| 摘要 |
PROBLEM TO BE SOLVED: To enable judging deterioration of an LD (semiconductor laser: laser diode) without stopping APC control operation in a semiconductor laser device provided with an APC circuit, and simplify circuit constitution. SOLUTION: A first differential amplifier circuit 105 which amplifies difference between the detection level VL of a PD(photodiode) and a reference level VR and controls a driving current of a driving current supplying circuit 106 with the amplified output, a level converting means constituted of a bias circuit 107, an adder 108 and a first switch 109, a sample hold circuit 110 holding an output of the first differential amplifier circuit 105 just before a deterioration judging command signal SD is received, a second differential amplifier circuit 112 which outputs a level differenceΔVX between the output of the circuit 105 when the signal SD is received and the output held by the sample hold circuit 110, and a deterioration judging circuit 113 outputting a deterioration judging signal of a semiconductor laser, are installed.
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