Giving to CREOL
CREOL, The College of Optics & Photonics

Seminar: "Photonics at the Exceptional Points: From Optical Sensing to Optomechanics" by Sahin K. Özdemir

Thursday, December 7, 2017 11:00 AM to 12:30 PM
CREOL Room A214

Sahin K. Özdemir
Department of Engineering Science and Mechanics
Pennsylvania State University


Whispering-gallery-mode (WGM) microresonators have emerged as excellent platforms for optical sensing, cavity-QED, optomechanics, low threshold lasing, and most recently for the realization of parity-time (PT) symmetry in optics. They represent open physical systems due to optical losses originating from absorption, coupling and radiation, and thus they are characterized by non-Hermitian Hamiltonians. By engineering their loss/gain profiles and coupling to other systems, WGM resonators can be brought to a non-Hermitian degeneracy known as an exceptional point (EP), where complex eigenvalues and the corresponding eigenstates of the system coalesce. The presence of an EP affects the system significantly, leading to nontrivial physics with interesting features. In this talk, after briefly reviewing the physics and the applications of WGM microresonators that we have developed in the past few years (e.g., detection and characterization of single nanoparticles, nonreciprocal light transmission, loss-induced lasing, etc), I will discuss the control of optical processes in WGM microresonators by operating them in the vicinity of EPs. I will discuss how we use these resonators to demonstrate enhanced optical sensing beyond what is capable with conventional optical sensors, and how EPs affect optomechanical interactions and phonon lasing. I will end the talk giving a brief summary of other interesting phenomena we study with WGM resonators and discussing some of the opportunities and challenges in photonics research, in particular within the framework of non-Hermitian optics.


Dr. Özdemir is an Assoc. Prof. of Engineering Science and Mechanics at Pennsylvania State University. Before joining Penn State, he was with Washington University in St. Louis (2009-2017). He received his BSc (1992) and MSc (1995) from the Middle East Technical University, Turkey, and PhD (2000) from Shizuoka University, Japan, all in electrical and electronics engineering. During 2000-2009 he was with The Graduate University for Advanced Studies and then with Osaka University working as project leader and senior scientist for various research programs of Japan Science and Technology Agency (JST) on photonic quantum information processing. Dr Özdemir has authored over 120 peer-reviewed papers on topics ranging from quantum photonics, PT-symmetric optics, and plasmonics to microcavities, optical sensing and optomechanics. He is a member of OSA and a senior member of IEEE.

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Mercedeh Khajavikhan

Demetrios Christodoulides

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