Total Reflection Condition Research Articles

Dynamical characteristics of an electromagnetic field under conditions of total reflection

The dynamical characteristics of electromagnetic fields include energy, momentum, angular momentum (spin) and helicity. We analyze their spatial distributions near the planar interface between two transparent and non-dispersive media, when the incident monochromatic plane wave with arbitrary polarization is totally reflected, and an evanescent wave is formed in the medium with lower optical density. Based on the recent arguments in favor of the Minkowski definition of the electromagnetic momentum in a material medium (Philbin 2011 Phys. Rev. A 83 013823; Philbin and Allanson 2012 86 055802; Bliokh et al 2017 Phys. Rev. Lett. 119 073901), we derive the explicit expressions for the dynamical characteristics in both media, with special attention to their behavior at the interface. In particular, the ‘extraordinary’ spin and momentum components orthogonal to the plane of incidence are described, and a canonical (spin–orbital) momentum decomposition is performed that contains no singular terms. The field energy, helicity, the spin momentum and orbital momentum components are everywhere regular but experience discontinuities at the interface; the spin components parallel to the interface appear to be continuous, which testifies to the consistency of the adopted Minkowski picture. The results supply a meaningful example of the electromagnetic momentum decomposition, with separation of spatial and polarization degrees of freedom, in inhomogeneous media, and can be used in engineering the structured fields designed for optical sorting, dispatching and micromanipulation.

Increase in the Lasing Efficiency of Thin-Film Lasers Based on 1.4- Distirylbenzene

The possibility of development of a thin-film 1,4-distirylbenzene–based laser lasing in the blue spectral range in solutions and films is investigated. The stimulated emission of 1,4-distirylbenzene in a polymethylmethacrylate film with transverse pumping by a YAG-Nd3+ laser is obtained for the threshold power density W = 0.44 MW/cm2. It is shown that incorporation of the additional amorphous SiO2 layer, improving the condition of total internal reflection on the boundary of the active medium, decreases the lasing threshold to 50–70 kW/cm2; in this case, the efficiency of radiation conversion is equal to 20%.

Amplified luminescence of heavily doped AlxGa1 – xN structures under optical pumping

Spectral, temporal, and polarisation characteristics of luminescence of heavily doped AlxGa1 – xN films on a sapphire substrate are studied under pulsed pumping at the wavelength λ = 266 m. Spectra of spontaneous emission related to donor – acceptor transitions are inhomogeneously broadened with the FWHM of above 0.5 eV and cover the entire visible range. Spectra of radiation emitted from an edge of investigated structure comprise several narrow-band equidistant components, each of them being split to TE and TM modes with mutually orthogonal polarisations. This is related to plane waves propagating inside a plane waveguide along a zigzag path in the conditions of total internal reflection from waveguide surfaces. The optical gains measured for Al0.5Ga0.5N/AlN at λ ≈ 510 nm, Al0.74Ga0.26N/AlN at λ ≈ 468 nm, and AlN/Al0.6Ga0.4N/AlN/Al2O3 at λ ≈ 480 nm were, respectively, ∼70, 20, and 44 cm−1. The luminescence quantum efficiencies measured for Al0.74Ga0.26N, Al0.65Ga0.35N, and Al0.5Ga0.5N films are, respectively, 0.79, 0.49, and 0.14; the transition cross sections calculated at emission band centres are ∼10−18 cm2.

In Ukrainian

Calculation of evanescent field in near-zone of quartz rough surface is presented. 2D vector Helmholtz equation by means of finite element approach is used. Shape of quartz surface is chosen as sequence of surface three-cornered form irregularities. It shown that (a) contrast range of evanescent field practically does not depend on length of scattering wave at illumination of quartz rough surface on condition of total light reflection especially in the case of height of irregularities ()is insignificant (£1nm); (b) the reflection light coefficient does not depend on the parameter; (c) the contrast of quartz rough surface diminishes when its correlation length increases; (d) on the average, distribution of evanescent field along the surface of quartz repeats the form of the rough surface.

Special inhomogeneous electromagnetic waves in hyperbolic metamaterials

Herein, it is shown that under conditions of total internal reflection of plane homogeneous electromagnetic waves at the interface of a hyperbolic metamaterial (HMM) and an ordinary isotropic medium, special inhomogeneous electromagnetic waves are excited in certain circumstances near the surface of the metamaterial and their amplitude changes with distance according to the non-exponential law. The existence conditions for such waves are established for the case when the optical axis is located within the interface plane and forms an angle with the plane of incidence. The energy flux and density of energy of special inhomogeneous waves in a HMM are determined.

Contact Measurements of Randomly Rough Surfaces

This manuscript presents an experimental effort to directly measure contact areas and the details behind these scaled experiments on a randomly rough model surface used in the “Contact Mechanics Challenge” (2017). For these experiments, the randomly rough surface model was scaled up by a factor of 1000× to give a 100 mm square sample that was 3D printed from opaque polymethylmethacrylate (PMMA). This sample was loaded against various optically smooth and transparent samples of PDMS that were approximately 15 mm thick and had a range in elastic modulus from 14 kPa to 2.1 MPa. During loading, a digital camera recorded contact locations by imaging the scattering of light that occurs off of the PMMA rough surface when it was in contact with the PDMS substrate. This method of illuminating contact areas is called frustrated total internal reflection and is performed by creating a condition of total internal reflection within the unperturbed PDMS samples. Contact or deformation of the surface results in light being diffusely transmitted from the PDMS and detected by the camera. For these experiments, a range of reduced pressure (nominal pressure/elastic modulus) from below 0.001 to over 1.0 was examined, and the resulting relative contact area (real area of contact/apparent area of contact) was found to increase from below 0.1% to over 60% at the highest pressures. The experimental uncertainties associated with experiments are discussed, and the results are compared to the numerical results from the simulation solution to the “Contact Mechanics Challenge.” The simulation results and experimental results of the relative contact areas as a function of reduced pressure are in agreement (within experimental uncertainties).

Paper-Based Plasmonic Surface for Chemical Biosensing by the Attenuated Total Reflection Method

ABSTRACTWe demonstrate the detection of an increase in refractive index and/or thickness by specific adsorption of proteins on a plasmonic surface on a paper substrate in the Otto configuration. Propagating surface plasmon resonance is observed on a gold surface deposited onto polymer-coated papers through angular scans of reflectivity in the Otto configuration under attenuated total reflection conditions. According to a surface analysis with atomic force microscope, the gold surface roughness on a polyvinyl chloride (PVC)-coated paper is comparable to that of a Si wafer, leading to the achievement of protein detection. On the other hand, the propagating length of the surface plasmons is shorter than that on the Si wafer. According to an observation of the gold surface with scanning electron microscope, the gold grain size on the PVC-coated paper is smaller than that on the Si wafer. Thus, many boundaries cause a reduction in the propagating length on the PVC-coated paper.

Polarization-Dependent Optical Sensor Based on Reduced Graphene Oxide

We report a polarization-dependent optical sensor based on reduced graphene oxide (rGO) and demonstrate its applications in detecting refractive indices. The s-polarized absorption of the rGO under the conditions of total internal reflection is unique over the range of 400–1100 nm and its amplitude is sensitive to the media that is in contact with the rGO. We have conducted detailed calculations and experiments to optimize the performance of the sensor. The sensitivity of the optical sensor is $3.10~\Delta $ R/RIU and its resolution is $9.7\times 10 ^{-4}$ RIU.

Magnetization precession induced by picosecond acoustic pulses in a freestanding film acting as an acoustic cavity

We report the magnetization dynamics excited by picosecond acoustic pulses confined in the acoustic cavity of freestanding nickel films. By detecting both sides of the sample we show that acoustic pulses moving back and forth inside the cavity efficiently control the magnetization precession. The multiple round trips of acoustic pulses, which survive for 12 bounces, enhance the amplitude of the magnetization precession by a factor of 4.5. Even though the conditions of total reflection are met in the freestanding film, the acoustic pulses have a large attenuation as compared to similar Ni films on $\mathrm{Si}{\mathrm{O}}_{2}$ substrate, for which we speculate that it is related to a stress induced by the substrate. Our results constitute a guideline for simple designs of acoustic cavities and for achieving a very large amplification of the magnetization precession angle. It is potentially useful for high-frequency magneto-optical modulators.

Spectroelectrochemical detection of specifically adsorbed cyanurate anions at gold electrodes with (111) orientation in contact with cyanate and cyanuric acid neutral solutions

The adsorption and reactivity of cyanate at Au(111) single crystal and Au(111)-25nm thin film electrodes is studied spectroelectrochemically in sodium perchlorate solutions and compared to those of cyanuric acid (C3N3O3H3). From the Surface Enhanced Infrared Reflection Absorption spectra obtained under Attenuated Total Reflection conditions (ATR-SEIRAS) it can be concluded that adsorbed cyanate species predominate at the electrode surface for low cyanate concentrations. However, for cyanate concentrations above 1mM, the similarity of the ATR-SEIRA spectra with those obtained in cyanuric acid containing solutions indicates that some species coming from cyanuric acid is formed and adsorbed at the (111) gold surface sites as the result of an electroless trimerization reaction. Taking into account the results of Density Functional Theory (DFT) calculations, the experimental voltammetric and ATR-SEIRAS results agree with the formation of adlayers of specifically adsorbed triketo-monocyanurate species that adsorb perpendicular to the electrode surface.

Voltammetric and in situ infrared spectroscopy studies of hydroxyurea electrooxidation at Au(111) electrodes in HClO4 solutions

The oxidation of hydroxyurea (H2NCONHOH, HU) at Au(111) single crystal and Au(111)-25nm thin film electrodes is studied spectroelectrochemically in HClO4 solutions using external reflection infrared and Surface Enhanced Infrared Reflection Absorption Spectroscopy under Attenuated Total Reflection conditions (ATR-SEIRAS). The in situ external reflection spectra prove the formation of dissolved carbon dioxide and adsorbed cyanate during the electrooxidation of HU. The enhanced surface sensitivity of the ATR-SEIRAS experiments facilitates the detection of adsorbed cyanate and allows the observation of other adsorbate bands tentatively ascribed to reaction intermediates involving partial oxidation of the HU molecules, some of them corresponding to nitrosyl groups.

Interface of photonic crystal heterostructure for broadening bandwidth of unidirectional light transmission

An all-optical diode (AOD) is a spatially nonreciprocal device that in the ideal case and for a specific wavelength allows light to totally transmit along the forward direction but totally inhibits light to propagate along the backward direction,yielding a unitary contrast.AODs are widely considered to be the key components for the next-generation all-optical signal processing,and completely analogous to electronic diodes which are widely used in computers for processing electric signals.Most of AOD designs suffer some serious drawbacks which make them not suitable for commercial and large-scale applications.Relatively large physical sizes are often needed,the balance between figure of merit and optical intensity is usually inadequate,and in some cases cumbersome structural designs are necessary to provide structural asymmetry.Among different approaches,the AOD based on two-dimensional (2D) photonic crystal (PC) heterostructure has shown significant advantages due to the capability of on-chip integration with other photonic devices.However,current PC heterostructure AOD (PCH-AOD) is based on the mismatch of directional bandgaps,which shows poor performance as a result of the relatively low forward transmittance (0.40) and contrast ratio (0.75) with a narrow bandwidth (about 10 nm).In order to improve the performance,here we propose a new PCH-AOD design based on the total reflection principle,which is able to achieve high forward transmittance and contrast ratio within a broad wavelength range.Our design is composed of two rectangle lattice 2D PC structures,in which periodically distributed air holes are embedded in silica (PC1) and silicon (PC2) materials,respectively.The two PCs are combined with an inclined interface along the -M direction of both PCs.In this way,the total reflection condition is satisfied when light propagates from silicon to silica material.The forward and backward propagating optical waves are incident along the -X direction of both PCs,in which direction there are transmission bands for TE mode centered at 1550~nm wavelength.A commercial software (R-soft) based on the finite-difference time-domain (FDTD) method is used to study the unidirectional transmission performance of the PCH-AOD.The results show that the forward propagating optical waves (from PC1 to PC2) can transmit efficiently through the device.In addition,we further improve the forward transmittance by exploiting the self-collimation effect of PCs and optimizing the coupling from PC1 to PC2.In the meantime,the light propagating along the backward direction (from PC2 to PC1) is blocked at the total reflection interface with near-zero transmittance.In this way,the unidirectional transmission is achieved without the reliance on the directional bandgap mismatch,and thus broad bandwidth is achieved.The AOD has a forward transmittance of 0.64 and a transmission contrast of 0.97 with a bandwidth of 553 nm at 1550 nm.The equal frequency contours (EFCs) of the PCs is plotted to demonstrate the working principle of the PCH-AOD.Finally,considering the experimental fabrication of the AOD device,we analyze the unidirectional transmission performance of a planar PCH-AOD with a finite thickness of 1500 nm.Despite a small reduction (12.3%) in the forward transmittance,the transmission contrast is maintained at about 0.97,and the unidirectional transmission bandwidth is increased to 600 nm.Therefore,our design can be implemented in practice and our work provides a theoretical framework for designing high performance PCH-AOD.In addition,our design allows an unprecedented high forward transmittance,contrast ratio and broad working bandwidth of the device at extremely low operational optical intensity,due to the total reflection condition,and the optimized forward propagation and coupling condition.The proposed device has a small footprint that is promising for next-generation on-chip applications.

Propagation of a filamentary femtosecond laser beam with high intensities at an air-solid interface

The propagation of a filamentary laser beam at an air-glass surface is studied by setting the incident angle satisfying the total reflection condition. The images of the trajectory of the filamentary laser beam inside the sample and the output far-field spatial profiles are measured with varying incident laser pulse energies. Different from the general total reflection, a transmitted laser beam is detected along the propagation direction of the incident laser beam. The energy ratio of the transmitted laser beam depends on the pulse energies of the incident laser beam. The background energy reservoir surrounding the filament core can break the law of total reflection at the air-glass surface, resulting in the regeneration of the transmitted laser beam.

Formation of cyanuric acid from cyanate adsorbed at gold electrodes

We report the formation of cyanuric acid species at Au(111) electrodes in cyanate-containing solutions, due to the electroless trimerization of isocyanic acid. Similar experimental bands in the range between 1300 and 1900cm−1 are observed in Surface Enhanced Infrared Reflection Spectroscopy experiments under Attenuated Total Reflection conditions (ATR-SEIRAS) with solutions containing either cyanate anions at high concentration or cyanuric acid. The experimental frequencies agree well with those obtained from Density Functional Theory (DFT) calculations for the adsorbed cyanurate anion, bonded to the metal in a tridentate configuration, with its molecular plane perpendicular to the metal surface.

Nonintrusive measurement of the liquid refractive index by using properties of the cuvette wall.

We present a method of nonintrusive measurement of the refractive index of a liquid in a glass cuvette, which uses some optical properties of the cuvette wall and the principle of total internal reflection. By coating a transmission-scattering paint layer on the outer surface of the cuvette, we transform an incident laser beam into a transmitted scattered light. When the transmitted scattered light reaches the interface between the container wall and the liquid inside, the light beams satisfying the condition of total internal reflection are reflected to the coating layer, automatically forming a circular dark pattern that is related to the refractive index of the liquid. Based on an analytic relation between the diameter of the circular dark pattern and the refractive index of the liquid, we devised a method of in situ nonintrusive refractive index measurement. We tested the effect of several parameters on the measuring accuracy and found that the optimal thickness of the transmission-scattering layer is in the range of 50-70 μm, and the aperture of the diaphragm should be in the range of 0.7-1.0 mm. We measured the refractive indices of ethanol, Coca Cola, and red wine, and achieved an accuracy of ±3×10-4 RIU (refractive index unit).

Acoustomechanical constitutive theory for soft materials

Acoustic wave propagation from surrounding medium into a soft material can generate acoustic radiation stress due to acoustic momentum transfer inside the medium and material, as well as at the interface between the two. To analyze acoustic-induced deformation of soft materials, we establish an acoustomechanical constitutive theory by combining the acoustic radiation stress theory and the nonlinear elasticity theory for soft materials. The acoustic radiation stress tensor is formulated by time averaging the momentum equation of particle motion, which is then introduced into the nonlinear elasticity constitutive relation to construct the acoustomechanical constitutive theory for soft materials. Considering a specified case of soft material sheet subjected to two counter-propagating acoustic waves, we demonstrate the nonlinear large deformation of the soft material and analyze the interaction between acoustic waves and material deformation under the conditions of total reflection, acoustic transparency, and acoustic mismatch.

Resonant tunneling effect in one-dimensional twinned lattice photonic crystal under total reflection conditions

Under total reflection conditions, it typically seems as though light waves will be reflected completely on the interface; in actuality, the waves can penetrate the medium as evanescent waves. In this paper, we present a twinned lattice photonic crystal with a unit cell composed of AB layers and their mirror. We assume that the refractive index n 0 of the input and output end is equal to n B and larger than n A . We first demonstrate the dependence of band structure on the incidence angle and normalized wavelength, in which the resonant tunneling bands are exposed. We then draw a comparison of bands between ABBA and AB. To conclude, we discuss the resonant tunneling effect in the twinned lattice photonic crystal under the total reflection conditions. As incidence angle increases, the resonant tunneling band ultimately vanishes completely.

Chemical state analysis of trace-level alkali metals sorbed in micaceous oxide by total reflection X-ray photoelectron spectroscopy

In order to determine the chemical states of radioactive cesium (137Cs or 134Cs) sorbed in clay minerals, chemical states of cesium as well as the other alkali metals (sodium and rubidium) sorbed in micaceous oxides have been investigated by X-ray photoelectron spectroscopy (XPS). Since the number of atoms in radioactive cesium is extremely small, we specially focused on chemical states of trace-level alkali metals. For this purpose, we have measured XPS under X-ray total reflection (TR) condition. For cesium, it was shown that ultra-trace amount of cesium down to about 100pgcm−2 can be detected by TR-XPS. This amount corresponds to about 200Bq of 137Cs (t1/2=30.2 y). It was demonstrated that ultra-trace amount of cesium corresponding to radioactive cesium level can be measured by TR-XPS. As to the chemical states, it was found that core-level binding energy in TR-XPS for trace-level cesium shifted to lower-energy side compared with that for thicker layer. A reverse tendency is observed in sodium. Based on charge transfer within a simple point-charge model, it is concluded that chemical bond between alkali metal and micaceous oxide for ultra-thin layer is more polarized that for thick layer.

Total Internal Reflection Accounts for the Bright Color of the Saharan Silver Ant.

The Saharan silver ant Cataglyphis bombycina is one of the terrestrial living organisms best adapted to tolerate high temperatures. It has recently been shown that the hairs covering the ant’s dorsal body part are responsible for its silvery appearance. The hairs have a triangular cross-section with two corrugated surfaces allowing a high optical reflection in the visible and near-infrared (NIR) range of the spectrum while maximizing heat emissivity in the mid-infrared (MIR). Those two effects account for remarkable thermoregulatory properties, enabling the ant to maintain a lower thermal steady state and to cope with the high temperature of its natural habitat. In this paper, we further investigate how geometrical optical and high reflection properties account for the bright silver color of C. bombycina. Using optical ray-tracing models and attenuated total reflection (ATR) experiments, we show that, for a large range of incidence angles, total internal reflection (TIR) conditions are satisfied on the basal face of each hair for light entering and exiting through its upper faces. The reflection properties of the hairs are further enhanced by the presence of the corrugated surface, giving them an almost total specular reflectance for most incidence angles. We also show that hairs provide an almost 10-fold increase in light reflection, and we confirm experimentally that they are responsible for a lower internal body temperature under incident sunlight. Overall, this study improves our understanding of the optical mechanisms responsible for the silver color of C. bombycina and the remarkable thermoregulatory properties of the hair coat covering the ant’s body.

Self-detection of x-ray Fresnel transmissivity using photoelectron-induced gas ionization

Electric response of an x-ray mirror enclosed in a gas flow ionization chamber was studied under the conditions of total external reflection for hard x-rays. It is shown that the electric response of the system as a function of the incidence angle is defined by x-ray Fresnel transmissivity and photon-electron attenuation properties of the mirror material. A simple interpretation of quantum yield of the system is presented. The approach could serve as a basis for non-invasive in situ diagnostics of hard x-ray optics, easy access to complementary x-ray transmissivity data in x-ray reflectivity experiments, and might also pave the way to advanced schemes for angle and energy resolving x-ray detectors.