| 摘要 |
PURPOSE:To prevent the variation of laser output due to the reflection of monitor output light from a semiconductor laser, the formation of an external optical resonator, and the like by a method wherein the surface of a photo receiving element is provided in eccentricity so as not to include at least the main axis, and the other non-photo receiving part including the main optical axis is provided with a photo absorber for preventing reflection. CONSTITUTION:When the main optical axis of laser monitor output is OO' and the optical axis determined by points P and O on the surface of the photo receiving element 2 is OP, the position for monitoring the element 2 is deflected on the surface on a stem 5 is such a manner that the minimum valve of the angle made between the OO' and OP becomes 2.5 or more. Enlargement of the distance between O' and P in order that the angle made between the OO' and OP bacomes 2.5 deg. or more enables the reflection of monitor output light not to turn back to the end surface for outout oscillation of laser element, even if the angle of the photo receiving element surface inclines toward a laser chip. Further, carbon black, etc. is kept placed as the high photo absorber 8, or black paint containing carbon is kept applied, in order to prevent the irregular reflection from the stem surface. |
