Gallium nitride for ultrasensitive thermo-active switching in terahertz metamaterial micro–nanophotonic devices

Abstract

The integration of metamaterials with semiconductors provides a distinct platform for dynamically controlling and manipulating terahertz waves to study the resulting interfacial coupling effects in Schottky junctions. The excellent performance of gallium nitride (GaN) is attributed to its outstanding optoelectronic properties, such as large diffusion lengths, bandgap tunability, and excellent charge carrier mobilities. However, the optoelectronic application of GaN in high-efficiency nanophotonic devices remains challenging. In this study, the remarkable conductivity change of GaN under the excitation of a thermal signal is exploited to demonstrate a hybrid GaN metamaterial device that exhibits sensitive switching of the metamaterial resonance within the terahertz spectrum. Additionally, the variation in temperature dynamically controls the contributions of the multipoles, eventually determining the active switching of the Fano resonance to highly radiative electric dipoles. Low-threshold dynamic control of the highly confined electric field strength is also observed in this system, which will tremendously benefit the new generation of micro-nanophotonic devices as active nonlinear filters and efficient lasers with enhanced functionalities over a broad range of the electromagnetic spectrum.