Ultrafast all-optical switching of dual-band plasmon-induced transparency in terahertz metamaterials

Abstract

An active ultrafast formation and modulation of dual-band plasmon-induced transparency (PIT) effect is theoretically and experimentally studied in a novel metaphotonic device operating in the terahertz regime, for the first time, to the best of our knowledge. Specifically, we designed and fabricated a triatomic metamaterial hybridized with silicon islands following a newly proposed modulating mechanism. In this mechanism, a localized surface plasmon resonance is induced by the broken symmetry of a C 2 structure, acting as the quasi-dark mode. Excited by exterior laser pumps, the photo-induced carriers in silicon promote the quasi-dark mode, which shields the near-field coupling between the dark mode and bright mode supported by the triatomic metamaterial, leading to the dynamical modulation of terahertz waves from individual-band into dual-band PIT effects, with a decay constant of 493 ps. Moreover, a remarkable slow light effect occurs in the modulating process, accompanied by the dual-transparent windows. The dynamical switching technique of the dual-band PIT effect introduced in this work highlights the potential usefulness of this metaphotonic device in optical information processing and communication, including multi-frequency filtering, tunable sensors, and optical storage.

Color coded metadevices toward programmed terahertz switching

“…Light-driven reconfigurable metasurfaces that carry modulation information in amplitude, phase, frequency, and polarization are receiving a great deal of attention and research due to their contactless, succinct construction and ultrafast response-ability [30][31][32][33][34][35][36][37][38] . The ultrafast modulation behavior benefits significantly from the photogenerated carrier relaxation dynamics of active materials, in particular intrinsic epitaxial silicon (Si) and amorphous germanium, which have lower preparation costs with relaxation times in the order of nanoseconds and picoseconds [39][40][41][42] . These materials are advantageous in the preparation of ultrafast terahertz metadevices.…”