Semiconductor laser device to detect a divided reflected light beam

摘要

An optical device for detecting a magneto-optical signal can be simplified and miniaturized in arrangement. An optical device for detecting a magneto-optical signal includes an optical element in which a light-emitting portion and a light receiving portion are closely disposed on a common substrate and in which reflected-back light obtained from a magneto-optical medium after light from the light-emitting portion was reflected on the magneto-optical medium is detected at a position near confocal position by the light receiving portion and another light receiving element. The reflected-back light from the magneto-optical medium is divided. One reflected-back light is detected by the light receiving portion of the optical element 1 and the other reflected-back light is detected by another light receiving element.