Center for Quantum Devices

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121.	Tilted Laser Cavities Make Brighter Beams McCormick Press Release - March 16, 2015 A simple tilt of geometry recently made quantum cascade lasers (QCLs) even brighter. Led by Manijeh Razeghi, the Walter P. Murphy Professor of Electrical Engineering and Computer Science, a team of researchers in the McCormick School of Engineering has designed a new laser technology with high power and high brightness. QCLs emit mid- to far-range infrared radiation that can be used for the detection of gases, chemicals, and pollutants in the atmosphere. Good beam quality is necessary for sending infrared light across great distances, but few structures have been able to achieve both high power and high brightness. Razeghiâ€™s group in the Center for Quantum Devices was able to achieve this using a remarkably simple technique: tilting the laser cavity. ... [read more]
122.	Building a More Versatile Frequency Comb McCormick Press Release - February 16, 2015 Frequency combs are the rulers of light. By counting a wavelengthâ€™s many oscillations, they measure distance and time with extraordinary precision and speed. Since the discovery of optical frequency combs in the 1990s, many applications in metrology, spectroscopy, and frequency synthesis have emerged. Research led by Manijeh Razeghi at Northwestern Universityâ€™s Center for Quantum Devices has overcome technical hurdles and demonstrated a room temperature, compact frequency comb based on a quantum cascade laser (QCL) with wide spectral coverage and high power. Unlike earlier frequency comb sources based on fundamentally mode-locked lasers or high-Q microresonators with intense optical pumping, Razeghiâ€™s solution is based on QCLs and electrically pumped solid-state sources. ... [read more]
123.	Abbas Haddadi Won the Best Paper Award for the Breakthroughs in Human-Centered Research SPIE Photonics West 2015 Conference - February 11, 2015 Abbas Haddadi won the award for "Breakthrough in Human-Oriented Applications," at the SPIE WEST 2015 Conference, which was held February 7-12, 2015 at the Moscone Center in San Francisco, California. Abbas Haddadi received the honor for his paper, titled, "High-performance dual-band mid-/long-wavelength infrared InAs/InAsSb type-II superlattice-based photodetectors for medical thermography applications," SPIE Photonics West 2015 is the largest and most influential event for the laser and photonics community in North America: 20,000 attendees, two exhibitions, 1,250 exhibiting companies, a wide range of papers on biomedical optics, biophotonics, translational research, industrial lasers, optoelectronics, microfabrication, optical MEMS, and more. ... [read more]
124.	Andy (Guanxi) Chen Won the Best Paper Award for the Breakthroughs in Human-Centered Research SPIE Photonics West 2015 Conference - February 11, 2015 Andy (Guanxi) Chen won the award for "Breakthrough in Human-Oriented Applications," at the SPIE WEST 2015 Conference, which was held February 7-12, 2015 at the Moscone Center in San Francisco, California. Andy (Guanxi) Chen received the honor for his paper, titled, "Worldâ€™s first pMp superlattice photodetectors enables high operating temperature infrared imaging," SPIE Photonics West 2015 is the largest and most influential event for the laser and photonics community in North America: 20,000 attendees, two exhibitions, 1,250 exhibiting companies, a wide range of papers on biomedical optics, biophotonics, translational research, industrial lasers, optoelectronics, microfabrication, optical MEMS, and more. ... [read more]
125.	David Heydari Won the Best Paper Award for the Breakthroughs in Human-Centered Research SPIE Photonics West 2015 Conference - February 11, 2015 David Heydari won the award for "Breakthrough in Human-Oriented Applications," at the SPIE WEST 2015 Conference, which was held February 7-12, 2015 at the Moscone Center in San Francisco, California. David Heydari received the honor for his paper, titled, "High-power quantum cascade lasers with angled cavities," SPIE Photonics West 2015 is the largest and most influential event for the laser and photonics community in North America: 20,000 attendees, two exhibitions, 1,250 exhibiting companies, a wide range of papers on biomedical optics, biophotonics, translational research, industrial lasers, optoelectronics, microfabrication, optical MEMS, and more. ... [read more]
126.	Neelanjan Bandyopadhyay Won the Best Paper Award for the Breakthroughs in Human-Centered Research SPIE Photonics West 2015 Conference - February 11, 2015 Neelanjan Bandyopadhyay won the award for "Breakthrough in Human-Oriented Applications," at the SPIE WEST 2015 Conference, which was held February 7-12, 2015 at the Moscone Center in San Francisco, California. Neelanjan Bandyopadhyay received the honor for his paper, titled, "Broadband quantum cascade laser tunable from 6.1 to 10.2Âµm," SPIE Photonics West 2015 is the largest and most influential event for the laser and photonics community in North America: 20,000 attendees, two exhibitions, 1,250 exhibiting companies, a wide range of papers on biomedical optics, biophotonics, translational research, industrial lasers, optoelectronics, microfabrication, optical MEMS, and more. ... [read more]
127.	New Infrared Photodetectors Improve Medical Screening McCormick Press Release - January 29, 2015 Led by Professor Manijeh Razeghi, members of Northwestern Universityâ€™s Center for Quantum Devices have improved the stability and lowered the cost of mid- and long-wavelength infrared photodetectors and focal plane array cameras. They achieved this by, first, using a novel type-II superlattice material called gallium-free indium-arsenide/indium-arsenide-antimonide or mercury-cadmium-telluride material. This design can be tuned to absorb a wide range of infrared wavelengths and a number of distinct infrared bands at the same time. This work is described in a paper published in the January 8 issue of Applied Physics Letters, the research was partially funded by DARPA, the Army Research Laboratory, the Air Force Research Laboratory, and NASA. ... [read more]
128.	Infrared Imaging Technique Operates at High Temperatures McCormick Press Release - January 23, 2015 From aerial surveillance to cancer detection, mid-wavelength infrared (MWIR) radiation has a wide range of applications. And as the uses for high-sensitivity, high-resolution imaging continue to expand, MWIR sources are becoming more attractive. A team of researchers at Northwestern Universityâ€™s Center for Quantum Devices (CQD) has incorporated new materials to develop detectors that can work at room temperature. Razeghi and her group developed an indium arsenide/gallium antimonide (InAs/GaSb) type II superlattice that demonstrated high-resolution MWIR images while operating at high temperatures. The new technique was particularly successful at obtaining infrared images of the human body, which has potential for vascular imaging and disease detection. ... [read more]
129.	Terahertz radiation from mid-infrared quantum cascade lasers Semiconductor Today - December 11, 2014 Northwestern Universityâ€™s Center for Quantum Devices in USA has developed a monolithic room-temperature terahertz (THz) source based on quantum cascade lasers (QCLs) [Q. Y. Lu et al, Appl. Phys. Lett., vol105, p201102, 2014]. The resulting device is tunable over the range 2.6THz-4.2THz, i.e. 47% of the central frequency. The team claims that the device is the first room-temperature, multi-section, two-color SGDFB-DBR structure to realize a monolithic tunable THz source.The researchers believe: â€œHigher THz power and continuous-wave operation can be further obtained by using a device structure with a higher THz conversion efficiency and better thermal packaging.â€ (Link) ... [read more]
130.	New Terahertz Device Could Strengthen Security McCormick Press Release - November 20, 2014 current terahertz sources are large, multi-component systems that sometimes require complex vacuum systems, external pump lasers, and even cryogenic cooling. The unwieldy devices are heavy, expensive, and hard to transport, operate, and maintain. A single-component solution capable of room temperature and widely tunable operation is highly desirable to enable next generation terahertz systems. In a recent paper in Applied Physics Letters, they demonstrate a room temperature, highly tunable, high power terahertz source. Based on nonlinear mixing in quantum cascade lasers, the source can emit up to 1.9 milliwatts of power and has a wide frequency coverage of 1 to 4.6 terahertz. By designing a multi-section, sampled-grating distribution feedback and distributed Bragg reflector waveguide, Razeghi and her team were also able to give the device a tuning range of 2.6 to 4.2 terahertz at room temperature. ... [read more]

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