A light emitting device (1) comprising a luminescent element (3) comprising a first face (31) and a second face (32), the first face comprising a light input surface and one of the first face and thesecond face comprising a light exit surface, the luminescent element (3) being adapted for receiving first light (4) with a first spectral distribution emitted by at least one laser light source (21,22, 23) at the light input surface, converting at least a part of the first light with the first spectral distribution to second light (5) with a second spectral distribution, guiding the second lightwith the second spectral distribution to the light exit surface and coupling at least a part of the second light with the second spectral distribution out of the light exit surface, and a heat sink element (7) arranged to be in thermal contact with at least a part of the luminescent element (3) extending between the first face (31) and the second face (32), wherein the first face (31) comprises across-sectional area A and the luminescent element (3) further comprises a length L being defined as the shortest distance between the first face and the second face and a characteristic length B ofthe cross sectional area A, the characteristic length B being defined as the square root of the cross sectional area A, and wherein, and wherein the length L and the characteristic length B of the cross sectional area A are chosen such that they satisfy any one of the relations L/B >= 2 * Ells/44(W/mm2) for LambdaTHC < 6 W/mK, L/B >= 1.3 * Ells/44(W/mm2) for 6 W/mK <= LambdaTHC <= 8 W/mK, and L/B>= 0.85 * Ells/44(W/mm2) for 8 W/mK < LambdaTHC, where Ells is the irradiance of the at least one laser light sources measured in W/mm2 and LambdaTHC is the thermal heat coefficient of the luminescentelement at room temperature.