| 摘要 |
PURPOSE: An optical transmission device for outputting stable optical signal is provided to steadily control the phase difference between two MZ modulators of the QPSK(Quarternary Phase Shift Keying) light modulator and two arms at the same time. CONSTITUTION: An optical modulator(610) comprises parallel-connected Mach-Zehnder interferometer type of a first modulator(620) and a second modulator(630). The light modulator performs the QPSK(Quarternary Phase Shift Keying) modulation by inputting output optical signal of the light source(600). By controlling an bias respectively about the first modulator and the second modulator and the light modulator, a output stabilizer stabiles a finical output signal of the light modulator. |
