PROTECTIVE CIRCUIT OF SEMICONDUCTOR LASER AND APPARATUS FOR MEASURING SEMICONDUCTOR LASER HAVING THE SAME

PROBLEM TO BE SOLVED: To provide the protective circuit of a semiconductor laser for preventing the semiconductor laser from being deteriorated or damaged by surely sensing the functional failure of a current limiting means for protecting the semiconductor laser against overcurrent even when the current limiting means is provided, and also to provide an apparatus for measuring the semiconductor laser having the circuit. SOLUTION: A current limiting circuit 23 having a constant-current element 33, an evaluating circuit 26 for evaluating the operating characteristics of the current limiting circuit 23, and a protective circuit unit 27 having a switching circuit 29 for connecting or cutting off between the current limiting circuit 30 and a bypass circuit 31, are provided at a current supply path 30 between a drive current source 22 and a measuring unit 28 (semiconductor laser 21). The evaluating circuit 26 evaluates the operating characteristics of the current limiting circuit 23 based on the output current of the current limiting circuit 23, supplied to the bypass circuit 31. Thus, the functional failure of the current limiting circuit 23 is early sensed. COPYRIGHT: (C)2004,JPO&NCIPI