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  • 1
    Electronic Resource
    Electronic Resource
    Optical and thermal analyses on multilayered thin films of a phase-change optical recording disk (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 1045-1050 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A computer simulation method to study a laser-induced transient temperature profile of a multilayered phase-change optical recording disk (PCORD) has been developed. The simulation program consists of two parts. One part is an optical analysis program based on the optical characteristic matrix method, and the other is a thermal analysis program based on the finite-element method. A new estimation method for thermal conductivity of recording films was proposed. The estimated thermal conductivity of the thin-film recording media was found to be 50% lower than that of the bulk. Reflectivity, absorbance, and temperature values obtained with this simulation method were compared with those measured by a spectrophotometer and an infrared radiation thermometer when the samples were irradiated in an Ar+ laser beam. The accuracy using this simulator was within 8% for reflectivity and absorbance and within 10% for temperature. A method of optimizing the laser-absorbing layer was studied. With this method simulations showed that the PCORD had a maximum contrast ratio and minimum recording time when thickness, thermal conductivity, and complex refractive index of the laser-absorbing film were 60 nm, 4.2×10−3 W/cm °C, and 2.6−i⋅0.0, respectively. This simulation could provide better film designs for PCORDs and the other optical disks of heat mode recording.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344456
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  • 2
    Electronic Resource
    Electronic Resource
    Temperature dependence of nonlinear absorption in InP doping superlattices (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 3641-3646 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Absorptive optical nonlinearity in InP doping superlattices grown by vapor-phase epitaxy is investigated in a 2–300 K temperature range. The absorption spectra have tails below InP band-gap energy, caused by the Franz–Keldysh effect due to the internal electric field. The absorption tail is almost temperature independent. This means that the periodic electric potential in the doping superlattice, responsible for the nonlinearity, is unchanged across this temperature range. Nonlinear absorption is evaluated by the pump-probe method. The large reduction in absorption coefficient is obtained even with a weak excitation light intensity. This enhancement in nonlinearity is due to prolongation of the excited-carrier lifetime. Nonlinear absorption increases as temperature decreases. This is due to the temperature dependence of the carrier lifetime.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341403
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of electron–hole interaction on electron spin relaxation in GaAs/AlGaAs quantum wells at room temperature (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 3394-3398 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigated electron spin relaxation with respect to the spatial electron–hole separation in GaAs/AlGaAs quantum wells at room temperature. The polarization dependent time-resolved photoluminescence method was used to measure the electron spin relaxation time by applying an electric field perpendicular to the quantum wells. The spin relaxation time had a strong electric field dependence and largely increased with an increase in the spatial electron–hole separation. These results cannot be explained by only the D'yakonov–Perel process, which has often been considered the cause of spin relaxation. We discuss the possible mechanisms that cause the spin relaxation by taking into account the electron–hole exchange interaction. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372356
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  • 4
    Electronic Resource
    Electronic Resource
    Design optimization of axially laminated rotors for synchronous reluctance motors (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 6298-6300 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This article describes a design optimization of an axially laminated rotor of the synchronous reluctance motor, using the optimization method combined with the magnetic field analysis. The magnetic flux distribution in the synchronous reluctance motor is distorted due to the complicated rotor configuration and the influence of magnetic saturation, which results in a large number of local minimum solutions. Therefore, taking account of the magnetic saturation by the finite element method, the authors propose a novel optimization approach by coupling the stochastic search method with the deterministic one. In the optimization process a suitable objective function for the stability of machine performances is also proposed. Finally some numerical results that demonstrate the validity of the proposed approach are presented. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372685
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  • 5
    Electronic Resource
    Electronic Resource
    Soft heating for hyperthermia using temperature-sensitive magnetic powders and fine metal rings (abstract) (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 5866-5866 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In local hyperthermia it is important to leave the temperature of surrounding normal tissues essentially unchanged while increasing the temperature of tumors to a desired level. Soft heating1 with temperature-sensitive magnetic materials is advantageous in heating deep-seated tumors because of the self-limiting ability. In order for the method to become available for large-scale tumors we have proposed to use temperature-sensitive magnetic powders, in which fine metal rings are dispersed. As the magnetic flux distribution varies with the temperature of the powders, the fine rings immersed in the powders with low temperatures generate heat more than rings located in the powders with high temperatures. Furthermore, the transition from the ferromagnetic to the nonferromagnetic state becomes sharp effectively. As a result it is expected to make the temperatures of powders in a broad region uniform. Figure 1 shows the temperature dependence of the magnetic powders used in experiments. Figure 2 shows the relation between the attained temperature of the powders and the ring resistances, comparing them in the case of iron powder. The figure reveals that it exists appropriate combination between the ring resistance, and the magnetic permeability of the powders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342183
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  • 6
    Electronic Resource
    Electronic Resource
    Nanometer-scale imaging of potential profiles in optically excited n-i-p-i heterostructure using Kelvin probe force microscopy (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 3069-3071 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on measurements of the potential profile of a GaAs/AlGaAs n-i-p-i multiple quantum well structure using a scanning Kelvin probe force microscope (KFM). Using this novel technique we directly measure with meV precision and sub-100 nm spatial resolution the potential difference between n-i-p-i layers with and without external optical excitation. The measured potential profiles, which have not been directly imaged previously, agree well with potential profiles calculated for optically excited n-i-p-i structures, but modified by band bending effects at the surface. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114867
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  • 7
    Electronic Resource
    Electronic Resource
    Direct observation of optical anisotropy in a GaAs/AlAs quantum well wire array (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 2969-2971 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using reflectance difference spectroscopy and transmittance difference spectroscopy, optical anisotropy in a quantum well wire array is directly observed at room temperature. The quantum wire array is a fractional-layer superlattice grown by metalorganic chemical vapor deposition on a vicinal (001)GaAs substrate. The size for quantum confinement of the wires is nominally 4×4 nm. Polarization dependence of optical absorption and refractive index is clearly observed between the directions parallel and perpendicular to the wires.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104711
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  • 8
    Electronic Resource
    Electronic Resource
    Nonlinear optical absorption in an n-InGaAsP/p-InP heterodoping superlattice (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 359-361 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Absorptive optical nonlinearity in an n-InGaAsP/p-InP heterodoping superlattice grown by vapor phase epitaxy is investigated. Although change in the absorption coefficient per an excited carrier obtained for the doping superlattice is comparable to that of bulk material, larger nonlinear absorption is induced by unit-intensity light illumination. This enhancement is attributable to prolonged carrier recombination lifetime due to the separation of electrons and holes in space. The nonlinear absorption caused by accumulated photocarriers can be explained by the combination of two effects: blocking of direct band-to-band transition in real space (band filling effect), and change in probability of indirect transition in real space (Franz–Keldysh effect) due to a modified internal electric field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99464
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  • 9
    Electronic Resource
    Electronic Resource
    Photon-spin controlled lasing oscillation in surface-emitting lasers (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 566-568 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on photon-spin controlled lasing oscillation in GaAs surface-emitting lasers at room temperature. We demonstrate experimentally that the partial electron-spin alignment, created by optically pumping the GaAs laser active media with circularly polarized pulses, drastically changes the polarization state of the lasing output, causing circularly polarized lasing emission. We discuss the laser polarization characteristics in relation to the measured electron-spin relaxation time. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121857
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  • 10
    Electronic Resource
    Electronic Resource
    Rapid relaxation of hot carriers in GaAs fractional-layer superlattice quantum wires (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 218-220 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We measure the hot carrier relaxation in two GaAs quantum wire arrays made from fractional-layer superlattices (FLS). Using femtosecond optical pump–probe spectroscopy, we measure the differential transmission spectra for various pump–probe time delays from which we determine the carrier thermalization times. Although the two FLS structures have different degrees of one-dimensional confinement at the band edge, we observe rapid (〈2 ps) and efficient carrier relaxation in both cases with no sign of the inhibited relaxation predicted for ideal one-dimensional structures. We believe that FLS quantum wire structures avoid relaxation bottlenecks because the shape of the FLS confinement potential produces high energy states which are two dimensional in character and which facilitate rapid energy relaxation. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117377
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