A lighting unit comprising (a) a waveguide, the waveguide comprising a first light exit surface, a second light exit surface configured opposite of the first light exit surface, and an edge, the lighting unit further comprising (b) a light source, configured for lighting the waveguide with light source light, thereby providing incoupled light source light within the waveguide, wherein the lighting unit is further configured to allow part of the incoupled light source light escape from the waveguide at one or more of the first light exit surface and the second light exit surface as outcoupled light source light, wherein the lighting unit further comprises (c) one or more of a first luminescent material adjacent to the first light exit surface and configured to provide first luminescent material light, and a second luminescent material adjacent to the second light exit surface and configured to provide second luminescent material light, wherein the first luminescent material and the second luminescent material are excitable by the outcoupled light source light, wherein the lighting unit is configured to provide during operation first light emanating from the lighting unit in a direction away from the first light exit surface and second light emanating from the lighting unit in a direction away from the second light exit surface, the first light comprising contributions of one or more of (i) the outcoupled light source light and (ii) one or more of the first luminescent material light and the second luminescent material light, the second light comprising contributions of one or more of (iii) the outcoupled light source light and (iv) one or more of the first luminescent material light and the second luminescent material light, the first light having a first spectral distribution, the second light having a second spectral distribution, characterized in that the first light exit surface comprises a plurality of first luminescent material domains comprising the first luminescent material, which cover part of the first light exit surface, with downstream of each first luminescent material domain a first reflector, wherein the first luminescent material domains are configured to generate first luminescent material light, and wherein the first reflectors are configured to couple at least part of the first luminescent material light out of the waveguide in a direction away from the second light exit surface, wherein the second light exit surface comprises a plurality of second luminescent material domains comprising the second luminescent material, which cover part of the second light exit surface, with downstream of each second luminescent material domain a second reflector, wherein the second luminescent material domains are configured to generate second luminescent material light, wherein the second reflectors are configured to couple at least part of the second luminescent material light out of the waveguide in a direction away from the first light exit surface, and wherein (i) the first light exit surface and second light exit surface differ in coverage with the first luminescent material domains and second luminescent material domains, respectively, or (ii) wherein the first luminescent material domains and the second luminescent material domains differ in luminescent material.