Wen, YongzhengGiorgianni, FlavioIlyakov, IgorQuan, BaogangKovalev, SergeyWang, ChenVicario, CarloDeinert, Jan-ChristophXiong, XiaoyuBailey, JoeChen, MinPonomaryov, AlexeyAwari, NileshRovere, AndreaSun, JingboMorandotti, RobertoRazzari, LucaAeppli, GabrielLi, JunjieZhou, Ji2023-07-172023-07-172023-07-172023-05-3110.1093/nsr/nwad136https://infoscience.epfl.ch/handle/20.500.14299/199234WOS:001017291600001Non-linear materials are cornerstones of modern optics and electronics. Strong dependence on the intrinsic properties of particular materials, however, inhibits the at-will extension of demanding non-linear effects, especially those second-order ones, to widely adopted centrosymmetric materials (for example, silicon) and technologically important burgeoning spectral domains (for example, terahertz frequencies). Here we introduce a universal route to efficient non-linear responses enabled by exciting non-linear Thomson scattering, a fundamental process in electrodynamics that was known to occur only in relativistic electrons in metamaterial composed of linear materials. Such a mechanism modulates the trajectory of charges, either intrinsically or extrinsically provided in solids, at twice the driving frequency, allowing second-harmonic generation at terahertz frequencies on crystalline silicon with extremely large non-linear susceptibility in our proof-of-concept experiments. By offering a substantially material- and frequency-independent platform, our approach opens new possibilities in the fields of on-demand non-linear optics, terahertz sources, strong field light-solid interactions and integrated photonic circuits.Metamaterials featuring locally enhanced non-linear Thomson scattering offer a practical and universal method for efficiently stimulating non-linear responses in linear solid materials.Multidisciplinary SciencesScience & Technology - Other Topicsnon-linear optical materialsterahertz harmonic generationthomson scatteringmagneto-electric couplingmetamaterialoptical 2nd-harmonic generationtext::journal::journal article::research article