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Page 17 of 32: Prev << 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 >> Next (315 Items)
161.
| Researchers Create World’s First High Performance Infrared Camera Based on Type-II InAs/GaSb Superlattices
Northwestern University McCormick News Article - November 15, 2010
Researchers from the Center for Quantum Devices at Northwestern University have created a new large-format infrared camera based on Type-II InAs/GaSb superlattices that produces much higher resolution images than previous infrared cameras.
Created by Manijeh Razeghi and her group, the long wavelength infrared focal plane array camera provides a 16-fold increase in the number of pixels in the image. Their results were recently published in the journal Applied Physics Letters, Volume 97, Issue 19, 193505 (2010).
The goal of the research is to offer a better alternative to existing long wavelength infrared radiation (LWIR) cameras, which, with their thermal imaging capabilities, are used in everything from electrical inspections to security and nighttime surveillance. Current LWIR cameras are based on mercury cadmium telluride (MCT) materials, but the Type-II superlattice is mercury-free, more robust, and can be deposited with better uniformity. This will significantly increase yield and reduce camera cost once the technology goes commercial. ... [read more]
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162.
| Researchers Create High-Power Single Mode Quantum Cascade Lasers
Northwestern University McCormick News Article - November 8, 2010
New laser technology developed by researchers at the Center for Quantum Devices may soon allow long-distance chemical analysis that could potentially be used in spills and warfare. Because chemicals absorb light in the infrared, it is possible to detect specific chemicals by using a laser and analyzing the returned light. But this long-distance mapping of chemicals by laser isn’t yet possible because researchers haven’t created a suitable laser source.
Manijeh Razeghi and her group have created new laser technology that combines the high-power output of a broad area mid-infrared quantum cascade laser (QCL) with a two-dimensional diffractive resonator design that controls both the wavelength and beam quality with the laser. This led to the demonstration of up to 34 watts of peak power at room temperature and near-diffraction-limited beam quality at 4.3 μm, which is near the absorption frequency of several important chemicals. That represents almost a significant improvement in output power for this type of laser source. ... [read more]
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163.
| European Semiconductor Laser Workshop at Pavia University in Italy
La Provencia - September 22, 2010
Among the invited speakers, in particular, there will be Manijeh Razeghi, one of the first scientists to develop semiconductor lasers in Europe in the
'80s ... [read more]
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164.
| Two Named Boeing Engineering Student of the Year
McCormick News Magazine - April 5, 2010
Two McCormick graduate students from the Center for Quantum Devices recieved first- and second-place awards in the 2009 Engineering Student of the Year competition sponsored by Boeing Company and presented by the aerospace publisher Flightglobal. Can Bayram (second from left) was one of two first place winners and Pierre-Yves Delaunay (second from right) won second place. Both are PhD canidates in electrical engineering and computer science working under the guidance of Profesor Manijeh Razeghi. John Tracy, Boeing's Chief technology officer and senior vice president of engineering, opperations, and technology (far right), presented the awards with Warren McEwan, Flightglobal's North American sales director (far left). ... [read more]
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165.
| Quantum Cascade Lasers Gain Efficiency
Optics and Photonics News (OPN) magazine, Vol. 21, Issue 4, p. 6 - April 2, 2010
Quantum cascade lasers (QCLs) have much potential in the mid-infrared spectral region, but their low energy efficiency has limited their application prospects. Two separate U.S. research teams have fabricated QCLs that significantly boost “wall plug efficiency,†or the ratio of the power the laser emits to the power that the device consumes.
At Northwestern University, OSA Fellow Manijeh Razeghi and her colleagues made a 4.85-µm-wavelength pulsed QCL with a wall plug efficiency of 53 percent at an operating temperature of 40 K. The authors wrote in their abstract, “In other words, we demonstrate a quantum cascade laser that produces more light than heat.†... [read more]
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166.
| Imaging Advances Boost Defense
Advanced Imaging magazine, p. 12-15 - March 31, 2010
New materials and new detector architectures pave the way for lighweight, high-sensitivity IR imagers. For years MCT has been the material of choice for imagin in the MWIR and LWIR spectral regions. However, recent advances in III-V-based Type-II superlattices (T2SLs) grown on gallium antimonide (GaSb) substrates promise to change all that. A team at Northwestern University, led by seminal T2SL researcher Manijeh Razeghi is making impressive strides in the development of MWIR and LWIR focal plane arrays. ... [read more]
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167.
| QCL peak power record smashed
Photonics Spectra magazine, February 2010, p. 19-20 - February 28, 2010
Only a year ago, the peak output power of a quantum cascade laser (QCL) was only 34W. Today, thanks to research at the Center for Quantum Devices (CQD), peak power of 120 W from a single device at room temperature has been achieved. This "breakthrough is particularly attractive for sensing chemicals at a distance and for infrared countermeasures," Professor Razeghi said, "because power is a luxury that defines range, speed, and sensitivity for targeting remote applications." ... [read more]
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168.
| Producing more light than heat from quantum cascade lasers
Semiconductor Today magazine, Vol. 5, Issue 1 - February 28, 2010
Two separate groups have reported increased wall-plug efficiency (WPE) for quantum cascade lasrs (QCLs) in Nature Phtonics: Manijeh Razeghi et. al at the Center for Quantum Devices (CQD) and Peter Liu et. al from Princeton and John Hopkins Universities. The CQD team uses a single-well injector to achieve 53% WPE at 40K with an emitting wavelength of 5 μm. In other words, they "Produce a quantum cascade laser that prduces more light than heat." ... [read more]
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169.
| Quantum Cascade lasers, a glass half full
NATURE PHOTONICS | NEWS AND VIEWS - February 15, 2010
Since the first report of its successful operation in the mid-1990s1, the quantum cascade laser (QCL) has evolved to become an important source of mid-infrared and terahertz radiation. However, it has historically been labelled as a device with a relatively poor efficiency of operation. This view may finally be about to change, thanks to the report in Nature Photonics by the Center for Quantum Devices of mid-infrared QCLs that provide wall-plug efficiencies reaching 50% for the first time. ... [read more]
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170.
| New Quantum Cascade Lasers Emit More Light Than Heat
Northwestern University McCormick News Article - January 11, 2010
Northwestern University researchers have developed compact, mid-infrared laser diodes that generate more light than heat — a breakthroughs in quantum cascade laser efficiency. The results are an important step toward use of quantum cascade lasers in a variety of applications, including remote sensing of hazardous chemicals. The quantum cascade laser (QCL) is a diode laser that is designed on the quantum mechanical level to produce light at the desired wavelength with high efficiency. Unlike traditional diode lasers, the device is unipolar, requiring only electrons to operate. A significant effort has been spent trying to understand and optimize the electron transport, which would allow researchers to improve the laser quality and efficiency.
“This breakthrough is significant because, for the very first time, we are able to create diodes that produce more light than heat,†says Razeghi. “Passing the 50 percent mark in efficiency is a major milestone, and we continue to work to optimize the efficiency of these unique devices.†... [read more]
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Address: Center for Quantum Devices; 2220 Campus Drive RM 4051; Evanston, IL 60208-0893
Phone: (847) 491-7251
Email: razeghi@northwestern.edu