| 摘要 |
PURPOSE:To keep a base output level of an optical signal with high stability and to suppress chirping by employing a photodetector responding nonlinearly to an optical input for at least one of plural photodetectors. CONSTITUTION:An optical output pulse 4 of a binary digital code from a rear side of a distribution feedback type semiconductor laser 1 is branched into two at a translucent mirror 12, inputted respectively to 1st and 2nd photodetectors 5, 15, and an optical output waveform is monitored. In this case, the detector 5 is a photodiode responding linearly to an optical input, and the detector 15 is a photo diode responding nonlinearly to an optical input (proportional to square of the optical input). Then outputs of the detectors 5, 15 are inputted to an arithmetic circuit 10 comprising an arithmetic section 18 and a control section via a DC amplifier 7 and a power detection circuit 8 and the optical base output component is calculated. Thus, the base output level of an optical signal is kept to a prescribed value, then the optical signal suppressing chirping is sent. |
