Quantum dot lasers epitaxially grown on Si are promising for an efficient light source for silicon photonics. Recently, considerable progress has been made to migrate 1.3 μm quantum dot lasers from off-cut Si to on-axis (001) Si substrates. Here, we report significantly improved performance and reliability of quantum dot lasers enabled by a low threading dislocation density GaAs buffer layer. Continuous-wave threshold currents as low as 6.2 mA and output powers of 185 mW have been achieved at 20 °C. Reliability tests after 1500 h at 35 °C showed an extrapolated mean-time-to-failure of more than a million hours. Direct device transparency and amplified spontaneous emission measurements reveal an internal optical loss as low as 2.42 cm −1 and injection efficiency of 87%. This represents a significant stride toward efficient, scalable, and reliable III−V lasers on onaxis Si substrates for photonic integrate circuits that are fully compatible with CMOS foundries.

High performance III-V lasers at datacom and telecom wavelengths on on-axis (001) Si are needed for scalable datacenter interconnect technologies. We demonstrate electrically injected quantum dot lasers grown on on-axis (001) Si patterned with {111} v-grooves lying in the [110] direction. No additional Ge buffers or substrate miscut was used. The active region consists of five InAs/InGaAs dot-in-a-well layers. We achieve continuous wave lasing with thresholds as low as 36 mA and operation up to 80°C.

We report InAs/InGaAs quantum dot (QD) waveguide photodetectors (PD) monolithically grown on silicon substrates. A high-crystalline quality GaAs-on-Si template was achieved by aspect ratio trapping together with the combined effects of cyclic thermal annealing and strain-balancing layer stacks. An ultra-low dark current of 0.8 nA and an internal responsivity of 0.9 A/W were measured in the O band. We also report, to the best of our knowledge, the first characterization of high-speed performance and the first demonstration of the on-chip photodetection for this QD-on-silicon system. The monolithically integrated waveguide PD shares the same platform as the previously demonstrated micro-ring lasers and can thus be integrated with laser sources for power monitors or amplifiers for pre-amplified receivers.

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Even at low Reynolds numbers, momentum can impact the shape of hydrodynamically focused flow. Both theoretical and experimental characterization of hydrodynamic focusing in microchannels at Reynolds numbers B25 revealed the important parameters that affect the shape of the focused layer. A series of symmetric and asymmetric microfluidic channels with two converging streams were fabricated with different angles of confluence at the junction. The channels were used to study the characteristics of Y-type microchannels for flow-focusing. Computational analysis and experimental results gathered using confocal microscopy and particle image velocimetry indicated that the orientation of the sheath and the sample stream inlets, as well as the absolute flow velocities, determine the curvature in the concentration distribution of the focused stream. Decreasing the angle of confluence between sheath and sample, as well as reducing the overall Reynolds number, resulted in a flat interface between sheath and focused fluids. Alignment of the faster flowing sheath fluid channel with the main channel also reduced the inertial effects and produced a focused stream with a flat concentration profile. Control over the shape of the focused stream is important in many biosensors and lab-on-a-chip devices that rely on hydrodynamic focusing for increased detection sensitivity.