Traveling wave optical modulator

A traveling-wave-type optical modulator comprising:

• a substrate having an electro-optical effect;
• an optical waveguide formed on the substrate;
• a modulating electrode that controls modulation of a light wave traveling through the optical waveguide, said modulating electrode comprising a signal electrode portion and a ground electrode portion;
• an input interface connected to an input side of the signal electrode portion;
• a terminator connected to an end of the signal electrode portion;
• and
• an adjustment filter, provided between the input interface and the signal electrode portion, that adjusts frequency characteristics,
• wherein
• frequency characteristics of the adjustment filter are adjusted to correspond to frequency characteristics of an electric/optical conversion response of the traveling-wave-type optical modulator,
• a driver that controls the traveling-wave-type optical modulator is connected between the input interface and the adjustment filter, or between the adjustment filter and the modulating electrode,
• the frequency characteristics of the adjustment filter are adjusted to correspond to frequency characteristics of a gain of the driver,
• the adjustment filter is a Bessel-Thompson filter, and
• a termination resistance of the terminator is adjusted to adjust an impedance difference between the modulating electrode and the terminator, thereby adjusting the frequency characteristics of the electric/optical conversion response of the traveling-wave-type optical modulator.