Circuits & Devices

Friday Nov 16, 2018 at 2:00 p.m. Mario Dagenais, Professor in the Department of Electrical and Computer Engineering, University of Maryland, will be presenting “Photonics Integration for Applications in Astrophotonics and Quantum Information”. Day & Time: Friday November 16th, 2018 2:00 p.m. ‐ 3:00 p.m. Speaker: Mario Dagenais Professor in the Department of Electrical and Computer Engineering, University of Maryland Organizers: IEEE Toronto Circuits & Devices Chapter Location: Room SF1101 10 King’s College Rd, Toronto, ON M5S 3G4 Contact: Mengqi Wang Abstract: We will describe our work on optical integration on a chip, in particular how to realize a complex waveguide Bragg grating for rejecting several emission lines from the atmosphere for astronomical observation and how to implement an integrated spectrometer based on Arrayed Waveguide Gratings (AWGs) or on echelle gratings. We will also present our work for creating an on-chip ultra-high rejection filter (> 100 dB) for applications in quantum information. Biography: Professor Dagenais’ research interests are in photonics integration, high efficiency photovoltaic conversion, and nitride optoelectronics. Professor Dagenais received his Ph.D. from the University of Rochester in 1978 working in Quantum Optics and photon correlations under the direction of Professor Mandel. Together with Jeff Kimble, he made the first observation of photon antibunching. He was a Research Fellow at Harvard University from 1978 to 1980, where he worked in nonlinear optics with Professor Bloembergen. From 1980 to 1987, he worked at GTE Laboratories on photonic switching and semiconductor lasers. He joined the University of Maryland in 1987 where he has been Professor of Electrical and Computer Engineering since 1991. He has more than 300 archival and conference publications. He has co-chaired several national and international meetings. Professor Dagenais is a Fellow of the Optical Society of America, a Fellow of IEEE, and a Fellow of the Electromagnetic Society.

Monday, September 24th 2018, Wei Jiang, Professor in the College of Engineering and Applied Sciences at Nanjing University, and an Associate Director of Optical Communications Systems & Network Engineering Research Center of Jiangsu Province will be presenting “Silicon Photonics: High-Density Integration for Novel Functionality”. Day & Time: Monday September 24th, 2018 2:00 p.m. ‐ 3:00 p.m. Speaker: Wei Jiang Professor in the College of Engineering and Applied Sciences at Nanjing University, Associate Director of Optical Communications Systems & Network Engineering Research Center of Jiangsu Province Organizers: Amr S. Helmy and IEEE Toronto Circuits & Devices Chapter Location: Room SFB 560 10 King’s College Rd, Toronto, ON M5S 3G4 Contact: Mengqi Wang Abstract: Silicon photonics can potentially transform the photonics technology owing to its low-cost fabrication and large-scale integration advantages. Integration can open up new opportunities, such as solid-state LIDARs for autonomous vehicles and chip-scale optical interconnects. To realize these opportunities, reducing device size and increasing integration density will be crucial. Towards these directions, this talk will discuss our recent experimental work on novel micro/nano-photonic structures, including photonic crystals, waveguide superlattices, and free-form structures. (1) A waveguide superlattice is introduced to enable low-crosstalk, high-density waveguide integration at half-wavelength pitches, which opens the door to high-performance optical phased arrays, next-generation LIDARs, and high-density space-division multiplexing. (2) Novel free-form structures are explored to create an ultra-short waveguide “taper”. Interestingly, the evolutionary algorithm yields an optimal structure with anomalous shapes. Through wavefront analysis, the role of a subtle “semi-lens” is identified. (3) Further opportunities in slow-light photonic crystal switches/modulators will also be briefly discussed. In many cases, underpinning physics needs to be fully understood first, and then be formulated into precise theory to guide experiments and achieve viable results. Biography: Wei Jiang is a professor in the college of engineering and applied sciences at Nanjing University, and an associate director of Optical Communications Systems & Network Engineering Research Center of Jiangsu Province. Prior to working at NJU, he was an associate professor in the department of electrical and computer engineering at Rutgers, the State University of New Jersey, USA. His current research interests include silicon photonics, photonic crystals, nanophotonics, and their applications in optical interconnects, communications, sensing, and computing. He contributed to the fundamental understanding of silicon electro-optic and thermo-optic devices, high-density waveguide integration, slow light, superprism effects, and photonic crystal interface properties. He received his B.S. degree in physics from Nanjing University, and his M.A. degree in physics and his Ph.D. degree in electrical and computer engineering from the University of Texas, Austin. Prof. Jiang received the DARPA Young Faculty Award, and IEEE Region I Outstanding Teaching Award, among other honors.

Wednesday May 31, 2017 at 2:10 p.m. Kei May Lau, Fang Professor of Engineering and Chair Professor at the Hong Kong University of Science and Technology will be presenting “InAs Quantum Dot Micro-disk Lasers Grown on Exact (001) Si Emitting at Communication Wavelengths”. Day & Time: Wednesday May 31, 2017 2:10 p.m. – 3:00 p.m. Speaker: Kei May Lau Fang Professor of Engineering and Chair Professor Department of Electronic and Computer Engineering Hong Kong University of Science and Technology Location: Room BA 1220 40 St. George Street Toronto, ON M5S 2E4 Contact: Junho Jeong Organizers: IEEE Toronto Photonics Society Abstract: To support an energy-efficient optical interconnect technology enabled by silicon photonics, development of low-energy-consumption active devices and the corresponding integration technology is needed. Most communication wavelength lasers with excellent device performance have been grown on III-V substrates and bonded to silicon. For integration, there are considerable advantages in a technology that allow growth and fabrication of such lasers on III-V/ Si compliant substrates. Quantum dot (QD) active layers grown on lattice-matched substrates have already shown their capability for lasers with low-threshold densities and temperature-independent operation. In addition, the reduced sensitivity of QD to defects and their unique capability of filtering dislocations make them an ideal candidate as the gain medium of hetero-integrated III-V on Si optical sources. In this talk, I will discuss the growth of multi-stack QDs on compliant substrates by MOCVD. Fabrication and laser characteristics of whispering-gallery-mode (WGM) micro-disk lasers using the grown epitaxial structures will also be discussed. Initial demonstration was achieved using simple a colloidal lithography process in combination with dry and wet-etching. The micro-disk lasers were one to four microns in diameter, with single mode lasing at either 1.3 or 1.55 μm, depending on the barrier/cladding system. With smooth sidewalls and sufficient undercut by wet etching of the pedestal, the air-cladded MDs exhibit ultra-low thresholds of a few mW by optical pumping. Preliminary results of electrically-pumped micro-lasers will also be presented. These energy-efficient microlasers are excellent candidates for on-chip integration with silicon photonics. Biography: Professor Kei May Lau is Fang Professor of Engineering at the Hong Kong University of Science and Technology (HKUST). She received the B.S. and M.S. degrees in physics from the University of Minnesota, Minneapolis, and the Ph.D. degree in Electrical Engineering from Rice University, Houston, Texas. She was on the ECE faculty at the University of Massachusetts/Amherst and initiated MOCVD, compound semiconductor materials and devices programs. Since the fall of 2000, she has been with the ECE Department at HKUST. She established the Photonics Technology Center for R&D effort in III-V materials, optoelectronic, high power, and high-speed devices. Professor Lau is a Fellow of the IEEE, and a recipient of the US National Science Foundation (NSF) Faculty Awards for Women (FAW) Scientists and Engineers (1991) and Croucher Senior Research Fellowship (2008). She is an Editor of the IEEE EDL and Associate Editor of Applied Physics Letters.