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Summary form only given. We present data that moves beyond this paradigm by exploring both spectral/spatial correlations between eigenstates of a disordered quantum well and examining spatial properties of the eigenstate itself. Unlike earlier work which relied on spectral and spatial diffusion for signal, degenerate cw nonlinear spectroscopy is utilized as an 'absorption-like' probe capable of mapping...
Summary form only given. We report on the first low temperature near-field luminescence investigation of a novel coupled wire-dot structure, allowing the assignment of different optical transition energies to different spatial areas of the sample and demonstrating carrier transport along the QWR into the dot. The schematic top view of the structure is shown together with an overview far-field photoluminescence...
Summary form only given. The difficulty of T-shaped quantum wires (T-QWRs) and lasers formed by the cleaved-edge overgrowth (CEO) method, the two-step-growth method combined by in-situ cleavage, with molecular beam epitaxy lies in the growth of high-quality layers on [110] cleaved surfaces We investigated local electronic-states in GaAs T-QWRs and constituent GaAs [110] QWs using high-resolution micro...
Summary form only given. We propose a class of laser designs based on oneand two-dimensional (1D and 2D) photonic crystals (PCs), which result in surface emitting lasers with a fabrication process similar to that used in edge-emitting distributed feedback lasers. The basic principle employed in our designs is based on our recent discovery that the output coupling characteristics of 2D gratings (or...
Summary form only given. There is considerable interest in the study of light emission from optical cavities whose dimensions are of the order of a wavelength in all three dimensions. Most work has been carried out on etched structures. We propose and demonstrate a novel method for the fabrication of GaAs semiconductor optical microstructures by self-organization during molecular beam epitaxial growth...
Summary form only given. Near-field Raman mapping are difficult experiments due to the extremely small Raman cross-section coupled with exceedingly low optical signal intensity of NSOM. To overcome the problem, surface-enhanced Raman spectroscopy (SERS) was employed to boost the Raman cross-section by an average enhancement of approximately six-orders of magnitude. Despite the low signal intensity,...
Summary form only given. We present many-atom dipole-dipole interaction in an ensemble of ultracold Rb atoms strongly coupled to the standing-wave field of a weakly driven high-finesse optical cavity. The many-atom light force changes the spatial distribution of the atoms, creating an asymmetry in the usually symmetric normal-mode spectrum.
Summary form only given. Excitons confined in nanocrystals or quantum dots attract much attention because they have a very long phase relaxation time that opens the way to the artificial coherent control of the excitons. CuCl quantum dot is a typical material in which the translational motion of the exciton is confined. In this paper, we report on the high resolution measurement of the resonant luminescence...
Summary form only given. Because of their small nanometer size and strong electronic confinement, quantum dots exhibit zero-dimensional electronic and optical effects which continue to be interesting for physics and promising for applications. To study single and clusters of self-organized semiconductor quantum dots, near-field optical nanoprobing is a powerful tool. Its spatial resolution surpasses...
Summary form only given. We show that a thermo-optically tuned optical waveguides array (OWA) exhibits supermodes that correspond to Wannier-Stark states (WSSs) with propagation constants forming a Wannier-Stark ladder (WSL) and that these features cause the existence of Bloch oscillations (BOs); the amplitudes and periods of which can be controlled by a temperature gradient.
Summary form only given. We recently proposed a new type of waveguide, the coupled-resonator optical waveguide (CROW), where an array of high Q resonators are coupled together. Under the tight-binding approximation, we found that the dispersion relation of a CROW can described by a coupling coefficient K and that its group velocity is greatly reduced. However, the concept of CROW is not necessarily...
Summary form only given. Exciton wavefunctions are sensitive to the confinement by sample surfaces, which makes the optical response of a slab very different from that of the infinitely extended medium. This complicated coupling between microscopic exciton polarization and macroscopic optical field has led to a variety of theoretical approaches over 40 years, which either start from a macroscopic...
Summary form only given. We have experimentally investigated the potential of narrow coherent population trapping resonances for precision applications like magnetometry or atomic frequency standards. CPT can be observed in /spl Lambda/ systems where two ground states are coupled to a common excited state by two near-resonant light fields. Effective formation of ground state coherences takes place...
Summary form only given. Two-beam coupling (TBC) with chirped pulses can be used to determine response times shorter than the chirped pulse duration. Here we explore the possibility of a direct determination of the electronic response time through measurements of two-beam coupling with pulses as short as 10 fs. We use fused silica as a model system. In numerical simulations we assume that the pulses...
Summary form only given. The investigation of coherent superposition states for atoms interacting with external potentials allows a completely new class of experiments directed towards coherent trapping and guiding of neutral atoms. In addition, the process of decoherence, i.e., the collapse of superposition states, is one of the basic concepts for our understanding of the connection between classical...
Summary form only given. Various types of optical solitons can be formed in the presence of the optical Kerr effect. They have been demonstrated in the time domain as stable light pulses, and in space as self-guided beams in a slab waveguide. Recently, there is a growing interest in discrete spatial solitons. The formation of discrete solitons in an array of coupled optical waveguides was demonstrated...
Summary form only given. In order to manufacture a modelocked, pulsed atom laser, we suggest the idea of making use of the atom-atom repulsion in a BEC to form a toroidal soliton which can then form a reproducible, coherent waveform. The relevant solitons have the form of a kink, or phase-singularity in the nonlinear Schrodinger equation. We suppose that the atoms are all trapped in a deep, toroidal...
Summary form only given. When a quantum-well exciton transition is resonant with a single mode of a high-Q microcavity, the normal modes ("cavity polaritons") of the coupled system are equal admixtures of the exciton and cavity. We have previously shown that, if the lower normal mode is excited by a phase-locked pair of optical pulses, the nonlinear response of a probe pulse tuned to the...
Summary form only given. The phenomena predicted to occur in nonlinear periodic structures include optical bistability, self-pulsation, pulse compression, Bragg soliton propagation, and the formation of gap solitons. Most of these phenomena have been observed recently in fiber Bragg gratings. One notable exception is the stationary gap soliton which has not been observed. The problem is that a periodic...
Summary form only given. As recently reported by Ebbesen et al. (1998), a subwavelength hole array in a metallic film shows extraordinary transmission of light at wavelengths much larger than the hole size. This unusual effect was attributed to the resonantly enhanced coupling of the incident beam into the surface plasmon polaritons. We report the measurement of the delay of a short pulse when transmitted...
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