We have studied the key optical emission parameters of laser diodes (emission wavelength, ; stripe contact width, ) mounted directly on F- and C-mount-type copper heat sinks, without intermediate elements (submounts). When effectively cooled by a thermoelectric microcooler, the lasers on the F-mount operated stably at output powers up to . The lasers were tested for reliable operation at an output power of for , and no decrease in output power was detected to within measurement accuracy. The experimentally determined maximum total efficiency is 71.7 % and the efficiency at a nominal output power of is 61 %. We compare parameters of the laser diodes mounted on C- and F-mounts and discuss the advantages of the F-mounts.