A laser assembly comprises a substrate, one or more standoffs and a semiconductor laser. The substrate has a first doped region and a second doped region. The second doped region is proximate to an upper surface of the substrate and forms a pn junction with the first doped region. The semiconductor laser is operative to emit light from an upper surface and a lower surface. Moreover, the semiconductor laser is attached to the upper surface of the substrate with the one or more standoffs such that the light emitted from the lower surface of the semiconductor laser impinges on the second doped region.