High-Quality-Factor WG Modes in Semiconductor Microcavity Pillars with Circular and Elliptical Cross Section

We observed whispering gallery resonances (WGMs) in semiconductor micropillars by employing geometry in which both excitation and collection of emission is in a direction normal to the sidewall surface of the pillars. The spectral positions of the peaks are found to be in a good agreement with the results of numerical modeling performed by finite difference time domain technique. The quality factors of WGMs (Q ~ 20000 for the 4-5 mum circular pillars) are found to be well in excess of Q-factors for the low k-vector "photonic dot" states measured from the same pillars. Due to high Q-factors and small modal volumes ~0.3 mum3 such WGM resonances can be used in cavity quantum electrodynamics experiments.