Higher-Spin Gauge Theories in Four, Three and Two Dimensions

We review the theory of higher-spin gauge fields in four and three space-time dimensions and present some new results on higher-spin gauge interactions of matter fields in two dimensions.Comment: LaTex, 37 pages, no figures, Invited talk at the Quantum Gravity Seminar in memory of academician Moisei Markov, June 12-19, 1995, Moscow; page format is changed, one reference is added and another one is correcte

Photonic Nano-Structures For Water Quality Monitoring

We propose a new type of sensors suitable for water quality testing and for monitoring water contamination levels in domestic, industrial and environmental applications. The proposed sensing scheme uses Fourier transform cavity-enhanced absorption spectroscopy and novel compact sensing elements based on nanostructured photonic crystal-type optical coatings enabling the sensitive Fourier-domain processing methodology and maximising the absorption path length within the measurement system. The measurement scheme is shown to be suitable for the determination of small changes in the water absorption coefficients at a discrete set of wavelengths in the visible spectral region in response to small concentrations of pollutants with high sensitivity. The proposed sensors are expected to provide real-time information on the water contamination levels, as well as potentially the types of substances dissolved

Higher Spin Gauge Theories in Any Dimension

Some general properties of higher spin gauge theories are summarized with the emphasize on the nonlinear theories in any dimension.Comment: 15 pages, Proceedings of Strings 2004, Paris, June 28-July

High-performance RF-sputtered Bisubstituted iron garnet thin films with almost in-plane magnetization

Bismuth-substituted iron garnet thin films of high quality are prepared by using RF magnetron sputtering technique in pure argon (Ar) plasma. All the developed garnet films show high magneto-optic (MO) response after being optimally annealed across the visible range wavelengths. The garnet films display almost in-plane magnetization component with adequate Faraday rotation and relatively low optical absorption over a wide spectral range of frequencies from visible to the infrared. These garnet-type thin films demonstrate excellent MO properties together with very low coercive field of about 30 Oe, and can be used in a wide range of magneto optical applications, especially in magneto-plasmonic/magneto-photonic crystal based microdevices

Magnetic Field Sensors And Visualizers Using Magnetic Photonic Crystals

Magneto-optical imaging is widely used to observe the domain patterns in magnetic materials, visualize defects in ferromagnetic objects, and measure the spatial distribution of stray magnetic fields. Optimized 1D magneto-photonic crystals enable a significant increase in the sensitivity of magneto-optical sensors. The properties of such devices based on the optimized reflection (doubled Faraday rotation) mode and the use of 1D magnetic photonic crystals as sensors are discussed. Experimental results of the fabrication and characterization of ferrite-garnet layers possessing uniaxial magnetic anisotropy are shown, and an optimized film structure suitable for magneto-optical imaging is proposed

Growth, Characterisation, And Properties of Bi1.8Lu1.2Fe3.6Al1.4O12 Garnet Films Prepared Using Two Different Substrate Temperatures

We prepare highly Bismuth substituted iron garnet of composition type Bi1.8Lu1.2Fe3.6Al1.4O12 by using low and high substrate temperatures (250°C and 680°C) during the deposition process inside the vacuum chamber of RF magnetron sputtering system. The crystallisation process of this garnet type thin film materials are performed by means of optimised high temperature oven annealing process and conduct several characterisation techniques to obtain and evaluate their properties. All the optimally annealed samples possess very promising and attractive properties. Comparatively low coercive force (below 15 Oe) is achieved in garnet films prepared at high substrate temperature of 680°C, simultaneously with high MO quality and almost in-plane magnetisation direction, which are the properties desired in various MO sensing, switching and imaging applications

Analysis, optimization, and characterization of magnetic photonic crystal structures and thin-film material layers

The development of magnetic photonic crystals (MPC) has been a rapidly evolving research area since the late 1990s. Magneto-optic (MO) materials and the techniques for their characterization have also continually undergone functional and property-related improvements. MPC optimization is a feature-rich Windows software application designed to enable researchers to analyze the optical and magneto-optical spectral properties of multilayers containing gyrotropic constituents. We report on a set of computational algorithms which aim to optimize the design and the optical or magneto-optical spectral analysis of 1D MPC, together with a Windows software implementation. Relevant material property datasets (e.g., the spectral dispersion data for the refractive index, absorption, and gyration) of several important optical and MO materials are included, enabling easy reproduction of the previously published results from the field of MPC-based Faraday rotator development, and an effective demonstration-quality introduction of future users to the multiple features of this package. We also report on the methods and algorithms used to obtain the absorption coefficient spectral dispersion datasets for new materials, where the film thickness, transmission spectrum, and refractive index dispersion function are known

Design of Reconfigurable Optical Interconnects Employing Opto-VLSI Processors

We investigate the design and performance of a reconfigurable optical interconnect structure based on vertical-cavity surface-emitting lasers (VCSEL), Opto-VLSI processors and photodetector arrays. We optimise a proof-of-concept 3-VCSEL-element structure that eliminates crosstalk caused by unwanted diffracted optical beams and show that a bit error role (BER) of 10\u2717 is feasible at 3.2 Gbps for each channel

Generalized Toda Field Theories

In this paper we introduce a unified approach to Toda field theories which allows us to formulate the classes of $A_n$, $B_n$ and $C_n$ models as unique models involving an arbitrary continuous parameter $\nu$. For certain values of $\nu$, the model describes the standard Toda theories. For other values of $\nu$ it defines a class of models that involve infinitely many fields. These models interpolate between the various standard Toda field theories. They are conformally invariant and possess infinitely many conserved higher-spin currents thus making them candidates for a new set of integrable systems. A general construction is performed, which can effectively be used for the derivation of explicit forms of particular higher-spin currents. We also study the currents in a different representation in which they are linear in the dynamical variables having, however, a non-linear Poisson bracket algebra. An explicit formula for this Poisson structure is found.Comment: 35 pages, latex, no figures; submitted to Nucl. Phys.