Phase‐Change Sb₂S₃ Multilayer Fabry‐Perot Devices: A Novel Approach to Nonvolatile Reprogrammable Multiphase Spatial Modulation

Nonvolatile reconfiguration of optical device characteristics at the micro‐ and nanoscale is essential for advancing intelligent photonics. In this study, a novel approach to nonvolatile, reprogrammable multiphase modulation is presented using multilayer thin‐film Fabry‐Perot devices that incorporate phase‐change Sb2S3, facilitating low‐cost customization for diverse applications. These devices are fabricated through thin film deposition and feature a pixelated multilevel phase modulation configuration via intermediate phase states of Sb2S3 controlled by laser direct writing. The multilayer structures employ a stratification strategy to control grain size and minimize domain formation in the crystalline Sb2S3 films, effectively mitigating refractive index inhomogeneity caused by birefringence. The experiments achieved multilevel phase modulations with a maximum reflectance phase modulation exceeding 1.6π. The resulting multiphase holograms effectively eliminate the twin image effect often encountered in binary‐phase holograms, demonstrating the capability of the devices for holographic image reconstruction. Leveraging the unique properties of phase‐change Sb2S3, the proposed method of etching‐free, pixelated laser‐writing fabrication provides a versatile platform for developing reprogrammable diffractive optical elements suitable for a wide range of intelligent photonics applications.