| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical transmission system capable of performing stable bias control by making a pull-in time to the optimum operation bias according to automatic bias control (ABC) uniform even when the output light level from an optical modulator varies or quantum efficiency of a photo diode which receives the output light is varied in the ABC of the optical modulator. SOLUTION: In an optical transmitter including the optical modulator 5, a direct current voltage extraction part 12 detects a direct current voltage of a voltage signal outputted from a signal conversion/amplification part 8 and performs the feedback to a gain control part 13 and, thereby, a pull-in gain to the optimum operation bias according to the ABC, that is, a loop gain of a control system is kept constant when the output optical intensity level of the optical modulator varies or even when the quantum efficiency of a photo receptor 7 is varied. COPYRIGHT: (C)2008,JPO&INPIT
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