Patent ID: 8879903

Claim:
An apparatus comprising: an interface between a network node and an optical fiber link to a remote node at an opposite end of said link, said link having a first and second optical fiber loops, each optical fiber loop having a transmitting optical fiber and a receiving optical fiber, said interface comprising: a network node input port configured to receive optical signals from said network node; a network node output port configured to transmit optical signals to said network node; first and second optical fiber link output ports configured to send optical signals from said network node input port to transmitting optical fibers of said first and second optical fiber loops to said remote node; first and second optical fiber link input ports configured to receive optical signals from said receiving optical fibers of said first and second optical fiber loops and passing said optical signals to said network node output port; a plurality of VOAs (Variable Optical Attenuators) configured to control the strength of signals on said first and second optical fiber link output ports; and a control unit configured to control said plurality of VOAs so that upon detection of a fault on one of said receiving optical fibers of said first and second optical fiber loops, a transmitting optical fiber of said optical fiber loop to which said fault-detected receiving optical fiber belongs is switched off; and an amplifier module configured to selectively amplify optical signals from said network node and transmit the amplified optical signals to said network node input port of said interface, wherein said amplifier module is further configured to restore optical signals in said optical fiber loop to which said fault-detected receiving optical fiber belongs according to a safety mechanism in a reduced power restart procedure.