Patent ID: 8208510

Claim:
A semiconductor laser device comprising: a semiconductor laser element; and a heat sink comprising (a) a plurality of plates, and (b) a channel in the heat sink for a coolant to flow therein, the plurality of plates include, in this order, at least (i) a mounting plate on which the semiconductor laser element is mounted, (ii) a first radiation-fin-forming plate having a plurality of first radiation fins that extend into a portion of the channel, (iii) a channel forming plate having (a) a circulation channel and (b) a first portion of a coolant supplying channel forming hall, and (iv) a second radiation-fin-forming plate having (a) a plurality of second radiation fins that extend into a portion of the channel, (b) a second portion of the coolant supplying channel forming hall that overlaps the first portion of the coolant supplying channel forming hall, and (c) coolant supplying channels that extend from the plurality of second radiation fins and overlap the first portion of the coolant supplying channel forming hall, wherein, the mounting plate comprises a material having a thermal expansion coefficient closer to that of the semiconductor element than that of the first radiation-fin-forming plate, the circulation channel comprises an opening that extends across each of the plurality of first radiation fins of the first radiation-fin-forming plate, and also extends across each of the plurality of second radiation fins of the second radiation-fin-forming plate, the circulation channel is positioned between the first and second radiation-fin-forming plates such that the circulation channel enables the coolant to flow between the plurality of first radiation fins of the first radiation-fin-forming plate and the plurality of second radiation fins of the second radiation-fin-forming plate, and at least one of the first and second radiation-fin-forming plates comprises a corrosion proof region that is configured to be in contact with the coolant.