Patent ID: 9709830
Date: 2017-07-18
CPC Classifications: G02F,H04B

Claim:
1. A phase modulation device comprising: a diode-type phase modulator which has a plurality of first side terminals arranged side by side on and connected to one side of an optical waveguide core along an optical axis of the optical waveguide core, and a second side terminal connected to an other side of the optical waveguide core along the optical axis of the optical waveguide core; electrodes each connected to each of the plurality of first side terminals; first conductivity type regions each formed on each of the first side terminals; a second conductivity type region formed on the second side terminal; and a control unit that controls electrical signals to be input to the phase modulator, wherein the control unit has switches connected to the electrodes and constant-current sources that supply a constant current to the electrodes and controls stepwise a phase change for light propagating in the optical waveguide core according to the number of the switches turned on, and a part of the second conductivity type region is crossing over the optical waveguide core, extended to a space between every two of the first conductivity type regions, and located close to the first conductivity type regions without contact with the first conductivity type regions, in a plan view.