| 摘要 |
<P>PROBLEM TO BE SOLVED: To stabilize an output optical signal by a simple device system even if characteristics of an optical modulator are fluctuated by the change of ambient temperature and the secular change when an optical duo binary modulation system is utilized. <P>SOLUTION: In the optical duo binary modulation system, DC bias voltage is increased and decreased so as to compensate DC drift of the optical modulator by the change of ambient temperature and the secular change and a bias controlling signal is formed based on the difference between time average power values of the output optical signals when the DC bias voltage is increased and decreased to correct the DC bias voltage to be the optimum value. <P>COPYRIGHT: (C)2004,JPO |
