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  • 1
    Call number: ZSP-594/C-7
    In: Japanese Antarctic Research Expedition
    Description / Table of Contents: Glaciological studies of the upper 10m of the ice sheet in East Antarctica were made during the JARE South Pole Traverse 1968-1969. The glaciological studies consisted of studies of surface snow and subsurface snow by means of pits as well as analyses of snow cores. Conditions of surface snow such as accumulation, roughness, density and hardness are described in this paper. It is found that the conditions are distinctly different in four regions along the route from Syowa Station to the South Pole, and that they have a close connection with the slope inclination. Relationship between the snow conditions and the slope inclination is discussed in terms of the dependence of wind speed on the slope inclination. Thus, it is concluded that the conditions of surface snow are mainly controlled by wind speed. Measurements of annual snow accumulations disclose that local variations in accumulations take place in a strong wind region, and coincide with local topography of the region. Also, distinct regional differences in accumulations during the summer season are discussed from the differences between cyclonic and anticyclonic precipitations. Studies of subsurface snow in 2m deep pits indicate that regions located in the north and south of 73°S are characterized respectively by compact fine-grained snow and well-developed depth hoar. Analyses of snow cores from the surface to a depth of 10m revealed the distribution of snow density in the upper 10m of the ice sheet along the route from Syowa Station to the South Pole. Regional profiles of snow density at the depths of 5 and 9m were different from those at the surface. This is due to the differences in the mean annual air temperature.
    Type of Medium: Series available for loan
    Pages: 27 S.
    Series Statement: Japanese Antarctic Research Expedition : Scientific reports : Series C, Earth sciences 7
    Branch Library: AWI Library
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 5555-5560 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Dual wavelength electro-optical bistability in resistor-biased and symmetric self electro-optic effect devices and their input power dependence are investigated using InGaAs/AlGaAs multiple quantum wells. A new principle to drive the devices using two widely separated wavelengths for signal and control light is proposed and demonstrated to obtain optical transmission bistability between two stable states of the signal light at λ1 by varying the control beam power at λ2. Detailed experimental results of signal power dependencies of the optical responses are presented and rigorously explained based on the voltage switching mechanism of the signal diode by the second control light using a simple load line analysis. Advantages of this new device configuration are discussed taking full merit of the transparency of the GaAs substrate to the signal wavelength.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 5064-5069 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have experimentally and theoretically studied electroabsorption properties of a novel superlattice having well width asymmetry and barrier sequence bi periodicity. Electric field-induced energy variations of the optical transitions observed by room temperature photocurrent spectroscopy show that several Stark-ladder branches in the fan diagram converge to different points. These "staggered" Stark ladders undergo large level anticrossings and result in a distinct blueshift of the optical absorption edge. Theoretical analyses on the variations of eigenenergies and the localization of wave functions of the Stark-ladder states clearly explain the experimental data. An advantage of the novel structure to optoelectronic device application is also shown in comparison with a conventional mono-periodic superlattice. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 444-450 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Wannier-Stark localization of asymmetric double well superlattices (ADW-SLs) has been investigated by low-temperature photocurrent spectroscopy. The ADW-SLs consist of arrays of asymmetric double quantum wells formed by coupling of two different size wells. Reflecting the difference in the eigenenergies of the two wells, the occurrence of the Stark-ladder transitions is, in principle, characterized by the superposition of two fan diagrams. Hence, four ±1st-order spatially indirect transitions are expected to exist. However, they are experimentally observed only partially. This selectivity is interpreted by considering the coupling pattern between two wells in the ADW-SLs. The control of the coupling pattern is a new concept to design SL structures and its Wannier-Stark localization. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 2729-2734 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: AlAs-GaAs superlattices were utilized for the waveguides in separate-confinement heterostructure laser diodes. A significantly low threshold current density Jth of 200 A/cm2 was achieved at a cavity length of about 500 μm for a graded-index superlattice-waveguide separate-confinement heterostructure laser diode. By photoluminescence measurements taken under a direct excitation condition, it was clearly demonstrated that the advantage of using the superlattice waveguide, i.e., the reduction of Jth value, is due to the improvement of heterointerface quality of the GaAs active layer. Moreover, a result on an all-binary SCH laser composed of the only AlAs and GaAs revealed that the Jth as considerably low as 400 A/cm2 was achieved at a cavity length of 400 μm.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 209-211 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is demonstrated that in an asymmetric coupled GaAs double quantum well structure, we are able to choose a lasing wavelength out of at least four quantum state transitions by cavity loss control. The assignments of the observed lasing transitions are determined by photoluminescence measurement for the laser wafer, as well as by calculations using an isolated potential well model. We propose that one can realize wide-range wavelength tuning and multistep wavelength switching functions by modifying the two-dimensional density of states.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 2754-2756 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An optical differentiation circuit with symmetric self-electro-optic effect devices is proposed and demonstrated. A novel method called global stability analysis of the differential photoresponse equation clearly shows the temporal dynamics of circuit operation.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2234-2236 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using photocurrent spectroscopy, we have studied optical absorption properties of strained InxGa1−xAs/Al0.15Ga0.85As multiple quantum wells grown by molecular beam epitaxy in the presence of electric fields perpendicular to the heterointerface. In the wavelength region where the bulk GaAs substrate is transparent, we observe the quantum confined Stark effect. Optical bistability of a self-electro-optic effect device is demonstrated at room temperature without removal of the GaAs substrate.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 376-378 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new self-electro-optic effect device is proposed and demonstrated in an InGaAs/AlGaAs multiple quantum well diode structure by using different wavelengths for the signal and control wavelengths. The single resistor biased device exhibits optical transmission bistability between two stable states of the signal beam at λ1 when the control beam power at λ2 is varied. The two wavelengths λ1 and λ2 may be widely separated so that one is absorbed in the substrate and the other transmitted eliminating the need for substrate removal. The separate wavelengths also eliminate interference effects simplifying the design of vertical device arrays enhancing the possibility of system integration.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 113-115 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Optical transitions in a novel biperiodic GaAs/AlAs superlattice consisting of asymmetric double quantum wells have been investigated as a function of an applied electric field by photocurrent spectroscopy. Due to the existence of two different heavy-hole localized states under the applied field, two types of Stark-ladder transitions are possible in the superlattice. It is found that, among four possible indirect ladder transitions between the nearest neighbor wells, two of them have larger oscillator strengths. This selectivity of the indirect ladder transitions is rigorously explained by selective resonance coupling between the inequivalent neighboring wells because of the introduced structural asymmetry. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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