Optical modulation device

1. An optical modulation device, comprising:

a silicon substrate;

a silicon optical waveguide formed above the silicon substrate;

a phase modulator disposed on part of the silicon optical waveguide;

a capacitor connected to the phase modulator and including a lower electrode and an upper electrode;

a resistor connected in parallel to the capacitor;

an appended part integrated with the upper electrode and connected to the resistor; and

an insulating layer provided between the phase modulator and the lower electrode disposed above the phase modulator, at a position included in the capacitor in a plane view,

wherein the appended part is smaller in area than the capacitor.

2. The optical modulation device according to claim 1 , further comprising a conductive layer connected to the resistor,

wherein the appended part includes a connection portion connected to the conductive layer.

3. The optical modulation device according to claim 1 , wherein the upper electrode is smaller in area than the lower electrode.

4. An optical modulation device, comprising:

a silicon substrate;

a silicon optical waveguide formed above the silicon substrate;

a phase modulator disposed on part of the silicon optical waveguide;

a capacitor connected to the phase modulator and including a lower electrode and an upper electrode;

a resistor connected in parallel to the capacitor;

an appended part integrated with the upper electrode and connected to the resistor; and

a driver circuit which is disposed directly above the capacitor and drives the phase modulator,

wherein the appended part is smaller in area than the capacitor.