A light-enhancement device includes a wavelength conversion member and a wavelength controlling element. The wavelength conversion member includes a light-transmissive substrate and wavelength conversion material which is disposed within the light-transmissive substrate for converting a portion of light with a first wavelength into another light with a second wavelength. The wavelength controlling element is disposed on a surface of the light-transmissive substrate for reflecting another portion of the light with the first wavelength into the light-transmissive substrate and enabling the portion of the light with the second wavelength to pass through the wavelength controlling element. A roughness of the surface of the light-transmissive substrate facing towards the wavelength controlling element is configured to be 0-1 μm.