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We demonstrate the influence of edge effects on the photothermal-induced phase shift measured by a homodyne quadrature laser interferometer and compare the experiments with rigorous theoretical descriptions of thermoelastic surface displacement of metals. The finite geometry of the samples is crucial in determining how the temperature is distributed across the material and how this affects the interferometer phase shift measurements. The optical path change due to the surface thermoelastic deformation and thermal lens in the surrounding air is decoded from the interferometric signal using analytical and numerical tools. The boundary/edge effects are found to be relevant to properly describe the interferometric signals. The tools developed in this study provide a framework for the study of finite size effects in heat transport in opaque materials and are applicable to describe not only the phase shift sensed by the interferometer but also to contribute to the photothermal-based technologies employing similar detection mechanisms. [ABSTRACT FROM AUTHOR]

Energy transfer processes in Yb3+-Tb3+ co-doped, low-silica calcium aluminosilicate glasses were analyzed. Luminescence and time-resolved measurements were used to study upconversion processes, such as Yb-Tb cooperative sensitization, Yb-Yb cooperative luminescence, and Yb-Tb cross relaxation. The quantum cross relaxation efficiency was evaluated as a function on the Yb3+ concentration, and the maximum estimated value was approximately 51%. In addition, the intensity of the upconversion luminescence from the Tb3+:5D4 level decreased by two orders of magnitude comparing the value at room temperature with that at 123 K. As a consequence, Yb-Yb cooperative luminescence around 500 nm became comparable with the intensity of upconversion from the Tb3+:5D4 level. Furthermore, a dependence of the upconversion kinetics luminescence on temperature was observed. The upconversion rise time was constant and equal to 65 μs for temperatures between 296 to 473 K and decreased from 65 to 19 μs, without variation in the decay part, when the temperature was lowered from 296 to 123 K. These results were explained by a phonon-assisted cooperative sensitization process for the population of the Tb3+:5D4 level. [ABSTRACT FROM AUTHOR]