Increased Endurance of Nonvolatile Photonics Enabled by Nanostructured Phase‐Change Materials

ABSTRACT The rapid rise of artificial intelligence, and in‐memory computing has reinvigorated research on scalable, energy‐efficient, and reconfigurable photonic hardware. Non‐volatile phase‐change materials (PCMs) are attractive, as they offer large refractive index contrast, wavelength‐scale footprints, and zero static power consumption. However, current PCM‐based electrically controlled photonic devices are plagued by high insertion loss and low endurance. One prevalent hypothesis for these material limitations come from electromagnetic scattering in the interface and large programming volumes, respectively. Here, we validate this hypothesis by showing that nano‐structuring of PCM minimizes optical loss and enhances the endurance. By tapering both ends of a wide bandgap PCM Sb 2 Se 3 segment on a silicon waveguide, we suppressed the insertion loss by ≈94% (resulting in a loss of ≈0.1 dB per π phase shift). Through combining tapering and segmentation, we achieved high optical modulation amplitude (≈70%), low loss (≈0.5 dB per π phase shift), low‐voltage (