Diffraction of cylindrical Bragg reflectors surrounding an in-plane semiconductor microcavity

In-plane microresonators consisting of an AlxGa1-xAs heterostructure wavegu ide and deep etched cylindrical trenches give both out-of-plane and lateral -light confinement. The air trenches, acting as a Bragg reflector also allo w diffraction into air, so that the far-field pattern reveals interesting i nformation on the resonant cavity modes. By the use of a two-dimensional cy lindrical model and a transfer-matrix method based on Hankel functions, the energy and angular dependences of the diffracted field are calculated and successfully compared to measurements.