SEMICONDUCTOR LASER CONTROLLER AND CONTROLLING METHOD

摘要

PROBLEM TO BE SOLVED: To prevent deterioration of lifetime of a semiconductor laser and deterioration of learning accuracy due to the temperature characteristic by driving the semiconductor laser with a pulse switching between micro powers in the vicinity of threshold current and detecting the peak and bottom levels of an emitted pulse. SOLUTION: A power detection current outputted from a semiconductor laser power photodetector 14 is converted through a current/voltage converting circuit 29 into a voltage value being delivered to a peak and bottom detection circuits 30, 31. Peak detection is controlled by a peak detection control signal (t) delivered from a central control block wherein H level of the signal (t) represents detection state and L level thereof represents detection off state. The bottom detection circuit 31 is controlled by a bottom detection control signal (u) having H level representing detection state and L level representing detection off state. A switching circuit 32 delivers any one of peak, bottom detection outputs y, z or the slew output x from the current/voltage converting circuit 29 by output select signals v, w.