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Klaus H. Ploog - One of the best experts on this subject based on the ideXlab platform.

  • Investigations of quantum trench tunneling diodes
    Applied Physics Letters, 1993
    Co-Authors: A. J. Peck, S. J. Bending, K. Von Klitzing, Klaus H. Ploog
    Abstract:

    We report on the realization of a new type of lateral tunneling diode with the potential for ultrahigh frequency (THz) operation. The diodes, which are fabricated by etching tiny quantum trenches into the surface of a GaAs/AlGaAs heterostructure, display extremely nonlinear current‐voltage characteristics. Tunneling barrier heights are obtained from a study of thermally activated current, and results are compared to those of a theoretical model of the structure based on the Finite Difference Form of the Poisson equation.

P.c. Noutsios - One of the best experts on this subject based on the ideXlab platform.

  • An improved Finite-Difference vector beam propagation Formulation for graded-index waveguides
    IEEE Photonics Technology Letters, 1994
    Co-Authors: G. L. Yip, P.c. Noutsios
    Abstract:

    An improved Finite-Difference vector beam propagation Formulation for graded-index waveguides is presented. The modification over the existing version involves a more accurate representation of the Fresnel operator in Finite-Difference Form that accounts for the gradient of the refractive index in the vector Hehmholtz equation. The modified scheme is assessed by calculating the TM mode propagation constants of single-mode planar guides that yield better agreement to the exact values over the existing scheme. Furthermore, the calculated coupling lengths of a vertical directional coupler show improved comparison to experimental data. >

D.m. Glenn - One of the best experts on this subject based on the ideXlab platform.

  • Soil heat flux estimation based on the Finite-Difference Form of the transient heat flow equation
    Agricultural and Forest Meteorology, 1992
    Co-Authors: B.s. Sharratt, Gaylon S. Campbell, D.m. Glenn
    Abstract:

    Soil heat flux (G) often aids in interpreting the response of plants to the growing environment, but methods of estimating G are needed that require limited soil temperature and physical property inFormation. This study describes a method for estimating G by implicitly solving the Finite-Difference Form of the transient heat flow equation for the apparent daily thermal conductivity. The derived apparent thermal conductivity and measured soil temperature gradient are applied to Fourier's law for estimating G. This method requires the measurement of soil bulk density and daily water content (for volumetric heat capacity) and hourly temperatures at three depths. Hourly G measured by heat flux plates buried at depths of 0.05 m in apple and peach orchards and 0.03 m in a barley stubble field were compared with G estimated using the harmonic method and our proposed Finite-Difference method. The Finite-Difference method perFormed better, as indicated by a smaller root-mean-square error (r.m.s.e.), than the harmonic method for 71 of the 83 daily data sets used in this study. The average r.m.s.e. in estimating hourly G for the 83 data sets was 10.9 W m−2 for the Finite-Difference method and 16.3 W m−2 for the harmonic method. Daily net warming or cooling of the soil was correctly estimated for 95% of the data sets using the Finite-Difference method. The harmonic method, however, results in no net warming or cooling of the soil when deviations are not accounted for in the periodicity.

G. L. Yip - One of the best experts on this subject based on the ideXlab platform.

  • An improved Finite-Difference vector beam propagation Formulation for graded-index waveguides
    IEEE Photonics Technology Letters, 1994
    Co-Authors: G. L. Yip, P.c. Noutsios
    Abstract:

    An improved Finite-Difference vector beam propagation Formulation for graded-index waveguides is presented. The modification over the existing version involves a more accurate representation of the Fresnel operator in Finite-Difference Form that accounts for the gradient of the refractive index in the vector Hehmholtz equation. The modified scheme is assessed by calculating the TM mode propagation constants of single-mode planar guides that yield better agreement to the exact values over the existing scheme. Furthermore, the calculated coupling lengths of a vertical directional coupler show improved comparison to experimental data. >

  • An Improved Finite-Difference Vector Beam Propagation for Graded-Index Waveguides
    1994
    Co-Authors: G. L. Yip
    Abstract:

    An improved Mte-Difference vector beam propaga- tion Formulation for graded-index waveguides is presented. The modification over the existing version involves a more accurate representation of the Fresnel operator in Finite-Difference Form that accounts for the gradient of the refractive index in the vector Helmholtz equation. The modified scheme is assessed by calculating the TM mode propagation constants of single-mode planar guides that yield better agreement to the exact values over the existing scheme. Furthermore, the calculated coupling lengths of a vertical directional coupler show improved comparison to experimental data.

A. J. Peck - One of the best experts on this subject based on the ideXlab platform.

  • Investigations of quantum trench tunneling diodes
    Applied Physics Letters, 1993
    Co-Authors: A. J. Peck, S. J. Bending, K. Von Klitzing, Klaus H. Ploog
    Abstract:

    We report on the realization of a new type of lateral tunneling diode with the potential for ultrahigh frequency (THz) operation. The diodes, which are fabricated by etching tiny quantum trenches into the surface of a GaAs/AlGaAs heterostructure, display extremely nonlinear current‐voltage characteristics. Tunneling barrier heights are obtained from a study of thermally activated current, and results are compared to those of a theoretical model of the structure based on the Finite Difference Form of the Poisson equation.