This PDF file contains the front matter associated with SPIE Proceedings Volume 9919, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

A tunable cylindrical all dielectric optical nanoantenna has been proposed. A silicon nanocylinder of radius 60 nm and height 150 nm has been considered. The azimuthally symmetric, complete forward scattering at first Kerker’s condition and backward scattering with minimum forward scattering at second generalized Kerker’s condition in near infra-red region has been observed for the proposed design which makes silicon nanocylinder a promising candidate for optical nanoantenna applications. The effect of the dimensions of the dielectric nanocylinder on the scattering properties of the cylindrical nanoantenna has been analyzed using finite element method. We have analyzed that the variation in diameter of nanocylinder has great influence on the strength of interference of electric and magnetic dipolar resonances. Further, we have observed tuning ability of the cylindrical nanoantenna with respect to the variation in its radius.

Iron oxide is a unique semiconductor material, either as a single nanoparticle, or as a component of multifunctional nanoparticles. Its desirable properties, abundance, non-toxicity, and excellent magnetic properties make it a valuable for many applications. Porous iron oxide nanorods are able to transduce light into heat through the photothermal effect. Photothermal heating arises from the energy dissipated during light absorption leading to rapid temperature rise in close proximity to the surface of the nanoparticle. The heating effect can be efficiently harnessed to drive/promote different physical phenomena. In this report, we describe the synthesis and properties of porous Fe₃O₄ for photothermal applications. We then demonstrate their use as photothermally enhanced and recyclable materials for environmental remediation through sorption processes.

A special class of nano-layered hyperbolic metamaterials (HMMs) has received special attention recently due to their unique optical property, namely that the dispersion of the dielectric constant for HMMs exhibits a topological transition in the iso-frequency surface from an ellipsoid to a hyperboloid. Using aluminum in metal-dielectric nano-layered structures offers several advantages over currently used noble metals. The plasma frequency of the aluminum is higher than that of gold or silver. As a result, aluminum exhibits metallic characteristics over a broader spectral range than gold and silver. In addition, SiO₂ is used as the dielectric for this hyperbolic metamaterial because it could be easily integrated into current CMOS technology and has near-zero losses in the UV region. In this investigation, we use generalized spectroscopic ellipsometry to study the distribution of Al within nano-layered samples fabricated using the RF sputtering technique under varying fabrication parameters with a goal of achieving hyperbolic dispersion. In our work, we developed an approach to analyzing generalized spectroscopic ellipsometry data for anisotropic Al/SiO₂ structures with strong absorption, which uses the 4x4 transfer matrix approach, also known as the Berreman-formalism. This developed approach allows obtaining permittivity in all three dimensions and importing theoretical permittivity models which are tailored to the Al/SiO₂ material’s optical and electrical properties. In this work, we investigate the methods of reducing Al oxidation during fabrication by means of varying the fabrication temperatures and pressure by fitting data from RC2 Ellipsometer (A.C. Woollam Co.), which has dual rotating compensators. Applications for this Al/SiO2 hyperbolic metamaterial will also be discussed.

Novel InSb quantum dot (QD) nanostructures grown by molecular beam epitaxy (MBE) are investigated in order to improve the performance of light sources and detectors for the technologically important mid-infrared (2-5 μm) spectral range. Unlike the InAs/GaAs system which has a similar lattice mismatch, the growth of InSb/InAs QDs by MBE is a challenging task due to Sb segregation and surfactant effects. These problems can be overcome by using an Sb-As exchange growth technique to realize uniform, dense arrays (dot density ~10¹² cm^-2) of extremely small (mean diameter ~2.5 nm) InSb submonolayer QDs in InAs. Light emitting diodes (LEDs) containing ten layers of InSb QDs exhibit bright electroluminescence peaking at 3.8 μm at room temperature. These devices show superior temperature quenching compared with bulk and quantum well (QW) LEDs due to a reduction in Auger recombination. We also report the growth of InSb QDs in InAs/AlAsSb ‘W’ QWs grown on GaSb substrates which are designed to increase the electron-hole (e-h) wavefunction overlap to ~75%. These samples exhibit very good structural quality and photoluminescence peaking near 3.0 μm at low temperatures.

Dielectric-plasmonic composite media are interesting systems as far as light trapping is considered owing to their enhanced interaction with light. Core-shell particles are of particular interest due to their strong scattering and geometry-dependent plasmon resonances which are tunable from visible to IR region. Design of random media with such highly scattering particles increases the probability of light getting trapped inside the medium due to the enhanced multiple scattering. Here we investigate the light scattering scenario in ZnS-Au core-shell random medium experimentally and also provide theoretical basis using Finite Difference Time Domain (FDTD) simulations. Back scattering and transmission simulations are carried out at standard wavelengths 405, 445, 532 and 632 nm. Effect of geometry on light scattering is also investigated by varying the aspect ratios of the particles. Scattering and absorption efficiency is calculated for particles in this size range using Mie theory. Strength and tunability of plasmon resonances are explained in terms of plasmon hybridization model. Core shell particles with core radius 100 nm and shell thickness of 6 nm are found to be optimal for light trapping over the entire visible region. Dielectric-plasmonic random media consisting of ZnS-Au core shell particles with optimized aspect ratio appear to be efficient candidate materials for light harvesting, sensing and optoelectronics.

In this experiment, the molybdate phosphors were manufactured by using the solid state amorphization with europium, yttrium and molybdenum. To investigate Eu_xY_y(MoO₄)₃ phosphor characteristics, the europium and yttrium were blended to different of mole ratio. The europium composition can improve phosphors luminous intensity. Phosphors characteristics was measured by X-ray diffraction, SEM and photoluminescence. The X-ray diffraction and SEM displayed phosphors crystal structure. The photoluminescence of molybdate phosphors show that the best excitation spectra emitting position was at 614nm. The molybdate phosphors was excited by UV laser. Therefore, this molybdate phosphors was suitable for UV-LED.

Monolithic passively mode-locked lasers are investigated based on chirped multilayer InAs/InGaAs QDs. Three chirped wavelengths, with stacking numbers of 2, 3 and 5 layers, are designed with capped InGaAs thickness of 4, 3 and 1 nm, respectively. The ridge-waveguide devices of 5-μm width and 3-mm length are fabricated to have absorber-to-gain length ratio of 1:9. A curve tracer is used to analyze the hysteresis on the light-current curve. Two kinks in the L-I curve are observed at threshold current near 50 mA and at higher current of about 150 mA. The lasing wavelength just above threshold is centered at 1268 nm and the RF spectrum of mode-locking is peaked at 13.32 GHz. At well above threshold of 200 mA, another RF peak at 13.21 GHz occurs that corresponds to shorter lasing wavelength around 1233 nm. The two lasing wavelengths are originated from ground-state transitions of two groups of InAs/InGaAs QDs. Simultaneous dual-wavelength mode-locking is therefore achieved at rather low forward current and low reverse bias by incorporating this novel design of QD structure.

The fabrication and optimization of plasmonic nanostructures have many interesting and important applications including advancements in surface-enhanced Raman spectroscopy (SERS). One popular and cost-effective method to fabricate plasmonic nanopatterns is by a colloid template. By combining close-packed colloid monolayer and dynamic shadowing growth, we demonstrate that a variety of nanopatterns, such as nano-triangles, nano-cup triangles, hexagonal holes, and dual triangles, can be fabricated by varying vapor deposition angle, the substrate azimuthal rotation, as well as the evaporation configuration. Especially when a two-source evaporator is used, dual triangles with different shapes and compositions are simultaneously formed. The formation of these nanopatterns can be predicted by numerical and Monte Carlo simulations. In addition, the visible localized surface plasmon resonance (LSPR) of these patterns can be tuned systematically by changing the deposition conditions and the colloidal monolayer. Their plasmonic properties can be understood through finite-difference time-domain simulations. The tunability of LSPR can be used to design optimized substrate for SERS.

This work presents the low temperature plasma-enhanced atomic layer deposition (PE-ALD) of TiN, a promising plasmonic synthetic metal. The plasmonics community has immediate needs for alternatives to traditional plasmonic materials (e.g. Ag and Au), which lack chemical, thermal, and mechanical stability. Plasmonic alloys and synthetic metals have significantly improved stability, but their growth can require high-temperatures (>400 °C), and it is difficult to control the thickness and directionality of the resulting film, especially on technologically important substrates. Such issues prevent the application of alternative plasmonic materials for both fundamental studies and large-scale industrial applications. Alternatively, PE-ALD allows for conformal deposition on a variety of substrates with consistent material properties. This conformal coating will allow the creation of exotic three-dimensional structures, and low-temperature deposition techniques will provide unrestricted usage across a variety of platforms. The characterization of this new plasmonic material was performed with in-situ spectroscopic ellipsometry as well as Auger electron spectroscopy for analysis of TiN film sensitivity to oxide cross-contamination. Plasmonic TiN films were fabricated, and a chlorine plasma etch was found to pattern two dimensional gratings as a test structure. Optical measurements of 900 nm period gratings showed reasonable agreement with theoretical modeling of the fabricated structures, indicating that ellipsometry models of the TiN were indeed accurate.

Metallic nanostructures can be utilized as heat nano-sources which can find application in different areas such as photocatalysis, nanochemistry or sensor devices. Here we show how the optical response of plasmonic structures is affected by the increase of temperature. In particular we apply a temperature dependent dielectric function model to different nanoparticles finding that the optical responses are strongly dependent on shape and aspect-ratio. The idea is that when metallic structures interact with an electromagnetic field they heat up due to Joule effect. The corresponding temperature increase modifies the optical response of the particle and thus the heating process. The key finding is that, depending on the structures geometry, absorption efficiency can either increase or decrease with temperature. Since absorption relates to thermal energy dissipation and thus to temperature increase, the mechanism leads to positive or negative loops. Consequently, not only an error would be made by neglecting temperature but it would be not even possible to know, a priori, if the error is towards higher or lower values.

In this work, we introduce a novel concept of hybrid nano-imprint mold based on a soft substrate with rigid relief features. Our approach combines the advantages of soft and rigid molding approaches, and at the same time overcomes their drawbacks. Specifically, this mold provides a unique combination of: (1) High pattern fidelity and small feature size as offered by hard molds and (2) low sensitivity to defects and ability to pattern curved substrates as offered by soft molds. The SSRF mold was fabricated by electron-beam lithography of Hydrogen Silsesquioxane (HSQ) on a sacrificial substrate, followed by transferring the obtained HSQ features to elastomeric PDMS substrate. The pattern replication was demonstrated on nano imprint of UV-curable resist.

Characterization of thin films doped with organic metal materials onto a silica substrate is presented. Films were prepared through sol-gel process, by using macrocycles with Cu as dopant by means of hydrolysis and acid catalyzed reaction of tetraethylorthosilicate. Z-scan technique was used to measure nonlinear optical properties, nonlinear absorption and refraction indexes.

In this paper, electric and magnetic resonances induced in the ellipsoidal dielectric nanoparticles in the optical range have been analyzed. Circular displacement currents excited inside the elliptical nano-particles by the incident light result in magnetic dipolar resonance in the dielectric nanoparticles. Kerker’s type scattering is observed due to the mutual interference of electric and magnetic resonances. The effect on the resonance conditions with the variation in the relative permittivity from E_r= 5 to E_r= 20 of the ellipsoidal nanoparticle has been observed. It has been analyzed that peaks of electric and magnetic resonances come closer by decreasing the electric permittivity of the nanoparticle, which leads to the increase in the directionality in the forward direction, as verified using Generalized Kerker’s condition. Further, far field scattering patterns have been obtained using the finite element method. Here, the electric and magnetic resonances have been optically induced up to quadrupolar modes. There is enhancement of the directionality in the forward direction when electric and magnetic resonances are in phase. Further, the effect of size of the linear array of ellipsoidal nanoparticles on the directionality has been analyzed. It has been observed that there is increase in the directivity by increasing the chain of the nanoparticles. Thus, the ellipsoidal nanoparticles can lead to the design of low loss and highly directional optical nanoantennas.

The potential for nanoengineering hybrid PVA hydrogel and hydrogel microsphere optical coatings is demonstrated with fine-tuning by the addition of (i) PNIPAm domains, (ii) water-hunting humectant CaCl₂, and (ii) polystyrene or SiO₂ colloidal crystals. The design and application onto substrates of the hydrogel scaffold is described. The addition of a temperature-triggered component as well as humectant and NIR reflectors are reported. The hybrid hydrogels appeared effective in sustainable adsorption cooling technology (ACT) over sustained periods. It is shown that the thermoresponsive (PNIPAm) domains act as an extra reserve, sweating water above 305K, prolonging the controlled release of water. It is also reported that the addition of humectant is crucial for the natural re-hydration of the hydrogels. For the moment PNIPAm microspheres have only short- lived ACT properties. Finally, coating with microspheres (MSs) in hydrogels produces a visible-NIR reflector effect that may allow optical feedback on ACT.

Polymer films containing plasmonic nanostructures are of increasing interest for development of responsive energy, sensing, and therapeutic systems. A series of novel gold nanoparticle (AuNP)-polydimethylsiloxane (PDMS) films were fabricated to elucidate enhanced optical extinction from diffractive and scattering induced internal reflection. AuNPs with dramatically different scattering-to-absorption ratios were compared at variable interparticle separations to differentiate light trapping from optical diffraction and Mie scattering. Description of interfacial optical and thermal effects due to these interrelated contributions has progressed beyond Mie theory, Beer’s law, effective media, and conventional heat transfer descriptions. Thermal dissipation rates in AuNP-PDMS with this interfacial optical reflection was enhanced relative to films containing heterogeneous AuNPs and a developed thermal dissipation description. This heuristic, which accounts for contributions of both internal and external thermal dissipations, has been shown to accurately predict thermal dissipation rates from AuNP-containing insulating and conductive substrates in both two and three-dimensional systems. Enhanced thermal response rates could enable design and adaptive control of thermoplasmonic materials for a variety of implementations.

Improved fundamental understanding of resonant optical and electric interactions between noble metal nanoparticles and 2D materials, such as semiconductive molybdenum disulfide (MoS₂), could benefit characterization of optoelectronic light harvesting schemes. Energy and damping of plasmon resonances of noble metal nanoparticle-decorated MoS₂ were examined via parallel synthesis of (a) approximate discrete dipole (DDA) simulations and (b) near-field electron energy loss (EELS) and far-field optical transmission spectroscopies. Energy of localized surface plasmon resonance altered by MoS₂ interactions was studied for gold nanospheres and silver nanoprisms. Augmented plasmon damping by injection of plasmon-excited electrons into the MoS₂ was measured in EELS and represented by DDA. These techniques support rapid improvements in nanoparticle-2D material prototypes for photocatalysis and photodetection, for example.

Silver (Ag) nanoparticles (NPs) have unique optical, electrical, and thermal properties that are being incorporated into products ranging from optical communication devices and photovoltaics to biological, DNA and other chemical sensors. The optical properties of silver nanoparticles are strongly influenced by their shape, size, distribution, and surrounding environment. One of the main challenges is to maximize the coupling efficiency of incident radiation into plasmonic resonances. In this paper, we present a method to optimize the selection of mono-dispersed Ag NPs size and the wavelength of incident radiation to enhance coupling efficiency. The results are supported by experimental measurements of optical properties of mono-dispersed silver nanoparticles.

Control of structural heterogeneity by rationally encoding of the molecular assemblies is a key enabling design of hierarchical, multifunctional materials of the future. Here we report the strategies to gain such control using solution- based assembly to construct a hybrid nano-assembly and a network hybrid structure of regioregular poly(3- alkylthiophene) - carbon nanotube (P3AT-CNT). The opto-electronic performance of conjugated polymer (P3AT) is defined by the structure of the aggregate in solution and in the solid film. Control of P3AT aggregation would allow formation of broad range of morphologies with very distinct electro-optical. We utilize interactive templating to confine the assembly behavior of conjugated polymers, replacing poorly controlled solution processing approach. Perfect crystalline surface of the single-walled and multi-walled carbon nanotube (SWCNT/MWCNT) acts as a template, seeding P3AT aggregation of the surface of the nanotube. The seed continues directional growth through pi-pi stacking leading to the formation of to well-defined P3AT-CNT morphologies, including comb-like nano-assemblies, super- structures and gel networks. Interconnected, highly-branched network structure of P3AT-CNT hybrids is of particular interest to enable efficient, long-range, balanced charge carrier transport. The structure and opto-electionic function of the intermediate assemblies and networks of P3AT/CNT hybrids are characterized by transmission election microscopy and UV-vis absorption.

We report here self-assembled 2.6 ML InAs QDs capped with GaAsN0.021 on GaAs (001) substrate grown under high arsenic overpressure and high power by solid source molecular beam epitaxy. With variation in GaAsN_0.021 layer thickness, InAs/GaAs QDs were studied by photoluminescence (PL) spectroscopy. It was found that with InAs dot density of 3 ×10¹⁰ cm^-2 and 4 nm GaAsN capping layer, emission wavelength was possible to extend beyond 1.5 μm at 300K. Rapid thermal annealing was carried out in nitrogen ambient for 30 sec at temperatures ranging from 700°C to 800°C and a continuous blue-shift for the nitride-capped QDs was observed at 19 K PL spectra, and the sample annealed at 800°C exhibited highest intensity with narrowest full width at half maximum (FWHM). Both the as-grown and annealed samples exhibited asymmetric PL behavior in low energy region at low temperature, associated to the N-related states or cluster of N atoms. The peak emission wavelength at the annealing temperature domain of 750-800°C was remained constant, attributed to no In/Ga diffusion at the interface between the dot and the barrier. Hence, the InAs/GaAs dots capped with 4-nm GaAsN_0.021 layer could be implemented in lasers in the temporal range of 750-800°C.