The electron-doping-induced phase transition of a prototypical perovskite SmNiO3 induces a large and non-volatile optical refractive-index change and has great potential for active-photonic-device applications. Strong optical modulation from the visible to the mid-infrared is demonstrated using thin-film SmNiO3. Modulation of a narrow band of light is demonstrated using plasmonic meta-surfaces integrated with SmNiO3.