Quantum dot nonlinearity through cavity-enhanced feedback with a charge memory

In an oxide apertured quantum dot (QD) micropillar cavity-QED system, we found strong QD hysteresis effects and lineshape modifications even at very low intensities corresponding to less than 0.001 intracavity photons. We attribute this to the excitation of charges by the intracavity field; charges that get trapped at the oxide aperture, where they screen the internal electric field and blueshift the QD transition. This in turn strongly modulates light absorption by cavity QED effects, eventually leading to the observed hysteresis and lineshape modifications. The cavity also enables us to observe the QD dynamics in real time, and all experimental data agrees well with a power-law charging model. This effect can serve as a novel tuning mechanism for quantum dots.Comment: 7 pages, 6 figure

Polarization degenerate solid-state cavity quantum electrodynamics

Quantum Matter and Optic

High-efficiency, high-speed VCSELs for optical interconnects

High-efficiency, high-speed, tapered-oxide-apertured vertical-cavity surface-emitting lasers (VCSELs) emitting at 980 nm have been demonstrated. By carefully engineering the tapered oxide aperture, the mode volume can be greatly reduced without adding much optical scattering loss for the device sizes of interest. Consequently, these devices can achieve higher bandwidth at lower current and power dissipation. In addition, the parasitics are reduced by implementing deep oxidation layers and an improved p-doping scheme in the top mirror. Our devices show modulation bandwidth exceeding 20 GHz, a record for 980 nm VCSELs. Moreover, 35 Gb/s operation has been achieved at only 10 mW power dissipation. This corresponds to a data-rate/power-dissipation ratio of 3.5 Gbps/mW. Most importantly, our device structure is compatible with existing manufacturing processes and can be easily manufactured in large volume making them attractive for optical interconnects