| 摘要 |
<P>PROBLEM TO BE SOLVED: To attain reduction of a circuit scale and simplification of control by performing compensation control of the optimal bias voltage of optical modulation operation without using a pilot tone. <P>SOLUTION: A driving part 13 adds a bias voltage to an input data signal to form a driving signal. An optical modulation part 10 modulates input light output from a light source part 12 according to the driving signal to output the modulated light as signal light. A normal rotation side monitor part 14a monitors signal light on the normal rotation side of the optical modulation part 10 to output a normal rotation side signal. A reverse rotation side monitor part 14b monitors signal light on the reverse rotation side of the optical modulation part 10 to output a reverse rotation side signal. A bias control part 15 controls the bias voltage so that a measured monitor ratio is a target value to be a ratio of the normal rotation side signal to the reverse rotation side signal when the operational point of the optical modulation part 10 is in a fixed position to an operation characteristic curve. <P>COPYRIGHT: (C)2010,JPO&INPIT |
