A diode-laser bar package includes a diamond composite heat-sink on which is soft-solder bonded a copper-pad having an area much greater than that of the diode-laser bar. A constraining-block of a metal having a CTE matching that of the diode-laser bar is hard-solder bonded to the conductive pad. The constraining-block is configured such that the conductive pad in the region of the diode-laser bar has a CTE about equal to that of the constraining-block, and, accordingly, the diode-laser bar.