| 摘要 |
PURPOSE:To judge and sort the quality of laser characteristics easily and securely by a method wherein both photo outputs from both Fabry-Perot resonator end surfaces are detected and compared at the step of laser chip. CONSTITUTION:Photodetectors 4 and 5 are controlled by power sources 6 and 7 so that the same level DC outputs are fed out to the same level photo inputs. Each detected signal thereof drives a display 10 via differential amplifier 9 by the appearance of the difference of detected signals of both detectors in a differential detection unit 9' only in the case of differences in both photo outputs from both the end surfaces of a chip 1. In other words, when the laser chip 1 is driven by a given current larger than the oscillation threshold value, the display 10 does not operate because of no output of the differential amplifier 9 in the case of the same photo output from both end surfaces, but the display 10 is set in operation only in the case of difference in photo output. |
