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Summary form only given. The optical response of nanostructured semiconductors around the bandgap is dominated by the properties of excitons in interface potentials fluctuating: on a mesoscopic length scale. On this length scale, scanning near-field optical microscopy (SNOM) extents the optical resolution to a fraction of the wavelength of light. The results of a finite difference time domain evaluation...
Summary form only given. Nanoscale structures can be tailored to provide enhanced, nanoscale near-field optics. For example, high-quality GaAs quantum dots can be fabricated by self-formed growth near the apex of AlGaAs tetrahedral pyramids. Photoluminescence studies have shown a thousand-fold enhancement of the far-field emission of an embedded quantum dot. This large enhancement arises because the...
Summary form only given. The enhancement of the light and matter interaction that can be obtained in periodic structures such as 1D photonic crystals or Fabry-Perot microcavities might be best used when the interaction considered is nonlinear. It has been theoretically shown that changes in the effective index of refraction of a dielectric material leading to large changes in reflection or transmission,...
Summary form only given. We consider two resonant molecules (or nano-particles) located near the tip of an apertureless near-field scanning optical microscope (NSOM). The tip serves as a probe that allows us to observe the molecules and control the coupling between them. Various models are considered for the nanosized probe tip: a point-like dipole, a small dielectric sphere, and an elongated spheroidal...
Summary form only given. Photo-enhanced chemical vapor deposition (PE-CVD) offers the possibility for the lateral integration (i.e., side by side) of different structures (different sequence of layers, materials, thickness and dopants), without the need of any lithography or etching, in a single growth run. In the PE-CVD process, with utilizing the optical near field with nanometric resolution as...
Summary form only given. In recent years, nanoparticles of metals, such as gold, silver, and copper, have attracted much attention because they have electrical and optical properties that are different from those of bulk metals. Electron dynamics and optical nonlinear response of metallic nanoparticles have been studied extensively and suggested that metallic nanoparticles are promising candidates...
Summary form only given. The physical nature of photoluminescence (PL) from semiconductor nanocrystals has been a subject of considerable debate. Earlier studies using organically-capped nanocrystals have shown that the PL arises primarily from dark excitonic states with a radiative lifetime of order microseconds. Recent advances in developing inorganically-capped nanocrystals have led to much improved...
Summary form only given. Recent progress in microfabrication involving, etching processes makes it possible to engineer three-dimensional (3D) nanostructures from MBE-grown planar Fabry-Perot micro-cavities. The optical mode is confined laterally by implementing a thin dielectric (native oxide) aperture layer on top of the cavity spacer. The sample under investigation consists of a 16 period GaAs/AlAs...
Summary form only given. Photonic crystals are nanostructured materials that possess a periodic modulation of the dielectric constant. We have fabricated two-dimensional (2D) triangular photonic crystals in which one of the elements is a phthalocyanine (Pc) dye. These Pc's have a wavelength dependent absorption and large nonlinear absorption and nonlinear refraction coefficients. Thus, in our new...
Summary form only given, as follows. In recent years there have been significant advances in the preparation of semiconductor quantum dots by colloidal chemistry routes. CdSe and InAs are examples of materials which can be made as nanocrystals of high quality. These nanocrystals provide an excellent proving ground for examining size dependent scaling laws, and a few examples are described briefly...
Summary form only given. We have developed a novel QD microcavity by coupling core/shell semiconductor nanocrystals resonantly to whispering gallery modes (WGMs) of a silica microsphere. We have shown that this composite microcavity system features a photon lifetime of order 0.1 Js, corresponding to Q-factors of order 10/sup 8/, four to five orders of magnitude greater than that of other semiconductor...
Summary form only given. The existence of quantum confinement in semiconductor nanocrystals allows to regard them as nanocavities for the electronic wavefunctions. The quantization of energy levels inside such nanocrystals results in quantization of the corresponding optical transitions. In fact, the absorption and photoluminescence spectra of various semiconductor nanocrystals possess rather a molecular-like...
Summary form only given. Ordered array of nanosize spheres are attractive for many linear and nonlinear applications. In particular, if one is able to tailor the nonlinear properties of the embedded material to the confining properties of its matrix, a substantial enhancement in the nonlinear optical properties is expected. Here we present results on the linear and nonlinear optical properties of...
Summary form only given. Reduction of the size of a material to a nanometric scale leads to drastic modifications of its properties. In metallic systems, they are largely conditioned by the alteration of the conduction electron scattering processes whose study is thus of both technological and fundamental interests. Time-resolved femtosecond techniques have been shown to be powerful tools for their...
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