| 摘要 |
PURPOSE:To cut off only a desired optical signal or attenuate it to a specific level by outputting one of branched light beams of a 1st optical signal through a 1st polarization plane selection part, making a 2nd optical signal incident on a 2nd polarization plane selection part, then branching and making branched light incident on the 1st polarization plane selection part. CONSTITUTION:The optical signal from a bus optical fiber 1 is branched by a branching part 11 in two directions, one is transmitted to the bus optical fiber 1, and the other is inputted to the 1st polarization plane selection part 12 to select only the optical signal having a specific plane of polarization, which is sent to the reception part 22 of a connected terminal station 20. On the other hand, the optical signal from the transmission part 21 of the connected terminal station 21 is guided to the 2nd polarization plane selection part 13 to select only an optical signal having its plane of polarization in a different direction from the specific direction and the selected light is made incident on the 1st polarization plane selection part 12. Therefore, part of the optical signal from the transmission part 21 of the terminal station is made incident on the reception part 22 of the terminal station through the 1st and 2nd polarization plane selection parts 12 and 13. Consequently, the angles of the polarization plane directions of the polarization plane selection parts are adjusted to input only the optical signal from the transmission part 21 to the reception part 22. |
