Full-core antimony sulfide platform for reconfigurable on-chip photonics

Chalcogenide phase-change materials exhibit large, reversible index shifts that promise nonvolatile, energy-efficient photonic technologies. Yet, current implementations either rely on ultrathin, lossy films integrated with passive Si/SiN waveguides, limiting index modulation, or exploit direct laser writing for localized switching, at the expense of strong optical confinement. Here we demonstrate an antimony trisulfide (Sb₂S₃) waveguide platform where the material itself forms the guiding core. The proposed architecture theoretically supports substantial modulation of both effective index and absorption, thereby providing a robust platform for the realization of reconfigurable and densely integrated photonic devices.