Analysis of electrorefractive index change in Ge/SiGe coupled quantum well for low-voltage silicon-based optical modulators

► We propose a novel Ge/SiGe coupled quantum well for optical modulators and switches. ► Its electrorefractive index change is analyzed using the k·p perturbation theory. ► It will exhibit a large refractive index change in 1.55 μm wavelength region. ► The structure is promising for low-voltage optical devices based on phase modulation.