A backlight (110-3) for a display system comprises a light source (112-3,112-4) to emit first light with a first spectral power distribution; a light regeneration layer (106-1,106-2) stimulated by the first light converts first light into second light having primary spectral components that correspond to primary (RGB) colors; and a notch filter layer (302-1,302-2) receives the second light to filter out secondary spectral components that do not correspond to the primary colors.