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A pair of copper bromide lasers in an oscillator-amplifier configuration was used to investigate the temperature dependence of the smallsignal gain, saturation intensity, and output power of the laser. The observations were explained in terms of the electron temperature and energy levels of transition. An optimum electrical input power of 1.6 kW and a corresponding operational temperature of 510 °C were determined for the maximum values of these parameters. The balance between the microscopic parameters, such as stimulated emission crosssection, laser upperlevel lifetime, and population inversion, which determine the behavior of the amplifying parameters and laser output power with respect to the operational temperature, has been investigated. We used the steadystate rate equation from the Hargrove model to determine the amplifying parameters, instead of the Frantz-Nodvik formula. The power extracted from the amplifier exceeds that achieved with the same device as the oscillator by more than 60%.

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Three steps anodization process is used to synthesize highly ordered and uniform multilayered titanium oxide (TiO 2 ) nanotubes and effect of different anodization voltages are studied on their physical properties such as structural, morphological and optical. The crystalized structure of the synthesized tubes is investigated by X-ray diffractometer analysis. To study the morphology of the tubes, field emission scanning electron microscopy is used, which showed that the wall thicknesses and the diameters of the tubes are affected by the different anodization voltages. Moreover, optical studies performed by diffuse reflection spectra suggested that band gap of the TiO 2 nanotubes are also changed by applying different anodization voltages. In this study using physical investigations, an optimum anodization voltage is obtained to synthesize the uniform crystalized TiO 2 nanotubes with suitable diameter, wall thickness and optical properties.

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