Optimizing Wavelength for Enhanced Cycling Durability of Laser‐Induced Phase Change in Sb₂S₃ Films: A Survey on Optical Transmission Phase Shift

Abstract The advancement of nonvolatile reconfigurable photonic elements has led to the development of Sb₂S₃ as a desirable phase change material for optical phase modulation in visible and near‐infrared wavebands. However, achieving long‐lasting cycling durability of the phase change remains a formidable challenge. Traditional characterization methods like transmittance or reflectance measurement fail to provide a quantitative assessment of the degree of phase change. To address this, the study focuses on enhancing the cycling durability of complete phase change in Sb₂S₃ films by manipulating the wavelength of a femtosecond laser for amorphization. To accurately measure optical transmission phase shifts during phase change experiments, a novel liquid‐crystal retardance matching technique based on the Mach–Zehnder interferometer is developed. This approach allows for a direct and quantitative assessment of the degree of phase change without relying on an optical model. The findings reveal that longer wavelengths and multi‐pulse irradiation with increasing pulse energy significantly enhance the cycling durability of the phase change. Additionally, the cost‐effective customization of nonvolatile photonic elements is demonstrated using laser direct writing, eliminating the need for lithography. It is anticipated that this work will drive advancements in Sb₂S₃‐based reconfigurable devices and contribute to the broader field of nonvolatile reconfigurable photonic elements.