| 摘要 |
PURPOSE:To always write with a constant light output even if the fine external amount of a semiconductor laser is varied by detecting a pulse light output peak value at the time of writing, and controlling a pulse current according to whether the detected value is larger than a reference value or smaller. CONSTITUTION:Converters 14, 15 are switched over to an R side when reading out with conversion control input (R/W), and the light output of a semiconductor laser 1 is so controlled by the output of a photodetector 8 by a bias current circuit 9 to a bias current Lb1(temperature T1) as to become LR. The converters 14, 15 are converted to a W side at the time of writing, the output of the photodetector 8 is compared by a comparator 11 with a reference value after detecting its peak, a compared output is applied to a pulse current controller 12, which controls a pulse driving current amplifier 13 so that a light pulse peak value becomes constant (LW) in response to data input, and the bias current is superposed on the output by means of an adder 16. |
