Lithography-Free Chalcogenide Canvas for Photonic Integrated Circuits.

Chalcogenide integrated photonic devices have garnered widespread attention due to their excellent wideband transparency. However, current fabrication methods primarily rely on mature silicon-based CMOS processes, which are not readily adaptable to chalcogenides, significantly hindering their development. Here, we present a flexible fabrication approach that judiciously leverages the intrinsic oxidation susceptibility of chalcogenide materials, transforming chalcogenide thin films into a lithography-free canvas for versatile integrated photonic devices. Using antimony sulfide (SbS) as an example, we demonstrate low-threshold laser-induced local oxidation using a continuous laser, achieving a refractive index modulation exceeding 0.7 and a spatial resolution of 0.6 μm in the near-infrared region. This technique enables flexible fabrication of various chalcogenide photonic devices. Based on this technique, we further fabricate a dynamic planar Fresnel zone plate, demonstrating dynamic beam focusing by exploiting the phase-change property of SbS, as well as high-precision spatial-spectral reconstruction at near-infrared using a millimeter-scale chalcogenide metasurface array. Our findings reveal the potential of chalcogenide thin films as a promising canvas for advanced photonic applications, providing a simplified and versatile fabrication pathway that significantly advances the field of chalcogenide integrated photonic devices.