Single rolled-up InGaAs/GaAs quantum dot microtubes integrated with silicon-on-insulator waveguides

We report on single rolled-up microtubes integrated with silicon-on-insulator waveguides. Microtubes with diameters of similar to 7 mu m, wall thicknesses of similar to 250 nm, and lengths greater than 100 mu m are fabricated by selectively releasing a coherently strained InGaAs/GaAs quantum dot layer from the handling GaAs substrate. The microtubes are then transferred from their host substrate to silicon-on-insulator waveguides by an optical fiber abrupt taper. The Q-factor of the waveguide coupled microtube is measured to be 1.5x10(5), the highest recorded for a semiconductor microtube cavity to date. The insertion loss and extinction ratio of the microtube are 1 dB and 34 dB respectively. By pumping the microtube with a 635 nm laser, the resonance wavelength is shifted by 0.7 nm. The integration of InGaAs/GaAs microtubes with silicon-on-insulator waveguides provides a simple, low loss, high extinction passive filter solution in the C+L band communication regime. (C) 2011 Optical Society of America