| 摘要 |
PROBLEM TO BE SOLVED: To obtain a semiconductor laser device for avoiding the shut-down of operation caused by the generation of a failure such as a short circuit or an opening without shortening an operation life span of the device, and also to provide a method for avoiding the shut-down of the operation of the semiconductor laser device. SOLUTION: A drive current to which a superimposed alternate current generated by a superimposed alternate current element generator 3 is superimposed is made to flow to a semiconductor laser 1 of the semiconductor laser device, and thereby a synchronization detecting circuit 4 detects a voltage signal synchronized with a frequency of the superimposed alternate current. A detection signal comparator 5 compares a differential resistance value of the semiconductor laser 1 calculated from the detected voltage signal with a preset failure determination differential resistance value, determines the occurrence of a failure when the differential resistance value of the semiconductor laser 1 is lower than the failure determination differential resistance value, and sends a switching signal to a current bypass control unit 6. The current bypass control unit 6 bypasses a drive current supplied to the semiconductor laser 1 based on the switching signal not to allow a current to flow to the semiconductor laser 1. COPYRIGHT: (C)2009,JPO&INPIT
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