| 摘要 |
PURPOSE:To stably produce light output from a semiconductor laser by partially extracting the light output, obtaining detected voltage from the mean value thereof and using it for feeding back a laser bias current, and also using the voltage obtained form the peak value for feeding back a signal current. CONSTITUTION:The input signal from a terminal 12 is applied to a laser drive circuit 11, the output from the circuit 11 is applied through a line 13 to a semiconductor laser 10 to thereby emit laser light therefrom. At this time the laser light is partially branched and fed to a photoelectric converter 18 having photodiodes or the like, and the output voltage from the converter 18 is applied to a peak detector 19 and a mean value detector 20. Then, the output from the detector 20 is applied to a comparator 14, which thereupon compares the output with a standard voltage applied to its terminal 14a to thereby produce a signal for controlling the amplitude to a circuit 11. The output from the detector 20 is also applied to a comparator 16, which thereupon compares it with a standard voltage applied to its terminal 16a to thereby produce a bias current to the laser 10 so that the light output from the laser 10 may become constant. |
