This PDF file contains the front matter associated with SPIE Proceedings Volume 8807, including the Title Page, Copyright information, Table of Contents, Invited Panel Discussion, and Conference Committee listing.

We investigate highly doped InAsSb layers grown by molecular beam epitaxy on GaSb substrates. Electrical and optical characterizations demonstrate a metallic behavior with the possibility to control the plasma frequency in the mid-infrared range by adjusting the doping level. Plasmonic resonators based on this new kind of metal can be realized for mid-IR applications. Sub-wavelength periodic arrays are fabricated in the InAsSb layer and localized surface plasmon resonances are observed in reflectance experiments. A perfect control of the doping level and of the geometry of the periodic arrays allows adjusting the frequency of the plasmonic resonances. Our work shows that GaSb-based materials could be the building block for all-semiconductor mid-infrared plasmonic devices.

Optical emission from an electronically coupled pair of nanoemitters is investigated, in a new theoretical development prompted by experimental work on oriented semiconductor polymer nanostructures. Three physically distinct mechanisms for photon emission by such a pair, positioned in the near-field, are identified: emission from a pairdelocalized exciton state, emission that engages electrodynamic coupling through quantum interference, and correlated photon emission from the two components of the pair. Each possibility is investigated, in detail, by examination of the emission signal via explicit coupling of the nanoemitter pair with a photodetector, enabling calculations to give predictive results in a form directly tailored for experiment. The analysis incorporates both near- and far-field properties (determined from the detector-pair displacement), so that the framework is applicable not only to a conventional remote detector, but also a near-field microscope setup. The results prove strongly dependent on geometry and selection rules. This work paves the way for a broader investigation of pairwise coupling effects in the optical emission from structured nanoemitter arrays.

The mixture of phenyltrimethoxysilane (PTMS) and mercaptopropyltrimethoxysilane (MPTMS) has been covalently bonded to the surface of the monodisperse silica spheres to attach the PbS nanoclusters. The Fourier transform infrared (FTIR) spectra of the modified silica spheres (MSSPh) with PTMS and MPTMS clearly indicates the phenyl ring and carbohydrate absorption band. The FTIR spectra of MSSPh after attaching the Pb²⁺ and converting Pb²⁺ to PbS show the characteristic absorption peaks. The stopband of unmodified silica spheres located at 830 nm. However, the stopband disappears after surface modification and PbS formation due to the hydrophobic nature of the silica spheres. The field emission scanning electron microscope images of the MSSPh and MSSPh-PbS show similar surface texture. The compositions of the MSSPh-PbS obtained by energy dispersive spectroscopy include silicon, oxygen, carbon, sulfur and lead with the atomic ratio (weight ratio) of 33.34 (46.31), 32.60 (25.80), 32.90 (19.55), 0.40 (0.64) and 0.75 % (7.70 %), respectively. The photoluminescence (PL) spectrum shows several luminescence peaks between 600 to 840 nm. The PL results indicate that the PbS nanoclusters (NCs) may have molecular characteristics with this growth process. A precisely controlled growth can be achieved by extensive washing and centrifuge processes.

The resonant and off-resonant Raman spectra of optical phonons in two-dimensional CdSe nanocrystals of 5, 6, and 7 monolayers are analysed. The spectra are dominated by SO and LO phonon bands of CdSe, whose frequencies are thickness-independent in the off-resonant Raman scattering but demonstrate an evident thickness dependence in the case of the resonant Raman scattering.

The capabilities for practical all-optical switch (AOS) operation, being picosecond switching times and femtojoule switching energies, are investigated in this work. Two distinct nanophotonic architectures are introduced. The first nanophotonic architecture uses nanostructures, in the form of semiconductor nanoparticles, to enhance the rate of surface recombination and provide picosecond switching times. Switching times down to 4.5 ps are demonstrated. The second architecture uses photonic nanoinjection, with high refractive index spheres, to create high-intensity pump-probe beam interaction at a GaAs surface. This architecture offers 10 ps switching times with switching energies as low as 50 fJ. Nanophotonic architectures such as these can provide the capabilities needed for future AOS implementations.

Light propagation in an integrated chain of metallic nanowires (MNW) is theoretically investigated by means of rigorous coupled wave analysis. First, we analyze the nanowires chain immersed in a dielectric homogeneous medium and we compute the eigenmodes dispersion relation and their field profiles. Depending on the nanowire aspect ratio, in addition to the longitudinal and the transversal chain modes, we found a new mode characterized by quadrupolar-like localized surface plasmons resonances well identified at the edge of the first Brillouin zone. We then consider the vertical coupling of the MNW chain with the fundamental TM0 mode of a planar dielectric waveguide. We demonstrate that high energy transfer can be obtained, by computing near field maps and spectral responses (transmission, reflection, and absorption) of the structure consisting in a finite number of nanowires. The coupling mechanism between the dielectric waveguide and the MNW chain is rigorously explained through the analysis of the eigenmodes dispersion relation.

The authors present a novel in-situ method of fabricating crystalline gold nanoparticles by self-organization. This nanoparticles are grown and modified in a surrounding thin film matrix using two different host materials (YBa₂Cu₃O_7-δ and SrTiO₃) prepared by a pulsed laser deposition technique. The crystalline Au nanoparticles are formed out of a gold seed layer whereby the thickness of the initial seed layer influences the particle size and their distribution density. As we will show, using a matrix based preparation technique offers several advantages over conventional preparation methods. On the one hand, nanoparticle size and the distribution density can be controlled individually. On the other hand, by choosing an appropriate matrix material as well as suitable growth conditions also the shape of the resulting particles can be modified. Thus, also anisotropic nanoparticles can be prepared without using highly sophisticated methods like electron beam lithography or focused ion beam techniques. As one might have to extract the nanoparticles or at least theirs tips from the surrounding matrix material to realize photonic applications, we will show that an extraction is easily possible by selectively etching the matrix. This extraction process does not influence the particle distribution, i.e. particles can be prepared and extracted at distinct positions on the substrate utilizing a patterning of the Au seed layer. A spectral characterization of extracted as well as embedded particles will be presented based on microspectroscopy as well as on measurements using an integrating sphere.

We develop a theory allowing one to calculate the energy spectra and wave functions of collective excitations in twoand three-dimensional quantum-dot supercrystals. We derive analytical expressions for the energy spectra of twodimensional supercrystals with different Bravias lattices, and use them to analyze the possibility of engineering the supercrystals' band structure. We demonstrate that the variation of the supercrystal’s parameters (such as the symmetry of the periodic lattice and the properties of the quantum dots or their environment) enables an unprecedented control over its optical properties, thus paving a way towards the development of new nanophotonics materials.

PbS quantum dots (QDs) with diameter of 2.9-7.4 nm were embedded into a porous matrix. The samples prepared by developed low-cost effortless method demonstrate linear dependencies of optical density and luminescence intensity on the QDs concentration and perfect homogeneity. Optical properties of quantum dots in the matrix were studied using absorption and steady-state and time-resolved photoluminescence spectroscopy. Luminescence lifetimes were found to be size-dependent and increase with decreasing of QDs size. The aging behavior of PbS QDs in a porous matrix was explored for a variety of QDs sizes. The energy transfer process in quasi-monodispersed PbS QDs ensemble was discovered.

We propose a new type of optical spectroscopy of anisotropic semiconductor nanocrystals, which is based on the welldeveloped stationary pump-probe technique, where the pump and probe fields are absorbed upon, respectively, interband and intraband transitions of the nanocrystals’ electronic subsystem. We develop a general theory of intraband absorption based on the density matrix formalism. This theory can be applied to study degenerate eigenstates of electrons in semiconductor nanocrystals of different shapes and dimentions. We demonstrate that the angular dependence of intraband absorption by nonspherical nanocrystals enables investigating their shape and orientation, as well as the symmetry of quantum states excited by the probe field and selection rules of electronic transitions.

An experimental study of the temperature dependence of photoluminescence time decay in size-controlled silicon nanocrystals in silicon nanocrystal/SiO2 superlattices is reported. The samples were prepared using thermal evaporation and subsequent thermally induced phase separation. The slow (microseconds) decay line shape is described well by a stretched exponential. The temperature dependence of the photoluminescence dynamics can be understood in terms of thermal activation of recombination processes, including hopping of carriers between localized states. Additional hydrogen treatment causes an increase in both parameters of the stretched exponential function. This behavior is interpreted as a consequence of H2-passivation of dangling bonds defects.

Nonradiative fluorescence resonance energy transfer (FRET) between lead sulfide quantum dots (QDs) of two different sizes embedded in porous matrix is observed by a fluorescence spectroscopy. Analysis of decays of photoluminescence from QD mixture shows that energy transfer in studied systems is determined by static quenching, specific for direct contact between QD-donor and QD-acceptor in the QDs close-packed ensembles. From steady-state spectral analysis it was found that efficiency of energy transfer depends on the molar ratio QD-donor/QD-acceptor and energy transfer from the donor to the acceptor passes by several channels.

Luminescent nanocrystals of AgIn_S2-ZnS (ZAIS) and core-shell AgInS₂-ZnS@ZnS (ZAIS@ZnS) nanostructures were synthesized with different compositions of the core AgInS2-ZnS solid solution. With this method, luminophores displaying a broad emission spectrum and a maximum emission tunable between 555 nm and 825 nm could be obtained. Their optical absorption and luminescence properties were studied in order to understand the evolution of their optical band gap, their photoluminescence quantum yield (PLQY) and the amount of defects. Ageing tests of the colloidal solutions of these nanocrystals under blue light excitation were also performed. We show that the high PLQY of ZAIS nanocrystals is correlated to the amount of defects they contain which explains the effect of both the composition and the synthesis method on the PLQY. We also show that ZnS coated nanocrystals exhibit high photostability under blue light excitation compared to their non-coated counterparts. These results emphasize the potential of ZAIS nanocrystals as highly luminescent and stable luminophores for white-LED applications.

We develop a theory of time-resolved pump–probe optical spectroscopy of intraband absorption of a probe pulse inside an anisotropic semiconductor nanorod. The absorption is preceded by the absorption of the pump pulse resonant to an interband transition. It is assumed that the resonantly exited states of the nanorod are interrelated via the relaxation induced by their interaction with a bath. We reveal the conditions for which the absorption of the probe’s pulse is governed by a simple formula regardless of the pulse’s shape. This formula is useful for the analysis of the experimental data containing information on the relaxation parameters of the nanorod’s electronic subsystem.

We study the stimulated Raman emission of a high-Q polydimethylsiloxane (PDMS)-coated silica microsphere on a silicon chip. In this hybrid structure, as the thickness of the PDMS coating increases, the spatial distribution of the whispering gallery modes moves inside the PDMS layer, and the light emission switches from silica Raman lasing to PDMS Raman lasing. The Raman shift of the PDMS Raman laser is measured at 2900 cm^-1, corresponding to the strongest Raman fingerprint of bulk PDMS material. The threshold for this PDMS Raman lasing is demonstrated to be as low as 1.3 mW. This type of Raman emission from a surface-coated high-Q microcavity not only provides a route for extending lasing wavelengths, but also shows potential for detecting specific analytes.