resistive heating of tungsten filament) with an electromagnetic/optical system (electroluminescence in semiconductor). This substitution eliminates thermal expansion and contraction issues while achieving higher efficiency through direct electrical-to-optical energy conversion in GaN-based quantum well structures
2Loss of energy
If lamp pumped solid state lasers are used for visible wavelengths, then they can produce laser output, but wall plug efficiency is only about 1% and they are large, expensive, and fragile
Solution Approach 1:
The patent extracts and eliminates the complex intermediate conversion stages of lamp-pumped solid state lasers. Instead of using lamps to pump gain crystals and then frequency conversion crystals, the invention directly uses electrically pumped GaN-based quantum well lasers to generate visible light, removing unnecessary components and achieving >10% wall plug efficiency
Solution Approach 2:
The patent creates a universal laser diode platform based on GaN quantum wells that can directly generate multiple visible wavelengths (blue, green, yellow) through electrical pumping alone, eliminating the need for separate pump sources and frequency conversion crystals required by traditional laser systems
3Loss of energy
If high power diode lasers are used, then they offer improved efficiency, but they face challenges in modulating at high speeds due to energy storage properties
Solution Approach 1:
The patent applies local quality optimization by using thin quantum well structures (5-20 nm) with specific compositional gradients and confined carrier injection zones. This localized structural design reduces parasitic capacitance and energy storage in the active region, enabling high-speed modulation while maintaining high efficiency through optimized recombination dynamics in the quantum well
Solution Approach 2:
The patent implements dynamic response optimization through engineered carrier transport mechanisms in the quantum well structure. By controlling electron-hole injection rates, confinement times, and extraction speeds through the heterostructure design, the system achieves both high energy efficiency and fast modulation speeds adaptable to different operating conditions
4Adaptability or versatility
If blue and green laser diodes are developed for broad deployment, then they can enable display technologies and projection systems, but conventional approaches suffer from thermal degradation and limited wall plug efficiency
Solution Approach 1:
The patent employs composite material structures combining GaN quantum wells with AlGaN barrier layers and cladding structures. This composite heterostructure achieves both high efficiency visible light emission and thermal management capabilities, enabling broad deployment in display and projection applications with wall plug efficiency exceeding 10%
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 results in brighter, more efficient blue and green laser diodes with narrower spectral widths and reduced thermal issues, enabling improved performance and broader deployment in applications like display technologies and projection systems.
Implementation Method 1
gallium and nitrogen containing substrates configured on the {20-21} family of planes or an off-cut of the {20-21} family of planes toward the plus or minus c-plane and/or toward the a-plane
Data Source
AI summary
An optical device includes a gallium and nitrogen containing substrate comprising a surface region configured in a (20-2-1) orientation, a (30-3-1) orientation, or a (30-31) orientation, within +/â10 degrees toward c-plane and/or a-plane from the orientation. Optical devices having quantum well regions overly the surface region are also disclosed.