Patent ID: 7227877

Claim:
A semiconductor laser device comprising: a stem body having a reference surface; a heat radiation block which is provided on the reference surface of the stem body and which has a semiconductor laser chip mounted on a side face thereof; and a lead which extends through the stem body, wherein a portion of the lead protruding on a reference surface side is placed on one side surface side of the heat radiation block on which the semiconductor laser chip is mounted, and the semiconductor laser device further comprises a cover which is attached to the side face of the heat radiation block at both ends thereof so as to surround the semiconductor laser chip and the portion of the lead protruding on the reference-surface side, in conjunction with the side face of the heat radiation block, and which is opened on at-least one side of the cover that is a beam-output side of the semiconductor laser chip, wherein the cover is only a semi-cylinder which does not extend beyond the heat radiation block.