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  • 1
    Electronic Resource
    Electronic Resource
    Low-temperature operating life of continuous 300-K AlxGa1−xAs-GaAs quantum-well heterostructure lasers grown on Si (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 6844-6849 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented on the continuous (cw) 77–200 K operational characteristics of cw 300-K AlxGa1−xAs-GaAs quantum-well heterostructure diode lasers grown on Si substrates. Operation is demonstrated for over 500 h with a junction temperature as high as ∼200 K for a diode previously operated cw 300 K for over 10 h with its junction side mounted away from the heat sink. The data indicate that longer cw 300-K lifetimes than previously demonstrated (17 h) may be possible. The effects of the optical power level on the degradation rate are examined, and it is shown that the maximum cw 300-K power output for these devices (∼30 mW/facet) is limited by catastrophic facet degradation. The effects of naturally occurring microcracks on device stability are also considered, and the effect of stress on the output polarization is measured and discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347674
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Native-oxide coupled-stripe AlyGa1−yAs-GaAs-InxGa1−xAs quantum well heterostructure lasers (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 2390-2392 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented on a high-performance native-oxide coupled-stripe AlyGa1−yAs-GaAs-InxGa1−xAs quantum well heterostructure laser realized by the recently introduced simple process of "wet'' oxidation (H2O vapor+N2,(approximately-greater-than)400 °C, 3 h) of the upper AlyGa1−yAs confining layer. If the native oxide between active stripes (ten 5 μm stripes on 10 μm centers) is brought into closer proximity with the waveguide and quantum well region (i.e., from 0.53 to 0.4 μm), the 10-stripe laser operates decoupled because of increased (coupling) absorption losses and some index guiding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104880
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Planar native-oxide index-guided AlxGa1−xAs-GaAs quantum well heterostructure lasers (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 1755-1757 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new form of planar index-guided laser diode is demonstrated with a relatively thick (∼0.4 μm) native oxide employed to define the lateral optical waveguide (transverse to the laser stripe). Oxidation of high-gap AlxGa1−xAs in a "wet'' ambient results in the transformation of most of the upper confining layer to a lower-index current-blocking native oxide outside of the active stripe. Planar quantum well heterostructure (QWH) AlxGa1−xAs-GaAs laser diodes fabricated by this process exhibit both optical and current confinement. Continuous 300 K threshold currents as low as 10 mA (uncoated facets) and kink-free single-longitudinal-mode operation are demonstrated for ∼2-μm-wide active region devices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106240
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Thin upper-confining layer AlxGa1−xAs-GaAs quantum well heterostructure laser diodes (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 1006-1008 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: AlxGa1−xAs-GaAs quantum well heterostructure (QWH) laser diodes with much thinner upper confining layers (0.6, 0.45, 0.3, and 0.2 μm) than usual (1–2 μm) are demonstrated. The diodes exhibit well behaved transverse far-field patterns, low broad-area pulsed threshold current densities, and high differential quantum efficiencies. The diodes with thinnest upper confining layers, ∼0.2 μm, have broad-area pulsed threshold current densities as low as Jth∼169 A/cm2 and a total external differential quantum efficiency ηT∼53% (∼500 μm long cavities). Stripe-geometry (40 μm wide) laser diodes made from the crystals with 0.2 μm upper confining layers exhibit room-temperature continuous (cw) threshold currents of 60 mA, output powers of ∼200 mW/facet (uncoated), and transverse far-field patterns with a full angle half power (FAHP) of 48°. Nonoptimized narrow-stripe (∼4 μm) native-oxide index-guided laser diodes fabricated on the same 0.2 μm confining layer QWH crystal operate at pulsed thresholds as low as 9 mA and continuous thresholds of 16 mA, with total external differential quantum efficiencies of 39% pulsed and 30% cw.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108563
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  • 5
    Electronic Resource
    Electronic Resource
    Native-oxide coupled-cavity AlxGa1−xAs-GaAs quantum well heterostructure laser diodes (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 2838-2840 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented demonstrating AlxGa1−xAs-GaAs quantum well heterostructure laser diodes consisting of an array of coupled cavities (19 μm long on 22 μm centers, ∼250 μm total length) arranged lengthwise in single 10-μm-wide laser stripes. The cavities are defined by a native oxide formed from a significant portion of the high-gap AlxGa1−xAs upper confining layer. The native oxide (grown at 425 °C in H2O vapor+N2 carrier gas) confines the injected carriers and optical field within the cavities, resulting in reflection and optical feedback distributed periodically along the laser stripe. These diodes exhibit single-longitudinal-mode operation over an extended range (relative to similar diodes fabricated without multiple cavities). At high current injection levels, longitudinal-mode spectra demonstrate unambiguously oscillation from the internal coupled cavities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105881
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Photopumped room-temperature edge- and vertical-cavity operation of AlGaAs-GaAs-InGaAs quantum-well heterostructure lasers utilizing native oxide mirrors (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 740-742 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented on the 300-K continuous and pulsed photopumped laser operation of AlyGa1−yAs-GaAs-InxGa1−xAs quantum-well heterostructure (QWH) crystals that utilize large-index-step high-contrast distributed Bragg reflector mirrors. The mirrors are formed by selective lateral oxidation (H2O+N2, 425 °C) of three lower and three upper AlAs layers in the structure, resulting in enhanced cavity Q in the vertical direction. The laterally oxidized mirrors, a small lower and an upper "stack'' that sandwich a lateral waveguide and double QW active region, are of sufficient quality to permit vertical-cavity laser operation of the QWH crystals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112216
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Planar single-facet teardrop-shaped AlxGa1−xAs-GaAs quantum well heterostructure laser (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 1818-1820 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented demonstrating the laser operation of an AlxGa1−xAs-GaAs quantum well heterostructure (QWH) crystal patterned into a smoothly curved folded resonator, a "teardrop''-shaped resonator, with a single output facet. A deep AlxGa1−xAs native oxide formed entirely through the top confining layer is utilized to produce a large effective index step for lateral optical confinement. The teardrop-shaped laser operates primarily in a TM (transverse magnetic) longitudinal mode polarized with a TM/TE (transverse electric) power ratio of 7:1. Continuous wave 300 K threshold currents as low as ∼127 mA, external differential quantum efficiencies of η∼15%, and total output power in excess of 75 mW (uncoated facet) are achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.110673
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Demonstration of perivascular echogenicities in congenital cytomegalovirus infection by colour Doppler imaging (1990)
    Springer
    European journal of pediatrics 150 (1990), S. 34-36 
    Details
    ISSN: 1432-1076
    Keywords: Colour Doppler imaging ; Cytomegalovirus infection ; Infants ; Intracerebral echogenicities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two children with congenital cytomegalovirus infection and intracerebral echogenicities were investigated by computer sonography and colour Doppler imaging (CDI). By simultaneous imaging of brain tissue and CDI, blood flow within the stripe-like echogenicities of the basal ganglia was demonstrated. Using CDI the echogenicities were identified as the walls of thalamostriate vessels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01959476
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    Polyposis of the gallbladder associated with metachromatic leukodystrophy (1993)
    Springer
    European journal of pediatrics 152 (1993), S. 450-451 
    Details
    ISSN: 1432-1076
    Keywords: Metachromatic leukodystrophy ; Polyposis of the gallbladder ; Ultrasound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report on two children with metachromatic leukodystrophy and polyposis of the gallbladder. In both patients ultrasound examination revealed a small gallbladder with a thickened echogenic wall and multiple polypoid masses. In one patient diagnosis of gallbladder polyposis was made 6 months before the first neurological symptoms occurred. As gallbladder polyposis is a rare phenomenon in childhood, metachromatic leukodystrophy should be excluded.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01955909
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Simultaneous palsy of facial and vestibular nerve in a child with Lyme borreliosis (1990)
    Springer
    European journal of pediatrics 149 (1990), S. 781-782 
    Details
    ISSN: 1432-1076
    Keywords: Lyme borreliosis ; Facial palsy ; Cochleovestibular palsy ; lymphocytic meningitis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe a boy with borreliosis characterized by lymphocytic meningitis and simultaneous palsy of facial and vestibular nerves on the left side. A mild sensoneural affection was also confirmed by brainstem evoked response audiometry. While symptoms of vestibular dysfunction quickly decreased during antibiotic treatment, facial palsy improved only slowly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01957280
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    Paper (German National Licenses)
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