Can elemental selenium act as optical phase-change material? An insight into its optical behavior

This study investigates the optical properties of monochalcogenide selenium (Se) and assesses its potential as a nonvolatile optical phase-change material (PCM). By leveraging spectroscopic ellipsometry and Raman spectroscopy, this research demonstrates that Se can undergo reversible, optically induced transitions between amorphous and crystalline phases. Compared to widely used PCMs, such as Ge2Sb2Te5 (GST), Sb2S3, and Sb2Se3, Se exhibits lower melting and crystallization temperatures, indicating reduced energy requirements for phase switching, which could be indeed activated optically by green light irradiation. Optical characterization further reveals that Se combines a high refractive index contrast with minimal absorption losses in the near-infrared, particularly at telecom wavelengths. These properties make Se a promising candidate for low-loss, energy-efficient active photonic components and switching devices.