Intersubband optical transitions, refractive index changes, and absorption coefficients are
numerically driven for direct bandgap strained GeSn/Ge quantum dots. The linear, third-
order nonlinear and total, absorption coefficients and refractive index changes are evaluated
over useful dot sizes' range ensuring p-like Γ-electron energy state to be lower than s-like L-
electron energy state. The results show strong dependence of the total absorption coefficient
and refractive index changes on the quantum dot sizes. The third order nonlinear …