Active dielectric metasurface based on phase‐change medium

Abstract

We propose all-dielectric metasurfaces that can be actively re-configured using the phase-change material Ge 2 Sb 2 Te 5 (GST) alloy. With selectively controlled phase transitions on the composing GST elements, metasurfaces can be tailored to exhibit varied functionalities. Using phase-change GST rod as the basic building block, we have modelled metamolecules with tunable optical response when phase change occurs on select constituent GST rods. Tunable gradient metasurfaces can be realized with variable supercell period consisting of different patterns of the GST rods in their amorphous and crystalline states. Simulation results indicate a range of functions can be delivered, including multilevel signal modulating, near-field coupling of GST rods, and anomalous reflection angle controlling. This work opens up a new space in exploring active meta-devices with broader applications that cannot be achieved in their passive counterparts with permanent properties once fabricated.

Further Wideband RCS Reduction on Metasurface by Introducing a Phasor Interference Element

“…the phasor sum of E1 and E2 will be dramatically counteracted due to the introduction of E3, and a result of R ≤ 0.11 (nearly −10 dB) can be obtained according to Equation (1). In summary, compared with Case I in Fig.…”

“…Metasurface (MS) is a 2-D artificial array constructed by the sub-wavelength elements in periodic or aperiodic arrangements [1][2][3][4][5]. In recent years, the MS constituted by artificial magnetic conductor (AMC) [6,7] with low radar cross section (RCS) [8][9][10] has aroused great interest of researchers due to its tremendous potential in military practice.…”

Dynamic Thermal Emission Control Based on Ultrathin Plasmonic Metamaterials Including Phase‐Changing Material GST

“…As temperature increases, many GST crystalline nuclei are formed at first and then numerous crystals gradually joint together to form the crystalline structure at crystallization temperature. The GST film in the intermediate phases consists of different proportions of amorphous and crystalline molecules, and the effective permittivity of such GST film can be estimated by effective‐medium theories based on the Lorentz‐Lorenz relation: m denotes the crystallization fraction of the GST film ranging from 0 to 100%, and are the permittivities of GST in the crystalline and amorphous phases. Simulated resonances are matched with the measured resonances by changing the crystallization fraction of GST from 0% to 100%.…”

“…The ultrathin feature is achieved by adopting the MIM plasmonic metamateirals, in which the emission wavelength can be controlled by the geometric size of top metallic particles without sacrificing the total device thickness. The dynamic low‐power‐consumption control is implemented by incorporating zero‐static‐power phase‐changing material Ge2Sb2Te5 (GST), which has been applied in various energy‐efficient switchable photonic devices . The whole structure shows a total thickness of 550 nm (∼0.023λ), which is well below the subwavelength scale.…”

Coherent control of high efficiency metasurface beam deflectors with a back partial reflector

“…[20][21][22][23] In addition, an interesting application of nanofilm MSs, namely, the coherent control of absorption via MSs, has been proposed and demonstrated experimentally even in single photon regime. 15,24,25 When a nanofilm MS is illuminated by a pair of counter-propagating light beams, light-matter interactions in the MS can be controlled by light interference between two counter-propagating beams.…”