In an embodiment, a heating device comprises a radiation source that emits a source radiation, a radiation emitting layer comprising an emitting layer host material and a luminescent agent, wherein the radiation emitting layer comprises an edge, an emitting layer first surface, and an emitting layer second surface; wherein the radiation source is coupled to the edge, wherein the source radiation is transmitted from the radiation source through the edge and excites the luminescent agent, whereafter the luminescent agent emits an emitted radiation, wherein at least a portion of the emitted radiation exits through the emitting layer second surface through an escape cone; an absorber layer, wherein the absorber layer comprises an absorber layer first surface and wherein the absorber layer first surface is in direct contact with the emitting layer second surface, wherein the absorber layer comprises an absorber that absorbs emitted radiation that escapes through the escape cone.