Al As ∕ Ga As micropillar cavities with quality factors exceeding 150.000

The authors report on AlAs∕GaAs micropillar cavities with unprecedented quality factors based on high reflectivity distributed Bragg reflectors (DBRs). Due to an increased number of mirror pairs in the DBRs and an optimized etching process record quality (Q) factors up to 165.000 are observed for micropillars with diameters of 4μm. Optical studies reveal a very small ellipticity of 5×10−4 of the pillar cross section. Because of the high Q factors, strong coupling with a vacuum Rabi splitting of 23μeV is observed for micropillars with a diameter of 3μm.