My groups’ research is focussed on developing novel optoelectronic materials by controlling the three-dimensional (3D) dimensions of semiconductors, polymers, noble metals, and superconductors. The motivation is twofold: to reveal novel electron-photon coupling physics, and to provide a platform for future technologies. Early work (1990’s) on photonic crystals led to a spin-off company which was one of the first to aggressively pursue CMOS-compatibly processed silicon-on-insulator as a photonics platform. That platform is now being widely developed world-wide, and the spin-off of our original spin-off, Lumerical Solutions Inc., is doing very well, based in Vancouver.
Current research thrusts are all based on exploiting this silicon photonics platform for quantum information purposes. We are working extensively with 5 nm diameter PbSe-based colloidal quantum dots (QD) as quantum emitters that can be integrated with silicon circuits. This is in close collaboration with chemists, and involves considerable fundamental characterization of the bare QDs, in addition to their integration with photonic circuits. We are working on a number of different processes for site-selectively binding the QD to the circuits, with ~ 20
nm resolution.
Our most recent projects involve introducing metals (Ag, Au in the form of metal nanoparticles (MNP), and NbTiN in the form of superconducting nanowires) to enhance the functionality of this platform. The MNPs are of intermediate dimensions (~ 30 nm), bridging the 5 nm scale of the QD, to the 500 nm scale of the photonic circuit elements. Plasmon resonances in these MNP can theoretically lead to exceedingly strong electron-photon coupling, but require the ability to control the separation of attached QD with single nanometre precision. We are collaborating with Bizzotto’s group to use DNA as a calibrated connector.
Commercial single photon infrared detectors are both exceedingly expensive, and noisy. There are therefore great benefits to be gained by integrating novel superconducting nanowire detectors directly onto the silicon waveguide platform, for single photon detection with orders of magnitude reduction in dark current as compared to commercial detectors. This involves the development of novel ebeam lithography and etching processes, currently all in-house.
All of these experimental efforts are in conjunction with extensive numerical modelling, both for the design of the structures, and understanding the results of experiments. We run our own cluster in AMPEL, and also make extensive use of Westgrid.
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