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Full-Text Articles in Physics

Evidence For Terahertz Acoustic Phonon Parametric Oscillator Based On Acousto-Optic Degenerate Four-Wave Mixing In A Silicon Doping Superlattice, Thomas E. Wilson Dec 2018

Evidence For Terahertz Acoustic Phonon Parametric Oscillator Based On Acousto-Optic Degenerate Four-Wave Mixing In A Silicon Doping Superlattice, Thomas E. Wilson

Physics Faculty Research

We report evidence for a 1.0-THz self-starting mirrorless acoustic phonon parametric oscillator (MAPPO) produced from acousto-optic phase-conjugate degenerate four-wave (D4WM) mixing in a THz laser-pumped silicon doping superlattice (DSL). The DSL was grown by molecular beam epitaxy on a (100) boron-doped silicon substrate. A superconducting NbTiN subwavelength grating was used to couple the THz laser radiation into the DSL. Superconducting granular aluminum bolometric detection, coupled with Si:B piezophonon spectroscopy, revealed excitation of THz coherent compressional and shear waves, along the ⟨111⟩ direction only. The Bragg scattering condition for distributed feedback, and the energy conservation requirement for the D4WM process, were …


Evidence For Terahertz Acoustic Phonon Parametric Oscillator Based On Acousto-Optic Degenerate Four-Wave Mixing In A Silicon Doping Superlattice, Thomas E. Wilson Dec 2018

Evidence For Terahertz Acoustic Phonon Parametric Oscillator Based On Acousto-Optic Degenerate Four-Wave Mixing In A Silicon Doping Superlattice, Thomas E. Wilson

Physics Faculty Research

We report evidence for a 1.0-THz self-starting mirrorless acoustic phonon parametric oscillator (MAPPO) produced from acousto-optic phase-conjugate degenerate four-wave (D4WM) mixing in a THz laser-pumped silicon doping superlattice (DSL). The DSL was grown by molecular beam epitaxy on a (100) boron-doped silicon substrate. A superconducting NbTiN subwavelength grating was used to couple the THz laser radiation into the DSL. Superconducting granular aluminum bolometric detection, coupled with Si:B piezophonon spectroscopy, revealed excitation of THz coherent compressional and shear waves, along the ⟨111⟩ direction only. The Bragg scattering condition for distributed feedback, and the energy conservation requirement for the D4WM process, were …


Conforming Nanoparticle Sheets To Surfaces With Gaussian Curvature, Noah P. Mitchell, Remington L. Carey, Jelani Hannah, Yifan Wang, Sean P. Mcbride, Xiao-Min Lin, Heinrich M. Jaeger Oct 2018

Conforming Nanoparticle Sheets To Surfaces With Gaussian Curvature, Noah P. Mitchell, Remington L. Carey, Jelani Hannah, Yifan Wang, Sean P. Mcbride, Xiao-Min Lin, Heinrich M. Jaeger

Physics Faculty Research

Nanoparticle monolayer sheets are ultrathin inorganic-organic hybrid materials that combine highly controllable optical and electrical properties with mechanical exibility and remarkable strength. Like other thin sheets, their low bending rigidity allows them to easily roll into or conform to cylindrical geometries. Nanoparticle monolayers not only can bend, but also cope with strain through local particle rearrangement and plastic deformation. This means that, unlike thin sheets such as paper or graphene, nanoparticle sheets can much more easily conform to surfaces with com- plex topography characterized by non-zero Gaussian curvature, like spherical caps or saddles. Here, we investigate the limits of nanoparticle …


Thermo-Mechanical Response Of Self-Assembled Nanoparticle Membranes, Yifan Wang, Henry Chan, Badri Narayanan, Sean P. Mcbride, Subramanian K.R.S. Sankaranarayanan, Xiao-Min Lin, Heinrich M. Jaeger Jul 2018

Thermo-Mechanical Response Of Self-Assembled Nanoparticle Membranes, Yifan Wang, Henry Chan, Badri Narayanan, Sean P. Mcbride, Subramanian K.R.S. Sankaranarayanan, Xiao-Min Lin, Heinrich M. Jaeger

Physics Faculty Research

Ultrathin membranes composed of metallic or semiconducting nanoparticles capped with short ligand molecules are hybrid materials that have attracted considerable research interest.1-12 In contrast to two-dimensional (2D) membranes such as graphene and transition metal dichalcogenides monolayers, nanoparticle membranes can be engineered to achieve widely tunable mechanical, electronic or optical properties through different combinations of inorganic cores and organic ligands. In terms of mechanical properties, these membranes can form large area (tens of microns in diameter) freestanding structures with high Young’s moduli (~GPa) and fracture strength.1,13-15 Molecular dynamics (MD) simulations have indicated how this mechanical robustness can arise from …