SEMICONDUCTOR DEVICE

PURPOSE:To improve productivity while obtaining a device, cost of which is reduced, by guiding laser beam for monitoring from a laser diode to a light- receiving element by using a beam-passing rod. CONSTITUTION:A laser diode 1, which emits laser beams in at least two directions and one laser beams of which are used as laser beams for monitor, and a beam-passing rod 11 guiding laser beams for monitoring the laser diode 1 to a light-receiving element 4 are mounted. The laser diode 1 and the light- receiving element 4 are fixed onto the same plane of a substrate 10 formed by Sic, AlN, etc. having high thermal conductivity. The laser diode 1 is disposed so as to emit laser beams in the vertical direction in the figure, the light- receiving element 4 is arranged on the outgoing direction side of laser beams for monitoring the laser diode 1, and the beam-passing rod 11 is disposed between the laser diode 1 and the light-receiving element 4.