This invention proposes to engineer the current density along the length of a laser diode to overcome the penalty associated with non-uniformity resulting from asymmetry in the gain, photon or carrier density despite having uniform contact. Optimizing the current density profile enables diode lasers to operate with greater power conversion efficiency or operate with equivalent power conversion…
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![Schematic showing mismatched coefficient of thermal expansion (CTE) coating](/sites/default/files/styles/scale_exact_400x400_/public/2024-02/IL-13312_Schematic.png?itok=5MN8Mf-U)
This invention proposes to engineer the temperature dependence of the emission wavelength of LEDs and laser diodes. The approach is to use a strain-inducing coating to counteract the intrinsic temperature coefficient of the emission wavelength of the LED or laser diode device thereby rendering it athermal. This invention avoids additional complexity, size, weight and power dissipation of…
![Photoconductive Semiconductor Laser Diodes and LEDs](/sites/default/files/styles/scale_exact_400x400_/public/2024-02/Photoconductive%20Semiconductor%20Laser%20Diodes%20and%20LEDs.png?itok=n50p3rOY)
This invention proposes a method to overcome the key limitation of electrically pumped lasers based on AlN, AlGaN, or AlInGaN, namely the lack of suitable shallow donor and acceptor dopants. As the band gap of these materials increases (and the emission wavelength decreases), both electrons and holes require greater thermal energies in order to ionize.
![Adobe Stock image laser beam](/sites/default/files/styles/scale_exact_400x400_/public/2024-02/stockimage_laserbeam.png?itok=U06HtIhR)
Laser diode lensing effect can be substantially reduced by creating a pattern interface such that the substrate is only attached at the diode mesa. This is achieved by either creating a pattern solder joint and/or pattern substrate.
![A digital twin (right) is the virtual representation of real-world objects and processes (left)](/sites/default/files/styles/scale_exact_400x400_/public/2023-06/DigitalTwin.jpg?itok=SkQtz1w4)
LLNL’s novel approach utilizes a number of techniques to improve reconstruction accuracy:
![A cold-spray chamber is shown during deposition, with the nozzle at the top of the image and a near-full density sample being fabricated in the center. Particles of the brittle thermoelectric bismuth telluride are accelerated to more than 900 meters per second, or almost Mach 3, in inert gas and directed onto a copper surface, laying down the strips that form the basis of a functioning thermoelectric generator to harvest waste heat. Graphic by Jacob Long/LLNL](/sites/default/files/styles/scale_exact_400x400_/public/2021-02/Cold%20Spray_875x500px.jpg?itok=hjM9UrWO)
![Intensification of laser in simulations and electrons being accelerated](/sites/default/files/styles/scale_exact_400x400_/public/2022-06/intensification%20of%20laser%20in%20simulations%20and%20electrons%20being%20accelerated_875x500px.jpg?itok=bdZS_mHA)
LLNL pioneered the use of tomographic reconstruction to determine the power density of electron beams using profiles of the beam taken at a number of angles. LLNL’s earlier diagnostic consisted of a fixed number of radially oriented sensor slits and required the beam to be circled over them at a fixed known diameter to collect data. The new sensor design incorporates annular slits instead,…
![Optics](/sites/default/files/styles/scale_exact_400x400_/public/2022-07/Optics.jpg?itok=it_V--Tv)
The LLNL method for optimizing as built optical designs uses insights from perturbed optical system theory and reformulates perturbation of optical performance in terms of double Zernikes, which can be calculated analytically rather than by tracing thousands of rays. A new theory of compensation is enabled by the use of double Zernikes which allows the performance degradation of a perturbed…