| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit for preventing output of laser light from a LD to be mounted on an optical module, in a transient state occurring when turning power on/off, for example.SOLUTION: A control circuit 2 for controlling over-emission of a semiconductor laser 3a to be mounted on an optical module 1 includes a switching transistor 6 connected in parallel with a LD3a, and an inverting gate circuit 7. The inverting gate circuit 7 is fed with power from a power supply VCC/VDD via a power supply maintenance circuit 8 constituted of a diode 8a and a bypass capacitor 8b. Input of the inverting gate circuit 7 is connected with the power supplies VCC, VDD. The inverting gate circuit 7 detects disconnection of this power supply, and conducts the switching transistor 6 by setting the output of the inverting gate circuit 7 to H level.SELECTED DRAWING: Figure 1 |
