A solid body made of an inactive, light transmissive material has embedded therein an optical fiber having a lengthwise segment in which a scattering structure is formed that is to redirect primary propagating light sideways out of the fiber. An active photoluminescent layer integrated in the optical fiber is to wavelength-convert the primary light into secondary light. The solid body is generally cylindrical but without rotational symmetry about the center longitudinal axis of the fiber. A portion of the outer side surface of the body is curved and is covered by an external reflector, while another portion of the outer side surface is uncovered by the reflector in order for the secondary light to emerge. Other embodiments are also described and claimed.