Mid-infrared Non-volatile Compact Optical Phase Shifter Based on Ge 2 Sb 2 Te 5

We demonstrated a low-loss, non-volatile optical phase shifter based on phase-change material, Ge 2 Sb 2 Te 5 operating at a $2\ \mu m$ wavelength. Using a $10-\mu m$ -long phase-change phase shifter, we obtained a $0.7\pi$ phase shift at $2\ \mu m$ with approximately 10 times smaller loss per phase shift than at $1.55\ \mu m$ .