| 摘要 |
PURPOSE:To prevent the semiconductor laser from being destructed by surge by a method wherein an inductor is provided in an input circuit of a constant current circuit, and a Zener diode and a capacity are connected between a control terminal and an output terminal. CONSTITUTION:In the DC bias circuit 5, the Zener diode 53 and the capacity 54 are connected between a base and emitter of a transistor 51 forming the constant current circuit, the inductor 55 being connected to a collector and a control signal S from a comparing circuit 3 being fed to the base of the transistor 51 through an operational amplifier 52. The Zener diode 53 prevents excess currents, and the capacity 54 and the inductor 55 prevent surge currents. With this construction, the laser destruction can be prevented. |
