Ultrafast vector movies of plasmonic skyrmions, merons, quasicrystalline structures and skyrmion bags on the nanoscale

Topological plasmonic and twistronics: Ulfrafast vector movies of plasmonic skyrmions, merons, quasicrystalline structures and skyrmion bags on the nanoscale

We utilize a new technique, time-resolved vector microscopy, that enables us to compose entire movies on a sub-femtosecond time scale and a 10 nm scale of the electric field vectors of surface plasmon polaritons. By using our vector microscopy technique, we are able to image the plasmonic spin-momentum-locking and the plasmonic skyrmion dynamics. Depending on the shape and geometrical phase, in combination with the helicity of the excitation beam, topological plasmonic quasiparticles are created: skyrmions, merons, as well as quasicrystalline excitations with 4D topology. We observe their entire field vector dynamics at subfemtosecond time resolution [1-6]. The figure on the right depicts a snapshot of the skyrmion electric field vector arrangement with sub-10 nm resolution on a single crystalline, atomically flat gold surface. 

When applying the concept of twistronics to plasmons, intriguing topological excitations arise, such as skyrmion bags. We find magic angles similar to twisted graphene which defines exceptional topological features. Utilizing topological plasmonics and twistronics will open the door to linear optical features on the few nm length scale [7], without the need for techniques such as STED.

About Harald Giessen

Harald Giessen graduated from Kaiserslautern University with a diploma in Physics and obtained his M.S. and Ph.D. in Optical Sciences from the University of Arizona in 1995 as J.W. Fulbright scholar. After a postdoc at the Max Planck Institute for Solid State Research in Stuttgart he moved to Marburg as assistant professor. From 2001-2004, he was associate professor at the University of Bonn. Since 2005, he is full professor and holds the Chair for Ultrafast Nanooptics in the Department of Physics at the University of Stuttgart. He is also co-chair of the Stuttgart Center of Photonics Engineering.

His research interests include Ultrafast Nano-Optics, Plasmonics, Active, Switchable and Chiral Metamaterials, 3D Printed Micro- and Nano-Optics, Medical Micro-Optics, Miniature Endoscopy, Novel mid-
IR Ultrafast Laser Sources, Applications in Microscopy, Biology, and Sensing. He has spun out three companies based on his research: NT&C (single particle spectroscopic microscopy), Stuttgart Instruments GmbH (Ultrabroadband tunable fs and ps laser sources from visible to mid-IR), and Printoptix GmbH (3D printed
microoptics). 

References
[1] S. Tsesses et al., Science 361, 993 (2018).
[2] S. Tsesses et al., Nano Lett. 19, 4010 (2019).
[3] B. Frank et al., Science Advances 3, e1700721 (2017).
[4] G. Spektor et al., Science 355, 1187-1191 (2017).
[5] T. Davis et al., Science 367, eaba6415 (2020).
[6] S. Tsesses et al., Science 387, 644 (2025).
[7] J. Schwab et al., Nature Physics (2025), in press.