Photon acceleration and tunable broadband harmonics generation in nonlinear time-dependent metasurfaces

• Published in: Nature communications Vol. 10; no. 1; p. 1345
• Main Authors: Shcherbakov, Maxim R., Werner, Kevin, Fan, Zhiyuan, Talisa, Noah, Chowdhury, Enam, Shvets, Gennady
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 22.03.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 132/122; 140/125; 142/126; 147/135; 639/624/399/1015; 639/624/400/385; 639/624/400/3923; Acceleration; Broadband; Coupled modes; Gases; Harmonic generations; Humanities and Social Sciences; Infrared signatures; Ionization; Lasers; Metasurfaces; multidisciplinary; Photons; Plasmas (physics); Pulse propagation; Radiation; Radiation sources; Science; Science (multidisciplinary); Time dependence; Tunable lasers; Upconversion
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-09313-8

Time-dependent nonlinear media, such as rapidly generated plasmas produced via laser ionization of gases, can increase the energy of individual laser photons and generate tunable high-order harmonic pulses. This phenomenon, known as photon acceleration, has traditionally required extreme-intensity laser pulses and macroscopic propagation lengths. Here, we report on a novel nonlinear material—an ultrathin semiconductor metasurface—that exhibits efficient photon acceleration at low intensities. We observe a signature nonlinear manifestation of photon acceleration: third-harmonic generation of near-infrared photons with tunable frequencies reaching up to ≈3.1 ω . A simple time-dependent coupled-mode theory, found to be in good agreement with experimental results, is utilized to predict a new path towards nonlinear radiation sources that combine resonant upconversion with broadband operation. Photon acceleration, which can be used to generate tunable high harmonic radiation, typically requires high-intensity lasers and long propagation distances. Here, Shcherbakov et al. show efficient photon acceleration at low power input power from a semiconductor metasurface, less than a micron thin.