| 摘要 |
PURPOSE:To stabilize an output from a semiconductor laser by a method wherein when an output of a semiconductor laser is null, by comparison between a small signal due to secular or thermal change in photo-detectors and amplifiers and a reference voltage of an amplifier, adjustment is made so that an output of the amplifier may be null. CONSTITUTION:By a driving circuit having an input which is an output of a modulation circuit 1a, a semiconductor laser 1 is operated. The laser beam output of the semiconductor laser 1 is detected by a photo-detector, and amplification in an amplifier 10 is done. The maximum output of the amplifier 10 is held in a peak hold circuit and its output is compared with a reference voltage V1 in a comparing circuit. In this process an offset voltage due to variation in a temperature or the like of the photo-detector and the amplifier is applied on the second comparator 11, and through comparing with a reference voltage V2 which is set when the offset voltage is null, a difference signal between them is applied on a gate circuit 15, and the offset voltage is controlled to be null. By this method an output of a semiconductor laser is stabilized. |
