Laser-induced reconfigurable wavefront control with a structured Ge₂Sb₂Te₅-based metasurface

Phase change materials have been widely exploited in active metasurfaces due to their large index contrast. Despite recent advances in phase-change metasurfaces, it remains a challenge to integrate diverse reconfigurable optical functionalities into a single metasurface. Here, we demonstrate an effective strategy to realize reconfigurable wavefront control by combining a Ge₂Sb₂Te₅-rod array with laser writing technology. Through arbitrarily modifying the position and power of laser source, the laser writing process helps to realize site-selective and multi-level phase change of Ge₂Sb₂Te₅ rods. Due to multi-level switching for optical properties of Ge₂Sb₂Te₅ material, the Ge₂Sb₂Te₅-rod array offers complete phase control and high amplitude modulation. Subsequently, various optical devices are designed in numerical simulation, including a phase-only hologram, dynamic meta-deflectors, a grayscale image and a perfect absorber. The structured Ge₂Sb₂Te₅-based metasurface with the combination of laser writing technology offers an effective way to explore various types of optical functionalities in the same device.