| 摘要 |
PROBLEM TO BE SOLVED: To prevent the spreading and quenching rate deterioration of the optical spectrum due to chirping and stably feed a high quality optical signal. SOLUTION: A first peak detector circuit 5 detects the max. value of only the AC component of a monitor signal of a photo diode 3. A second peak detector circuit 6 detects the max. value of the DC component plus AC component of the monitor signal. A first A/D converter 8 converts the max. value of the AC component only into a digital value a. A second A/D converter 9 converts the max. value of the DC component plus AC component into a digital value b. An arithmetic circuit 10 operates the equation b-2a, based on the digital values a and b. A bias current control circuit 11 controls the bias current, based on the operation result. A comparator 7 compares the max. value of the AC component only with a set value and a pulse current control circuit 12 controls a pulse current, based on the comparison result. |
