| 摘要 |
PROBLEM TO BE SOLVED: To check inside degradation of a laser diode by comparing the width of an emitted natural emission light spectrum with the width of the natural emission light spectrum emitted from the good quality laser diode by driving the laser diodes. SOLUTION: When there is a dark part 10 inside an optical waveguide part 2, the intensity modulation caused by the dark part 10 is superposed with the natural emission light spectrum, so that the differenceΔPd between the maximum value and the minimum value of the natural emission light spectrum is larger than the differenceΔP between those of the natural emission light spectrum of a laser chip 6 that is without the dark part 10. The good or bad of laser chips 6 is evaluated by comparing the widthΔP1 of the natural emission light spectrum of the testing laser chips 6 with the widthΔP of the light spectrum of the good laser chip. Based upon the test result, the good or the bad are marked on the laser chips 6.
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