| 摘要 |
An amplifier is provided for amplifying weak signals propagating along optical fibers for use in a system providing signal monitoring capability without disrupting the main signal path. The amplifier comprises a source of optical amplification energy (64), an optical switch (56) and plurality of doped optical fibers (52). The optical signals to be amplified are propagated along the doped fibers (52) and into a plurality of input ports (54) in the optical switch (56). The amplification energy is directed into an output port (58) of the optical switch (56), causing it to propagate into the doped fiber selected by the state of the switch. In this way, the signal propagating along the selected doped fiber is amplified prior to passing through the optical switch. The amplifier also comprises a mechanism for separating the amplified signal from the amplification energy in an output fiber (60) connected to the output port (58) of the switch (56). The amplifier preferably includes gratings (66) positioned in the doped optical fibers(52) to reflect any remaining amplification energy back through the doped optical fiber after the amplification energy has passed once through the doped optical fiber. In a system for monitoring a plurality of optical communications signals, each of the plurality of weak signals to be selected and amplified consists of optical energy tapped from the communications signals to be monitored. |
