Patent ID: 8676053

Claim:
A repeater, comprising: a first optical amplifier, a second optical amplifier, a first gating unit, a second gating unit, a first coupler, a second coupler, a third coupler, and a fourth coupler, wherein: the first optical amplifier is configured to amplify optical signals transmitted by an uplink fiber; the second optical amplifier is configured to amplify optical signals transmitted by a downlink fiber; the first coupler is connected with the fourth coupler through the first gating unit, the second coupler is connected with the third coupler through the second gating unit; the first gating unit is configured to gate a first probe light, wherein a first end of the first gating unit is connected with a first output end of the first coupler, an input end of the first optical amplifier is connected with a second output end of the first coupler, an input end of the first coupler is connected with an uplink fiber of a previous span, a second end of the first gating unit is connected with a first output end of the fourth coupler, an input end of the second optical amplifier is connected with a second output end of the fourth coupler, and an input end of the fourth coupler is connected with a downlink fiber of a next span; and the second gating unit is configured to gate a second probe light, wherein a first end of the second gating unit is connected with a first input end of the second coupler, an output end of the first optical amplifier is connected with a second input end of the second coupler, an output end of the second coupler is connected with an uplink fiber of the next span, a second end of the second gating unit is connected with a first input end of the third coupler, an output end of the second optical amplifier is connected with a second input end of the third coupler, and an output end of the third coupler is connected with a downlink fiber of the previous span.