This PDF file contains the front matter associated with SPIE Proceedings Volume 7755, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

CdSe quantum dots had been synthesized with a hot injection method. It was shown that the addition of Pb ions in the initial precursor solution changed the morphology of CdSe nanocrystals from slightly prolate ellipsoid to branched rod. Photoluminescence (PL) of the branched nanocrystals showed rapid depression of emission intensity due to the morphological development to the branched nanocrystal induced by Pb addition. Low temperature PL spectrum indicated that the surface recombination of charge carrier resulted in the large depression of emission from the branched nanocrystal.

In this work the Eu³⁺ ion was used as optical probe, by considering its hypersensitive transitions to follow changes in the local environment. Eu³⁺ ions were incorporated into gel via dissolution of soluble species into the initial precursor TiO₂ sol. The TiO2/Eu³⁺ films were spin-coated on glass wafers. A spectroscopic study of the Eu³⁺ impurity in function of the heat treatment provided to the TiO₂ matrix was done. Anatase nanophase was obtained after heat treatment at 600°C for 1h and it was detected by X-ray diffraction. An absorption band located in the UV region between 300-360 nm is due to the band gap of the titania host. Results of emission and excitation spectra at room temperature of Eu³⁺ inserted in the TiO₂ matrix are presented. The ratio of the ⁷F₂/⁷F₁ transitions was calculated. The evolution of this ratio was interpreted in terms of the Eu³⁺ symmetry site change when the nanocrystalline TiO₂ phase was obtained.

First generation dendrimers having a high level of size/shape/symmetry homogeneity were fabricated using a synthetic scheme that employs highly quantitative copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions in combination with a molecular architecture that favors homogeneity. An "outside-in" or convergent synthetic approach was employed wherein dendrons having Sierpinski triangular fractal architectures were coupled to core structures having D_2h or D_3h point group symmetries to form the desired dendrimers. The individual dendrons consisted of branched-backbone conductive polymers having benzene branch points and 1,2,3-triazole linkages with uninterrupted π-electron cloud overlap throughout. Each dendron was then coupled to a benzene core structure having acetylene substituents by means of a CuAAC reaction so as to extend the uninterrupted π-conjugation from the dendron to the core structure for imparting conductivity throughout the entire dendrimer. The resulting dendrimers maintained the point group symmetry of their core structure, with the core structure serving to electronically couple the dendrons to one another by extension of their uninterrupted π-electron systems. Synthesis of these first generation dendrimers provides a proof of principle for the synthesis of higher generation conductive dendrimers. Since the nanophotonic properties of conductive dendrimers may be dependent, at least in some instances, upon their size, shape, and symmetry, enhancements with respect to their homogeneity may unmask new nanophotonic properties.

The photonic band gap of colloidal crystal films made of polystyrene nanospheres was controlled by dry etching technology using hyperthermal neutral beam. Vertical deposition technique was applied to prepare colloidal crystal films with face centered cubic lattice structure using aqueous suspension of monodispersed polystyrene particles. The pseudogap of these colloidal photonic crystals was tuned by etching the films with neutral beam, which reduces the size of the constituent polystyrene particles. Isotropic reduction of the particles in collodial crystal films resulted in the blue shift of stop band of the photonic band gap materials. By changing the etching time, the reflected colors of the dry-etched colloidal crystals were successfully controlled.

We study four compressively strained GaInSb/AlGaInSb type I multi quantum-well (QW) laser structures grown on GaAs, with increasingly strained QWs, aimed at emitting at ~4μm. This wavelength region is highly important for applications such a free space communication, biomedical imaging and trace gas sensing. The structures are analysed using photoluminescence, photo-modulated reflectance and, at room temperature, using our novel, recently developed Fourier transform infrared surface photo-voltage spectroscopy technique (FTIR-SPS). Neither photoluminescence nor photo-modulated reflectance managed to give any characterisation information at room temperature or such detailed information even at low temperatures. However, FTIR-SPS clearly yielded a full set of transitions for all four samples including not only the barrier bandgap, but also the QW ground state transition, from which the device operating wavelengths can be inferred, and up to five excited state QW transitions. The full set of measured transition energies are then compared closely with those predicted by an 8-band k.p model which takes account of the band anisotropy and strain. There is generally a good agreement between the QW transitions predicted by the model and those measured experimentally, but there is also a strong indication that the current literature values for the AlGaInSb bandgap seem to be in considerable error for the present alloy compositions. The FTIR-SPS technique gives information of great importance when designing future devices to emit in this wavelength region.

Highly luminescent semiconductor nanocrystals with graded band gap were synthesized using hot injection method. The band gap of nanocrystals were controlled by gradual incorporation of sulfur to CdSe nanocrystals by applying severely asymmetric composition of reactants ([Cd]/[Se,S]>>1). The maximum emission wavelength of the grown nanocrystals was varied by controlling the concentration ratio of VI group element, ie. Se and S. A green light was emitted from Cd(Se,S) nanocrystals with [Se]:[S]=1:3 in the reactant mixture and the maximum quantum yield measured by comparing with Rhodamine 6G exceeded 80%

This work presents the structural, morphological and luminescent properties of Y₃Al₅O₁₂:Ce³⁺(0.1%)-Pr³⁺(0.1%) nanophosphors synthesized by a hydrothermal precipitation method. It was observed that the incorporation of Amonium hydroxide (NH₄OH, Ammonia) increases the YAG (%)/YAM(%) ratio, leading to an increase of 83% in the overall emission under 460 nm excitation. The nanophosphor with the highest content of YAM, presented the best broad green-yellow- red emission band corresponding to Ce³⁺ and Pr³⁺ emissions under 340 nm excitation. The average nanocrystallite size was 50 and 55 nm for the samples with and without Ammonia respectively. Quenching of the overall emission after an annealing treatment at 1100°C is observed in spite of reaching single YAG crystalline phase. That suggests Pr⁴⁺ and/or color centers formation due to the estequiometric unbalance as a consequence of the YAM to YAG transformation. By taking advantage of the broad emission under 340 nm and using a blue dye, we produced white light with CIE coordinates of (0.30, 0.36).

Terahertz (THz) spectroscopy is an important tool to study properties of semiconductors to gain important insight into materials. Generating THz radiation as freely propagating beam made THz Spectroscopy an ideal tool for investigating various behaviors. Effect of THz-Time Domain Spectroscopic (THz-TDS) irradiation, applied to a potential well structure, is considered here based upon an experimentally verified model. At ambient temperature, there will be two mechanisms of scattering alongside others: charge-charge scattering and electron-phonon scattering as proposed by Hendry et al. GaAs-Al_xGa_1-xAs double barrier heterostructure was selected. Mole fractions were chosen for which appropriate Γ-band conduction energy differences were considered. Only optical phonon interactions were considered. Effects of these mechanisms have been demonstrated in terms of broadening of transmission probabilities, group velocity, phase coherence, quantum well transit time and most importantly, charge density against various pump fluences. To get full impact of THz-TDS for charge density, modified Fermi distribution was considered and significant results were obtained. An experimental setting emitting electron at different injection energy can be employed to enumerate broadening in terms of plasma frequency and thus, pump fluence. Also, the impact of different elemental compositions in the AlGaAs/GaAs or other resonant tunneling structures may be very precisely determined.

A laser induced photoacoustic technique has been employed to measure the thermal effusivity value of natural rubber latex in the liquid as well as in the solid state. The nano Zinc Oxide particles synthesized via precipitation technique is incorporated to the natural rubber latex. The influence of molar fractions of nanoparticles on the thermal effusivity value of host polymer is investigated. Detailed analysis of the results shows that the rubber latex in the solid state exhibits lower value for the thermal effusivity value in comparison to the liquid state. The molar fraction of the nanoparticle is found to influence the effective thermal effusivity value in a substantial manner. Results are explained in terms of nanoparticle and phonon assisted thermal energy transport in these samples.

We present the results of numerical and experimental studies of spatial and temporal separation of femtosecond light pulses in 1D photonic crystals (PC) in Laue diffraction geometry. The porous silicon PC are fabricated by electrochemical etching using and contain 400 pairs of alternating layers with optical thickness 600 and 680 nm, so that the center of the photonic band gap is placed at about 2600 nm. Spatial splitting of the laser pulse into two, one of them corresponding to the transmitted beam and the second - to the diffracted one, are observed. It is shown that the diffraction angle of the second beam changes when the wavelength of light is tuning, in accordance with the theoretical estimations.

Flexible Plasma Enhanced Chemical Vapor Deposition (PECVD) technology of Diamond Like Carbon (DLC) thin film preparation on the surface of Si and organic glasses has been elaborated. Modification of PECVD equipment has been implemented by integrating ion and magnetron sources. In this paper toluene (C₇H₈) has been used as a nanocmposite film forming hydrocarbon which decomposition yields to the multi component plasma in vacuum chamber. Nitrogen has been used as a dopand. Investigation of plasma composition influence to the optical and mechanical properties of DLC films has been observed. The presence of sp³ and sp² hybridization states have been proven by Raman spectroscopy and their ratios have been estimated with the help of I_D, I_G characteristic lines for different technological conditions. High precision refractive index and thickness measurements of DLC films have been implemented by means of laser ellipsometer. Refractive indices of prepared films have been varied in the region 1.5-3.1 and thicknesses have been varied in the region 50-250 nm. Extraordinary change in refractive index has been explained with the help of formation of differently sized sp² carbon based clusters in the sp³ matrix. Different types of carbon and hydrogen bonds have been observed in the obtained structures by means of FTIR. Obvious prospectives of DLC nanocomposite film as a promissing nanophotonic material has been discussed.