Generic wave characteristics in heterogeneous materials

  • Formulated a theoretical framework for the quantitative prediction of wave phenomena in the intermediate frequency regime. The theory resolves the classical problem concerning the definition and calculation of group velocity in a strongly scattering medium, and gives quantitative explanation of observed multiple acoustic modes in colloidal systems.

Magnitude of the spectral function plotted as a function of normalized frequency and wave vector

Key publications:

  1. “Theory of Acoustic Excitations in Colloidal Suspensions“, X. Jing, Ping Sheng and Minyao Zhou, Phys. Rev. Lett. 66, 1240 (1991).
  2. “Acoustic and Electromagnetic Quasi-Modes in Dispersed Random Media“, X. Jing, Ping Sheng and M. Zhou, Phys. Rev. A46, 6513 (1992).
  3. “Group Velocity in Strongly Scattering Media“, J. Page, Ping Sheng, H. Schriemer, I. Jones, X. Jing, and D. Weitz, Science 271, 634 (1996).

 

  • Wave localization is usually characterized by exponential decay of the wave function in space.  However, for pulse reflection from a random medium there can also be a signature of wave localization manifest statistically in the power spectrum of the reflected wave time series.  This signifies a wave localization signature in the time domain.

Key publications:

  1. “Multiple-Scattering Noise in One Dimension: Universality through Localization-Length Scaling“, Ping Sheng, Z. Q. Zhang, B. White and G. Papanicolaou, Phys. Rev. Lett. 57, 1000 (1986).
  2. “Wave Localization Characteristics in the Time Domain“, B. White, Ping Sheng, Z. Q. Zhang and G. Papanicolaou, Phys. Rev. Lett. 59, 1918 (1987).
  3. “Wave Localization and Multiple Scattering in Randomly-Layered Media“, Ping Sheng, B. White, Z. Q. Zhang, and G. Papanicolaou, in “Scattering and Localization of Classical Waves in Random Media”, edited by P. Sheng (World Scientific Publishing Co., Inc. Singapore, 1990), p. 563.

 

  • Clarified the relationship between the generic phenomenon of heat conductivity plateau in disordered materials and phonon scattering, phonon localization, and the Ioffe-Regel criterion; the first to point out the criterion of critical index of refraction (or wave impedance) contrast for 3D classical wave localization.

Key publications:

  1. “Scalar-Wave Localization in a Two-Component Composite“, Ping Sheng and Zhao-Qing Zhang, Phys. Rev. Lett. 57, 1879 (1986).
  2. “Heat Conductivity of Amorphous Solids: Simulation Results on Model Structures“, Ping Sheng and M. Y. Zhou, Science 253, 539 (1991).
  3. “Phonon Transport in Strong-Scattering Media“, Ping Sheng, M. Zhou and Z. Q. Zhang, Phys. Rev. Lett. 72, 234 (1994).

 

  • Patented a non-plane wave, focused-energy electromagnetic wave solution that can propagate indefinitely without distortion and invented a practical way for its approximate realization.

Key publication:

  1. “Optical Playback System Having Increased Depth of Field”, U.S. Patent #4,179,708 Ping Sheng and A. H. Firester.