Experimental observation of evanescent modes at the interface to slow-light photonic crystal waveguides

We experimentally study the fields close to an interface between two photonic crystal waveguides that have different dispersion properties. After the transition from a waveguide in which the group velocity of light is v(g) ~ c/10 to a waveguide in which it is v(g) ~ c/100, we observe a gradual increase in the field intensity and the lateral spreading of the mode. We attribute this evolution to the existence of a weakly evanescent mode that exponentially decays away from the interface. We compare this to the situation where the transition between the waveguides only leads to a minor change in group velocity and show that, in that case, the evolution is absent. Furthermore, we apply novel numerical mode extraction techniques to confirm experimental results.     

Polarization dynamics of an ordinary light wave interacting with a nematic liquid crystal

Experimental observations and theoretical calculations of the interaction of an ordinary light wave with a homeotropically aligned nematic liquid crystal (NLC) are presented. It was observed that by increasing the light power, aperiodic, damped, periodic and stochastic oscillations of the polarization of the light wave take place. Theoretically, the self-consistent problem of the interaction of the director of a homeotropic NLC with a plane light wave of ordinary type was treated and the change in the polarization state of the transmitted-light wave was calculated. Calculations reproduced the existence of aperiodic, damped and periodic oscillations, in qualitative agreement with the experimental results.     

Fourier synthesis of a three-dimensional surface by the method of multiangle projection of fringes

A new method is proposed for contactless measurements of the surface shape of diffusely reflecting objects. The method is based on the multiangle projection of fringes and the joint processing of the obtained images by Fourier synthesis. It improves the spatial resolution of the reconstructed surface of an object in all directions and simultaneously decreases the shaded areas on an object.     

Charge segregation and a nonuniform magnetic state in donor-and acceptor-doped LaMnO3

A coordinated study of the magnetic, electrical, optical, and EPR properties of LaMnO₃ single crystals doped by donors (7 at. % Ce) and acceptors (7 at. % Sr) revealed that in all cases, except undoped LaMnO₃, charge segregation associated with large-scale crystal-field fluctuations occurs and the magnetic properties originate from the existence of ferromagnetic phase inclusions and localized ferrons in the matrix with a canted magnetic structure.     

Interference effects in 1<Emphasis Type="Italic">s</Emphasis> → π* resonance excitation processes of the no molecule

A ¹Π → X ¹Σ⁺ fluorescence in the NO⁺ molecular ion observed after Auger decay of the 1s ^?1 π* resonances of the N*O molecule and NO* was studied theoretically. The energies and probabilities of the transition between the vibrational levels of the electronic states, determining the excitation and Auger decay of the resonances of the nitrogen monoxide molecule and further radiation-induced decay of the NO⁺ molecular ion were calculated by the first principles method. Multiplet splitting of the resonances of N*O and NO* and interference of the amplitudes of excitation of the molecule through various vibrational levels of the intermediate resonance explain the observed dependences of the intensity of A ¹Π(υ′) → X ¹Σ⁺(υ″) fluorescence on the excitation radiation energy. The discrepancies between the calculated and experimental integrated intensities of fluorescence point to the necessity of studying cascade processes determined by radiation transitions in NO⁺, including dipole transitions with a changed net spin.     

Effect of solution volume on the rate of metal recovery and its distribution in porous cathode

By means of earlier developed dynamic model of porous electrode, numerical analysis is given of the effect of the division into smaller parts of optimal volume V _opt of metal-containing solution circulating through the porous electrode, which ensures both achieving of the metal preset recovery and the prescribed final porosity in the critical cross-section of the porous cathode, most strongly filled with the deposit. It is shown that the result depends significantly on the presence (or absence) of oxidant ions in the solution. In the absence of oxidant, the division of V _opt is desirable; it entails some improving of the distribution uniformity and increase in the deposit eventual mass. On the contrary, in the presence of oxidant such a division brings about marked negative consequences: (1) the metal deposit stronger localization at the porous electrode front edge and (2) decrease in the deposit’s final mass. It was shown that these phenomena result from the formation of anodic zone in the porous electrode rear side in the initial stage of the processing of the second and subsequent portions of solution. This is promoted by low polarization in this part of the porous electrode and the presence of a soluble metal deposited here during the final stage of electrolysis of the solution preceding portion.     

Model of the magnetorefractive effect in manganites within the effective medium theory

The magnetorefractive effect (MRE) in manganites has been studied within the effective medium theory. The MRE has been calculated in manganites La_1–xK_xMnO₃ (x = 0.1 and 0.15) for light transmission and reflection. Good agreement with experimental results demonstrates direct relation of the MRE to the magnetoresistance and optical properties of manganites with various substitution levels. It has been shown that the MRE can exceed 10% in the near- and mid-IR region near the magnetic phase transition and can change sign during light transmission and reflection in the region of phonon modes. The results make it possible to recommend the MRE as a contactless method for studying magnetoresistive materials and for developing sensors and microelectronic elements.     

Release mechanisms for polyelectrolyte capsules

Polyelectrolyte capsules have recently been introduced as new microscopic vehicles which could have high potential in the biomedical field. In this critical review we give an introduction to the layer-by-layer (LbL) technique which is used to fabricate these polyelectrolyte capsules as well as to the different triggers that have been exploited to obtain drug release from these capsules. Furthermore, other types of triggered delivery systems are compared and critically discussed with regard to their clinical relevance. (171 references.).