Patent ID: 8165473

Claim:
An optical-time-division-multiplexing differential phase shift keying signal generating apparatus comprising: an optical-time-division-multiplexing differential phase shift keying signal generating section including: an optical splitter dividing an optical pulse train in two into a first optical pulse train and a second optical pulse train; a first phase modulator generating, from the first optical pulse train that is inputted thereto, a differential phase shift keying signal of a first channel that is coded by a differential phase shift keying system, and outputting the differential phase shift keying signal of the first channel; a second phase modulator generating, from the second optical pulse train that is inputted thereto; a differential phase shift keying signal of a second channel that is coded by the differential phase shift keying system, and outputting the differential phase shift keying signal of the second channel; an optical coupler that optical-time-division-multiplexes the differential phase shift keying signal of the first channel and the differential phase shift keying signal of the second channel, and generates and outputs a 2:1 multiplex optical-time-division multiplexing differential phase shift keying signal; and a monitor signal branching device branching off and taking out a monitor signal from the 2:1 multiplex optical-time-division-multiplexing differential phase shift keying signal, an optical carrier phase difference detecting section, including: an optical carrier interferometer that divides the monitor signal that is inputted into first and second divisional monitor signals, and provides a time delay corresponding to one bit of the monitor signal to the second divisional monitor signal, and generates and outputs an interference monitor signal that is obtained by combining a generated delayed second divisional monitor signal and the first divisional monitor signal and causing them to interfere; and an interference signal detecting section extracting an alternating current component of the interference monitor signal from the interference monitor signal that is inputted, and generating and outputting an optical carrier phase difference detection signal that is a voltage signal proportional to a time average intensity of the alternating current component.