SEMICONDUCTOR LASER DRIVING DEVICE

摘要

PURPOSE:To obtain the stable low and high output beams by using a control circuit which detects the output light intensity of a semiconductor laser and controls the output current value of the 1st current source according to said detected light intensity together with a holding circuit and a control means. CONSTITUTION:A control signal S1 is delivered from a control circuit in a low output oscillation mode and immediately before shift to a high output oscillation mode. The low band frequency component passed through an LPF 10 is sampled and held by a sampling/holding circuit 14 with the timing of the signal S1. Then a switching circuit 15 performs switching of signals between the circuit 14 and a power amplifier 11 by a control signal S2 delivered from the control circuit. Here an automatic optical output control APC is frozen. A recording enable state is secured when a control signal S3 delivered from the control circuit is supplied to a gate 14. Then the high output oscillation is secured. The output light intensity is always kept constant by decreasing sufficiently the freezing time of the APC compared with the changing time of the temperature characteristics of the semiconductor laser.