Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 86: Semiconductor Lasers

HL 86.3: Talk

Thursday, March 29, 2012, 15:30–15:45, EW 015

Influences on random laser modes in dependence of their localization strength — •Janos Sartor, Daniel Schneider, Felix Eilers, and Heinz Kalt — Karlsruher Institut für Technologie (KIT) Karlsruhe

In a strongly scattering medium that provides optical gain, laser activity can be observed without an external resonator. In a so called random laser the coherent feedback is provided by multiple scattering. Optically pumped ZnO powders with a grain size in the order of the emitted wavelength provide optical gain and strong scattering at the same time and can therefore be used to examine random lasing activity. In our work we want to discuss important influences on the lasing properties like the temperature or the mean free path of light, which can be controlled by using powders with different grain sizes. When the mean free path is close to the limit where localization of light can occur, two different kinds of modes can be observed. Either modes that extend over large areas of the sample or strongly localized ones. We use samples of reduced size to reduce the strong fluctuations usually found for random lasers in order to be able to examine the behavior of single lasing modes. They behave different under influences like sample size or excitation density.