Self-induced thermal nonlinearities in InGaAsP microtubes at telecom wavelengths

We demonstrate, for the first time, dynamical thermal effects in InGaAsP microtubes at telecom wavelengths. Such effect can be avoided or exploited for passive or active applications by choosing appropriate resonance wavelengths. \ua9 2012 OSA.Peer reviewed: YesNRC publication: Ye

Optically pumped rolled-up InAs/InGaAsP quantum dash lasers at room temperature

We have investigated the fabrication and optical performance of free-standing rolled-up InGaAsP tube optical cavities, wherein self-organized InAs quantum dots or dashes are incorporated as the gain media. Such tubular optical cavities are formed when the coherently strained InAs/InGaAsP quantum dot/dash nanomembrane is selectively released from the host substrate. We have achieved lasing from rolled-up InAs/InGaAsP quantum dash microtubes at room temperature under continuous wave optical pumping. The measured threshold is 3c6 W, and the Purcell factor and the spontaneous emission coupling factor are estimated to be 3c6.54 and 3c0.87, respectively. \ua9 2013 IOP Publishing Ltd.Peer reviewed: YesNRC publication: Ye

Dynamical thermal effects in InGaAsP microtubes at telecom wavelengths

We report on the observation of a dynamical thermal effect in InGaAsP microtubes at telecom wavelengths. The microtubes are fabricated by releasing a strained semiconductor bilayer and are picked up by abruptly tapered optical fibers for subsequent coupling with adiabatically tapered optical fibers. As a result of absorption by InAs quantum dots embedded in the tube structure, these microtubes show dynamical thermal effects at wavelengths around 1525 nm and 1578 nm, while they are passive at longer wavelengths near 1634 nm. The photon absorption induced thermal effect is visualized by generating a pair of microbottles. The dynamical thermal effect can be avoided or exploited for passive or active applications by utilizing appropriate resonance wavelengths. \ua9 2012 Optical Society of America.Peer reviewed: YesNRC publication: Ye

Three-fold Symmetric Doping Mechanism in GaAs Nanowires

A new dopant incorporation mechanism in Ga-assisted GaAs nanowires grown by molecular beam epitaxy is reported. Off-axis electron holography revealed that p-type Be dopants introduced in situ during molecular beam epitaxy growth of the nanowires were distributed inhomogeneously in the nanowire cross-section, perpendicular to the growth direction. The active dopants showed a remarkable azimuthal distribution along the (111)B flat top of the nanowires, which is attributed to preferred incorporation along 3-fold symmetric truncated facets under the Ga droplet. A diffusion model is presented to explain the unique radial and azimuthal variation of the active dopants in the GaAs nanowires