Enhanced mode extraction in AlO/sub x//GaAs microcavity pillars and circular gratings

Here we report enhanced spontaneous emission intensity in AlOx/GaAs micropillars with InGaAs quantum dot (QD) ensemble emitters, measured using photoluminescence (PL). The PL from the QD ensemble was emitted into discrete transverse micropillar modes. We then measured the PL spectrum of pillars whose outer rim is replaced with an increasing number of concentric rings to form a high-order circular grating. As more periods were added to the grating, narrow transverse micropillar mode emission was suppressed and became dominated by a broad grating-extracted mode.