Patent ID: 7616843

Claim:
An optical functional device comprising: an input optical waveguide for receiving input of a light wave signal; first and second branch optical waveguides; a splitter connected to said input optical waveguide to branch said light wave signal into two parts to be routed to said first and second branch optical waveguides; an optical modulating unit provided for, at least, one of said first and second branch optical waveguides to modulate the light wave signal that propagates through a corresponding branch optical waveguide for which said optical modulating unit is provided; a combiner for recombining the light wave signals from said first and second branch optical waveguides; and an output optical waveguide for outputting the combined light wave signal, wherein said optical modulating unit comprises: a ring-type optical waveguide disposed so as to be optically coupled to the corresponding branch optical waveguide; and a means for varying an amplitude branching ratio between the corresponding branch optical waveguide and said ring-type optical waveguide, wherein said means for varying the amplitude branching ratio comprises: two couplers inserted in series in the corresponding branch optical waveguide, and a phase modulating unit disposed between said two couplers and inserted in the corresponding branch optical waveguide for varying a phase of the light wave signal that propagates through the corresponding branch optical waveguide, wherein the corresponding branch optical waveguide and said ring-type optical waveguide are coupled at positions of said couplers through the corresponding couplers.