PHYS SEMINAR:A Fistful of Research: Metamaterials, plasmonics....

Guest: Kaan Güven 

Title: A Fistful of Research: Metamaterials, plasmonics and nonlinear photonics

Date/Time: 30 May 2024, 13.40

Location: FENS L062

Abstract:In this multi-partitioned talk, I present an overview of our recent studies. The first part is on electromagnetic metamaterials. I start by reminiscing “Poor Man’s Cloak”, our earlier work on a metamaterial invisibility cloak, and continue with coding metasurfaces that are a recent spinoff. A metasurface is simply a patterned layer to induce a phase and/or amplitude gradient of the transmitted and reflected electromagnetic waves for wavefront shaping. Digital coding metasurfaces are based on unit cells whose reflection phase is discretized at a desired operation frequency. Current studies focus on integrating electronic, thermal, optical switching/tuning processes to the unit cell’s response towards fully pixelated dynamic control. I present our recent collaboration with Izmir Institute of Technology and Middle East Technical University on a thermally switchable beam-splitter metasurface in THz regime using vanadium oxide (VO2) layer and give a perspective to the state-of-the-art research for potential studies.

The second part involves a computational study on plasmonic gold nanoparticles for their utilization in cancer diagnosis and therapy. With a brief presentation of the research field and prevalent problems, I highlight the contribution of our systematic study on the design of plasmonic gold nanoparticles that addresses several problems at once to enhance the nanoparticle assisted cancer therapy. The last part presents a system combining plasmonics and nonlinear photonics. We show that the coupling dynamics of surface-plasmons and an optical soliton comprises a nonlinear Josephson junction in remarkable analogy to that of Bose-Einstein condensates of atoms in double-well laser traps. The dynamics can be enriched by adding dissipation, gain and tunable coupling to exhibit bifurcations, limit cycles and various phenomena including Rosen-Zener transitions, Shapiro resonances. This became a seminal work to our subsequent studies with extensions to the quantum regime where it provides a nonlinear non-Hermitian system. Finally realizing that I might have drifted in too many directions, I wrap up the portfolio and indicate future research directions that I would like to venture.

Bio:Kaan Güven is a faculty at the Physics Department, Koç University since 2009. He received his Ph.D in Condensed Matter Physics in 1999 at Bilkent University. He was a postdoctoral researcher at Max-Planck Institute for Solid State Research, Stuttgart, and then at the Nanotechnology Research Center (NANOTAM) at Bilkent University. He conducted theoretical, experimental and computational studies within nationally and internationally funded research projects. He published 50+ articles and received a number of awards for his studies in metamaterials and photonic crystals. His research focuses on electromagnetic metamaterials, plasmonics, nonlinear photonics. Current items on his workbench are digital metasurfaces, non-linear, non-Hermitian dynamical phenomena in optical, plasmonic systems, and -quite recently- reservoir computing.