Akturk, M.Crotti, G.Schirato, A.Vinel, VincentZaccaria, R. ProiettiTrifonov, A. A.Buchvarov, I. C.Neshev, D. N.Leo, G.Maiuri, M.Della Valle, G.Cerullo, G.2025-06-242025-06-242429-1390ORCID:/0000-0002-4508-8646/work/170128371http://www.scopus.com/inward/record.url?scp=85174585708&partnerID=8YFLogxKhttps://hdl.handle.net/1885/733764544Steering the polarization of light at an ultrafast speed is a crucial functionality for a plethora of applications, including free-space optical links for high-speed information processing and recording. Nonlinear metamaterials have recently been developed for ultrafast manipulation of light polarization by all-optical means (i.e., upon excitation by a femtosecond control pulse). Here, we demonstrate strong birefringence features in a reconfigurable, anisotropic AlGaAs metasurface, achieving more than 90° rotation of the polarization ellipse at a few picosecond timescales.This work is part of the METAFAST project that received funding from the European Union Horizon 2020 Research and Innovation program under grant agreement no. 899673.enPublisher Copyright: © 2023, META Conference. All rights reserved.202385174585708