Electro-Thermal Analysis of Dynamically Phase Controlled GST-Based Metasurfaces Enhanced by Graphene's Plasmonic Effect

The study presents a method for dynamically adjusting metasurfaces by manipulating the phase of incident light within the structure. Local heaters constructed from graphene are employed to perform this manipulation. Controlling the bias voltages applied to graphene can regulate the crystallization levels of phase-change materials, thus changing the metasurface's behavior. The plasmonic effect of graphene, which is caused by surface plasmon polaritons, is utilized to increase absorbance rates by adjusting structural parameters. The dynamic range of the proposed metasurface is achieved between <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$0^\circ$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$300^\circ$</tex-math></inline-formula> for the phase of reflected waves at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda = 1.55\,\rm{µm}$</tex-math></inline-formula> wavelength. The simulation has been done by emphasizing the inclusion of Four nonlinear factors that link temperature and electric current, which include the electrical conductivity <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sigma (T(t))$</tex-math></inline-formula> of graphene and Ge <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> Sb<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula>Te<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{5}$</tex-math></inline-formula> (GST) material, the thermal conductivity <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\kappa (T(t))$</tex-math></inline-formula>, and the crystallinity percentage <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$L_{c}(T(t))$</tex-math></inline-formula> of GST material at different temperatures. As temperature distribution throughout the GST material is non-uniform, making it difficult to predict the crystalline percentage uniformly, Two scenarios have been adopted in this work to simulate the crystalline percentage as accurately as possible. Furthermore, we demonstrate the metasurface's efficacy as a beam steering and LiDAR device, emphasizing its enhanced thermal isolation between unit cells and the synergistic integration of graphene's plasmonic effects to achieve superior absorption and reconfigurable functionality.