| 摘要 |
PROBLEM TO BE SOLVED: To produce technology enabling the adjustment of the output high level of a modulator driving IC. SOLUTION: A stripline directional coupler 48 for connecting an optical modulator and a modulator driving IC 42 is provided in the system and the optical modulator and the modulator driving IC 42 are separated in a DC by the stripline directional coupler 48. Thus, even when a DC bias to be supplied to the side of the optical modulator of the stripline directional coupler 48 is changed, the bias does not affect the optical modulator and the adjustment of the output high level of the modulator driving IC is made possible. |
