| 摘要 |
PROBLEM TO BE SOLVED: To provide a driving method for realizing zero-chirp in a Mach-Zehnder modulator that has a non-linear phase change characteristic with respect to a voltage applied to a phase modulation area.SOLUTION: As drive electric signals to first and second phase modulation areas provided on two corresponding arms composing an optical modulator, a DATA1 signal and a DATA2 signal are applied to the first phase modulation area and the second modulation area respectively. At this time, in respective eye patterns for modulation voltages, all cross points at which rises and falls of modulation voltages cross in a transition area for a mark level with a big absolute value of modulation voltage and a space level with a small absolute value of modulation value, are set so as to shift in a direction in which an absolute value is greater than a center value of modulation voltage. Also, an amplitude at which the DATA1 signals are regulated by a half-wavelength voltage of the first phase modulation area is made equal to an amplitude at which the DATA2 signals are regulated by a half-wave voltage of the second phase modulation area. |
