Semiconductor Mach-Zehnder Optical Modulator and IQ Modulator

A semiconductor Mach-Zehnder optical modulator comprising:

• a first arm waveguide and a second arm waveguide both on a substrate;
• a first input-side lead line on a dielectric layer and having one end to which a modulation signal is input, the dielectric layer being on the substrate;
• a second input-side lead line on the dielectric layer, the second input-side lead line being adjacent to the first input-side lead line, the second input-side lead line having a first end end to which a signal complementary to the modulation signal is input;
• a first phase modulation electrode line and a second phase modulation electrode line both on the dielectric layer, the first phase modulation electrode line and the second phase modulation electrode line being along the first arm waveguide and the second arm waveguide, respectively, and a first end side of the first phase modulation electrode line and a first end side of the second phase modulation electrode line being connected to a second end side of the first input-side lead line and a second end side of the second input-side lead line, respectively;
• a first output-side lead line and a second output-side lead line both on the dielectric layer, the first output-side lead line and the second output-side lead line being bent in a direction crossing an extending direction that the first arm waveguide and the second arm waveguide extends in a plane of the dielectric layer, and a first end side of the first output-side lead line and a first end side of the second output-side lead line being connected to a second end side of the first phase modulation electrode line and a second end side of the second phase modulation electrode line, respectively;
• a first electrode and a second electrode configured to apply the modulation signals propagating through the first phase modulation electrode line and the second phase modulation electrode line to the first arm waveguide and the second arm waveguide, respectively;
• and
• a first ground line on the dielectric layer along a propagation direction of the modulation signal and disposed outside of the first input-side lead line, the first phase modulation electrode line, and the first output-side lead line.

A semiconductor Mach-Zehnder optical modulator comprising:

• a first arm waveguide and a second arm waveguide both on a substrate;
• a first input-side lead line on a dielectric layer and having one end to which a modulation signal is input, the dielectric layer being on the substrate;
• a second input-side lead line on the dielectric layer, the second input-side lead line being adjacent to the first input-side lead line, the second input-side lead line having a first end end to which a signal complementary to the modulation signal is input;
• a first phase modulation electrode line and a second phase modulation electrode line both on the dielectric layer, the first phase modulation electrode line and the second phase modulation electrode line being along the first arm waveguide and the second arm waveguide, respectively, and a first end side of the first phase modulation electrode line and a first end side of the second phase modulation electrode line being connected to a second end side of the first input-side lead line and a second end side of the second input-side lead line, respectively;
• a first output-side lead line and a second output-side lead line both on the dielectric layer, the first output-side lead line and the second output-side lead line being bent in a direction crossing a direction that the first arm waveguide and the second arm waveguide extends in a plane of the dielectric layer, and a first end side of the first output-side lead line and a first end side of the second output-side lead line being connected to a second end side of the first phase modulation electrode line and a second end side of the second phase modulation electrode line, respectively;
• a first electrode and a second electrode configured to apply the modulation signals propagating through the first phase modulation electrode line and the second phase modulation electrode line to the first arm waveguide and the second arm waveguide, respectively;
• a first ground line on the dielectric layer along a propagation direction of the modulation signal and disposed outside of the first input-side lead line, the first phase modulation electrode line, and the first output-side lead line;
• a second ground line formed on the dielectric layer along the propagation direction of the modulation signal and in an outside of the second input-side lead line, the second phase modulation electrode line, and the second output-side lead line;
• and
• terminal resistors connected to a second side of the first output-side lead line and a second side the second output-side lead line;
• wherein the first phase modulation electrode line and the second phase modulation electrode line are formed along the first arm waveguide and the second arm waveguide;
• and
• wherein the first output-side lead line and the second output-side lead line are bent in a direction crossing an extending direction of the first arm waveguide and the second arm waveguide in a plane of the dielectric layer and connected to the terminal resistors.