The invention provides a lighting device comprising a plurality of solid state light sources and an elongated ceramic body having a first face and a second face defining a length (L) of the elongated ceramic body, the elongated ceramic body comprising one or more radiation input faces and a radiation exit window, wherein the second face comprises the radiation exit window, wherein the plurality of solid state light sources are configured to provide blue light source light to the one or more radiation input faces and are configured to provide to at least one of the radiation input faces a photon flux of at least 1.0*1017 photons/(s·mm2), wherein the elongated ceramic body comprises a ceramic material configured to wavelength convert at least part of the blue light source light into at least converter light, wherein the ceramic material comprises an A3B5O12:Ce3+ ceramic material, wherein A comprises one or more of yttrium (Y), gadolinium (Gd) and lutetium (Lu), and wherein B comprises aluminum (Al).