Design, optimization, and performance evaluation of GSST clad low-loss non-volatile switches

In this paper, we investigate the performance of a self-sustained ON-OFF switch incorporating a new phase change material ${\text{Ge}_2}{\text{Sb}_2}{\text{Se}_4}{\text{Te}_1}$Ge₂Sb₂Se₄Te₁ (GSST) with a silicon rib waveguide at the telecommunication wavelength 1.55 µm. A full-vectorial $\textbf{H}$H-field finite-element method is used to find the effective index and modal loss of the quasi-TE modes in the GSST-Si waveguide. Both the electro-refraction and electro-absorption type design are studied, and the effects of GSST thickness and Si slab thickness on the device performance are presented. These results suggest that a GSST-Si rib waveguide with a 500 nm wide Si core, 60-90 nm Si slab thickness, and 40-60 nm GSST layer could be a realistic switch design that can yield a very compact, 5 µm long device with only 0.135 dB total insertion loss and more than 20 dB extinction ratio.