A5029301752- Semiconductor Quantum Structures and Devices
- Advanced Fiber Laser Technologies
- Nonlinear Photonic Systems
- Semiconductor Lasers and Optical Devices
- Nonlinear Dynamics and Pattern Formation
- Advanced Semiconductor Detectors and Materials
- Quantum Dots Synthesis And Properties
- Nanowire Synthesis and Applications
- Surface and Thin Film Phenomena
- Laser Material Processing Techniques
- Quantum and electron transport phenomena
- Nonlinear Waves and Solitons
- Advanced Chemical Physics Studies
- Diamond and Carbon-based Materials Research
- Laser-Matter Interactions and Applications
- Photonic and Optical Devices
- Photorefractive and Nonlinear Optics
- nanoparticles nucleation surface interactions
- Optical Network Technologies
- Molecular Junctions and Nanostructures
- Optical Coatings and Gratings
- Electronic and Structural Properties of Oxides
- Advanced Surface Polishing Techniques
- Semiconductor materials and devices
- Force Microscopy Techniques and Applications
South Dakota School of Mines and Technology
2012-2017
Utah State University
2005-2013
University of Arkansas at Fayetteville
1999-2008
University of Central Florida
2005
University of California, Berkeley
1985
We report the first observation of discrete optical surface solitons at interface between a nonlinear self-focusing waveguide lattice and continuous medium. The effect power on localization process these self-trapped states edge an AlGaAs array is investigated in detail. Our experimental results are good agreement with theoretical predictions.
The atomic arrangement of the technologically important As-rich $\mathrm{GaAs}(001)\ensuremath{-}(2\ifmmode\times\else\texttimes\fi{}4)$ reconstructed surface is determined using bias-dependent scanning tunneling microscopy (STM) and first-principles electronic structure calculations. STM images reveal relative position depth atomic-scale features within trenches between top-layer As dimers, which are in agreement with $\ensuremath{\beta}2(2\ifmmode\times\else\texttimes\fi{}4)$ structural...
We report the first experimental observation of modulation instability in a discrete optical nonlinear array.Received 13 November 2003DOI:https://doi.org/10.1103/PhysRevLett.92.163902©2004 American Physical Society
Many applications in industry utilize a layered elastic structure which relatively thin layer of one material is bonded to much thicker substrate. Often the fabrication process imperfect and cracks occur at interface. This paper concerned with plane strain, time-harmonic problem single on half space different crack Green’s functions for uncracked medium are used appropriate form integral theorem derive scattered field potentials arbitrary incident fields cracked space. These turn reduce...
We report on the influence of chemical composition (Al, Ga)As surface formation strain induced three-dimensional (3D) InAs islands. The experiments have been carried out using a molecular beam epitaxy facility combined with scanning tunneling microscope enabling in situ characterization. evolution density and morphology these islands is investigated as function Al composition. deposition, substrate temperature, annealing time effects island are studied. morphologies well that reconstructed...
We investigate experimentally and numerically the interaction of a highly localized, single-channel discrete soliton (blocker) with wide, tilted beam in one-dimensional AlGaAs array. In agreement theory blocker is observed to discretely shift its position by multiple channels, depending on intensity relative phase beam.
We report on the use of in situ scanning tunneling microscopy to study As/P exchange InP(001) surfaces by molecular beam epitaxy. Results demonstrate that process can be controlled selectively produce either quantum wires or dots. 15 nm wide self-assembled nanowires are observed, and they elongated along dimer row direction InP(001)-2×4 surface with a length over 1 μm flat top 2×4 surfaces. In addition, when annealed no arsenic overpressure, reconstruction transforms from 4×2 transform into...
The recent theoretical predictions and experimental observations of discrete surface solitons propagating along the interface between a one- or two-dimensional continuous medium waveguide array are reviewed. These were found in second order (periodically poled lithium niobate) third nonlinear media, including AlGaAs, photorefractive media glass, respectively.
We have investigated both theoretically and experimentally the power threshold of discrete Kerr surface solitons at interface between a one-dimensional (1D) (waveguide array) continuous 1D (slab waveguide) AlGaAs medium. Decreasing thresholds were predicted measured for soliton trapping sites with increasing distance from boundary. The approached asymptotically required equivalent width in an infinite lattice. minimum coincided interchannel coupling strength.
The interaction between parallel beams in one-dimensional discrete Kerr systems has been investigated using arrays of coupled channel waveguides. experiments were performed AlGaAs waveguides at 1550 nm which corresponds to photon energies just below one half the semiconductor's bandgap. input intensity and relative phase was varied output patterns recorded. Observed behavior ranging from a linear response, soliton interactions moderately then strongly localized spatial solitons. Finally...
We have observed the incoherent interaction between a highly confined (blocker) soliton and wide, moving signal beams of different wavelength in one-dimensional discrete Kerr medium. Digital switching blocker solitons to successive adjacent channels was measured with increasing power via both one two cascaded interactions an AlGaAs waveguide array, operations equivalent reconfigurable three-output router.
The role of As4 molecules in Ga diffusion on the GaAs(001)-(2×4) reconstructed surface has been studied using a combined molecular beam epitaxy and scanning tunneling microscopy multichamber facility. We deposited 10% plane atoms onto an otherwise pristine surface, while exposed to two separate equivalent pressures 10−5 10−6 Torr. higher flux resulted production fewer larger islands, indicating that increasing increases total interrogation area available before forming islands.
We report a study on self-assembled InAs quantum wires planar surface of InP(001), grown by molecular-beam epitaxy and examined in situ scanning tunneling microscopy photoluminescence (PL). The detailed morphology the including width height distributions is presented. cover more than 95% area. spectral range PL emission includes technologically important 1.55 μm. In emission, high optical anisotropy 50% has been observed at 4.2 K room temperature indicating strong confinement.
We report arrays of self-assembled quantum dots through roughening transition strained but atomically flat layers into three-dimensional (3D) islands. Atomically two-dimensional InGaAs epilayers were grown on GaAs(001) substrates below 360°C. When heated higher than 420°C, they observed to undergo transitions. The morphology, height, and width the resultant 3D features found be a strong function annealing time temperature. Furthermore, at particular set parameters, dot chains observed....
We present an investigation of the morphology InP/GaInP three-dimensional (3D) islands obtained by molecular beam epitaxy. This material system should represent counterpart InGaAs/GaAs for visible range. The are found to be truncated pyramids with observable phosphorous-rich surface reconstruction on top. effect P overpressure reveals a path achieve extremely homogeneous 3D through island shape transition. These results help us understand emerging issue
We have investigated polarization-dependent photoluminescence in InP/InAs/InP quantum wires directly formed on the top of InP substrates. With excitation laser intensity we observed an anomalously large blueshift peak using a cw with extremely low intensities. also evidence band-gap renormalization. In addition, measured two-photon luminescence spectra and confirmed their dependence polarization.
A method for fabricating self-assembled InGaAs quantum dashes on a nominal GaAs(001) substrate is presented. layers were grown substrates at low temperature to suppress the Stranski-Krastanov transition as well indium segregation and desorption, then annealed high temperatures induce self-assembly. While typical direct growth annealing has yielded only dot shapes, our approach enabled us control shape of nanostructures from dots eventually dot-chains. The major factor controlling was found...
Isochronal thermal annealing effect on the photoluminescence (PL) spectra of intersublevel transitions in InAs self-assembled quantum dots was investigated. Several peaks due to were observed PL two samples consisting 10 stacks and InP barriers. furnace temperature range 500–800 °C conducted samples. The results show that intensity dramatically reduced, a new peak attributed wetting layer after thermally annealed above 550 °C. A small blue shift intermixing observed.
The excitation and propagation of both scalar vector optical waves in one-dimensional nonlinear arrays channel waveguides was investigated theoretically experimentally. In this arrangement discrete solitons are also possible through the coexistence two orthogonally polarized fields. At high input power levels a rapid collapse back to incidence occurred over small range for inputs.
Using 800 nm, 25-fs pulses from a mode locked Ti:Al2O3 laser, we have measured the ultrafast optical reflectivity of MBE-grown, single-layer In0.4Ga0.6As/GaAs quantum-dot (QD) samples. The QDs are formed via two-stage Stranski-Krastanov growth: following initial InGaAs deposition at relatively low temperature, self assembly occurs during subsequent higher temperature anneal. capture times for free carriers excited in surrounding GaAs (barrier layer) as short 140 fs, indicating efficiencies...