Far field radiation pattern from quantum boxes located in micropillars

Due to a lower mode volume, 3D structures lead to higher radiative lifetime reduction and a measured Purcell factor of 5 has been reported recently for quantum boxes located in micropillar cavities. Since this type of structure is etched from a planar microcavity it is interesting to study the emission directivity for different pillar diameters. We observe a broadening of the angular emission (/spl lambda/=932 nm) when the pillar diameter decreases. Other investigations concerning the angular behaviour for the various discrete modes show that the angular radiation pattern is strongly wavelength dependent and results both from planar microcavity effects and mode diffraction.