Total Internal Reflection

The ''nano-particle image velocimetry'' technique uses evanescent-wave illumination generated by total internal reflection at the wall to excite colloidal neutrally buoyant fluorescent tracer particles. The displacement of these particles over time as they are convected by the flow then gives the flow velocity components tangential to the wall. Since the extent of the illumination region normal to the wall is comparable to the particle diameter, a major source of error in this technique is particle ''mismatch'' within a pair of images due to Brownian diffusion causing a particle to move in to or out of the illuminated region. The ''brightness'' (proportional to the amount of imaged fluorescence) and size of individual particle images in nPIV data are discussed. A sequence of artificial nPIV images are generated for a known uniform velocity field with the particles subject to hindered Brownian diffusion. The velocity fields calculated from these artificial images are compared with the known velocity field to determine the effect of Brownian diffusion-induced particle mismatch on nPIV accuracy. A similar analysis is carried out for experimental nPIV images. The results provide design guidance for experimental measurements using the nPIV technique.

An infrared spectrum of the boundary water near a solid/water interface has been observed, which is distinguished from the bulk water using a novel analytical technique. The technique employs the variableangle polarization specific (VAPS) attenuated total reflection (ATR) infrared spectrometry and a characteristic of principal component analysis (PCA). To date, near-field optical techniques or artificial polycrystalline water thin-layer formation technique have been used to study the structure of boundary-water molecules below the limitations of spatial resolution. Here, however, we show that the combination technique of VAPS-ATR and PCA analytically overcomes the difficulty of spatial resolution and detection limit, so that we selectively observe the boundary water. The orientation of the boundary-water molecules has been evaluated using the resolved infrared spectra obtained as the PCA loadings. In addition, it was also suggested that there was an intermediate layer between the boundary water layer and bulk water.

A novel plasmonic nanoledge device was presented to explore the geometry-induced trapping of nanoscale biomolecules and examine a generation of surface plasmon resonance (SPR) for plasmonic sensing. To design an optimal plasmonic device, a semianalytical model was implemented for a quantitative analysis of SPR under plane-wave illumination and a finitedifference time-domain (FDTD) simulation was used to study the optical transmission and refractive index (RI) sensitivity. In addition, total internal reflection fluorescence (TIRF) imaging was used to visualize the migration of fluorescently labeled bovine serum albumin (BSA) into the nanoslits; and fluorescence correlation spectroscopy (FCS) was further used to investigate the diffusion of BSA in the nanoslits. Transmission SPR measurements of free prostate specific antigen (f-PSA), which is similar in size to BSA, were performed to validate the trapping of the molecules via specific binding reactions in the nanoledge cavities. The present study may facilitate further development of single nanomolecule detection and new nanomicrofluidic arrays for effective detection of multiple biomarkers in clinical biofluids.

The article discusses fiber-optic sensors (FOS) based on the Bragg gratings for measuring systems for diagnostics of stressstrain state. Currently, such diagnostic systems are widely used in construction, industry and civil engineering. The physical principle of deformation diagnostics using FOS. The issues of mounting the sensor on the measured area (detail) are separately discussed. The principle of processing the hardware and software of sensors based on Bragg gratings is described. Research method-bench experiments that were carried out on an equal-deformation beam in order to evaluate the change in the width of the reflected FOS peak at different lengths recorded by the Bragg gratings in order to determine the optimal one. The change in the spectrum of the reflected peak under various deforming influences was monitored. Based on the results obtained, recommendations are made on the use of gratings of various lengths in the diagnostic systems for the stress-strain state of parts and assemblies for civil engineering tasks.

We developed photodefined, multimode-fiber compatible waveguides based on epoxies. These waveguides will be embedded in backplane PCB's for optical interconnect applications using 850 nm VCSELs as light sources. Apart from very low loss, the material selection took into account, PCB compatibility and low yellowing due to high temperature processing (for PCB lamination and soldering). The waveguides showed losses < 0.06 dB/cm at 832 nm and 633 nm. Their loss increase after aging (1 hr at 185 °C) was limited to 0.04 dB/cm at 850 nm. Waveguides realized on FR-4 (epoxyfiberglass) PCB material are demonstrated.

A new approach for achieving spatially correlated localized surface plasmon resonance (LSPR) spectroscopy and atomic force microscopy (AFM) imaging based on through-the-objective white light total internal reflection (TIR) is described. Using this technique, we successfully demonstrate spatially correlated measurements as well as the effect of tip-nanoparticle interactions including the ability to controllably manipulate nanoparticle position. Significant red shifts are observed in the LSPR spectra of single nanoparticles with successive AFM scans in ambient conditions. Identical experiments performed under water conclusively show that the shifts are caused by the small amount of water that collects between the tip and the sample in ambient AFM.

Introducción: la investigación examina las iniciativas que surgen después de la aprobación del convenio 169 de la OIT en Honduras y el interés hacia pueblos que habían sido ignorados por los gobiernos asimilados con la consiguiente pérdida de sus culturas. Metodología: Investigación Acción Participativa, exploró las comunidades pech en Honduras. Contextualizada en el marco del Programa Integral de Protección Ecológica y Rescate de la Herencia Cultural, del Programa de Naciones Unidas para el Desarrollo (PNUD), se validó la información y se generaron propuestas para el desarrollo sostenible, a través de talleres y visitas a comunidades. Resultados: El diagnóstico de 1994 abordó las necesidades prioritarias de los pech, integrando enfoques históricos, culturales y socioeconómicosy se exploran las interacciones resultantes de estas relaciones enmarcadas en una coyuntura única en el siglo xx. Conclusiones: La inserción de la academia y del mundo del “desarrollo socioeconómico” en el contexto local trajo consecuencias que algunos podrían considerar positivas y negativas, desde una visión crítica.
Palabras clave: Diagnostico rural participativo, pech, relecturas etnográficas, cooperación al desarrollo.

This chapter gives an overview of the formation of evanescent fields excited by an objective lens. We discuss some of the different phenomena that emerge at the interface between a high index couplant and relatively low index sample. We show how surface plasmons are excited in the presence of a thin gold film. We discuss the application of surface waves microscopy with excitation of microscopic objectives and conclude that significant applications reside in the area of localized measurement of refractive index. A key challenge in surface microscopy is to maintain the high spatial resolution in the presence of waves that propagate relatively long distances along the sample surface, methods to achieve this high resolution are discussed in some detail. For cellular imaging while surface plasmons can give good images, evanescent waves generated by excitation from light incident above the critical angle can produce very high quality

Three different substrates for the analysis of liquid samples by Total Reflection X-Ray Fluorescence with Synchrotron Radiation (SR-TXRF) were investigated and compared: Lucite (Perspex), Kimfoil and Mylar. Dry targets were prepared by pipetting 5 µl aliquotes of the liquid samples (synthetic standards and fresh water samples) on the different substrates. A five fold reduction of the continuous background and a corresponding reduction of the elementary detection limits were observed when thin polymer film substrates were used instead of the common thick Perspex substrate.

The discrete sources method has been applied to perform a computer simulation analysis of different total internal reflection microscopy schemes. It has been found that the positioning of the objective lens beneath a glass prism can provide a considerable advantage for determination of the particle-film distance.

Heterogeneous electron transfer (ET) reactions at the polarised water 1,2-dichloroethane (DCE) interface are studied by in situ UV-Visible spectroscopy in total internal reflection mode. The reduction of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and the oxidation of 1,1%-dimethylferrocene (DMFc) by the hexacyanoferrate redox couple are considered. The generation of products in the organic phase is monitored spectroscopically and correlated to the simultaneous current response. Both systems exhibit a good correlation between optical and electrochemical responses, highlighting the ideal behaviour of these redox couples for electron transfer studies at liquid liquid interfaces. The kinetics of ET between hexacyanoferrate and TCNQ is analysed also by chronoabsorptometry and potential modulated reflectance spectroscopy. The potential dependence of the ET rate constant is discussed within the framework of the ET models for ITIES.

Hollow core photonic bandgap fibers provide a new geometry for the realization and enhancement of many nonlinear optical effects. Such fibers offer novel guidance and dispersion properties that provide an advantage over conventional fibers for various applications. Dispersion, which expresses the variation with wavelength of the guided-mode group velocity, is one of the most important properties of optical fibers. Photonic crystal fibers (PCFs) offer much larger flexibility than conventional fibers with respect to tailoring of the dispersion curve. This is partly due to the large refractive-index contrast available in the silica/air microstructures, and partly due to the possibility of making complex refractive-index structure over the fiber cross section. In this paper the fundamental physical mechanism has been discussed determining the dispersion properties of PCFs, and the dispersion in a gas filled hollow core photonic crystal fiber has been calculated. We calculate the dispersion of air filled hollow core photonic crystal fiber, also calculate the dispersion of N 2 gas filled hollow core photonic crystal fiber and finally we calculate the dispersion of He gas filled hollow core photonic crystal fiber.

Left-handed materials have superlensing effects that enable them to surmount the optical diffraction limit. A photonic crystal is able to mimic some properties of all-angle left-landed materials. In this study, the all-angle negative refraction criteria of photonic crystals are evaluated. The MIT Photonic-Bands program is employed to calculate the band structure of walled honeycomb photonic crystals, and the finite-difference time-domain method is used to provide a snapshot of the electric field distribution inside and outside the honeycomb photonic crystals. The results indicate that the all-angle negative refraction phenomena of the honeycomb photonic crystals are correlated with the orientation of the photonic crystals. Furthermore, the role of the uncoupled modes varies based on their orientation to the all-angle negative refraction photonic crystals, in one case assisting negative refraction and in the other case preventing it. The results suggest that symmetric properties should not be ignored when considering the negative refraction of photonic crystals.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

For 4, we take the e reduced width obtained" from shell-model calculations' (8, ' = 0.03). We know that in the present model the summed reduced widths must be conserved. Since the experimental reduced widths total 0.76 =0.34+ 0.43, we take e, ' = 0.77 -8, ' = 0.74. Then 8 (6.72) = I oq+ Pe, l' aIld e"'(6.3) = l-pe, +o. e, l2. Using the previously determined values of n' and P' and taking the signs so as to increase the width of the 6.72-MeV state, we obtain 8 2(6. 72) =0.29 and 8~(8.3) =0. 47, which are in remarkable agreement with the ex- perimental values. Thus, the large e reduced width of the 6.72-MeV state appears to have a

A method for treatment of the transverse or longitudinal shifts of multiply internally reflected light beams is developed in terms of eigenfunctions for the reflection processes. Localized wave packets composed of plane-wave eigenfunctions are used to discuss the detailed structure of the shifted intensity distributions for several experimental conditions. %'ith this approach image widths and over-all shifts, as well as splittings between images, can be calculated. The predictions are compared with the experimental results of Imbert and are found to agree with the observed transverse splitting between left and right circularly polarized light beams. Since the theory presented here disagrees with that proposed by Imbert in several respects, experiments are suggested which would distinguish between alternative theories.

Metasurfaces have facilitated the replacement of conventional optical elements with ultrathin and planar photonic structures. Previous designs of metasurfaces were limited to small deflection angles and small ranges of the angle of incidence. Here, we have created two types of Si-based metasurfaces to steer visible light to a large deflection angle. These structures exhibit high diffraction efficiencies over a broad range of angles of incidence. We have demonstrated metasurfaces working both in transmission and reflection modes based on conventional thin film silicon processes that are suitable for the large-scale fabrication of high-performance devices.

A plasmonic infrared (IR) filter was experimentally and theoretically investigated. A localized surface plasmon polariton (LSPP) mode which was angle-independent in almost fully incident angle was observed. Through the use of the LSPP mode, an IR reflection-type notch filter with an ultrahigh immunity for the angular deviation was realized. An angle-independent reflection dip was designed at = 6:2 m with a full-width at half-maximum of 0.5 m. The experimental result shows that the position and the line shape of the resonant dip at = 6:2 m remain the same for an increasing incident angle from 20 to 60 . The optical properties can be engineered by tuning thickness of the cavity layer. The proposed notch filter presents a large angular tolerance means that the superior angular stability makes it more feasible as it is put into practical applications.

The photon trapping nano-structures help to enhance quantum efficiency and reduce reflection for MSM photodetector that allows fast Si photodetectors at wavelength 800-950nm. The nanostructure consist of micro holes reduces reflection and bends normally incident light into the lateral modes in the absorbing layer.

We propose a total-internal-reflection optical switch with a Bragg reflector waveguide. Slowing light in a Bragg reflector waveguide gives us an extremely large change in the equivalent refractive index of the waveguide, which is increased by a factor of more than 10 near a cut-off wavelength. Slowing light is caused by the giant waveguide dispersion of a Bragg reflector waveguide. The proposed structure enables a large bending angle of over 40 degrees even for reasonable refractive index changes of waveguide materials. The calculated result shows a possibility of large-scale and compact cross-bar waveguide optical switches.

In this dissertation, we propose numerical techniques to explain physical phenomenon of nonlinear photonic crystal fiber (PCF). We explain novel physical effects occurred in PCF subjected to very short duration pulses including soliton. To overcome the limitations in the analytical formulation for PCF, an accurate and efficient numerical analysis is required to explain both linear and nonlinear physical characteristics. A vector finite element based model was developed to precisely synthesize the guided modes in order to evaluate coupling coefficients, nonlinear coefficient and higher order dispersions of PCFs. This finite element model (FEM) is capable of evaluating coupling length of directional coupler implemented in dual core PCF, which was supported by existing experimental results. We used the parameters extracted from FEM in higher order coupled nonlinear Schrödinger equation (HCNLSE) to model short duration pulses including soliton propagation through the PCF. Split-step Fourier Method (SSFM) was used to solve HCNLSE. Recently, reported experimental work reveals that the dual core PCF behaves like a nonlinear switch and also it initiates continuum generation which could be used as a broadband source for wavelength division multiplexing (WDM). These physical effects could not be explained by the existing analytical formulae such as the one used for the regular fiber. In PCF the electromagnetic wave encounters periodic changes of material that demand a numerical solution in both linear and nonlinear domain for better accuracy. Our numerical approach is capable of explaining switching and some of the spectral features found in the experiment with much higher degree of design freedom. Numerical results can also be used to further guide experiments and theoretical modeling.

In this paper, coupling characteristics of dualcore photonic crystal fiber (PCF) are studied extensively using vector finite element method, which has the potential to realize wavelength selective MUX-DEMUX for wavelength division multiplexing (WDM) application. Dispersion characteristic is also reported and demonstrates the wavelength region where it can support short duration soliton like pulses.

In this dissertation, we propose numerical techniques to explain physical phenomenon of nonlinear photonic crystal fiber (PCF). We explain novel physical effects occurred in PCF subjected to very short duration pulses including soliton. To overcome the limitations in the analytical formulation for PCF, an accurate and efficient numerical analysis is required to explain both linear and nonlinear physical characteristics. A vector finite element based model was developed to precisely synthesize the guided modes in order to evaluate coupling coefficients, nonlinear coefficient and higher order dispersions of PCFs. This finite element model (FEM) is capable of evaluating coupling length of directional coupler implemented in dual core PCF, which was supported by existing experimental results. We used the parameters extracted from FEM in higher order coupled nonlinear Schrödinger equation (HCNLSE) to model short duration pulses including soliton propagation through the PCF. Split-step Fourier Method (SSFM) was used to solve HCNLSE. Recently, reported experimental work reveals that the dual core PCF behaves like a nonlinear switch and also it initiates continuum generation which could be used as a broadband source for wavelength division multiplexing (WDM). These physical effects could not be explained by the existing analytical formulae such as the one used for the regular fiber. In PCF the electromagnetic wave encounters periodic changes of material that demand a numerical solution in both linear and nonlinear domain for better accuracy. Our numerical approach is capable of explaining switching and some of the spectral features found in the experiment with much higher degree of design freedom. Numerical results can also be used to further guide experiments and theoretical modeling.

Internal waves propagate obliquely through a stratified fluid with an angle that is fixed with respect to gravity. Upon reflection on a sloping bed, striking phenomena are expected to occur close to the slope. We present here laboratory observations at moderately large Reynolds number. A particle image velocimetry technique is used to provide time-resolved velocity fields in large volumes. Generation of the second and third harmonic frequencies is clearly demonstrated in the impact zone. The mechanism for nonlinear wavelength selection is also discussed. Evanescent waves with frequency larger than the Brunt-Väisälä frequency are detected and experimental results agree very well with theoretical predictions. The amplitude of the different harmonics after reflection is also obtained.

Spin coating is introduced as a simplified method to prepare model surfaces of cellulose. Prior to spin coating, trimethylsilyl cellulose (TMSC), a nonpolar derivative of cellulose, is synthesized in order to dissolve the otherwise immiscible cellulose. After the spin coating deposition of TMSC on an untreated silicon or gold substrate, the TMSC layer is subjected to vapor phase acid hydrolysis, which regenerates it back to cellulose. X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance infrared spectroscopy (ATR-IR) revealed the films' chemical structure to be similar to pure cellulose. Spin coating parameters such as spinning speed, concentration of the coating solution, and nature of the solvent were varied to obtain diversity in morphology and thickness of the films. The optimal spin coating parameters resulted in a cellulose film with 20 nm thickness and 10% roughness, determined by atomic force microscopy (AFM). Preliminary experiments with modifying the chemistry and varying the water content of the films were also conducted.

This paper reports measurements of particle-wall and particle-particle interactions in levitated colloidal ensembles using integrated total internal reflection microscopy (TIRM) and video microscopy (VM) techniques. In levitated colloidal ensembles with area fractions of φA ) 0.03-0.25, ensemble TIRM measured height distribution functions are used to interpret particle-wall interactions, and VM measured pair distribution functions are used to interpret particle-particle interactions using inverse Ornstein-Zernike (OZ) and three-dimensional inverse Monte Carlo (MC) analyses. An inconsistent finding is the observation of an anomalous long-range particle-particle attraction and recovery of the expected Derjaguin-Landau-Verwey-Overbeek (DLVO) particle-wall interactions for all concentrations examined. Because particlewall and particle-particle potentials are expected to be consistent in several respects, the analytical and experimental methods employed in this investigation are examined for possible sources of error. Comparison of inverse OZ and three-dimensional inverse MC analyses are used to address uncertainties related to dimensionality, effects of particle concentration, and assumptions of the OZ theory and closure relations. The possible influence of charge heterogeneity and particle size polydispersity on measured distribution functions is discussed with regard to inconsistent particle-wall and particle-particle potentials. Ultimately, achieving a consistent understanding of particle-wall and particle-particle interactions in interfacial and confined colloidal systems is essential to numerous complex fluid and advanced material technologies.

A thermo-optic switch using total internal reflection waveguide was fabricated for optical true time delay. Experimental result shows that the crosstalk in the bar state is as low as -42dB and the total insertion loss is only -4dB at the wavelength of 1.55µm. A power consumption of 130mW and switching speeds of 2ms are obtained as well, which makes the device qualified to be used in the application of optical true time delay.

In this work, we propose a structured illumination (SI) method based on a two-photon excitation (TPE) scanning laser beam. Advantages of TPE methods include optical sectioning, low photo-toxicity, and robustness in the face of sample induced scattering. We designed a novel multi-spot point spread function (PSF) for a fast, two-photon scanning SIM microscope. Our multi-spot PSF is generated with a phase retrieval algorithm. We show how to obtain the phase distribution and then simulate the effect of this distribution on a spatial light modulator (SLM), which produces the multi-spot PSF in the object plane of the microscope. We produce simulations that show the viability of this method. The results are simulated and a multi-spot PSF scanning SIM microscope is proposed.

In this work, we propose a structured illumination (SI) method based on a two-photon excitation (TPE) scanning laser beam. Advantages of TPE methods include optical sectioning, low phototoxicity, and robustness in the face of sample-induced scattering. We designed a novel multispot point spread function (PSF) for a fast, two-photon scanning SIM microscope. Our multispot PSF is generated with a phase retrieval algorithm. We show how to obtain the phase distribution and then simulate the effect of this distribution on a spatial light modulator (SLM), which produces the multispot PSF in the object plane of the microscope. We produce simulations that show the viability of this method. The results are simulated and a multispot PSF scanning SIM microscope is proposed.

Polarized internal reflection spectroscopy has been applied for i.r. studies of evaporated thin layers of pyrimidine bases and W photochemistry in them,Bxperimental conditions like self-polarization of the i,r. spectrometer,polarization ratio of the polarizer, damaged surfaces of the internal reflection element,which all may lead to rather great errors,are discussed.Application for thin layers of uracil is presented.

We simulate a total internal reflection tomography experiment in which an unknown object is illuminated by evanescent waves and the scattered field is detected along several directions. We propose a full-vectorial threedimensional nonlinear inversion scheme to retrieve the map of the permittivity of the object from the scattered far-field data. We study the role of the solid angle of illumination, the incident polarization, and the position of the prism interface on the resolution of the images. We compare our algorithm with a linear inversion scheme based on the renormalized Born approximation and stress the importance of multiple scattering in this particular configuration. We analyze the sensitivity to noise and point out that using incident propagative waves together with evanescent waves improves the robustness of the reconstruction.

This highly interdisciplinary team has developed dual-color, total internal reflection microscopy (TIRF-M) methods that enable us to optically detect and track in real time protein migration and clustering at membrane interfaces. By coupling TIRF-M with advanced analysis techniques (image correlation spectroscopy, single particle tracking) we have captured subtle changes in membrane organization that characterize immune responses. We have used this approach to elucidate the initial stages of cell activation in the IgE signaling network of mast cells and the Toll-like receptor (TLR-4) response in macrophages stimulated by bacteria. To help interpret these measurements, we have undertaken a computational modeling effort to connect the protein motion and lipid interactions. This work provides a deeper understanding of the initial stages of cellular response to external agents, including dynamics of interaction of key components in the signaling network at the "immunological synapse," the contact region of the cell and its adversary.

A layer of chiral liquid crystal (CLC) with a photonic bandgap in the visible range has excellent reflective properties. Recently, two director configurations have been proposed in the literature for CLC between two substrates with periodic photo-alignment: one with the director parallel to the substrates and one with the director in the bulk parallel to the tilted plane. The transmission experiments under large angles of incidence (AOI) presented in this work prove that, in the bulk, the director does not remain parallel with the substrates. Because of the inclined helical axis, the full reflection band can be observed at a smaller AOI than in planar CLC. For sufficiently large AOI, the reflection of diffracted light is prohibited by total internal reflection and efficient diffraction occurs in the forward direction.

A layer of chiral liquid crystal (CLC) with a photonic bandgap in the visible range has excellent reflective properties. Recently, two director configurations have been proposed in the literature for CLC between two substrates with periodic photo-alignment: one with the director parallel to the substrates and one with the director in the bulk parallel to the tilted plane. The transmission experiments under large angles of incidence (AOI) presented in this work prove that, in the bulk, the director does not remain parallel with the substrates. Because of the inclined helical axis, the full reflection band can be observed at a smaller AOI than in planar CLC. For sufficiently large AOI, the reflection of diffracted light is prohibited by total internal reflection and efficient diffraction occurs in the forward direction.

Single-molecule localization microscopy (SMLM) enables far-field imaging with lateral resolution in the range of 10 to 20 nanometres, exploiting the fact that the centre position of a single molecule’s image can be determined with much higher accuracy than the size of that image itself. However, attaining the same level of resolution in the axial (third) dimension remains challenging. Here, we present SIMPLER, a photometric method to decode the axial position of single molecules in a total internal reflection fluorescence (TIRF) microscope. SIMPLER requires no hardware modification whatsoever to a conventional TIRF microscope, and complements any 2D SMLM method to deliver 3D images with nearly isotropic nanometric resolution. Examples of the performance of SIMPLER include the visualization of the nuclear pore complex through dSTORM with sub-20 nm resolution and of microtubule cross-sections resolved with sub-10 nm through DNA-PAINT.

The simulated model calculates the phase matching angle for a parallel isotropic slab made of Zinc Telluride (ZnTe), Cadmium Telluride (CdTe), Gallium Arsenide (GaAs) wavelength of 10.6 μm by determining the wave-vector mismatch. The model also generates the status of fulfillment of Total Internal Reflection (TIR) inside the semiconductor slab. The simulated results indicate phase matching angle of 0.9034 rad for a slab thickness of 800 μm in case of ZnTe and 0.5457 rad for CdTe taking the slab thickness as 500 μm. The phase matching angle for ZnSe is 1.481 rad and that of GaAs is materials. For all the cases, the TIR condition is found satisfying.

Total Internal Reflection (TIR) is used to probe the molecular organization at the surface of a tilted chiral smectic liquid crystal at temperatures in the vicinity of the bulk antiferroelectricferroelectric phase transition. Data are interpreted using an exact analytical solution of a real model for ferroelectric order at the surface. In the mixture T3, ferroelectric surface order is expelled with the bulk ferroelectric-antiferroelectric transition. The conditions for ferroelectric order at the surface of an antiferroelectric bulk are presented.

Total Internal Reflection (TIR) is used to probe the molecular organization at the surface of a tilted chiral smectic liquid crystal at temperatures in the vicinity of the bulk antiferroelectricferroelectric phase transition. Data are interpreted using an exact analytical solution of a real model for ferroelectric order at the surface. In the mixture T3, ferroelectric surface order is expelled with the bulk ferroelectric-antiferroelectric transition. The conditions for ferroelectric order at the surface of an antiferroelectric bulk are presented.

An explicit relationship between the Lorenz-Mie resonances and nonlinear optics of a microsphere has been found. We have constructed an approximate analytic method which allows an adequate assessment of the threshold for stimulated Raman scattering in microspheres. Systematic investigation of the characteristic equation, using approximate analytic expressions, reveals that not all modes have the same quality. Some resonances with very high quality correspond to a physical situation in which the spherical waves can be envisioned as whispering-gallery light waves that are totally internally reflected by the sphere boundary, without suffering almost any loss.

We propose a water-based multitouch multimedia user-interface based on total-internal reflection as viewed by an underwater camera. The underwater camera is arranged so that nothing above the water surface is visible until a user touches the water, at which time anything that penetrates the water's surface becomes clearly visible. Our contribution is twofold: (1) computer vision using underwater cameras aided by total internal reflection; (2) hyperacoustic signal processing (frequency shifting) to capture the natural, acoustically-originating sounds of water rather than using synthetic sounds. Using water itself as a touch screen creates a fun and playful user interface medium that captures the fluidity of the water's ebb and flow. In one application, a musical instrument is created in which acoustic disturbances in the water (received by underwater microphones or hydrophones) are frequency-shifted to musical notes corresponding to the location in which the water is touched, as determined by the underwater computer vision system.

In this work we present a novel nanomaterial coating technique using evanescent wave (EW). The gradient force in the EW is used as an optical tweezer for tweezing and self-assembling nanoparticles on the source of EW. As a proof of the concept, we have used a laser coupled etched multimode optical fiber, which generates EW for the EW assisted coating. The section-wise etched multimode optical fiber is horizontally and superficially dipped into a silver/gold nanoparticles solution while the laser is switched on. The fiber is left until the solution recedes due to evaporation leaving the fiber in air. The coating time usually takes 40-50 min at room temperature. The scanning electron microscope image shows uniform and thin coating of self-assembled nanoparticles due to EW around the etched section. A coating thickness <200 nm is achieved. The technique could be useful for making surface-plasmon-resonance-based optical fiber probes and other plasmonic circuits.

The optical properties of inhomogeneous cerium dioxide (CeO2) films on aluminum (Al) sublayer are investigated. The dependencies of the reflection, scattering, and absorption of coherent electromagnetic radiation as functions of the incidence angle and polarization are studied. The experimental and numerical studies show the existence of an incidence angle at which the scattering and absorption of coherent radiation with s-polarization increase simultaneously and the specular reflection becomes just about a few percents. The angle corresponds to an excitation of Fabry-Perot resonator modes. This effect opens up great prospects for manipulation (tuning) of the reflection from the inhomogeneous films.

A dielectric multilayer platform has been investigated as a foundation for two-dimensional optics. In this paper, we present, to the best of our knowledge, the first experimental demonstration of absorption of Bloch surface waves in the presence of graphene layers. Graphene layers have been grown previously via CVD on Cu foils and transferred layer by layer by PMMA-wet transfer method. We exploit total internal reflection configuration and multi-heterodyne scanning near-field optical microscopy as a far-field coupling method and near-field characterization tool, respectively. The absorption is quantified in terms of propagation lengths of Bloch surface waves. A significant drop (about 17 times shorter) in the propagation length of surface waves is observed in the presence of single layer of graphene.

Surfactant adsorption to the liquid–solid interface is of great importance to many industrial and consumer processes; from detergency to crop spraying and drilling for oil, the understanding of how these molecules behave is crucial to their design and further efficiency improvement. This thesis describes how a Raman spectrometer for use in total-internal reflection (TIR)-Raman spectroscopy was built and commissioned to provide a new, open bench system. The prime aim was to improve on the time resolution of our existing commercial spectrometer (to &lt;1 s) and allow for easy modification. TIR-Raman spectroscopy allows us to be surface-selective by only measuring the Raman spectrum from very close to the interface, where the evanescent field excites molecules attached to, or very close to the surface. As this field decays exponentially with distance, only a small region at the interface is probed (≈100 nm). Using an in-line mixer we were able to record adsorption and desorption isothe...

The kinetics of methyl orange transfer across the water1,2-dichloroethane interface is studied by potential-modulated reflectance (PMR) and ac-impedance. The frequency dependence analysis of both techniques provide complementary information about charge transfer kinetics and the potential distribution across the interface. The PMR signal is obtained under total internal reflection from the liquidliquid interface. It is concluded that the PMR responses are originated from the ac flux of ion crossing the interface, and therefore provide a direct analysis of the faradaic responses. This technique is also less sensitive to uncompensated resistance effects in comparison to the admittance analysis. In the case of methyl orange transfer, a standard apparent rate constant of (4.5 90.7) 10 -2 cm s -1 and a transfer coefficient of 0.409 0.03 were estimated from the frequency dependence of the PMR.