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Hot-phonon generation in THz quantum cascade lasers

Journal of Physics: Conference Series 2007年第1期92卷 012018-012018页

作者： Spagnolo, V. Vitiello, S. Scamarcio, G. Williams, B.S. Kumar, S. Hu, Q. Reno, J.L. INFM Regional Laboratory LIT3 Dipartimento Interateneo di Fisica M. Merlin Politecnico di Bari Bari 70126 Via Amendola 173 Italy INFM Regional Laboratory LIT3 Dipartimento Interateneo di Fisica M. Merlin Università di Bari Bari 70126 Via Amendola 173 Italy Department of Electrical Engineering and Computer Science Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge MA 02139 United States Sandia National Laboratories Department 1123 MS 0601 Albuquerque NM 87185-0601 United States

Observation of non-equilibrium optical phonons population associated with electron transport in THz quantum cascade lasers is reported. The phonon occupation number was measured by using a combination of micro-probe photoluminescence and Stokes/Anti-Stokes Raman spectroscopy. Energy balance analysis allows us to estimate the phonon relaxation rate, that superlinearly increases with the electrical power in the range 1.5 W - 1.95 W, above laser threshold. This observation suggests the occurrence of stimulated emission of optical phonons. © 2007 IOP Publishing Ltd.

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Multi-view video coding using view-interpolated reference images

Multi-view video coding using view-interpolated reference im...

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25th PCS: Picture Coding Symposium 2006, PCS2006

作者： Yamamoto, Kenji Yendo, Tomohiro Fujii, Toshiaki Tanimoto, Masayuki Kitahara, Masaki Kimata, Hideaki Shimizu, Shinya Kamikura, Kazuto Yashima, Yoshiyuki Department of Electrical Engineering and Computer Science Graduate School of Engineering Nagoya University NTT Cyber Space Laboratories NTT Corporation NTT Advanced Technology Corporation

ISBN: (纸本)300018726X

In order to compress a multi-view video efficiently, we should consider two redundancies;one is the redundancy between pictures in one view and the other is the redundancy between views. In this paper we introduce an approach, which is based on H.264/AVC and is aiming to reduce both redundancies. The extended techniques from H.264/AVC are as follows: 1. inter-view prediction, 2. Asymmetric Macroblock partitioning (AMP), 3. view-interpolation prediction. The experimental results show that PSNR. gains up to 2.0 dB in comparison with H.264/AVC simulcast by using 1, and 2. By using 3 in addition, it gains up more at low bitrate.

关键词： Image coding

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Guest Editorial price-based access control and economics of networking

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IEEE Journal on Selected Areas in Communications 2006年第5期24卷 937-938页

作者： Mazumdar, Ravi R. Courcoubetis, Costas A. Duffield, Nick Kesidis, George Odlyzko, Andrew Srikant, R. Walrand, Jean University of Waterloo Department of Electrical and Computer Engineering Waterloo Ont. N2L 3G1 Canada Athens University of Economics and Business Department of Informatics Athens 10434 Greece AT and T Laboratories Florham Park NJ 07932-0971 United States Pennsylvania State University Department of Electrical and Computer Engineering University Park PA 16802 United States University of Minnesota Digital Technology Center Minneapolis MN 55455 United States University of Illinois at Urbana-Champaign Coordinated Science Laboratory Urbana IL 61801 United States University of California at Berkeley Department of Electrical Engineering and Computer Sciences Berkeley CA 94720 United States Department of Electrical and Computer Engineering University of Waterloo Waterloo Ont. Canada Department of Electrical and Computer Engineering Purdue University West Lafayette IN United States Royal Statistical Society Canada Canada Canada Canada Network Economics and Services Group Theory Economics and Systems Laboratory Athens University of Economics and Business Athens Greece Network Management and Performance Department AT and T Laboratories-Research Florham Park NJ United States Electrical Engineering and Computer Science and Engineering Departments Pennsylvania State University University Park United States Digital Technology Center United States University of Minnesota Minneapolis United States University of Illinois Urbana-Champaign United States Department of Electrical and Computer Engineering Canada Coordinated Science Laboratory United States Department of Electrical Engineering and Computer Sciences University of California at Berkeley Berkeley United States Belgian American Education Foundation United States

No abstract available

关键词： Access control Pricing Web and internet services IP networks Optimal control Quality of service Impedance History Internet telephony Convergence

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Effects of n -type modulation-doping barriers and a linear graded-composition GaInAsP intermediate layer on the 1.3 μm AlGaInAs/ AlGaInAs strain-compensated multiple-quantum-well laser diodes

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Journal of Vacuum science and technology B: Microelectronics and Nanometer Structures 2006年第2期24卷 623-628页

作者： Lei, Po-Hsun Yang, Chyi-Dar Wu, Ming-Yuan Wu, Meng-Chyi Cheng, K.Y. Lin, Chia-Chien Ho, Wen-Jeng Department of Computer Science Engineering Diwan College of Management Madou Tainan 721 Taiwan Department of Microelectronic Engineering National Kaohsiung Marine University Kaohsiung 811 Taiwan Research Institute of Electronics Engineering National Tsing Hua University Hsinchu 300 Taiwan Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign Urbana IL 61081 Advanced Technology Laboratory Telecommunication Laboratories Chunghwa Telecom Co. Ltd. Yang-Mei Taoyuan 326 Taiwan

We report the fabrication, characterization, and comparison of four 1.3 μm AlGaInAsAlGaInAs strain-compensated multiple-quantum-well (SC-MQW) laser structures: (1) sample A-with only an undoped SC-MQW active region, (2) sample B-with an undoped SC-MQW active region and a linear graded-composition (LGC) GaInAsP intermediate layer, (3) sample C-with an n -type modulation-doping (MD) SC-MQW active region, and (4) sample D-with an n -type MD-SC-MQW active region combined with a LGC GaInAsP intermediate layer. The inclusion of either n -type modulation-doped SC-MQW active region or LGC GaInAsP intermediate layer can improve the performance of a laser diode (LD). The LD sample D, which includes both an n -type MD-SC-MQW active region and a LGC GaInAsP intermediate layer, exhibits the best overall performance including a threshold current of 12.5 mA, a characteristic temperature of 85 K in 20-80 °C temperature range, a lasing wavelength shift of 0.38 nmK, and a relaxation frequency response of 9.9 GHz. © 2006 American Vacuum Society.

关键词： Semiconductor lasers

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A Very Fast and Low Power Pseudo-Incrementer for Address Bus Encoder/Decoder

A Very Fast and Low Power Pseudo-Incrementer for Address Bus...

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International Conference on Microelectronics, ICM

作者： Hadi Parandeh-Afshar Ali Afzali-Kusha Ali Khakifirouz Nanoelectronics Center of Excellence School of Electrical and Computer Engineering University of Tehran Tehran Iran Department of Electrical and Computer Engineering Microsystems Technology Laboratories Massachusetts Institute of Technology USA

This paper presents a very fast yet low power pseudo incrementer structure which may be used in address bus encoders/decoders. This structure, which is based on the ripple carry incrementer, is much faster than the incrementer. Using this structure, the delay and the power of address bus encoders/decoders may be reduced considerably. Analytical and synthesis results show that the structure is faster than current incrementer circuits while its circuit area and power are much smaller than those of current fast incrementers.

关键词： Decoding Delay Circuits Digital systems Energy consumption Paper technology Encoding Design methodology Power engineering computing Power engineering and energy

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MEMS and microsystems courses with national and international dissemination

MEMS and microsystems courses with national and internationa...

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113th Annual ASEE Conference and Exposition, 2006

作者： McAfee, Leo Najafi, Khalil Gianchandani, Yogesh Wise, Kensall D. Maharbiz, Michel M. Aslam, Dean Bergstrom, Paul Friedrich, Craig University of Michigan United States IEEE ASEE Department of Electrical Engineering and Computer Science University of Michigan United States MI United States WIMS ERC United States EECS Department College of Engineering Interdisciplinary Professional Degree Program in Integrated Microsystems Department of Electrical Engin-eering and Computer Science Department of Manufacturing Technology Department of Biomedical Engineering AIMBE United States United States National Academy of Engineering United States Electrical Engineering and Computer Science Chemical and Biomedical Engineering Departments University of Michigan Ann Arbor United States Wireless Integrated Microsystems NSF ERC National Nanotechnology Initiative Network Michigan State University United States Engineering Research Center for Wireless Integrated MicroSystems United States Michigan Technological University United States Michigan Technological University Houghton MI United States Microfabrication Facility Michigan Tech. United States

The Wireless Integrated microsystems (WIMS) engineering Research Center (ERC) has developed a broad comprehensive MEMS and microsystem curriculum suitable for upper-level undergraduate students, graduate students, and industry professionals. Five core courses were in the initial curriculum design. The design had flexibility that invited development of other core courses, as well as related technical electives and breadth electives. The core courses provide instruction in MEMS, microsystems, major design and laboratory measurements, and societal impact. The course enrollments have been strong. A master of engineering in integrated microsystems degree program was developed so that industry professionals would have a focused set of coursework, while providing flexibility that would permit custom tailoring of the total course package to serve specific needs. Distance education dissemination of the courses as whole courses, or as discrete portions of course materials, was intended to be available;that goal has been realized. The core courses originate at the University of Michigan (UM), and have been distributed to Michigan State University (MSU), Michigan Technological University (MTU), Howard University (HU), University of Puerto Rico - Mayaguez (UPRM), and Western Michigan University (WMU). Rochester Institute of technology (RIT) has used materials from the UM core courses in its offerings. Other institutions that have used the course web-streaming video and course materials are University of Lille, Darmstadt University, and Middle East Technical University. © American Society for engineering Education, 2006.

关键词： Curricula

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Controlling Ultra Wide Band Transmissions from a Wireless Micromachined Geiger Counter

Controlling Ultra Wide Band Transmissions from a Wireless Mi...

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IEEE International Conference on Micro Electro Mechanical Systems

作者： C.K. Eun R. Gharpurey Y.B. Gianchandani Center for Wireless Integrated Microsystems Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor USA Department of Electrical and Computer Engineering University of Technology Austin USA

This paper reports a parametric study of the wireless spectrum generated by discharge-based devices with focus specifically on micromachined Geiger counters as a function of the packaging, biasing circuitry, and sample isotope. Experiments are conducted with discharge devices attached to commercial high voltage (HV) packages with hermetic sealing capabilities. Influences of packaging as well as isotope type are studied and reported. Preliminary results show that current discharges emit RF spectra spanning a bandwidth greater than 3 GHz, which extends into the ultra wideband (UWB) window (from 100 MHZ to 10.6 GHz) that decreases in intensity with increasing observer distance.

关键词： Ultra wideband technology Counting circuits Radiation detectors Packaging Chemical sensors Isotopes Radio frequency Wireless sensor networks Glass Parametric study

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A microfabricated electrospray thruster using ridge emitters and ceramic-ball extractor location

A microfabricated electrospray thruster using ridge emitters...

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AIAA/ASME/SAE/ASEE 42nd Joint Propulsion Conference

作者： Gassend, B. Velásques-García, L.F. Lozano, P.C. Akinwande, A.I. Martínez-Sánchez, M. Massachusetts Institute of Technology Cambridge MA 02139 United States MIT Department of Electrical Engineering and Computer Science 32 Vassar Street Cambridge MA 02139 United States AIAA United States MIT Department of Aeronautics and Astronautics Microsystems Technology Laboratories 77 Massachusetts Avenue Cambridge MA 02139 United States MIT Department of Aeronautics and Astronautics 77 Massachusetts Avenue Cambridge MA 02139 United States Department of Electrical Engineering and Computer Science 77 Massachusetts Avenue Cambridge MA 02139 United States Department of Aeronautics and Astronautics 77 Massachusetts Avenue Cambridge MA 02139 United States

ISBN: (纸本)1563478188

We describe the fabrication and testing of an 1 cm by 1 cm microfabricated externally wetted electrospray thruster, which uses the ionic liquid EMI-BF4 as a propellant. In an electrospray thruster, an electrostatic field is used to extract ions or charged droplets from a liquid placed at the tip of a needle, and accelerate them. The novelty of our design is in the use of microfabricated ridges with regularly spaced tips as emitters, as well as the use of ceramic balls to position the extractor grid relative to the emitters and ensure electrical insulation. After describing the design of the thruster, we present the test firings we have done to date. In these tests, emission starts around 2 kV. To the best of our knowledge, this is the first time an externally wetted electrospray thruster has been fired with an integrated extractor electrode. Emission patterns gathered by firing into an aluminum plate show that the tips placed along the ridge allow emission to occur at multiple points along the ridge;without the tips, emission only occurs at the ends of the ridges.

关键词： Electrostatics

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High-power terahertz quantum cascade lasers

High-power terahertz quantum cascade lasers

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Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser science Conference, CLEO/QELS 2006

作者： Williams, Benjamin S. Kumar, Sushil Hu, Qing Reno, John L. Department of Electrical Engineering and Computer Science Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge MA 02139 United States Sandia National Laboratories Dept 1123 MS 0601 Albuquerque NM 87185-0601 United States

We report the demonstration of quantum-cascade lasers at ∼4.4 THz (λ ∼ 68 μm) that emit 248 mW peak power in pulsed mode, and 138 mW continuous-wave power at heat-sink temperatures of 10 K. © 2003 Optical Soc... 详细信息

ISBN: (纸本)1557528136

关键词： Quantum cascade lasers

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Long wavelength terahertz quantum-cascade lasers with one-well injector

Long wavelength terahertz quantum-cascade lasers with one-we...

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Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser science Conference, CLEO/QELS 2006

作者： Kumar, Sushil Williams, Benjamin S. Hu, Qing Reno, John L. Department of Electrical Engineering and Computer Science Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge MA 02139 United States Sandia National Laboratories Dept. 1123 MS 0601 Albuquerque NM 87185-0601 United States

We report operation of terahertz quantum-cascade lasers at frequencies down to 1.86 THz (λ≈161 μm) using a single quantum-well injector that significantly reduces free-carrier losses. The laser threshold current de... 详细信息

ISBN: (纸本)1557528136

关键词： Threshold current density

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