Patent ID: 8655116

Claim:
A Mach-Zehnder optical modulator comprising: a semiconductor chip; a waveguide in the semiconductor chip, wherein the waveguide has an impedance; a traveling wave electrode, including an input portion and an output portion, to which a signal is applied for modulating light passing through the waveguide; first and second wires: a power supply line having an impedance and connected to the input portion via the first wire; and a termination resistor having a resistance and connected to the output portion via the second wire, wherein capacitance between the output portion and a grounding point is larger than capacitance between the input portion and the grounding point, the impedance of the power supply line is larger than the impedance of the waveguide, the impedance of the waveguide is larger than the resistance of the termination resistor, and Zwg≈(Zin+Ro)/2, where Zwg is the impedance of the waveguide, Zin is the impedance of the power supply line, and Ro is the resistance of the termination resistor.