This PDF file contains the front matter associated with SPIE Proceedings Volume 8463 including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

Interaction between surface plasmons at two interfaces inside a meta-insulator-metal (MIM) structure is one of the interesting physical phenomena in nanophotonics. We have started to create a plasmonic active spectral filter based on the MIM structure for a developing white light-emitting diode (LED) visible-light communication. An optical active filter at visible region assisted by surface plasmon resonance (SPR) in MIM structure of vacuum-deposited thin films on glass substrate has been studied both experimentally and theoretically. Interface between the first thin silver layer (M1, around 50 nm-thick) and bulk glass slide is appropriate for excitation of SPR at particular wavelength and incident angle of illumination light. And spatial extension of the SPR wave may cause an effective propagating mode confined in the insulator layer (I, around 150 nm-thick) by both M1 and the second thick silver layer (M2, around 200 nm-thick). Such an energy conversion from the illuminating light to the propagating SPR modes corresponds to an evident absorption dip on spectral reflectance curve of the MIM structure, and the shape of dip may vary widely in response to material and configuration of the MIM. The spectral and angular reflectance of the prototypical MIM structure has been measured by spectrophotometer for P- and S-polarized light because the plasmonic effect inside the MIM structure depends strongly on the polarization of light. Such the characteristic reflection feature has also been studied by using both the usual transfer matrix method and 2D electromagnetic simulation based on the finite element method. In this talk, several striking and preliminary MIM prototypes will be introduced and discussed.

The efficient coupling of light from a tapered fiber coupled microsphere resonator to localized surface plasmon modes of Au-coated tip was demonstrated. To verify efficient localized surface plasmon excitation at the metal tip via a tapered fiber coupled microsphere resonator, we measured second harmonic generation from the top of Au-coated tip. From the results, in spite of a weak CW excitation, we succeeded in repeatedly observing SHG from the top of the Au-coated tip via a tapered fiber coupled microsphere resonator system, which could focus the light with the coupling efficiency of about 63.2 % into the nanoscale domain of the metal tip with the effective cross section of 358.2 nm².

Water droplets were either pushed or pulled with an UV light on the surface of vertically aligned and superhydrophobic ZnO nanorods (NRs). The contact angle of the droplets reduce to a lower value due to the absorption of UV by ZnO NRs and a circulating current was observed inside the droplet. The droplets were either pushed away from or pulled toward to the center of the UV light depending on the locations of the droplets to the UV light. It is obvious that in the pushing mode, the circulating current dominate the direction of the movement of the droplets, while in the pulling mode, the contact angle change dominate the direction of the droplet movement

We develop a method to detect surface plasmon polaritons (SPP) launched by a sub-wavelength slit structure using optical microscopy. The mechanism relies on an ultra-thin layer of polymer, whose thickness is varied with nano-scale precision to enable matching between the momentum of incident light and that of SPPs on the metal surface adjacent to the slit exit. At an optimal layer thickness, the SPP coupling efficiency is enhanced about six times relative to that without the layer. The enhanced efficiency results in distinctive and bright signatures visible under a far-field optical microscope. We show how this method can be used for parallel measurement of SPPs through a simple experiment in which the SPP propagation distance is extracted from a single microscope image. We also use optical microscopy to image SPPs focussed by a curved array of holes, obtaining results that are consistent with previous measurements using near-field optical microscopy.

Modern advanced energy systems such as coal-fired power plants, gasifiers, or similar infrastructure present some of the most challenging harsh environments for sensors. The power industry would benefit from new, ultra-high temperature devices capable of surviving in hot and corrosive environments for embedded sensing at the highest value locations. For these applications, we are currently exploring optical fiber evanescent wave absorption spectroscopy (EWAS) based sensors consisting of high temperature core materials integrated with novel high temperature gas sensitive cladding materials. Mathematical simulations can be used to assist in sensor development efforts, and we describe a simulation code that assumes a single thick cladding layer with gas sensitive optical constants. Recent work has demonstrated that Au nanoparticle-incorporated metal oxides show a potentially useful response for high temperature optical gas sensing applications through the sensitivity of the localized surface plasmon resonance absorption peak to ambient atmospheric conditions. Hence, the simulation code has been applied to understand how such a response can be exploited in an optical fiber based EWAS sensor configuration. We demonstrate that interrogation can be used to optimize the sensing response in such materials.

Erbium oxide is a promising candidate for possible applications as Si-based light emitting devices in nanoscale electronics. The current report presents findings pertaining to the effects of the structural properties of erbium-based thin films on their photoluminescence characteristics. Erbium metal films were deposited on silicon via electron beam evaporation followed by thermal oxidation. The effects of post-deposition annealing conditions on the structural and optical properties of the thin films were examined using a variety of techniques, such as spectroscopic ellipsometry, xray diffraction, and x-ray photoelectron spectroscopy. It was shown that the thin films evolved as function of thermal treatment from an Er-rich to an ErO-rich (700°C) to an Er₂O₃-rich (900°C) phase due to an increase in oxygen incorporation with higher oxidation temperatures. At temperatures ≥ 1000°C, out-diffusion of silicon from the substrate led to the formation of erbium monosilicate. Furthermore, the photoluminescence spectra of these various phases were measured, and the correlation between structural properties and luminescence characteristics will be discussed in this paper.

Light-field cameras capture the intensity, position, and angular information of light from a scene, enabling after-the-fact focusing and 3D rendering from a single exposure. The sensitivity, pixel density, and directional resolution of light-field sensors could be increased by taking advantage of the unique photonic effects present in nanoscale and microscale structures. We demonstrate that semiconductor nanoshell whispering gallery resonators are a versatile platform for dense, ultra-thin photosite arrays. We show experimentally that an array of nanocrystalline silicon shells only 50 nm thick is as absorptive as a micron-thick planar film. We further show that we can tune the separation and size of the nanoshells by etching the underlying nanosphere template and that we can readily transfer the array onto a flexible substrate. Next, we describe the phenomenon of photonic nanojets emanating from small dielectric microlenses and microlens arrays. We devise a sensor architecture that uses the super-resolution foci formed by these nanojets to separate light into different nanoshell photosites depending on the angle of incidence. The proximity of the microlenses to the photosites corresponds to a small effective f-number, which enables main camera optics with very large apertures for light collection. In optical simulations, we demonstrate directional resolution in the integrated light-field sensor at acceptance angles of up to 35 degrees from normal incidence.

Thanks to the localized surface plasmon resonance of silver nanoparticles, mesoporous titania films loaded with silver salts manifest a photochromic behavior that can be used to perform updatable laser microinscriptions. Under UV illumination, the silver salts are reduced into silver nanoparticles and the illuminated areas become grey-brown. This coloration can be completely erased by oxidizing the silver nanoparticles with a polychromatic or monochromatic visible light whose spectrum lies in the resonance band of silver nanoparticles. The paper investigates the usage of such photochromic Ag/TiO₂ films for creating an updatable random texturing. Random textures are produced on coated glass samples, initially homogeneous, by exposing them to speckle patterns resulting from the scattering of a UV laser beam from an optically rough surface. The stability of such textures under homogeneous UV post-exposures is investigated as a function of the speckle exposure time. Under optimized exposure conditions, the textures remain stable enough for a long time and the differences between textures are sufficiently discriminative to use the texturing process for goods authentication. This is demonstrated by calculating the correlation coefficient of thousands of couples of texture images. The numerical treatment of images has the advantage to be robust to changes in the sample repositioning between different image records. The rewritability of the samples is characterized through the comparison of different textures successively erased and written at the same place on multiple samples.

Two series of Mg_xZn_1-xO/ZnO multiple quantum wells with 18 at.% and 27 at.% of magnesium content in barrier layers and well width L_w from 1 nm to 20 have been grown by pulsed laser deposition method. The stimulated emission is observed in photoluminescence spectra excited by pulsed laser (λ_exc=248 nm). The pump density threshold of stimulated emission nonmonotonously depends on the well width that is associated with an increase of the internal quantum efficiency of two-dimensional structures caused by a reduction of radiative lifetime of excitons at decreasing of the well width as it has been shown by the time-resolved photoluminescence spectra analysis. The minimum value of a lifetime τ_r=355 ps was obtained for the Mg_0.27Zn_0.73O/ZnO MQW with the well width L_w=2.6 nm.

We investigate a femtosecond pulse propagation in the medium, containing nanorods, with taking into account the dependence of TPA from the aspect ratio of nanorods. The influence of detuning between the central frequency of the absorption spectrum and the central frequency of spectrum of the laser pulse is considered as well as the dependence of the absorption spectrum on the aspect ratio of nanorods. We consider two important cases: formation of pure absorptive grating and formation of both absorptive and refractive gratings due to detuning of central frequency of wave packet from central frequency of absorption spectrum. Under the weak absorption we found out the acceleration of light or slowing of light (fast light or slow light) in comparison with light propagation in the linear medium. Using spatial-temporal analogy, one can see that this phenomenon is similar to the displacement of the laser beam centre in moving medium under thermal response or under thermal response and evaporation of clouds and fogs. The direction of the motion is perpendicular to the direction of incident laser beam. We found out also the soliton formation under neglecting of the nonlinear absorption: a depletion of laser energy is close to zero.

Temperature dependence is a key parameter in designing quantum well lasers. In this work, we calculated the effects of temperature on the energy levels and emitted wavelength for PbSe/PbSrSe Single Quantum Well Laser at four different temperatures: 77K, 150K, 200K, 250K, and 300K. This material system is currently being used in Tunable Laser Spectroscopy which plays a key role in detecting biomarker molecules in exhaled breath at wavelengths in the infrared region. We determined the system design parameters to obtain the desired emitted wavelengths associated with certain disease biomarkers as a function of temperature. Our calculated emitted wave lengths are in excellent agreement with experimental data assuming parabolic and nonparabolic energy band structures. Moreover, we calculated the effects of temperature on the confinement factor, gain and current density. The modal gain versus current density curved showed that the nominal current density and the saturation level increases with temperature similar to other material systems.

The dichalcogenide MoS₂, which is an indirect-gap semiconductor in its bulk form, was recently shown to become an efficient emitter of photoluminescence as it is thinned to a single layer, indicating a transition to a direct-gap semiconductor due to confinement effects. With its layered structure of weakly coupled, covalently bonded twodimensional sheets, it can be prepared, just as graphene, using mechanical exfoliation techniques. With these techniques, few- and single-layer flakes can be prepared. Raman spectroscopy is a sensitive tool to determine the number of layers of a flake, as two characteristic Raman modes in MoS₂ shift to higher or lower frequency with the number of layers. In addition to previously reported Raman modes in MoS₂, we observe an interlayer shear mode at very low frequencies, which also shifts with the number of layers. We use scanning Raman spectroscopy to map and characterize MoS₂ flakes.

The development of oxygen sensors has positively impacted the fields of medical science, bioengineering, environmental monitoring, solar cells, industrial process control, and a number of military applications. Fluorescent quenching sensors have an inherent high sensitivity, chemical selectivity, and stability when compared to other types of sensors. While cerium oxide thin films have been used to monitor oxygen in the gas phase, the potential of cerium oxide (ceria) nanoparticles as the active material in sensor for oxygen gas has only recently been investigated. Ceria nanoparticles are one of the most unique nanomaterials that are being studied today due to the diffusion and reactivity of its oxygen vacancies, which contributes to its high oxygen storage capability. The reactivity of the oxygen vacancies, which is also related to conversion of cerium ion from the Ce⁺⁴ to Ce⁺³ state, affects the fluorescence properties of the ceria nanoparticles. Our research demonstrates that the ceria nanoparticles (~7 nm in diameter) have application as a fluorescence quenching sensor to measure dissolved oxygen in water. We have found a strong inverse correlation between the amplitude of the fluorescence emission (λ_excitation = 430 nm and λ_peak = 520 nm) and the dissolved oxygen concentration between 5 – 13 mg/L. The Stern-Volmer constant, which is an indication of the sensitivity of gas sensing is 184 M^-1 for the ceria nanoparticles. The results show that ceria nanoparticles can be used in an improved, robust fluorescence sensor for dissolved oxygen in a liquid medium.

We report on a technique for precise hole drilling in optical fibers using tightly focused femtosecond laser pulses. This direct laser writing approach makes it possible to minimize the amount of waveguide material for uncompromised mechanical performance of the fiber. The proof-of-the-principle of the fiber integration into a microfluidic chip is demonstrated. We show that fabricated holes in the waveguides can be used for measurement of absorption coefficient and refractive index changes at 1x10^-3 refractive index units and 2 cm^-1 for refractive index and absorption changes, respectively. Simple design and integration possibility of laser-fabricated waveguide sensors is prospective for optofluidic applications.

Selectively patterned periodic metal nanodots are prospective for use in photonic, plasmonic and magnetic storage devices. Here, we proposed a simple method to fabricate metal nanodots by block copolymer self-assembly and electron beam lithography. Block copolymer self-assembly is a facile method to fabricate periodic nanostructures such as cylinder and sphere in a large area. These self-assembled nanostructures are useful as templates and scaffolds for the fabrication of periodic metal nanodots. In this study, we used polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) and fabricated perpendicular PMMA cylinders onto substrate in PS matrixes. After UV irradiation and immersion in acetic acid, cylindrical nanopores of PS were fabricated. We performed electron beam lithography onto these PS nanoporous thin films. PS is negative tone resist for electron beam lithography. If the electron dose was enough large for PS resist, nanoporous structures were fabricated only in exposed areas after development by solvent, which dissolves PS. We evaporated Au onto these patterned nanoporous templates and sonicated these metal evaporated films in tetrahydrofuran (THF). In consequence, metal nanodots were fabricated only in exposed areas. The diameter and pitch of these nanodots were approximately 20 nm and 40 nm, respectively. These values were almost equal to block copolymer self-assembled cylinder structures. Finally, we demonstrated a simple method for fabricating periodic metal nanodots only in selective areas.

The use of optical excitation in MEMS elements triggers several mechanisms that can be properly used for enhancing its mechanical response. This is particularly interesting when MEMS components are used as the transducer element on energy harvesting applications involving opto-mechanical conversion schemes. One of the pathways is based on the thermal response of the vibrating structures. In this contribution we have analyzed how a MEMS structure consisting on a clamped-clamped beam responds mechanically to the heating of the element. This heating is produced by the partial absorption of an incident radiation at the IR band. A thin metal layer evaporated on top of the suspended beam acts as the infrared light absorber. The gap forms an optical interferometer which couples the light absorption to the mechanical deflection of the CC-beam. This effect can be enhanced by a proper design of the whole mechanical geometry. Both, the optical absorbance and the energy conversion to the thermal domain of the MOEMS device are analyzed. Additionally, the transduction to the mechanical domain in the form of beam vibrations of the optical energy absorbed by the structure and transformed into heat is also modeled. This paper focus on the analytical model that is necessary to understand the involved physical mechanisms and the results obtained from the simulation of the device.

In this contribution we show that the fundamental diffraction limit of optical cavities can be overcome using a transformation-optical approach. Transformation optics has recently provided a new method for the design of devices to control electromagnetic fields, based on the analogy between the macroscopic Maxwell's equations in complex dielectrics and the free-space Maxwell's equations in a curved coordinate system. It offers an elegant approach to exploit the full potential of metamaterials. We show how transformation optics can be used to achieve the opposite e ect of an invisibility cloak; instead of prohibiting the electromagnetic waves from entering a predefi ned region, we encapsulate the light waves within such a finite region. This allows us to design cavities with extraordinary properties. We have been able to demonstrate theoretically the existence of eigenmodes whose wavelength is much larger than the characteristic dimensions of the device. Furthermore, our cavities avoid the bending losses observed in traditional microcavities, so the quality factor is only limited by the intrinsic absorption of the materials. Finally, we also demonstrate how the combination of radial and angular transformations allows developing cavities without bending losses using right-handed material parameters only.^{1, 2}

The cis-trans isomerization of azobenzene upon S₁(n,π*) excitation is studied both in gas phase and in solution. Our study is based on ab initio non-adiabatic dynamics simulations with the non-adiabatic effects included via the fewest-switches surface hopping method with potential-energy surfaces and couplings determined on the fly. The non-adiabatic couplings have been computed based on overlaps of CASSCF wave functions. The solvent is described using classical molecular dynamics employing the quantum mechanics/molecular mechanics (QM/MM) approach. Azobenzene photoisomerization upon S₁(n,π*) excitation occurs purely as a rotational motion of the central CNNC moiety. Two non-equivalent rotational pathways, corresponding to clockwise or counterclockwise rotation, are available. The course of the rotational motion is strongly dependent on the initial conditions. The internal conversion occurs via a S₀/S₁ crossing seam located near the midpoint of both of these rotational pathways. Based on statistical analysis it is shown that the occurrence of one or other pathways can be completely controlled by selecting adequate initial conditions.

The effect of the solvent on the reaction mechanism is small. The lifetime of the S₁ state is marginally lowered; the effect does not depend on the polarity, but rather on the viscosity of the solvent. The quantum yield is solvent dependent; the simulations in water give smaller quantum yield than those obtained in n-hexane and in gas phase.

A sandwich structure including subwavelength grating and low-index thin film as a broadband polarizing beam splitter (BPBS) is demonstrated. The BPBS is studied by using the rigorous coupled-wave analysis (RCWA) numerical scheme. The low-index thin-film with optimum thickness forms between the silicon substrate and the subwavelength grating. While the thickness of low-index thin film is larger than 0.6 m, the reflectivity of TE wave is larger than 0.95 in the wavelength region [1.29 m, 1.66 m] under the normal incidence. In this region, the reflectivity of TM wave is low. Meanwhile, it is also found that while the thickness of low-index thin film rise to 0.9 m, the extinction ratio of TM polarization is less than 0.047 in the wavelength region [1.35 m, 1.48 m]. Therefore, the designed sandwich structure consisted of subwavelength grating, low-index thin film and silicon substrate can be used as broadband polarizing beam splitter.

This paper reports a study of stochastic resonance in a huge quantum dot network for single-electron (SE) circuits. Such circuits, which are controlled by the Coulomb blockade, are one type of next-generation information-processing device. However, they are very sensitive to noises such as thermal noise and device mismatch noise. Thus, we introduce the stochastic resonance phenomenon into the circuit to improve its noise tolerance. Stochastic resonance is a phenomenon that was discovered in the brains of living things in noisy environments and was modeled for neural networks. When the phenomenon occurs, its harnessing of noise energy makes weak signals become clear. In current research, SE devices that operate with stochastic resonance have been reported. However, signals were attenuated in particularly noisy environments. In contrast, it was reported that a huge molecular network amplified weak signals by harnessing noise energy. The report said the current-voltage characteristics of the molecular network described the Coulomb blockade under a noisy environment. Thus, a huge quantum dot network that is partly similar to a molecular network is expected to amplify the weak signal harnessing noise, when the current-voltage characteristics of the network show the Coulomb blockade. To confirm this, in this study we use the Monte Carlo method to simulate the noisy-environment operation of a quantum dot network comprising quantum dots and tunneling junctions. We observe the current-voltage characteristics of the network, when changing the network size (5×5, 10×10, and 100×100) and the noise intensity (0 K, 2 K, 5 K, and 10 K for operating temperature, and 0%, 5%, 10%, and 30% for device mismatch). As a result, we are able to observe the Coulomb blockade under the appropriate noise strength, which in this study is 5 K or less with thermal noise, and 30% with device mismatch. From the results, we conclude the network operates correctly under appropriate noise strength. Moreover, the noise energy amplifies the network current, indicating that SE circuits can function as signal-amplifying devices.

This paper reports the study of a two-dimensional device-error-redundant single-electron (SE) circuit. The circuit is an SE reaction-diffusion (RD) circuit that imitates the unique behavior of the chemical RD system and is expected to be a new information processing system. The original RD system is a complex chemical system that is said to express selforganizing dynamics in nature. It can also be assumed to operate as parallel information processing systems. Therefore, by imitating the original RD system for SE circuits, this SE-RD circuit can perform parallel information processing that is based on a natural phenomenon. However, the circuit is very sensitive to noise because it is controlled by a very small amount of energy. It is also sensitive to device errors (e.g., circuit parameter fluctuations in the fabrication process). Generally, fluctuations caused by errors introduced in manufacturing the circuit components trigger incorrect circuit operations, including noises. To overcome such noises, the circuit requires redundant properties for noise. To address this issue, we consider mimicking the information processing method of the natural world for the circuit to obtain noise redundancy. Actually, we previously proposed a unique method based on a model of neural networks with a stochastic resonance (SR) for the circuit. The SR phenomenon, which was discovered in studies of living things (e.g., insects), can be considered a type of noise-energy-harnessing system. Many researchers have proposed SR-based applications for novel electronic devices or systems. In networks where SR exists, signals can generally be distinguished from noise by harnessing noise energy. We previously designed SE-SR systems and succeeded in making an architecture for an SE circuit that has thermal noise redundancy. At the time, we applied an SR model proposed by Collins to our circuit. Prior to our current study, however, it had not yet been confirmed whether SE circuits have device-error redundancy. In this study, we attempt to confirm this by using Monte Carlo simulation to study the characteristics of the abovementioned SE-RD circuit. Simulation results indicate that the SE-RD circuit, which is based on an SR model, has not only deviceerror redundancy but also thermal noise redundancy. The circuit is therefore expected to prove that the parameter matching step in the circuit fabrication process can be omitted.