Semiconductor lasers generate a significant amount of heat during operation, which causes a number of undesirable effects including increasing the current necessary for a given emission intensity and shorter device lifetime. Especially quantum cascade lasers (QCL) are sensitive to temperature, which results in a reduction in light emission or a cessation of laser operation. <br><br> <strong>Technology</strong><br> The QCL consists of an active zone which comprises a cascade structure and an insulating heat-dissipating zone which is laterally adjoined to the active zone. The active zone, which generates heat, is made from a semiconductor material with high crystalline order. The insulating heat-dissipating zone is made from an electrically insulating, heat conducting material which is identical to the semiconductor material of the active zone. The electrically insulating property of the heat-dissipating material is based on a reduced level of crystalline order compared to the semiconductor material of the active zone. The crystal defects result from growth on an underlying amorphous film. The pre-patterned substrate is made of a robust amorphous material and is able to withstand temperatures of growth and processing up to ~ 600 °C. The active regions are defined prior to epitaxy so that the processing is largely finished (except for metallization) when the structure emerges from the epitaxy reactor. <br><br>
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In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
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The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
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