Patent ID: 8059971

Claim:
An optical reception device, comprising: a Mach-Zehnder type 1-bit delay unit having one or a plurality of phase control functions of controlling a phase state of light, the Mach-Zehnder type 1-bit delay unit having first and second optical output ports; photoelectric conversion means for branching a part of an optical output signal output from the first optical output port of the Mach-Zehnder type 1-bit delay unit and converting it into an electric signal; a phase control unit that produces a phase control signal on the basis of the electric signal output from the photoelectric conversion means, the phase control unit comprising: phase comparison means for comparing phases of a component of the electric signal output from the photoelectric conversion means and a dither signal, and generating an error signal representing the result of the comparison, a phase control circuit that converts the error signal from the phase comparison means into a DC voltage, and an adder that produces the phase control signal by superimposing the dither signal onto the DC voltage, the phase control signal being sent to the Mach-Zehnder type 1-bit delay unit to control a phase state of the Mach-Zehnder type 1-bit delay unit; and a balanced receiver that differentially receives the optical output signals from the first and second output ports, and produces therefrom an electric output signal.