An illumination device includes a bulb including a segment of at least second order curvature and a cylindrical segment. A least two laser diodes are coupled with the bulb such that laser beams emitted by the at least two laser-diodes propagate inside the bulb through total internal reflection. The laser beams propagating in the bulb expand in the bulb, are evenly mixed and exceed outward from the bulb as a volumetric light flux.