GaN Laser Diode Lateral Epitaxial Overgrowth for High Confinement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current laser technologies for blue and green wavelengths are inefficient, large, expensive, and fragile, limiting their broader deployment due to low wall plug efficiency, size, and sensitivity to temperature, as well as challenges in high-speed modulation and precise alignment requirements.
Innovation Solution
The use of nonpolar, semi-polar, or polar c-plane oriented gallium and nitrogen containing substrates for fabricating laser diodes with a method involving a gallium and nitrogen containing substrate, release material, n-type and p-type materials, transparent conductive oxide, and bonding to a handle substrate, enabling the formation of ridge waveguide structures and high confinement factor laser cavities through lateral epitaxial overgrowth and wafer bonding techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lamp pumped solid state lasers with second harmonic generation are used, then blue and green laser output is achieved, but wall plug efficiency is only ~1% and the system is large and fragile
Solution Approach 1:
The patent replaces the mechanical lamp pumping system with a semiconductor diode laser pumping system. The diode laser directly pumps the gain crystal to produce infrared light at 1064 nm, which is then frequency doubled to green light at 532 nm. This substitution eliminates the need for fragile lamps and achieves wall plug efficiencies of 5-10%, representing a significant improvement in both efficiency and system reliability.
Solution Approach 2:
The patent changes the pumping wavelength parameter from broad-spectrum lamp pumping to specific 808 nm diode laser pumping. This parameter change enables direct pumping of the gain crystal's absorption band, improving energy transfer efficiency and reducing the need for complex optical components, thereby increasing wall plug efficiency and system robustness.
2Use of energy by moving object
If diode pumped solid state lasers with SHG are used, then wall plug efficiency improves to 5%-10%, but system cost increases and precise temperature control is required
Solution Approach 1:
The patent introduces thermal management components including heat sinks and temperature control systems as intermediaries between the diode laser and gain crystal. These components mediate the thermal interaction, allowing the system to maintain precise temperature control (±1°C) which is critical for the gain crystal's lasing performance and the overall efficiency of the laser system.
3Use of energy by moving object
If directly doubled diode lasers are used, then efficiency and cost are improved, but severe sensitivity to temperature limits application
Solution Approach 1:
The patent implements preliminary thermal management by incorporating heat sinks and temperature control systems before the laser operation begins. The system pre-cools or pre-heats the gain crystal and diode laser to their optimal operating temperatures, and maintains these temperatures throughout operation through active feedback control. This preliminary action prevents temperature drift from affecting laser performance, enabling stable operation across various environmental conditions.
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 ultra-high confinement factor ridge laser cavities with reduced threading dislocation density, improved cleaved facet quality, and increased efficiency, enabling more compact, reliable, and cost-effective blue and green laser diode production suitable for broader applications.
Implementation Method 1
subjecting the release material to an energy source to initiate release of the gallium and nitrogen containing substrate member
Implementation Method 2
using at least PEC etching
Implementation Method 3
double ITO cladding layers... provide ultra high confinement of the optical mode within the active region
Implementation Method 4
ridge waveguide structures... provide ultra high confinement of the optical mode
Implementation Method 5
Lateral epitaxial overgrowth (LEO) is a growth technique... to reduce the density of extended defects
Implementation Method 6
The wafer bonding technique... allows for the transfer of the laser structure to the handle substrate
Data Source
AI summary
A method for fabricating a laser diode device includes providing a gallium and nitrogen containing substrate member having a surface region, forming a patterned dielectric material overlying the surface region to expose a portion of the surface region within a vicinity of an recessed region of the patterned dielectric material and maintaining an upper portion of the patterned dielectric material overlying covered portions of the surface region, and performing a lateral epitaxial growth overlying the exposed portion of the surface region to fill the recessed region and causing a thickness of the lateral epitaxial growth to be formed overlying the upper portion of the patterned dielectric material. The method also includes forming an n-type gallium and nitrogen containing material, forming an active region, and forming a p-type gallium and nitrogen containing material. The method further includes forming a waveguide structure in the p-type gallium and nitrogen containing material.