Abstract: A semiconductor laser comprising a laser diode which is mounted on a semiconductor chip which has a monitoring photodiode formed therein so as to monitor the laser light output of the laser diode. The cathode of the laser diode and the anode of the monitoring photodiode are connected together, and a suitable forward voltage for the laser diode and reverse voltage for the monitor photodiode is provided by a single power supply which results in a simple construction of an output detection circuit for the monitor photodiode which produces an increased output over prior art devices.

Abstract: A photodetector includes a center photosensitive section having a surface for receipt of light reflected from an optical recording medium in producing information recorded on the optical recording medium. The center photosensitive section includes a plurality of photosensitive elements separated by a space from one another. A non-reflective transparent film is provided on substantially the whole area of the surface of the center photosensitive section to cover the photosensitive elements and the space.