| 摘要 |
PURPOSE:To put an optical receiving device in stable and secure operation by providing a polarization state conversion part, a polarization state detection part, and a feedback control part and fixing output linear polarized light in reference phase. CONSTITUTION:A received light wave from the output terminal of an optical fiber 1 for transmission is made incident on the polarization state conversion part 2, which converts the polarization state of the incident light wave into a desired reference state. The rays of light are made then incident on the polarization state detection part 3, which compares its state with a necessary reference polarization state to detect an error signal consisting of the phase error of the plane of polarization of the incident linear polarized light. The error signal is led to the feedback control part 4, processed, and converted into a necessary control signal, which is fed back to the conversion part 2 to make the polarization state of the incident light close to the desired reference polarization state, so that the phase error of the plane of polarization of the incident linear polarized light is eliminated. Then, the conversion output light from the conversion part 2 becomes desired reference polarized light, which is supplied to the optical receiving device 5 while having the plane of polarization in reference phase. Consequently, a stable and secure optical communication is carried out. |
