Characterization of surface-plasmon modes in metal-clad optical waveguides

Finite-element analysis, based on the vector H-field formulation and incorporating the perturbation technique, is used to calculate the complex propagation characteristics of metal-coated dielectric waveguides. The propagation and attenuation characteristics of the surface-plasmon modes at the metal/dielectric interfaces are presented. The effects on the optical properties of metal-clad optical fibers with infinite and finite cladding thickness and the formation of the supermodes due to the coupling between the surface-plasmon modes in the presence of different surrounding materials are also investigated.     

A rigorous comparison of the performance of directional couplerswith multimode interference devices

The authors report, for the first time, a direct comparison between a directional coupler and a multimode interference-based device, in relation to their performance characteristics such as crosstalk, polarization dependence and the effect of fabrication tolerances. The coupling efficiency for a nonidentical coupler, produced inadvertently due to problems with fabrication tolerances, is also demonstrated. The vector finite element (FE) and the least squares boundary residual (LSBR) methods are employed as the numerical tools used in this simulation study     

Investigations on the nucleation kinetics of Tetrathiourea mercury(II) tetrathiocyanato zinc(II) single crystals

The solubility and metastable zone width of Tetrathiourea mercury(II) tetrathiocyanato Zinc(II): Hg(N₂H₄CS)₄Zn(SCN)₄ (TMTZ) were determined for the first time and thereby the possibility of growing bulk size single crystals of TMTZ in a mixture solvent of ethanol and water was estimated. The induction period was recorded for the different supersaturation ratios (S = 1.1, 1.2, 1.3 and 1.4), which reveals that the induction period of TMTZ decreases with increase in supersaturation. The metastable zone width of TMTZ was found to be in the range 35-45 °C. The measured value of interfacial tension values found to vary from 0.9318 to 2.048 mJ/m².     

Role of oxygen content in the structural and the superconducting properties of high temperature superconducting ErBa2Cu3O y

Samples of high temperature superconducting system ErBa₂Cu₃O _y prepared by the standard ceramic technique were found to have single phase. To vary the oxygen content in the samples, the mother compound was reduced by vacuum-annealing at different temperatures for a fixed period. The oxygen content was measured by gravimetric and iodometric titration procedures. The structural changes induced due to the variations in the oxygen content were studied by X-ray methods.     

Cooperative effect of Zn and Ga doping in YBa2Cu3O7

The creation of local magnetic moments at the plane and chain Cu-sites in YBa₂Cu₃O₇ due to incorporation of Ga³⁺ and Zn²⁺ has been studied with respect to the superconducting transition temperature and structural parameters of the compound. The result indicates that the local moments are created due to slowing down of spin and charge fluctuations in the planes and chains respectively due to doping.     

Numerical and experimental analysis on tensile properties of banana and glass fibers reinforced epoxy composites

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