Rapid Prototyping of Reflective Beam-Steering Metasurfaces with the Plasmonic Phase-Change Material In₃SbTe₂

Metasurfaces have evolved as prime candidates for miniaturized optical components to tailor the light-matter interaction. Conventionally, the fabrication and design of such metasurfaces with complex antenna structures are well-developed and precise but need clean-room access and multiple fabrication steps. While metasurfaces based on polarization conversion are limited to low efficiencies, metasurfaces with antennas above a metallic mirror reach much higher efficiencies by keeping the initial polarization. Here, we showcase rapid prototyping of reflective beam-steering metasurfaces to optimize their efficiency. We exploit the nonvolatile insulator-to-metal transition of the infrared plasmonic phase-change material In₃SbTe₂ (IST). Via direct laser writing, we optically program reflective beam-steering metasurfaces with grating strips of varied width into thin IST layers and measure the anomalous reflection at a wavelength of 8.6 μm. Reconfiguring the grating bar widths and hence the covered phase range within the supercell leads to improved anomalous reflections of up to 75%. Our work enables reconfigurable, high-efficiency metasurfaces in the infrared range.