Polarimetry analysis and optical contrast of Sb₂S₃ phase change material

Abstract

Phase-change materials (PCMs) are the cornerstone for the development of reconfigurable and programmable photonic devices. Sb2S3 has been recently proposed as an interesting PCM due to its low-losses in the visible and near-IR. Here, we report the use of imaging polarimetry and spectroscopic ellipsometry to reveal and directly measure the optical properties of Sb2S3 both in crystalline and amorphous states obtained upon crystallization by annealing in air of chemical bath deposited amorphous Sb2S3. The Mueller Matrix polarimetric analysis reveals the strong anisotropy of the Sb2S3 crystallites which crystallize in radial spherulitic domains in contrast to the optical isotropy of the amorphous films. A refractive index contrast of Δn = 0.5 is demonstrated while maintaining low-losses at telecommunications C-band, i.e., λ = 1550 nm.