Anisotropic optical properties of silicon nanowire arrays based on the effective medium approximation

► Bruggeman model is used to approximate dielectric functions of Si nanowire arrays. ► Anisotropic wave propagation is employed to predict the optical properties. ► The results show quasi-diffuse behavior on optical absorption at both polarizations. ► The hemispherical absorptance of SiNW array on Si substrate is higher than bulk Si.