High–refractive index nanostructured dielectrics have the ability to locally enhance electromagnetic fields with
low losses while presenting high third-order nonlinearities. In this work, we exploit these characteristics to achieve efficient ultrafast all-optical modulation in a crystalline gallium phosphide (GaP) nanoantenna through the optical Kerr effect (OKE) and two-photon absorption (TPA) in the visible/near-infrared range. We show that an individual GaP nanodisk can yield differential reflectivity modulations of up to ~40%, with characteristic modulation times between 14 and 66 fs, when probed at the anapole excitation (AE). Numerical simulations reveal that the AE represents a unique condition where both the OKE and TPA contribute with the same modulation sign, maximizing the response. These findings highly outperform previous reports on sub–100-fs all-optical switching from resonant nanoscale dielectrics, which have demonstrated modulation depths no larger than 0.5%, placing GaP nanoantennas as a promising choice for ultrafast all-optical modulation at the nanometer scale.
License type:
http://creativecommons.org/licenses/by-nc/4.0/
Funding Info:
This work was supported by the Quantum Technology for Engineering (QTE)
program of the A*STAR (Singapore) and the A*STAR SERC Pharos program, grant no. 152 73
00025 (Singapore). G.G. and E.C. acknowledge support from the PICT grant no. 2017-2534.
S.A.M., Y.L., and E.C. acknowledge the Deutsche Forschungsgemeinschaft (German’s
Excellence Strategy EXC 2089/1–390776260). S.A.M. further acknowledges the EPSRC (EP/
M013812/1) and the Lee-Lucas Chair in Physics. Y.L. also acknowledges funding received from
the European Union’s Framework Programme for Research and Innovation Horizon 2020
(2014–2020) under the Marie Skłodowska-Curie grant agreement no. 754388 (LMU Research
Fellowships). M.P.N. would like to thank the UNSW Scientia Fellowship Program for ongoing
support.
Description:
Please find the link to the article at the publisher's URL: https://doi.org/10.1126/sciadv.abb3123