Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 37: ZnO: devices

HL 37.2: Talk

Wednesday, March 25, 2009, 16:30–16:45, POT 51

Localized modes in ZnO random lasers — •Johannes Fallert, Janos Sartor, Roman J. B. Dietz, Daniel Schneider, Viktor Zalamai, Claus Klingshirn, and Heinz Kalt — Institut für Angewandte Physik, Universität Karlsruhe (TH), Germany

Zinc oxide nanoparticles can act as gain and scattering medium in a random laser where light emission can be significantly amplified. In this work we focus on the degree of spatial localization for random lasing modes. By investigating the laser emission of defined micro-structured fields, filled with nanocrystalline ZnO powder, we can easily allocate the position of the differently localized modes in SEM images of the sample. The observed emission lines can be attributed to modes provided by random alignment of ZnO nanoparticles at a certain position within the field while emission from single, large grains can be excluded. Recent theoretical papers predict that strongly localized and even extended modes lead to random lasing [1]. In agreement with these predictions we observe the coexistence of laser modes with strong as well as weak localization.

[1] D.S. Wiersma, Nature Physics 4, 359 (2008)