Controlled Transfer of Single Rolled-Up InGaAs–GaAs Quantum-Dot Microtube Ring Resonators Using Optical Fiber Abrupt Tapers

We report on the controlled transfer of single rolled-up semiconductor microtube-based optical cavities from their host substrate to a foreign one. Such microtube devices, with diameters of ~5 ¿m, wall thicknesses of ~50 nm, and lengths of >100 ¿m, are fabricated by selectively releasing a coherently strained InGaAs-GaAs quantum-dot layer from the handling GaAs substrate. With the use of fiber abrupt tapers inserted into two ends of the tubes, rolled-up microtubes are lifted off from the substrate and subsequently transferred, with a precisely controlled position, onto the cleaved facet of a single-mode fiber. The resulting devices exhibit strong coherent emission at room temperature and may lead to integrated micro- and nanoscale lasers with greatly simplified packaging.