| 摘要 |
PURPOSE:To monitor beams emitted from a second main surface by monolithically forming a photodetector such as a photodiode to the second main surface. CONSTITUTION:Beams L generated in an active layer 1 are reflected, using a first main surface 5 and another surface 13 as mirror surfaces, thus conducting laser oscillation. Beams are monitored by a photodiode 15 consisting of P-type clad layer 3 and an N-type contact layer 10 at that time, and an optical output emitted can be kept constant. The forbidden band width of an N-type contact layer 10 shaping one part of the photodiode 15 is controlled so that absorptance to laser beams during the reciprocation of the layer 10 is brought to 50% or less. The control can be executed by controlling the composition of the N-type contact layer 10 or controlling thickness thereof, but it can also be adjusted by fluctuating bias voltage applied to a P-N junction consisting of the P-type clad layer 3 and the N-type contact layer 10. |
