Colloquium Series: Dr. Mikael Käll, Chalmers University of Technology

Prof. Mikael Käll, Department of Physics,Chalmers University of Technology, Göteborg, Sweden

Thursday August 17, 2023 4pm Dey Hall, The Toy Lounge Rm. 409

 Title: Metasurface Microparticles Driven by Optical Forces

 High-index dielectric metasurfaces that deflect light or alter its polarization state experience photon recoil forces and torques due to conservation of linear and angular momentum. We utilized this effect to construct miniature “metavehicles” able to navigate across a surface in water under plane-wave illumination while being steered through the incident polarization [1]. The control scheme does not involve gradient forces, in contrast to the vast majority of previous optical manipulation studies, yet the forces generated are strong enough to let the metavehicles work as transporters of microscopic cargo, such as biological cells. Depending on how the metasurface is constructed, metavehicles can be optimized for different behaviors and functionalities, thereby opening the door to novel fundamental studies and applications in fields like microrobotics, micromachines, and active matter.

[1] Andrén et al, Nature Nanotechnology 16, 970-974 (2021).

Bio:

Mikael Käll is an experimental physicist focusing on fundamental and applied nanooptics and biophotonics. His current research projects mainly deal with the physics and applications of optical metasurfaces and optical forces. He has previously worked with topics like surface-enhanced Raman scattering, plasmonic biosensors, optical antennas, light toxicity in yeast cells, and strongly correlated electron systems. He has co-authored more than 250 journal papers that have been cited more than 25000 times to date.