Fig. 1: Mechanism of a pixelated electrical-programmable graphene-integrated plasmonic metasurface.
From: Electrically programmable pixelated coherent mid-infrared thermal emission
a Schematic of a \(3\times 3\) pixelated MIM active metasurface driven by graphene field-effect transistors (Gr-FETs). Each pixel contains an upper layer of an Au nanoantenna array for coherent mid-infrared emission (with wavelengths \({\uplambda}_{1},{\uplambda}_{2}\)). The beneath layers of Al2O3 and Au serve as the gate dielectric and spacer, and the gate electrode and mirror for the Gr-FET and metal-insulator-metal (MIM) metasurface, respectively. Inset: Addressable pixelated mode under a source-drain voltage \({V}_{d}\) with a patterned gate electrode assigning one gate voltage (\({V}_{g1}\), \({V}_{g2}\), or \({V}_{g3}\)) to each pixel. b Scanning electron microscope (SEM) image (scale bar: \(35\,{{\upmu }}{{{\rm{m}}}}\)) of the fabricated active metadevice with its zoom-in image (scale bar: \(800\,{{{\rm{nm}}}}\)) revealing the nanosquare meta-atoms with an edge length of \(500\,{{{\rm{nm}}}}\). c Finite-difference time-domain (FDTD) simulations of resonant spectra as nanosquare sizes vary between \(500\,{{{\rm{nm}}}}\) and \(750\,{{{\rm{nm}}}}\). The mid-infrared transparency of graphene permits customized meta-atom designs for versatile coherent emission.
