We propose a repeated bidirectional WDM transmission system using casc
aded WDM MUX/DMUX pairs as narrow-bandpass filters and reflection atte
nuators, Fiber span is increased by inserting unidirectional EDFA's be
tween WDM MUX/DMUX pair as in-line amplifiers. A three channel hybrid
system with one 10-Gb/s and two 2.5-Gb/s channels is also demonstrated
in the 1550-nm region for transmission over 150 km of dispersion-shif
ted fiber, Negligible power penalty due to back reflection was observe
d.