Bi-Directional Optical Amplifiers For High-Performance Wdm Systems

Bi-directional signal transmission may provide a number of cost and system performance advantages relative to undirectional transmission. Bidirectional multichannel systems operating at less than half channel capacity can be operated using half as many active fibers as their undirectional counterparts. This allows network operators to conveniently lease unused fiber capacity while planning for future upgrades. At full capacity, uni-and bidirectional systems with equal channel capacity require equal numbers of transmitters, receivers and amplified fiber links. Providing spare terminal equipment, however, is simplified since each transmitter station requires half as many distinct wavelengths as an equal capacity undirectional counterpart.