SEMICONDUCTOR DEVICE

PURPOSE:To simplify a package structure and to attain effective heat dissipation by a construction wherein only the surface of a supporting substrate whereon a laser diode and a light-receiving element for monitoring are mounted is covered directly with a device cap, while a reflecting surface tilted at an arbitrary angle is formed in a part of the inside. CONSTITUTION:A laser diode 1 and a light-receiving element 2 for monitoring are mounted on the surface of a supporting substrate 3, while a device cap 7 provided with an output window 8 of a glass pane or the like is installed so that it covers only the surface side of the supporting substrate 3 whereon the laser diode 1 and the light-receiving element 2 for monitoring are mounted, and packaging is implemented. Besides, a reflecting surface 11 tilted at a prescribed angle is formed in a part of the inside of the device cap so that a monitoring output 10a of the laser diode 1 can be inputted by reflection to the light-receiving element 2 to be monitored, and a laser output 10 from the output window 8 is adjusted for use. Accordingly, the number of required components can be reduced and an action of heat dissipation can be improved remarkably when compared with prior-art examples.