| 摘要 |
PROBLEM TO BE SOLVED: To provide a laser drive circuit capable of always uniformly controlling a maximum optical output, an extinction ratio, and a duty cycle even if a threshold current and the conversion efficiency of a laser diode (LD) fluctuate. SOLUTION: There are provided a light-emitting circuit 21a composed of an LD, an LD drive circuit 22 for driving the light-emitting circuit, a bias circuit 23 for adding a bias current to a pulse current outputted from the LD drive circuit, a light-receiving circuit 21b for receiving monitor light outputted from the light-emitting circuit, an I/V conversion circuit 24 for performing the current-voltage conversion of an output of the light-receiving circuit, a maximum value detection circuit 25 and an average value detection circuit 26 for detecting maximum and average values of output voltages of the I/V conversion circuit, respectively, a first comparison circuit 27 for comparing a detected maximum value with a first criterion to perform the feedback of the result to the LD drive circuit, and a second comparison circuit 29 for comparing a detected average value with a second criterion to perform the feedback of the result to the bias circuit. COPYRIGHT: (C)2009,JPO&INPIT
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