| 摘要 |
PURPOSE:To prevent the reduction in the interference efficiency by scrambling a polarized wave plane of a signal light or a local oscillation light in the tuning, detecting the polarized wave state of a mixed light after the end of tuning and making the polarized plane of the signal light and the polarized plane of the locally oscillated light coincident with each other. CONSTITUTION:The polarized wave plane as to the signal light 1 or the local oscillation light 3 sent via a polarized wave controller 4 in the tuning is scrambled and after the tuning is finished, the polarized wave state of a mixture light in a photocoupler 5 is detected and the polarized wave control of the signal light 1 or the local oscillation light 3 sent via the polarized wave controller 4 is applied so that the polarized plane of the signal light during reception and the polarized plane of the locally oscillated light are made coincident. Thus, the missing of the transmission light in the tuning is avoided and stable tuning and reception are attained. Thus, the deterioration in the interference efficiency between the received light and the locally oscillated light due to the fluctuation of the polarized wave in the optical transmission line is prevented. |
