| 摘要 |
PROBLEM TO BE SOLVED: To select one of two functional devices without external operation nor control. SOLUTION: Two ports 12a and 14a of an up line and two ports 12b and 14b of a down line are led out of a pressure-tight housing 10. Optical circulator 20a and 20b route signal lights through optical equipment 18a when using the port 12a as a signal input port and the port 14a as a signal output port and through optical equipment 16a in the reverse case. The optical circulators 20b and 22b route the signal lights through optical equipment 18b when using the port 12b as a signal input port and the port 14b as a signal output port and through optical equipment 16b in the reverse case. |
