An illumination system including a light source, a light guide including an output surface, emissive material positioned between the light source and the output surface of the light guide, and an interference reflector positioned between the emissive material and the output surface of the light guide is disclosed. The light source emits light having a first optical characteristic. The emissive material emits light having a second optical characteristic when illuminated with light having the first optical characteristic. The interference reflector substantially transmits light having the second optical characteristic and substantially reflects light having the first optical characteristic.