| 摘要 |
In a laser driving device for stabilizing the optical output level of a semiconductor laser, a drive circuit supplies a drive current signal to the laser. A monitoring photodiode is provided for partially receiving the optical laser output to produce an electrical monitor signal indicative of the actual output level of the laser. A differential amplifier is connected to the photodiode to serve as a comparator for receiving a reference signal indicative of a reference output level of the laser, and for detecting a difference between values of the monitor signal and the reference signal to produce a comparison signal indicative of a change in the actual optical output level of the laser. An abnormal current eliminator is connected to the comparator, for, when the laser is disenergized or just after it is driven to become operative, controlling the comparator so that the comparison signal has a limited amplitude, whereby a current component undesirably supplied as the driven current to the laser is forcibly decreased to eliminate abnormal current from flowing in the laser. |
