A semiconductor laser stack apparatus 1 comprises three semiconductor
lasers
2a to 2c, two copper plates 3a and 3b,
two lead plates 4a and 4b, a supply tube 5, a
discharge tube 6, four insulating members 7a to 7d,
and three heat sinks 10a to 10c. Here, the heat
sink 10a to 10c is formed by a lower planar member
12 formed with a supply water path groove portion 22, an intermediate
planar member 14 formed with a plurality of water guiding holes 38, and
an upper planar member 16 formed with a discharge water path groove portion
30 which are successively stacked one upon another, whereas their contact
surfaces are joined together. The heat sink 10a to 10c
is provided with pillar pieces 24 for connecting the bottom face of
supply water path groove portion 22 and the lower face of intermediate planar
member 14 to each other, and pillar pieces 32 for connecting the
bottom face of discharge water path groove portion 30 and the upper face
of intermediate planar member 14 to each other.
