Optical Microtube Ring Resonators

In this work, we demonstrate that semiconductor microtubes fabricated by utilizing the self-rolling mechanism of epitaxially grown strained bilayers can act as optical ring resonators. The mode structure is probed by the photoluminescence of an optically active material, i.e. self-assembled quantum dots, embedded inside the microtube wall. We find a spectrum of sharp modes, which is in very good agreement with the result of a theoretical modelling of the microtube as a closed thin dielectric waveguide. This novel kind of microcavity, in which the optically active material is intrinsically located close to the optical field maximum, is a good candidate for both, new optoelectronic devices and cavity quantum electrodynamic experiments.