| 摘要 |
PROBLEM TO BE SOLVED: To provide such a bias control method and device for an optical modulator that an optical modulator including a plurality of optical modulation parts for use in BOCDA is operated stably for a long period of time and can be easily set to a desired bias point.SOLUTION: An optical modulator includes a port for applying a bias voltage to a part of a modulation electrode, with respect to each optical modulation part. The bias control method includes: an initial preparation step of measuring variation in intensity of output light while scanning a voltage with a voltage width exceeding a half-wave voltage of the optical modulation part corresponding to each port, and determining a voltage to be applied to the port so that the intensity of output light from the optical modulator is a prescribed value; and a step of sequentially performing the initial preparation step for all ports so that timings relating to scanning do not overlap, and then measuring variation in intensity of output light while scanning a voltage in the vicinity of a prescribed application voltage value with a fluctuation width equal to or smaller than the half-wave voltage for the port, and performing fine adjustment of an application voltage so that the output light has a prescribed value. |
