OSE Seminar by Prof. Vassilios Kovanis on Limit Cycles and Isochrons in Tunable Photonic Oscillators

Departmental News

Prof. Vassilios Kovanis

Posted: February 20, 2023

Speaker: Prof. Vassilios Kovanis; Virginia Tech, Arlington Virginia

Date: Thursday, February 23th, 2023

Time:  12:15 PM - 1:15 PM

Location:  CHTM, Room 103 & Zoom

Limit Cycle oscillators are used to model a broad range of periodic nonlinear phenomena. Using the Optically Injected Semiconductor Oscillator as a paradigm, we will demonstrate that at specific islands in the detuning and injection level map, the period-one oscillation frequency is simultaneously insensitive to multiple perturbation sources. In our system these include the temperature fluctuations experienced by the master and slave lasers as well as fluctuations in the bias current applied to the slave laser. Tuning of the oscillation frequency then depends only on the injected optical field amplitude. Experimental measurements are in good quantitative agreement with numerical modeling and analysis based on reduced generalized Adler type equations. These special operating regions should prove valuable for developing ultra-stable nonlinear oscillators, such as sharp linewidth, frequency tunable photonic microwave oscillators. Finally, the concept of an Isochron originally developed in Mathematical Biology will be reviewed and placed for efficient design of stable frequency sources via systems of coupled limit cycle oscillators.


Vassilios Kovanis is serving as a Virginia Tech Innovation Campus Founding Faculty and Collegiate Professor at the Bradley Department of Electrical and Computer Engineering at Virginia Polytechnic Institute and State University. He is Directing the Virginia Tech Masters (EE & CPE) at the Innovation Campus and Coordinating the Project Based learning of this graduate program. The MEng has the following five emphasis areas, Quantum Engineering, Machine Learning and Applications, Secure Information Systems and Networks, Electronic Power Systems, Signal Processing, Learning and Communication Systems. Vassilios past work experience includes faculty positions at the University of New Mexico, Albuquerque, New Mexico, at the Rochester Institute of Technology, Rochester, New York. And he served as the Chair of the Department of Physics from 2015 to 2019 in Astana KZ at Nazarbayev University. He was credited with establishing an Applied Physics Department at the bottom of the steppe via injection of US innovation culture. During the five years he recruited hired and onboarded an international expatriate team of research professionals as faculty to teach, mentor and establish research portfolios, as well advocated to the students to continue their careers to graduate schools in flagship US R1 institutions. He served as the technical advisor of the photonics technologies branch at the Air Force Research Laboratory, Dayton Ohio. The branch had over twenty staff members and was operating a whole host of laboratories, fabrication facilities as well as managing a set of national photonic initiatives. His responsibilities included directing and executing an Air Force Office of Scientific Research line for photonic oscillators and quantum dot multi section devices for generation of diverse waveforms. He also worked as a DARPA agent for microwave photonics, high precision oscillators and transformational antenna programs. He was the lead technical program manager on the optical metamaterials enterprise mandated by the Office of the Secretary of Defense.