GaN m-plane nonpolar laser structure for directional emission
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Solution Overview
Problem
Conventional light bulbs and laser technologies face issues such as high thermal energy dissipation, reliability problems due to thermal expansion, broad spectral emission leading to inefficient illumination, and challenges in achieving directional and focused light, especially for blue and green wavelengths, which limits their application in modern technologies.
Innovation Solution
The development of optical devices using nonpolar or semipolar gallium-containing substrates like GaN, InN, InGaN, AlGaN, and AlInGaN for emitting electromagnetic radiation, specifically designed with m-plane nonpolar crystalline surface regions and laser stripe configurations to achieve efficient and directional light emission in the blue and green spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional light bulbs use tungsten filament to emit light, then illumination is achieved, but more than 90% of energy dissipates as thermal energy
Solution Approach 1:
The patent transitions from thermal radiation (incandescent) to electroluminescence (LED) by changing the fundamental emission mechanism. This parameter change from thermal to electrical excitation enables direct conversion of electrical energy to light, achieving wall plug efficiencies exceeding 50% compared to less than 10% for conventional bulbs.
2Adaptability or versatility
If conventional light bulbs emit light in all directions, then omnidirectional illumination is achieved, but directional and focused light for projection displays and optical data storage cannot be obtained
Solution Approach 1:
The patent employs localized emission regions through patterned electrode structures and selective contact formation on the LED chip. This creates specific emission zones that can be optically coupled with lenses and waveguides to achieve directional beam patterns suitable for projection displays and optical data storage applications.
Solution Approach 2:
The patent utilizes vertical cavity surface emitting laser (VCSEL) structures that emit light perpendicular to the chip plane, adding a vertical dimension to light emission. This enables direct coupling with optical fibers and waveguides, providing superior directionality and focusability compared to lateral emitting structures.
3Power
If lamp pumped solid state lasers with second harmonic generation are used to produce green and blue lasers, then laser output is achieved, but the lasers are too inefficient, large, expensive, and fragile for broad deployment
Solution Approach 1:
The patent extracts and eliminates the intermediate frequency conversion stages (infrared laser + nonlinear crystal = green/blue) by directly generating blue and green wavelengths using InGaN LED active regions. This removes the complexity of lamp pumping, infrared optics, and second harmonic generation crystals, resulting in compact, efficient, and robust devices.
Solution Approach 2:
The patent replaces the mechanical/optical complexity of lamp pumping and frequency conversion with direct electrical injection and electroluminescence in semiconductor quantum wells. This substitution of the emission mechanism eliminates moving parts, alignment requirements, and fragile optical components.
4Power
If gain crystal in solid state lasers has energy storage properties, then laser action is achieved, but the lasers are difficult to modulate at high speeds
Solution Approach 1:
The patent replaces the thermal and mechanical processes of lamp pumping and crystal vibration with direct electrical carrier injection and recombination. This enables modulation speeds in the nanosecond to picosecond range, limited only by the electrical circuit and carrier recombination time, rather than the thermal time constants of bulk crystals.
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
These devices achieve high wall plug efficiency, improved reliability, and directional emission, enabling cost-effective and efficient laser applications with enhanced performance in the blue and green wavelength range, surpassing conventional technologies in terms of efficiency and applicability.
Implementation Method 1
optical devices using nonpolar or semipolar gallium-containing substrates like GaN, InN, InGaN, AlGaN, and AlInGaN for emitting electromagnetic radiation
Data Source
AI summary
An optical device includes a gallium nitride substrate member having an m-plane nonpolar crystalline surface region characterized by an orientation of about â1 degree towards (000-1) and less than about +/â0.3 degrees towards (11-20). The device also has a laser stripe region formed overlying a portion of the m-plane nonpolar crystalline orientation surface region. In a preferred embodiment, the laser stripe region is characterized by a cavity orientation that is substantially parallel to the c-direction, the laser stripe region having a first end and a second end. The device includes a first cleaved c-face facet, which is coated, provided on the first end of the laser stripe region. The device also has a second cleaved c-face facet, which is exposed, provided on the second end of the laser stripe region.