Quantum dots in a tube as light emitters, waveguides and ring resonators

We present micro‐photoluminescence investigations of InAs quantum dots (QDs) integrated into self‐rolling InGaAs/GaAs strained layers. Light, which originates from the QDs at the laser excitation spot and propagates with a component parallel to the tube axis (kz ≠ 0), can be detected at the tube ends using a special μ‐PL method, which features independent locations of excitation and collection. With light collection in the vicinity of the laser excitation spot we detect sharp peaks in the spectrum, which we attribute to constructive interference of light circulating around the tube axis (kz = 0). The spectral positions and shapes of these whispering gallery mode‐like resonances as well as the spatial mode distribution inside the tube are modeled using calculations based on the finite difference time domain method.