Toward Direct Laser Writing of Dual‐Layer Metasurfaces with the Plasmonic Phase‐Change Material In₃SbTe₂

Abstract Metasurfaces have emerged as a versatile tool for tailoring light‐matter interaction. Combining multiple metasurfaces and antenna arrays in a multi‐layer structure promises intrinsic chiral structures as well as circumventing conventional metasurface drawbacks such as chromatic aberrations. For non‐volatile metasurface tuning, phase‐change materials (PCMs) have evolved as prime candidates. Recently, the plasmonic PCM In 3 SbTe 2 (IST) has been established which can be reversibly switched from an amorphous dielectric to a crystalline metallic state in the infrared via laser irradiation. While optically reconfiguring antenna shapes with IST has been extensively studied in a single layer structure, fabrication of a multi‐layer IST metasurface for individual resonance control in the different layers has not been shown yet. Here, a proof‐of‐concept of individual resonance control is shown in a dual‐layer IST metasurface with precise laser pulses from the top and from the bottom through the substrate. The complex switching dynamics and temperature distribution with Multiphysics simulations are theoretically explored. Subsequently, two antenna structures in both layers for multiple polarization dependent resonances are investigated. Finally, chiral meta‐atoms are combined as possible applications for dual‐layer IST metasurfaces. A wide range of applications is envisioned for dual‐layer metasurfaces by rapid prototyping chiral and reconfigurable antenna structures.