Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 58: Photonic Crystals: Experiment

HL 58.4: Talk

Thursday, March 25, 2010, 16:45–17:00, H13

Optical Microresonators Fabricated by Epitaxial DBR Overgrowth of Pyramidal GaAs Cavities — •Daniel Rülke, Matthias Karl, Dongzhi Hu, Daniel M. Schaadt, Heinz Kalt, and Michael Hetterich — Institut für Angewandte Physik and DFG Center for Functional Nanostructures (CFN), Karlsruher Institut für Technologie (KIT), 76131 Karlsruhe, Germany

Based on the fabrication technique of recently investigated pyramidal GaAs microresonators, we have developed a method to create microcavities with the shape of truncated pyramids sandwiched between two distributed Bragg reflectors (DBRs). To this end, an AlAs sacrificial layer is utilized for facet formation in a wet-chemical etching process. The sacrificial layer is then removed in a selective etching step and, after a further selective etching step, truncated pyramids with a DBR underneath are obtained. Overgrown with a second DBR on top, these cavities serve as high-quality (Q) resonators with observed Q-factors of optical modes up to 8000. Compared to conventional cylindric pillar-resonators their smooth facet angle of about 20^∘ promises reduced scattering losses at the edges of the cavity and a reduced density of leaky modes.