Enhanced light extraction from circular Bragg grating coupled microcavities

A sevenfold enhancement of light extraction over a 130nm bandwidth from a semiconductor at room temperature was achieved using circular Bragg gratings (CBGs) etched around the periphery of a vertical-cavity light-emitting structure. The CBG defined an in-plane circular cavity for light trapped in guided modes. Maximum enhancement was observed with CBGs that efficiently coupled circular cavity modes into resonant extracted modes of the vertical cavity. The enhancement factor corresponded to a 41% external efficiency.