Spatial emission characteristics of a semiconductor microtube ring resonator

We demonstrate preferential and directional emission from a rolled up semiconductor microtube ring resonator with a quantum well embedded as an optically active material. The emission of resonant optical modes appears preferentially at the inside edge of the tube with a direction 60∘ to the tangent of the ring. The emission of leaky modes shows an entirely different behavior. Here, tangential emission seems to be preferred at both the inside and the outside edge.