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A microstructural characterization was made on YBa2Cu3O7 samples prepared by on a step-edged substrate as well as TlBa2Ca2Cu3Ox (Tl-1223) polycrystalline films with single grain boundaries. The study investigated the activation energy via measurements of current conduction across each material's grain boundaries. It revealed the influence of a polycrystalline's grain boundaries on the negative curvature of the Tl-1223 sample.

The impact of a substrate's geometry on the microsructural development and superconducting characteristics of epitaxial Tl2Ba2CaCu2Ox thin films prepared on LaAlO3 and SrTiO3 is studied. The experiment measured the films's critical current density and resistivity for magnetic fields parallel to the substrate twins. It reveals the occurence of resistivity drops and higher critical current density at fields above 2 T for the LaAlO3-grown films.

The current status of fiber based optical parametric oscillators is presented with a focus on pulsed systems employing microstructure fibers. It is shown based on standard expressions for parametric processes in optical fibers that systems employing short (less than a few cm) optical fibers lead to superior performance in terms of wavelength tunability and output power. Practical guidelines for realizing a working system are given. These devices are now practical as ultrafast pulsed-light sources and for extending the wavelengths of operation of existing mode-locked fiber lasers. [ABSTRACT FROM PUBLISHER]

A microstructure-fibre-based optical parametric amplifier with a gain slope of ∼200 dB/W/km in the 1550 nm range is demonstrated, for the first time to the authors' knowledge. By using only 12.5 m-long fibre, gains were obtained of >20 dB over a bandwidth of approximately 30 nm, achieving a peak net gain of 25.4 dB. [ABSTRACT FROM AUTHOR]