| 摘要 |
PROBLEM TO BE SOLVED: To reduce the number of optical fibers required for connection among three stations. SOLUTION: With respect to WDM couplers 1 to 3, light goes from ports A to ports C through and goes from ports A to ports D by crossing and goes from ports B to ports C by crossing. Signal light having a wavelength λAB in the range of a through wavelength inputted from an end A goes in an WDM coupler 1 through and is transmitted to an end B. Signal light having a wavelength λAC in the range of a cross wavelength crosses in the WDM coupler 1 and is inputted to the port B of the WDM coupler 2 and crosses in the WDM coupler 2 and is transmitted to an end C. In the same manner, signal light from other ends (B and C) are branched in accordance with wavelengths and are transmitted. Thus, each station and the branch device are connected by a pair of fiber cables to transmit the signal light among stations. Consequently, one up repeater and one down repeater are enough on the transmission line. |
