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  • 1
    Electronic Resource
    Electronic Resource
    Comparison of gain and threshold current density for InGaAsP/GaAs (λ=808 nm) lasers with different quantum well thickness (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 8832-8834 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigated the quantum-size effects of quantum well (QW) on gain and threshold current density for InGaAsP/GaAs (λ=808 nm) laser diodes. In this work, a comparison is made of lasers with different QW thickness while keeping the optical confinement factors constant. We found that the threshold current density and differential efficiency were not affected by narrowing the QW thickness. The theoretical model taking into account the mixing of the valence bands and momentum relaxation for InGaAsP/GaAs lasers with spontaneous emission (optically pumped) measurement shows that the absence of difference between these structures can be attributed to the high relaxation rate. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362508
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  • 2
    Electronic Resource
    Electronic Resource
    Wide range magnetic electron spectrograph (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 1233-1238 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An electron spectrograph is described that covers electron energies from 400 eV to 200 keV with an energy resolution of 10%. This overlaps the range of electrostatic deflection devices at low energy and solid state detectors at high energy. The spectrograph uses magnetic deflection of the electrons to achieve energy separation and images the full range of energies on a single plane. The magnetic circuit uses the fringing field of two axially located magnets to attain the large energy range. Six separate electron beams can be dispersed in the field, each entering the circuit from a different angle. This is a particular advantage when measuring plasma electron three-dimensional velocity distributions. The angular response of the instrument is particularly favorable and the stray magnetic field is sufficiently low to meet spacecraft requirements. Compared with electrostatic deflection devices, the spectrograph is particularly advantageous for measuring high energy electron plasma velocity distribution functions with fast time resolution at modest energy resolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140296
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  • 3
    Electronic Resource
    Electronic Resource
    Temperature dependence of threshold current density Jth and differential efficiency ηd of high-power InGaAsP/GaAs (λ=0.8 μm) lasers (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 253-255 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An experimental and theoretical study on temperature dependence of the threshold current density Jth and differential efficiency ηd for the InGaAsP/GaAs laser diodes emitting at λ=0.8 μm was performed. Threshold current density Jth increases and differential efficiency ηd decreases as temperature is increased mainly because of thermal broadening of the gain spectrum. However, the measured temperature dependence of Jth and ηd could not be explained when only this effect was considered. In this letter, the temperature dependence of momentum relaxation rate (h-dash-bar)/τ of carriers was investigated by performing the photoluminescence study. At high temperature, increase of the momentum relaxation rate (h-dash-bar)/τ leads to reduction of the gain and mobility and increase of the optical loss, causing higher Jth and lower ηd as experimentally observed. The resulting theoretical model provides a good explanation for the mechanism of the increase of Jth and decrease of ηd. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114193
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  • 4
    Electronic Resource
    Electronic Resource
    Optimized structure for InGaAsP/GaAs 808 nm high power lasers (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 3251-3253 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optimized structure for the InGaAsP/GaAs quaternary material lasers (λ=0.808 μm) is investigated for the most efficient high-power operation through an experiment and theoretical study. A comparative study is performed of threshold current density Jth and differential efficiency ηd dependence on cavity length (L) for two different laser structures with different active layer thickness (150 and 300 A(ring)) as well as for laser structures with different multiple quantum well structures. A theoretical model with a more accurate formulation for minority leakage phenomenon provides explanation for the experimental results and sets general optimization rules for other lasers with similar restrictions on the band gap and refractive index difference between the active layer and the cladding layers. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113394
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  • 5
    Electronic Resource
    Electronic Resource
    Gain-assisted superluminal light propagation (2000)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 406 (2000), S. 277-279 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Einstein's theory of special relativity and the principle of causality imply that the speed of any moving object cannot exceed that of light in a vacuum (c). Nevertheless, there exist various proposals for observing faster-than- c propagation of light pulses, using anomalous dispersion near ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35018520
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  • 6
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    A CONTROVERSIAL Biography: Baillet's "La vie de Monsieur Descartes" (1963)
    Frankfurt am Main : Periodicals Archive Online (PAO)
    Romanische Forschungen. 75:3/4 (1963) 316 
    Details
    ISSN: 0035-8126
    Topics: Romance Studies
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:6222-1963-075-03-000006
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  • 7
    Electronic Resource
    Electronic Resource
    Quantum eraser (1991)
    [s.l.] : Nature Publishing Group
    Nature 353 (1991), S. 507-508 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - Scully et al.1 propose several two-source interference experiments. In one, the interference effect is wiped out by measurements that are so 'delicate' as not to disturb the system, although they yield information about the source of the detected particle. In another experiment dealing with ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/353507b0
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  • 8
    Electronic Resource
    Electronic Resource
    Balò's concentric sclerosis: MRI (1996)
    Springer
    Neuroradiology 38 (1996), S. 322-324 
    Details
    ISSN: 1432-1920
    Keywords: Demyelinating disease ; Sclerosis ; Brain ; Magnetic resonance imaging ; Computed tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a case of Balò's concentric sclerosis. In the past, the diagnosis was usually made post mortem. In this case, we found that CT demonstrated only low-density lesions, but not their concentric pattern. However, MRI showed a striking feature, reminiscent of histopathology of Balò's concentric sclerosis, and played an important role in antemortem diagnosis of this rare demyelinating disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00596578
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  • 9
    Electronic Resource
    Electronic Resource
    Hypoplasia of the internal carotid artery with intercavernous anastomosis (1998)
    Springer
    Neuroradiology 40 (1998), S. 252-254 
    Details
    ISSN: 1432-1920
    Keywords: Key words Arteries ; abnormalities and anomalies ; Artery ; carotid ; internal ; Anastomosis ; intercavernous
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a symptomatic case of unilateral hypoplasia of the internal carotid artery with an intercavernous anastomosis, a very rare developmental anomaly. The symptoms were caused by occlusion of the proximal middle cerebral artery which possibly related to the haemodynamic stress caused by the anomalous intercavernous anastomosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050578
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  • 10
    Electronic Resource
    Electronic Resource
    Balò's concentric sclerosis: MRI (1996)
    Springer
    Neuroradiology 38 (1996), S. 322-324 
    Details
    ISSN: 1432-1920
    Keywords: Key words Demyelinating disease ; Sclerosis ; Brain ; Magnetic resonance imaging ; Computed tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a case of Balò's concentric sclerosis. In the past, the diagnosis was usually made post mortem. In this case, we found that CT demonstrated only low-density lesions, but not their concentric pattern. However, MRI showed a striking feature, reminiscent of histopathology of Balò's concentric sclerosis, and played an important role in antemortem diagnosis of this rare demyelinating disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00596578
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    Paper (German National Licenses)
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