Polaron effects on the refractive index changes in cylindrical quantum dots with parabolic potential

► The refractive index changes is greatly enhanced and the peak shift to the aspect of high energy when considering the influence of electron-LO-phonon interaction. ► The refractive index changes are strongly affected by the incident optical intensity, parabolic potential and the applied electric field. ► The nonlinear refractive index changes will be decreased with the increase of I, but the linear term does not change with intensity.