Fig. 1
(a) Schematic diagram of a liquid crystal on metasurface device: The foundation of the device consists of a 100 nm-thick layer made of TiW (10% titanium and 90% tungsten). A 15 nm-thick \(\hbox {Al}_2\hbox {O}_3\) (alumina) thin film is deposited over the TiW layer using atomic layer deposition (ALD). A patterned antenna, consisting of 40 nm-thick molybdenum, is deposited on top of the \(\hbox {Al}_2\hbox {O}_3\) film using electron beam lithography (EBL). The space above these structures is filled with E7 liquid crystal, known for its excellent electro-optical properties that enable dynamic light modulation when electrically controlled. The rotation of the liquid crystal is schematically drawn in four combinations of \(\hbox {V}_{antenna}\) = 0 V or 1 V and \(\hbox {V}_{metal}\) = 0 V or − 1 V. The red line is the electric field line. (b) The reflectivity of the LConeMeta device can be modeled with the modified Fabry-Perot oscillator. \(\psi _{LC}\) represents the round-trip propagation phase delay in LC\(\_\)1, \(r_{11}\) is the surface reflectivity coefficient at the air/liquid crystal boundary, \(t_{12}\) is the transmission coefficient at the air/liquid crystal boundary, \(r_{22}\) and \(t_{21}\) represent the reflectivity and transmission coefficients at the liquid crystal/air boundary, and \(|\rho _{22}| e^{\phi _{meta}}\) is the complex reflectivity at the liquid crystal/metasurface boundary. (c) Metasurface can generate the plasmon waves such as SPP (surface plasmon polariton) and GSP (gap surface polariton). (d) Transmission Electron Microscopy (TEM) image, which provides a detailed view of the microstructure and the layering within a sample metasurface device.
