| 摘要 |
The present invention is a miniaturized differential M phase-shift modulator (M = 2 n : n is 2 or more) in which a plurality of Mach-Zehnder type light modulators (2,3) adapted to output a DPSK-modulated signal light by applying a driving voltage signal are arranged in parallel and that comprises a multiplexing waveguide (4) adapted to output a DMPSK-modulated light by multiplexing outputs of the plurality of the Mach-Zehnder type light modulators, wherein a phase-shift voltage that produces a phase shift difference of substantially 2À/M for each of a plurality of the signal lights multiplexed by the multiplexing waveguide (4) is applied to each of the plurality of the Mach-Zehnder type light modulators (2,3) by means of a bias supply part (12-3) controlled by a bias control circuit (10) together with the driving voltage signal. |
