| 摘要 |
PURPOSE:To eliminate tracking error by providing a photodetector detecting a sub beam to a region other than the region projecting a laser beam spot of a radiation end face of a semiconductor laser chip projecting the laser beam spot. CONSTITUTION:A signal relating to the tracking state of a laser beam is extracted in the semiconductor device by gold wires 6, 7 for photodiode electrodes. That is, in using the semiconductor device, the pickup is constituted to detect only a main beam 17 by photodiodes 2, 3 via a beam splitter 12 and no sub beam is reflected at the radiation end face of an LD1. Thus, the tracking error is not caused, due to the disturbance of a tracking signal caused by projecting the sub beam onto the disk again and the reception of the beam by the photodiode and any nonreflection coating is required as its countermeasure. |
