Active Control of Temperature‐Sensitive GaN‐Graphene van der Waals Heterojunctions Integrated Metasurfaces: A Platform for Multifunctional Micro–Nanophotonic Devices.

Van der Waals (vdW) heterojunctions composed of GaN/graphene have high transmittance and excellent carrier transport properties. The combination of multidimensional hybrid heterojunctions with metasurfaces can open up many fascinating prospects for novel optical components over a broad range of the electromagnetic spectrum. This work experimentally demonstrates a multifunctional temperature‐sensitive meta‐device based on GaN/graphene vdW heterojunctions integrated with a metasurface. Notably, it is discovered that the conductivity of the vdW heterojunctions increases rapidly when it is excited by a thermal signal, resulting in a significant change in the relative phase retardation as well as amplitude modulation of an incident THz wave. Then a continuous wavelet transform is used instead of the traditional Fourier transform, and the two‐dimensional wavelet coefficient card is built to achieve fast detection over a wider range of temperature. Simultaneously, the variation of temperature dynamically controls the contributions of the multipoles, eventually determining the active switching of exotic anapoles with extreme non‐radiative confinement to highly radiative electric dipoles. This work offers the possibility of designing novel chip‐scale multifunctional thermal tuning devices and promotes the potential application of active micro‐nanophotonic devices in temperature sensors, terahertz modulators, and dynamic near‐field imaging. [ABSTRACT FROM AUTHOR]