Behrad Gholipour
University of Alberta

Abstract

Photonic metamaterials research is driving the development of a variety of innovative devices with unprecedented functionalities. Recently, research in this field has recognized and sought solutions to the application-dependent technological drawbacks of reliance upon noble plasmonic metals, including optical losses, low-melting-points, cost and CMOS-incompatibility. The quest for alternative material platforms now encompasses chalcogenide semiconductors, transparent conductive oxides, nitrides, and 2D materials. Among these material platforms, our work centres around devices made from alloys of sulfur, selenium, tellurium and oxygen often referred to as chalcogenide glasses, as they offer a highly versatile material platform for various nanophotonic applications. They present various high- and low-index dielectric, low-epsilon and plasmonic properties across ultra-violet (UV), visible and infrared frequencies, in addition to an ultra-fast, non-volatile, electrically or optically induced switching capability between amorphous and crystalline phase states with markedly different electromagnetic properties. Additionally, in this domain, refractory graded-index metal-oxides that can be grown as large area metacoatings with tunable structural colour and amorphous photo-ionic metal-selenides that offer non-volatile reconfiguration without the need for a phase transition, also offer highly versatile and overlooked material platforms for the realization of a range of reconfigurable and adaptive optoelectronic devices.

In this talk, I will give a brief overview of our activities at the Nanoscale Optics Lab at the University of Alberta where we are exploring graded-index and photo-tunable metal-chalcogenides as highly versatile alternative material platforms for various free-space and integrated nanophotonic devices with applications in computing, sensing, display and telecommunications.

Bio

Dr Behrad Gholipour, is Assistant Professor of Photonics at the Electrical and Computer Engineering Department at the University of Alberta, Edmonton, Canada, where he established and leads the Nanoscale Optics Lab (www.nanoscaleoptics.com) and the Alberta Metal-Chalcogenide Manufacturing Facility (AM2F). He is widely recognized for his seminal work in the design and manufacturing of reconfigurable nanoscale free-space and integrated optoelectronic devices using chalcogenide and perovskite semiconductors. His work has resulted in >100 peer reviewed journal and conference publications, including multiple high-profile publications in Science, Nature Materials, Nature Photonics, Nature Communications and Advanced Materials journals, many of which have been chosen as magazine cover articles. He is also the holder of one US patent and a frequent referee for >10 leading publications in optoelectronics, material science and physics. His research has over the years also gained high public interest as evident by the plethora of news articles published about his work in trade and day-to-day magazines, websites and blogs including Yahoo news, Physics World, Engadget, Electronics Weekly and Science Daily. He is also the recipient of the UK ICT Pioneer and Petro-Canada Young Innovator awards. He serves as an editorial board member of the IOP Journal of Optics and Wiley Advanced Photonics Research and a member of the program committee of SPIE Metamaterials conference. He is also a frequent organizer of various symposia and has served as guest-editor for a number of nanotechnology, materials and optics journals.

Larry Widrow
Queen's University

Abstract

The disk of the Milky Way comprises some 100 billion stars on nearly circular orbits about the Galactic centre. Within a few years, the Gaia Space Telescope will measure positions and velocities for over 1% of these stars. By combining equilibrium models of the Galaxy with these observations we can construct the Galactic rotation curve, which allows us to infer the large-scale structure of the dark matter halo. We can also construct a model for the mass distribution in the Solar Neighbourhood, which allows us to infer the local density of dark matter. However, even a cursory study of the Milky Way reveals structures that signal a departure from equilibrium. The most prominent of these are the Galactic bar, spiral arms, and warping of the outer disk. I will describe recent observations of some more subtle departures from equilibrium and discuss ways in which these observations can lead to refined models of the Galaxy and a more complete picture of the Galaxy's dynamics.