Pump-Wavelength Selective All-Optical Terahertz Metasurface with Independent Amplitude and Frequency Modulations.

Abstract

Tunable terahertz (THz) metasurfaces based on optical control are crucial in high-speed communication, nondestructive testing, and imaging. However, realizing independent optical tunability of multiple functions in the THz band remains challenging due to limitations in control materials. Here, we experimentally demonstrate a novel THz metasurface that employs two control materials combined with an electric-field-coupled inductor capacitor microstructure to achieve all-optical independent modulations of amplitude and frequency. Amplitude modulation is achieved through near-infrared optical pumping, reaching a maximum modulation depth of 94.42%. Broadband frequency modulation, spanning 0.21 THz, is accomplished using visible light pumping. The independent modulation function is owing to the odd-order nonlinear polarization characteristics of perovskite and the selective photon transition between the bottom Si island and the perovskite film. This work introduces a novel approach for all-optical independent modulation of THz devices, offering valuable insights for developing all-optical metasurfaces, intelligent light windows, and multidimensional ultrafast switches.