Nonlinear optics, a research area that is emerged after the invention of laser in 1960, continues to be widely explored with a broad range of applications from optical communication and spectroscopy to quantum photonics. A long-standing goal is to realize nonlinear optical structures at progressively low optical power and electrically-tunable, which is difficult given the small nonlinear coefficients of bulk materials. Currently, there arises a new type of 2D nonlinear optical materials with fascinating properties such as broadband saturable absorption and ultrafast carrier dynamics with a large nonlinear refractive index. Graphene with the ease of fabrication, compatibility with CMOS technology and silicon photonics is a strong contender for a new class of optoelectronic and photonic devices and circuits well-suited for both classical and quantum systems. In this talk, I will first review graphene’s relevant physics for its application in nonlinear optics complemented by our theoretical work on the quantum treatment of its nonlinear Kerr coefficient. This includes how the Kerr coefficient can be electrically-tuned for device operation as well as new physics of anomalous optical saturation. I will then present our systematic experimental investigation of measuring Kerr coefficient through optical self modulation effect, with an emphasis on its wavelength dependence and temporal evolution via combined z-scan and pump-probe measurements. Finally, I will present our experimental work on ultrafast optical modulation/switching and bistability in a hybrid graphene-silicon photonic crystal nanocavities providing a world-record of modulation/switching speed and depth with the lowest optical power for an integrated nonlinear silicon-based photonic devices.
Hamed was born in Tehran, Iran and did his BSc. in Electrical Engineering (Major in Telecommunications) at K. N. Toosi University of Technology, Tehran, Iran. He received his MSc. in Electrical Engineering (Major in Electromagnetic Fields & Waves) from AmirKabir University of Technology with honors. In 1998, he joined the Department of Electrical & Computer (E&CE) at the University of Waterloo and obtained his PhD with distinction on December 2001. After his PhD, he spent 10 months as a postdoctoral fellow in Department of E&CE, focusing on superconducting single photon detectors and THz photonic devices and then moved to Institute for Quantum Computing (IQC) as a Research Assistant Professor where he established Integrated Quantum Optoelectronics Lab (IQOL). He becomes an Assistant Professor at Department of E&CE in 2005, and Department of Physics & Astronomy at University of Waterloo. He was promoted with tenure to the rank of Associate Professor in 2010 and to the rank of full professor in 2015. In 2012, he spent his sabbatical at Harvard School of Engineering and Applied Sciences. He offered graduate courses in Quantum Electronics & Photonics and Modern Optics in applied physics program and Applied Quantum Mechanics for Undergrad students at Harvard University. He has held a visiting associate professor position at Harvard University till end of 2013. He has been a faculty member at IQC from 2005 to 2014. He has been the primary guest editor in special issue of "Superconducting Quantum Electronics & Photonics" in IEEE Journal of Selected topics in Quantum Electronics for March/April 2015 issue. He is elected to be in the editorial board of Nature Scientific Report from 2015. In 2018, he has received an IDEX fellowship from Universite de Bordeaux in France and spend summer 2018 to conduct a research on graphene’s magnetophotonics at Bordeaux Institut d’Optique. He is an affiliate member of Perimeter Institute for Theoretical Physics (PI) and Waterloo Institute for Nanotechnology. He is a senior member of IEEE and APS.